Orthognathic Surgery

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CHAPTER 12  Orthognathic Surgery Treatment Planning
• Figure 12-10  The five Platonic solids described by Euclid.
Tetrahedron
4 vertices. 6 edges. 4 faces.
Cube
8 vertices. 12 edges. 6 faces.
Octahedron
6 vertices. 12 edges. 8 faces.
Icosahedron
12 vertices. 30 edges. 20 faces.
Dodecahedron
20 vertices. 30 edges. 12 faces.
was said to arise “when between parts of the whole there are
definite ratios in proportions.”61,100 In music, for example,
Aristotle recognized the octave as the most beautiful conso­
nance when taking into consideration that the number of
oscillations between the basic tone and the octave can be
expressed by the first numbers of a natural series: 1 : 2. He
also had the opinion that rhythmic relations of a poetic verse
should be based on small numerical ratios to reach a beauti­
ful impression.41 Like Plato, Aristotle believed that beauty
was commensurate of the separate parts to the whole.
The young Alexander the Great of Macedonia (Fig.
12-11) succeeded to the throne after his father’s assassina­
tion (336 B.C.). He went on to conquer most of Asia
Minor, Syria, Egypt, and Babylon, and he then founded the
City of Alexandria near the mouth of the Nile. Alexandria
developed into the intellectual center of the hemisphere,
and it included a library that is said to have held more than
700,000 books. The first group of scholars at the center
included the young Euclid (300 B.C.), who authored a
complete text about the history of mathematics that
included many of his own original ideas (Fig. 12-12). The
Elements was a 13-volume work on geometry and number
theory.43 Each book contained a number of theorems (i.e.,
from 10 to 100) that follow a series of definitions. Scholars
believe that the Elements is primarily a collection of theo­
rems described by other mathematicians that was then
supplemented by at least some original work by Euclid.
Proclus, a Greek mathematician who lived several centuries
after Euclid, wrote the following in his commentary about
the Elements: “Euclid, who put together the Elements, col­
lecting many of Eudoxus’ theorems, perfecting many of
Theaetetus, and also bringing to irrefutable demonstration
the things which were only somewhat loosely proven by his
predecessors.”5 For example, Pythagoras was probably the
source of most of Books 1 and 2; the ideas of Hippocrates
were found in Book 3, and those of Eudoxus were in Book
5; Books 4, 6, 11, and 12 probably came from other Pythag­
orean or Athenian mathematicians. Euclid is credited with
replacing Fallacious’ proofs with his own more rigorous
versions. Most of the definitions, postulates, and axioms
within the Elements date back to Plato. Euclid also authored
• Figure 12-11  Sculpture of Alexander the Great of Macedonia. From

342 SECTION 2  Planning, Surgical Technique, and Complications
surviving major book about architecture from classic antiq­
uity (Fig. 12-13). This treatise indicates a mastery of archi­
tecture and engineering, and it crystallizes the importance
of precise proportions as a fundamental component of
beauty in the human form. Interestingly, in the records that
remain, no mention is made by Vitruvius of Pythagoras,
Polykleitos, or Euclid. This lack of acknowledgement by
Vitruvius is striking in its absence; thus, it likely represents
lost documents rather than a lack of awareness.
Fortunately, Vitruvius’ treatise would later be rediscov­
ered by the Florentine humanist Poggio Bracciolini (1414).
It was Leon Battista Alberti (1404-1472) who then revital­
ized Vitruvius’ works by writing a widely read seminal trea­
tise on architecture, De Re Aedificatoria, which was published
in 1450.35 During the High Italian Renaissance, this volume
had a great influence on artists, scholars, and architects,
including Leonardo da Vinci (1452-1519) and Michelan­
gelo (1475-1564).72 Vitruvius is most remembered for his
basic assertion that a structure must exhibit the three quali­
ties of firmitas, utilitas, and venustas: it must be strong
(durable), useful, and beautiful. According to Vitruvius,
architecture is an imitation of nature: “As birds and bees
built their nests, so humans construct housing, from natural
materials that give them shelter against the elements.”61
When perfecting the art of building, ancient greeks designed
and defined the three architectural orders: Doric (Fig.
12-14), Ionic (Fig. 12-15), and Corinthian (Fig. 12-16).100
These architectural orders gave the Ancient Greek buildings
a sense of proportion and continuity that was believed to
be as important as the proportions of the greatest known
work of art: the human body. This led Vitruvius to define
the proportions of the human body in words that would
later be illustrated by Leonardo da Vinci’s Vitruvian Man
(1437; Fig. 12-17). The human body as described by Vit­
ruvius was inscribed in a circle and in a square. These are
considered the fundamental geometric patterns of the
cosmic order.102
almost a dozen other books that covered topics from music
to mechanics and optics. His book Optics contains some of
the earliest studies of perspective. Interestingly, until the
20th century, Euclid’s Elements remained second only to the
Bible with regard to the number of books sold worldwide.
Euclid’s textbook, through various translations, has remained
actively referenced for more than 2300 years.
The golden ratio or golden section appears in the Ele­
ments, primarily in relation to proportions in Book 6: On
Divisions of Figures.43 Book 6 survives only partially in an
Arabic translation, and it discusses the division of geometric
figures into two or more parts or into parts in given ratios.
It is likely that Euclid’s primary interest in the golden ratio
was as a means of geometric interpretation of the construc­
tion of the five Platonic solids. This discussion is also found
in Book 13, which constructs the five regular Platonic solids
that are inscribed within a sphere. Euclid calculated the
ratio of their edges to the radius of the sphere and proved
that there are no other regular solids to be found. Curiosity
about the structure and design of these Platonic Solids were
of much interest to Ancient Greek intellectuals.47 In addi­
tion, throughout the Elements, Euclid described several
theorems and their proofs, which also employed the golden
ratio. Although no documentation has been found to
confirm Euclid’s knowledge of Polykleitos’ Kanon or Aris­
totle’s stated requirements of beauty (i.e., order, proportional­
ity, and control of sizes), it is almost inconceivable that these
ideas did not influence him.
Marcus Vitruvius Polio (80 B.C.-15 B.C.) came two cen­
turies after Euclid; he was a Roman writer, architect, and
engineer. At one point, he even served as Chief of Artillery
for the Roman Army. His written work De Architectura, a
10-volume treatise on architecture, is not just remarkable
for its originality and contents but also for being the only
• Figure 12-12  The 13-volume Elements text written by Euclid.
• Figure 12-13  The 10-volume De Architectura text written by
Marcus Vitruvius Polio.

343
CHAPTER 12  Orthognathic Surgery Treatment Planning
After the destruction of the great Alexandrian library—
first by Roman, then by Christian, and finally by Muslim
groups—the center of study came to an end (529 A.D.).
With the ascendancy of Islam and the initial attempts of
Islamic groups to destroy everything “non-Islam,” many of
the earlier Greek and Roman literary works were lost as the
Arab world became the dominant center for intellectual
study. Abu Kmil Shuja (850-930), who was known as
al-Hasib al-Misri (translated as “The Calculator from
Egypt”), shared his rediscovery of Euclid’s works through
Arabic translations.
Abu Kmil’s books would later serve as a basis for Leon­
ardo of Pisa’s further understanding of Euclid’s geometric
principles. Leonardo of Pisa (1170-1250) was also known
as Fibonacci, Leonardo Bonacci, Leonardo Pisano Bogollo,
and Leonardo Fibonacci; he was considered the most tal­
ented mathematician of the late middle ages.25 He is best
• Figure 12-14  A, Illustrations of Doric architecture. B, Doric archi­
tecture as demonstrated by the Parthenon from Ancient Greece. Cour­
tesy Charlotte-Mecklenburg Historic Landmarks Commission. http://

Doric Order
Cornice
Frieze
Architrave
Capital
Shaft
A
B
• Figure 12-15  A, Illustrations of Ionic architecture. B, Ionic architec­
ture as demonstrated by the Temple of Athena Nike from Ancient
Greece. Courtesy Charlotte-Mecklenburg Historic Landmarks Com­
mission.
Ionic Order
Cornice
Frieze
Architrave
Capital
Shaft
Base
A
B
remembered by the modern world for spreading knowledge
of the Hindu-Arabic numeral system (i.e., digits 0 through
9) in Europe; this was primarily done through publication
during the earlier 13th century of the Book of Calculations
or Liber Abaci.97 His second contribution was the recogni­
tion of a number sequence that became known as the Fibo­
nacci numbers (Fig 12-18). Within the Liber Abaci, Fibonacci
posed and solved a classic problem involving the growth of
a hypothetical population of rabbits that was based on ideal­
ized assumptions (Fig 12-19). The solution was a sequence
of numbers that was later named after Fibonacci. Although
this number sequence was known to Indian mathematicians
as early as the sixth century, it was Fibonacci’s Liber Abaci
that introduced it to the West.101 In the sequence of the
Fibonacci numbers, each number is the sum of the previous

344 SECTION 2  Planning, Surgical Technique, and Complications
This is seen in the simplest of natural forms: the shell of the
chambered nautilus. As the nautilus outgrows each chamber,
it builds a new chamber for itself, but this always has the
same shape (Fig. 12-20). If the nautilus lives a long life, it
will spiral around and around, growing even larger but
always looking exactly the same at every scale. Interestingly,
by using the Fibonacci sequence of numbers, you
can build a nautilus that is based on squares by starting with
a square of size 1 and successively building new “rooms”
with sizes that correspond with the Fibonacci sequence.39
Running through the centers of the squares, a smooth curve
can be drawn that corresponds to the nautilus spiral (see
Fig. 12-20, B). This self-similar curve, which keeps its
shape at every scale, is called equiangular because a radial
line from the center always makes the same angle to the
curve. This curve was also known to Archimedes of Ancient
two numbers, starting with 0 and 1. Thus, the sequence
begins 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, and so
on. Interestingly, the higher up in the sequence, the closer
two consecutive numbers in the sequence—when divided
by each other—will approach the golden ratio of approxi­
mately 1 : 1.618 or 0.618 : 1. The sequence of the Fibonacci
numbers and their relative ratios have been found with
consistency in nature, art, and classic objects of beauty. They
would soon be recognized and used by the Renaissance
painters.
The Fibonacci numbers and the golden ratio are found in
the most basic forms in nature.25 For example, spirals arise
from a property of growth called “self-similarity” (i.e., the
tendency to grow in size but to maintain the same shape).
• Figure 12-16  A, Illustrations of Corinthian architecture. B, Corinthian
architecture as demonstrated by the Temple of the Sybil from Ancient
Greece. Courtesy Charlotte-Mecklenburg Historic Landmarks Com­
mission.
Corinthian Order
Cornice
Frieze
Architrave
Capital
Shaft
Base
A
B
• Figure 12-17  Vitruvian Man by Leonardo da Vinci. This idea was
described by Marcus Vitruvius Polio.
• Figure 12-18  Fibonacci numbers.
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
3
3
3
5
5
5
8
13
4
4
6
6
6
10
20
15
15
10

345
CHAPTER 12  Orthognathic Surgery Treatment Planning
captured the fundamental relationship between beauty and
mathematics when he stated that “humans seem to react with
a sense of pleasure to forms that possess certain symmetries
[proportions] and obey certain mathematical rules.”35,61
Leon Battista Alberti was an author, artist, architecture,
poet, priest, linguist, philosopher, cryptographer, and
general Renaissance humanist. Alberti regarded mathemat­
ics (as summarized by Euclid) to be the common ground
of the arts and the sciences. For Alberti, beauty was “the
harmony of all parts in relation to one another.” He stated
that “this concord is realized in a particular number, propor­
tion and arrangement demanded by harmony.”35,61 Alberti’s
thoughts on harmony were referenced back to Pythagoras
and Euclid, but he set them in a fresh context. He studied
Ancient Roman sites, ruins, and objects and made detailed
observations that are cataloged in his Ten Books of Architec­
ture (De Re Aedificatoria), which was published in 1450
A.D. His writings were patterned after the De Architectura
by Vitruvius (46 B.C.-30 B.C.) and covered a wide range
of subjects, from history to town planning to engineering
to the philosophy of beauty.
Three Renaissance genius mathematicians and artists
were clearly influenced by Euclid’s ideas72: Piero della Fran­
cesca (1415-1492), Leonardo da Vinci (1452-1519), and
Luca Pacioli (1446-1517). Piero della Francesca was known
as a mathematician, a geometer, and an artist. His painting
was characterized by its serene humanism and its use of
geometric forms, particularly in relation to perspective and
foreshortening (Fig. 12-21). It is known that he was at least
acquainted with Leon Battista Alberti’s mathematical and
architectural work and that he would also have a significant
influence on Luca Pacioli’s thinking.71 Three important
mathematical treatises were written by Piero: Abacus Treatise
(Trattato d’Abaco); Short Book on the Five Regular Solids
(Libellius de Quinque Corporibus Regularibus); and Perspec­
tive on Painting (De Prospectiva Pingendi). The subjects
covered in these writings include mathematics, algebra,
geometry, and innovative work on both solid geometry and
perspective. Much of Piero’s work would later be rewritten
Greece, who—philosophically and religiously—thought of
this curve as both spiraling inward forever as well as spiral­
ing outward forever. Euclid’s golden ratio mathematically
describes this finding both in nature and in the Fibonacci
numbers.
Euclid’s ideas have had an enormous impact throughout
the centuries,5 first on the medieval Italian philosopher St.
Thomas Aquinas (1225-1274) and then on the Renaissance
Italian architect L.B. Alberti (1404-1472).72 Aquinas
• Figure 12-19  Fibonacci numbers as described through breeding
rabbits. The sequence 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233,
and so on—in which each term (starting with the third) is equal to the
sum of the two preceding terms—was appropriately dubbed the Fibo­
nacci numbers during the 19th century by the French mathematician
Edouard Lucas (1842-1891).
Time = 0
1
2
3
4
5
Pairs = 1
1
2
3
5
8
• Figure 12-20  A, Photograph of the chambered nautilus, which demonstrates structural anatomy. B, The golden ratio as found in
the spiral structural anatomy of the nautilus.
B
F
C
D
E
A
A
B

346 SECTION 2  Planning, Surgical Technique, and Complications
he emphasized his desire to reveal the secret to the creation
of harmonic forms through the use of the golden ratio (or
the divine proportion). Pacioli used the square and the
compass (which are clearly visible in the background of his
well-known self-portrait) to both analyze the works of
others and to help artists achieve divine proportions in their
paintings (Fig. 12-22). It is believed that Pacioli invited
Leonardo da Vinci to provide 60 illustrations, primarily of
solid objects, to clarify the importance of the divine propor­
tion. (Fig. 12-23). Leonardo’s drawings are the first illustra­
tions of geometric figures in the dual state of skeletonic
(vacuum) and solid (solidum) (Fig. 12-24). This allowed for
a distinct interpretation between front and back. Pacioli
wrote of da Vinci’s contributions to society by stating that
“he is the most excellent painter in perspective, architect,
musician and man endowed with all virtues.”71 Pacioli’s text
largely restates the earlier published work of the Roman
architect Marcus Vitruvius Polio.5 Within the text, Pacioli
states the following:
“The ancients, having taken into consideration the
rigorous construction of the human body, elaborated all
their works, especially their holy temples, according to
these proportions; for they found here the two principal
figures without which no project is possible: the perfection
of the circle, the principle of all regular bodies, and the
equilateral square.”
It is clear from a woodcut sketch included in De Divina
Proportione (1509) that Luca Pacioli understood the impor­
tance of the golden ratio as it applies to the human face
(Fig. 12-25). It is also believed that, at the request of Pacioli,
Leonardo da Vinci took Vitruvius’ written words and drew
them out in a diagram that he called Vitruvian Man (1487;
see Fig 12-17).61 The image depicts a male figure in two
superimposed positions with his arms and legs apart and
simultaneously inscribed in a circle and a square. The
by others, including Luca Pacioli.71 Piero’s work on solid
geometry appears in Pacioli’s De Divina Proportione, which
is believed to have been illustrated by Leonardo da Vinci.
Piero’s Perspective on Painting (De Prospectiva Pingendi)
clearly refers to Euclid’s Elements and Optics. Piero used
Euclid’s written works to demonstrate that, to achieve per­
spective in a painting, the artist must rely on the scientific
basis of visual perception. Piero’s treatise De Prospectiva
Pingendi became the standard manual of the day for artists
who attempted to paint plain figures and solids.
Luca Pacioli (Fra Luca Bartolomeo de Pacioli) lived from
1446 to 1517. He was a Franciscan friar and an Italian
mathematician.71 He later collaborated with Leonardo da
Vinci, and he also made seminal contributions to the field
that is now known as accounting. In 1494, his first book—
Summa di Aritmetica, Geometria, Proporzioni e Proporzion­
alità was published in Venice. This text compiled the
knowledge of the time related to arithmetic, algebra, geom­
etry, and trigonometry. Pacioli identified Fibonacci (Leon­
ardo of Pisa) as the primary source for his basic facts. Several
years later, he met, collaborated with, lived with, and taught
mathematics to Leonardo da Vinci. Pacioli also completed
the three-volume treatise The Divine Proportion (De Divina
Proportione), which applies to geometrical proportions,
letters, and architecture constructions. The original manu­
script, which was written around 1496 to 1498, is preserved
in Milan; it was published in Venice in 1509.71 Within the
text, Pacioli lists five reasons why a more appropriate name
for Euclid’s golden ratio would be “the divine proportion.”
References and analogies to the church and godliness clarify
Pacioli’s belief that the divine proportion is spiritual and uni­
versal. He was also interested in the process of painting, and
• Figure 12-21  Madonna and Child with Saints by Piero della
Francesca.
• Figure 12-22  Self-portrait by Pacioli.

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CHAPTER 12  Orthognathic Surgery Treatment Planning
• Figure 12-23  Drawings by Leonardo da Vinci confirming the golden ratio found in humans and other mammals. From Royal Col­
lection Trust/©Her Majesty Queen Elizabeth II 2013.
illustrated interpretation of Vitruvius’ words is sometimes
also called the Canon of Proportions; the original drawing is
stored in the Galleria dell’Accademia in Venice, Italy. It is
known that Vitruvius described the human figure as being the
principal source of correct proportions and symmetry among the
classic orders of architecture. da Vinci’s Vitruvian Man beauti­
fully demonstrates the blend of art and science envisioned
by intellectuals during the renaissance, and it provides a
clear understanding of the artist’s keen interest in the pro­
portions of the human form. Like Plato, da Vinci believed
the workings of the human body to be an analogy of the
workings of the universe. According to Leonardo himself,
in a note that accompanied the drawing, “it was made as a
study of the proportions of the male human body as
described by Vitruvius” (“Palmus autem habet quattuor
digitos”).61,72 Vitruvius’ words, which Leonardo attempted
• Figure 12-24  Virgin of the Rocks by Leonardo da Vinci, confirming
the golden ratio. From Stamperia d’Arte Fratelli Alinari. Bibliotecca
Reale, Turin, Italy. Photo Credit: Alinari/Art Resource, NY.
• Figure 12-25  Woodcut Sketch by Leonardo da Vinci, confirming
the golden ratio.
to draw out in pen and ink on paper, are found in Vitruvius’
De Architectura 3.1.2-3, which reads as follows:
For the human body is so designed by nature that the face,
from the chin to the top of the forehead and the lowest
roots of the hair, is a tenth part of the whole height; the
open hand from the wrist to the tip of the middle finger is
just the same; the head from the chin to the crown is an
eighth, and with the neck and shoulder from the top of
the breasts to the lowest roots of the hair is a sixth; from
the middle of the breasts to the summit of the crown is a
fourth. If we take the height of the face itself, the distance
from the bottom of the chin to the underside of the nostrils
is one-third of it; the nose from the underside of the
nostrils to a line between the eyebrows is the same; from
there to the lowest roots of the hair is also a third,
comprising the forehead. The length of the foot is one-sixth
of the height of the body; of the forearm, one-fourth; and
the breadth of the breasts is also one-fourth. The other
members, too, have their own symmetrical proportions,

348 SECTION 2  Planning, Surgical Technique, and Complications
• Figure 12-27  Mona Lisa by Leonardo da Vinci.
• Figure 12-26  Head of an Old Man by Leonard da Vinci, confirming
the golden ratio. From Royal Library, Windsor Castle, Windsor, Great
Britain. Photo Credit: Alinari/Art Resource, NY.
and it was by employing them that the famous painters
and sculptors of antiquity attained to great and endless
renown. Similarly, in the members of a temple, there
ought to be the greatest harmony in the symmetrical
relations of the different parts to the general magnitude of
the whole. Then again, in the human body, the central
point is naturally the navel. For if a man is placed flat on
his back, with his hands and feet extended, and a pair of
compasses centered at the navel, the fingers and the toes of
his two hands and feet will touch the circumference of a
circle described therefrom. Just as the human body yields a
circular outline, so too a square figure may be found from
it. For if we measure the distance from the soles of the feet
to the top of the head, and then apply that measure to the
outstretched arms, the breadth will be found to be the
same as the height, as in the case of plain surfaces which
are perfectly squared.61,72
For some scholars and artists of the High Italian Renais­
sance, the golden ratio was elevated from a simple mathe­
matical formula to become a way of explaining natural
phenomena and a tool to be used in the painting of objects
and human forms.66,93 By the mid 1400s, advances in tech­
nology allowed artists to use lenses, concave mirrors, and
other methods to help them to create realistic-looking
paintings. Many of today’s critics believe that, simply by
using their innate aesthetic sense, talented artists, architects
and designers of that time period created art, built struc­
tures, and designed objects that closely approximate the
golden ratio.46 Skeptics often claim that the most attractive
and harmonious objects were methodically designed by
their artists to adhere to the golden ratio measurements;
they also believe that many of the great artists’ designs were
simply superimposed on laid-out golden ratios. Interest­
ingly, many other scholars deny that the Greeks (e.g.,
Euclid) made any direct aesthetic associations with the
golden ratio. Thus, some questions remain unanswered:
Throughout antiquity and during the Renaissance, did artists
consciously use the golden ratio as part of their technique? Did
they model their work on precise mathematical dimensions, or
was their aesthetic and artistic sense the guiding force that
inevitably closely approximated the golden ratio?
The analysis of Leonardo’s drawing entitled A Head of an
Old Man (Fig. 12-26) leaves little doubt that he was, at the
very least, intrigued by various proportions of the face. This
drawing shows how Leonardo used standard rectangles to
determine dimensions in his paintings. Because classic art
requires “harmony” and because we know that Leonardo
collaborated with Pacioli and that he was believed to be the
illustrator of Divine Proportions, Leonardo’s use of the
golden ratio in his paintings would be an obvious extension
of his mathematic knowledge and artistic principles. Most
of today’s art critics place Leonardo’s Mona Lisa on a short
list of the most beautiful faces ever painted (Fig. 12-27).
Debate continues regarding Leonardo’s conscious use of
the golden ratio in this well-known work. Interestingly,
da Vinci is said to have revised the Mona Lisa for more than
10 years before his death without ever fully finishing the
work to his own satisfaction.
After Leonardo, the golden ratio as an artistic principle
likely fell from favor. To my knowledge, no prominent
philosopher or artist was known to have actively used the
golden ratio again until Adolf Zeising (1810-1876).105
Zeising was formally trained in psychology, mathematics,
and philosophy. He found the golden ratio expressed in all
things, including in the skeletons of animals and the branch­
ing of their veins and nerves (Fig. 12-28). In connection
with his theory involving golden-ratio–based human body
proportions, Zeising (1854) wrote what he called the “uni­
versal law of proportions,” “in which is contained the
ground-principle of all formative striving for beauty and
completeness in the realms of both nature and art, and

349
CHAPTER 12  Orthognathic Surgery Treatment Planning
ratio in his masterpiece The Sacrament of the Last Supper
(1955; Fig. 12-31) and the experimental piece of music
Binary Universe (2006) by Brian Transeau. A strong advo­
cate for the conscious application of the golden ratio to art,
the design of objects, and architecture was Le Corbusier
(1887-1965).32,59 His legacy remains one of the most influ­
ential in modern architecture. He developed an intense
interest in proportional systems and their role in all forms
of aesthetics. Le Corbusier’s fascination with the importance
of the golden ratio in aesthetics centered around his belief
that basic forms and structures are the underpinning of
natural phenomenon. He developed what he called the
Modulor in the tradition of Vitruvius with the intention of
improving both the appearance and function of all manmade
objects and architecture (Fig. 12-32).59 He was also a strong
believer in the idea that ideal harmony in music (as stated
which permeates, as a paramount spiritual ideal, all struc­
tures, forms and proportions, whether cosmic or individual,
organic or inorganic, acoustic or optical; which finds its
fullest realization, however, in the human form.”34
The famous German psychologist, Gustav Fechner, was
inspired by Adolf Zeising’s book Der Goldene Schnitt and
began a series of inquiries to see if the golden rectangle had
psychological aesthetic impact.34 A golden rectangle is one
with side lengths that reflect the golden ratio. A distinctive
feature of this shape is that, when a square section is
removed, the remainder creates another golden rectangle.
In other words, it has the same proportions as the first.
Another section can be removed infinitely, with the same
results. Fechner’s work was published in 1876. He made
thousands of measurements of commonly seen rectangles
(e.g., writing pads, books, playing cards, windows) and
found that most were close to phi (Fig. 12-29). He also
tested people’s preferences and found that most people
prefer the shape of the golden rectangle. Fechner’s experi­
ments were repeated and validated by others, including
Witmar (1894), Lalo (1908), and Thorndike (1917).34
By the late 1800s, knowledge of and the conscious use
of the golden ratio by painters, architects, and designers was
well documented.34 There are clear examples where these
professionals have modeled their end products to conform
with Euclid’s golden ratio. In 1946 in The Geometry of Art
and Life, Matila Ghyka presented an analysis of the face of
the tennis champion Helen Wills.34 He made several mea­
surements of Wills’ face, all of which were shown to be
consistent with the divine proportion (Fig. 12-30). More
recent examples include Salvador Dali’s use of the golden
• Figure 12-28  Human Ratio by Zeising, confirming the golden ratio.
• Figure 12-29  Ideal Rectangle by Fechner, confirming the golden
ratio.
1
1.618
• Figure 12-30  Facial proportions of Helen Wills by Matila Ghyk,
confirming the golden ratio. From Matila Ghyk: The Geometry of Art
and Life, 1946, Kessinger Publishing, Oct. 30, 2004, p. 102.

350 SECTION 2  Planning, Surgical Technique, and Complications
the creation of the most important end products; rather, an
approximation of the golden ratio is.
In the realm of facial aesthetics and reconstructive
surgery, clinicians from all involved fields have from time
to time attempted to match facial aesthetics to a strict
mathematical model (e.g., normative cephalometric mea­
surements) without always considering individual biologic
variations and aesthetic nuances* (Fig. 12-33). When
doing so, they have often fallen short of their objective.
In 1984, Ricketts reported about a significant number
of golden proportions when analyzing the facial skeleton
and overlying soft tissues.83-91 He was a strong advocate
of the use of these divine proportions as a guide for
planning the correction of dentofacial deformities via
orthognathic surgery (Fig. 12-34). The validity of Ricketts’
approach to facial analysis for the correction of jaw deformi­
ties has been questioned by some while supported by
most.8,12,15,30,50,73,74,75,76,94 For the clinician who is asked to
correct a congenital or developmental craniofacial or
by Pythagoras) could only be achieved through the applica­
tion of the golden ratio to numbers.
Current Philosophy
From Pythagoras, Polykleitos, Plato, Aristotle, Euclid, Vit­
ruvius, Galen, Fibonacci, Piero, da Vinci, and Pacioli as well
as the more recent Le Corbusier and all of their disciples
for more than 2.5 millennia, we have learned that the pro­
portions of the parts to the whole affect the observers’
impression of beauty and attractiveness.1,3,7,23,26,29,36,56,62,82,96
From the premier artists, architects, and designers through­
out the centuries, we know that mirror-image symmetry
and the harmony of proportions matter when judging facial
aesthetics. They have also shown by example that the
precise—even to the millimeter—achievement of an exact­
ing mathematical ratio is not sufficient or even preferred for
• Figure 12-31  The Sacrament of the Last Supper by Salvador Dali,
confirming the golden ratio. Copyright Salvador Dali, Fundacio Gala-
Salvador Dali, Artists Rights Society (ARS), New York, 2013.
• Figure 12-32  Modular Man by Le Corbusier, confirming the golden
ratio. Copyright 2013 Artists Rights Society (ARS), New York/ADAGP,
Paris/F.L.C.
• Figure 12-33  Skeletal proportions according to cephalometric
analysis.
• Figure 12-34  Human face with use of the Rickett’s divider, confirm­
ing the golden ratio.
*2, 4, 10, 11, 16, 21, 22, 24, 28, 31, 33, 37, 38, 51, 52, 60, 64, 65, 70,
78, 79, 95, 103, 104, 108, 153, 177, 200, 241, 246

351
CHAPTER 12  Orthognathic Surgery Treatment Planning
dental analysis should be fresh in the surgeon’s mind. The
patient’s facial structures are examined while he or she is
upright and sitting in the natural head position (NHP). This
is considered the most rational, physiologic, and anatomic
orientation of the head and neck for the evaluation of the
face, jaws, and teeth.* This is generally not the head and
neck position in which the patient with a dentofacial defor­
mity will naturally relax. Rather, the clinician must place
the patient in the NHP. The teeth are also placed in centric
relation or with a normal freeway space, and the lips are
relaxed (i.e., not pursed together). The clinician then
observes the patient three dimensionally at different angles
in both repose and with dynamic facial expressions. It is
from the NHP that the surgeon makes crucial decisions regard­
ing what facial features are abnormal and the extent of required
surgical reorientation.
Global Head and Neck Assessment:
Seven Critical Aspects
1. Quality of the overlying soft-tissue envelope of the head and
neck. The surgeon must recognize distortions of the soft-
tissue envelope that will self-correct after the skeleton is
reconstructed versus intrinsic soft-tissue malformations
and deformities that will not (e.g., hypoplasia, hyperpla­
sia, effects of trauma and aging).
2. Symmetry and harmony of the upper facial skeleton (i.e.,
cranial vault, orbits, nasofrontal process, and zygomatic
arches). Although most individuals with dentofacial
deformities have relatively normal upper facial skeletons,
some do not (i.e., those with hemifacial microsomia or
Treacher Collins syndrome).
3. Morphology of unique aesthetic units of the face (e.g., exter­
nal nose, external ears, periorbital soft tissues).
4. History of temporomandibular joint symptoms and signs
and the documentation of any limitations in the mandibu­
lar range of motion.
5. History of cervical spine symptoms and signs and the docu­
mentation of the safe neck range of motion.
6. Symmetry and harmony of the lower facial skeleton (i.e.,
maxilla, mandible, and chin region). The patient with a
dentofacial deformity will have significant variations
from normal in this region of the craniofacial skeleton.
7. Dental rehabilitative needs (i.e., restorative and periodon­
tal) as well as orthodontic aspects.
Evaluation of the Overlying
Soft-Tissue Envelope
An individual with a routine developmental jaw dispropor­
tion will generally have a normal overlying soft-tissue
envelope that is simply distorted by the underlying
skeletal disharmony. Alternatively, normal variations in the
maxillofacial deformity, attention is directed to both form
and function. As R. Buckminster Fuller stated, “rarely are
the two objectives divergent.”61 For the achievement of a
harmonious face, attention is directed toward the practical
objectives of improving the upper airway and the occlusion,
which will affect speech, swallowing, chewing, and breath­
ing. Facial aesthetic perfection is not a specific millimeter
distance or degree of angulation but rather a visual impres­
sion at conversational distance in three-dimensional life. At
the same time, neither divine proportions nor biologic reali­
ties and the patient’s personal preferences can be ignored
throughout the process.
The rediscovery of the importance of achieving an
approximation of Euclidean proportions and mirror-image
symmetry as a treatment objective in the correction of
dentofacial deformities remains an essential step in the
education of all students of the human face.
Part II: Clinical Evaluation
of the Patient with
a Dentofacial Deformity
Background
In the correction of a dentofacial deformity, the clinician’s
aesthetic sense and knowledge of patient-specific biologic
and psychosocial factors must be condensed into precise
millimeter measurements and angular changes that are then
accomplished on the surgically sectioned (osteotomized)
maxilla, mandible, and chin region with a goal of establish­
ing Euclidean facial proportions and improved function.*
Although there is no singular normative table of numbers
or a formula that can be relied on to direct the surgeon to
the golden ratio, a methodical approach is nevertheless
required. The clinician’s vision is based on 1) fundamental
aesthetic principles 2) the biologic realities of the tissues
3) patient-specific dysfunctions (e.g., chewing, swallowing,
speech articulation, breathing, lip closure/posture) and
4) individual treatment preferences (e.g., timing, tech­
niques, extent of intervention).† It is expected that a degree
of uneasiness about the end result will be felt by both the
operating surgeon as well as the patient and his or her family
during this process. With clinician experience, this creative
tension for the surgeon and the uncertainty of the patient
and his or her family are reduced; however, these can never
be fully alleviated before surgery.
At the time of the preoperative, direct, face-to-face
planning examination of the patient by the operating
surgeon, several evaluations will have already been carried
out.118,136,193,199,197,247 A review of relevant medical data in
combination with facial photographic, radiographic, and
*24, 124, 126, 133-135, 151, 168, 172, 171, 177, 181, 180, 184, 185,
225-227, 234, 238, 239, 243
*107, 111, 112, 122, 125, 138, 139, 161, 162, 166, 206, 207, 210, 215,
219, 223, 228, 229, 240, 248, 249
†114, 115, 116, 123, 127, 128, 129, 143, 144-150, 158, 174, 186, 189-
191, 201-204, 208, 211, 222

352 SECTION 2  Planning, Surgical Technique, and Complications
the periorbital (eyelid) regions, the external ears, and
the nose.
The periorbital (adnexal) tissues may be of special con­
cern as a result of 1) congenital hypoplasia (e.g., Treacher
Collins syndrome, hemifacial microsomia, upper eyelid
ptosis), 2) previous trauma (e.g., medial or lateral canthal
injury, nasolacrimal apparatus injury, upper or lower
eyelid injury), or 3) the normal aging process (e.g., descent,
deflation, ptosis). The individual’s eyelid appearance may
either add a sparkle to or be a distracting focal point of the
face. For example, distortions of the lower eyelids are gen­
erally seen in patients with dentofacial deformities that are
associated with maxillary deficiency and relative mandibu­
lar excess (i.e., negative vector relationship of the eyeballs
and lower lids). This negative vector relationship affects the
aesthetic appearance of the midface, which only worsens
with age (see Chapter 25 and Fig. 12-35, D). Maxillary
horizontal advancement and clockwise rotation in con­
junction with mandibular ramus osteotomies corrects the
skeleton and has positive effects on the soft tissues of the
eyelids and the midface contours (see Chapter 20 and
Fig. 12-35, K & L).
The external ears display considerable variations in size,
shape, extent of protuberance, and asymmetry (see Chapter
39). Forensic pathologists consider details of auricular mor­
phology to be as unique to the individual as that individual’s
fingerprints. In association with specific syndromes (e.g.,
hemifacial microsomia, Treacher Collins syndrome), there
may be auricular hypoplasia or a malformation that ranges
from total microtia to cupping to just an abnormal location
of the ears on the side of the face (see Chapters 27 and 28).
Significant disproportion of the external ears, as a stand­
alone and distinct feature, can be a distracting aesthetic
aspect in the presence of an otherwise attractive face. An
external ear set-back procedure may be carried out as part
of the orthognathic surgery or later as a separate operation
(see Chapter 39).
The external nose will display a wide range of aesthetic
variation due to unique bony, cartilaginous, and soft-tissue
anatomy (see Chapter 38). In the presence of a dentofacial
deformity, the middle third of the central face (i.e., the
nose) may appear bigger or smaller than its actual size (Fig.
12-35, L). The correction of the presenting jaw discrepancy
toward Euclidean proportions will improve harmony
between the upper, middle, and lower thirds of the face.
After this is accomplished, a more accurate assessment of
the actual nasal aesthetic unit can be made. Disproportion
of the nose as a standalone aesthetic unit may nevertheless
exist and benefit from alteration (see Chapter 38). Dysfunc­
tion of the nose characterized by chronic obstructive nasal
breathing and inadequate sinus drainage should also be
recognized and dealt with at the appropriate time (see
Chapter 10). Clarification of these issues with the patient
and his or her family at the first consultation visit as well
as additional discussion at the time of orthognathic plan­
ning and again after surgical healing is essential to achieve
patient satisfaction (see Chapter 7).
thickness and quality of the skin, density of sweat glands,
fat distribution, and degree of pigmentation are to be
expected.
An example of soft-tissue distortion (not deformity) is
seen with maxillomandibular deficiency (see Chapter 23).
The impression of “chubby cheeks” and excess fat in the
neck is typical. With maxillomandibular (skeletal) advance­
ment and vertical lengthening, the normal facial contours
and curvatures will be restored.
There are exceptions with which the soft-tissue envelope
is directly affected by a malformation (e.g., Treacher Collins
syndrome, hemifacial microsomia, cleft lip, hemifacial
hypertrophy), previous trauma (e.g., burns, lacerations), or
scarring after infection. When a jaw deformity is associated
with a syndrome (see Chapters 27 through 31), clefting (see
Chapters 32, 33, and 34), or a soft-tissue traumatic defor­
mity (see Chapter 35), the soft-tissue envelope may require
special consideration.
Evaluation of the Upper Facial Skeleton
For most individuals who present with dentofacial deformi­
ties, the upper facial skeleton (i.e. cranial vault, orbits, and
zygomas) will be reasonably symmetric and proportionate.
There are exceptions that result from 1) congenital anoma­
lies (e.g., craniofacial microsomia, Treacher Collins syn­
drome, Apert syndrome, Crouzon syndrome), 2) traumatic
events (e.g., molding during infancy, torticollis, previous
facial bone fractures with malunion), and 3) tumors (e.g.,
fibrous dysplasia, neurofibromatosis).
With routine dentofacial deformities, minor upper face
skeletal variations from normal are expected; they may
include differences in the convexity of the forehead (i.e., the
anterior cranial vault) or the prominence of the supraorbital
ridge (i.e., anterior frontal sinus wall bulging). Minor
mirror-image asymmetries of the upper face are also
common (e.g., external ear position, eyebrow height, cranial
nerve VII dysfunction). When present, facial variations and
asymmetries should be documented through medical-
quality photographs and then discussed with the patient
and his or her family from the outset.
In the presence of a dentofacial deformity the cheeks
and cheekbones may appear bigger or smaller than they
actually are. The correction of the jaw deformity toward
Euclidian proportions is likely to change the observer’s
impression. An example of this phenomenon is seen in the
patient with maxillary deficiency in combination with rela­
tive mandibular excess (Fig. 12-35, K & L). When the
maxilla is advanced and rotated clockwise in conjunction
with mandibular ramus osteotomies, the apparent flat
cheekbones, deficient infraorbital rims, and enlarged nose
typically disappear (see Chapter 20).
Evaluation of Unique (Discrete) Facial
Aesthetic Units
There are discrete aesthetic units of the face that stand
out and that should be independently considered, including
Text continued on p. 360

353
CHAPTER 12  Orthognathic Surgery Treatment Planning
Or
Or
Or
Orthththththththththththththth
r ogn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
g atathicicici Su
Su
Su
Su
S rg
r ery
ry
ry
ry; J.C.
C.
C.
C Pos
os
os
os
os
os
os
os
os
os
os
o nicicicicick
B
Or
Or
Or
Or
Or
Or
Or
Orththththththththththththththththth
r ogn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
g atata hicicicici Su
Su
Su
Su
S rg
r ery
ry
ry
ry; J.C.
C Pos
os
os
os
os
os
os
os
os
os
os
os
os
os
os
os
os
os
os
os
os
o nicicicici k
A
• Figure 12-35  A 17-year-old boy with a diagnosis of left hemimandibular elongation. This dentofacial deformity affects the patient’s
chewing, swallowing, speech articulation, lip closure/position, and breathing. He has normal cervical spine function and neck range
of motion. He has no temporomandibular disorder, and he has a full range of mandibular motion. The upper facial skeleton (i.e., the
cranial vault, the orbits, and the zygoma) is symmetric and with normal proportions. The facial soft-tissue envelope is distorted by
the maxillomandibular deformity but without malformation. During his early teenage years, the patient underwent an initial phase of
orthodontics without success. He was referred for surgical evaluation and then underwent a combined orthodontic and surgical
approach. With the relief of dental compensation, his surgery included a maxillary Le Fort I osteotomy in segments (horizontal
advancement, cant correction, vertical change, arch expansion, and clockwise rotation); bilateral sagittal split ramus osteotomies
(cant correction and mandibular straightening); osseous genioplasty (straightening and minimal advancement); and septoplasty/
inferior turbinate reduction. A, Frontal facial view in repose before treatment. Occlusal views before orthodontic retreatment are also
shown. B, Frontal view with smile before surgery. Occlusal views with orthodontic (dental) decompensation in progress.
Continued

354 SECTION 2  Planning, Surgical Technique, and Complications
Or
Or
Or
Orththththththththththththtr ogn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
g atathicicici Su
Su
Su
Su
S rg
r ery
ry
ry
ry; J.C.
C.
C.
C Pos
os
os
os
os
os
os
os
os
os
os
o nicicicicick
C
Maxillary Surgical Plan
Frontal View:
Maxillary midline
No change
Cant correction 4 mm
Anterior vertical
2 mm
2 mm (L)
2 mm (R)
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
O thththththththththththththththtr ogn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gnatatatatatatatatatatatatatathicicicicicicicicicicicicicicicic Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Surg
r ery
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry; J.C.
C.
C.
C.
C.
C. Pos
os
o nicick
D
C, The planned surgical repositioning of the maxilla is clarified during the
preoperative direct visual examination. Frontal view changes will include no maxillary dental midline
change; 4-mm cant correction (up 2 mm at the left first molar and down 2 mm at the right first molar);
and a 2-mm vertical lengthening at the incisors. D, Profile facial view before treatment. Lateral cepha­
lometric radiograph before treatment.
• Figure 12-35, cont’d

355
CHAPTER 12  Orthognathic Surgery Treatment Planning
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
O ththththththththththththtr ogn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gnatatatatatatatatatatatatatatatathicicicicicicicicicicicicicicic Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Surg
r ery
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry; J.C.
C.
C.
C.
C.
C. Pos
os
o nicick
E
Maxillary Surgical Plan
Profile View:
Anterior vertical
2 mm (lengthen)
Posterior vertical 0 mm
Horizontal
8 mm (advance)
Maxillary clockwise rotation (2 mm) to enhance profile aesthetics
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
O ththththththththththththtr ogn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gnatatatatatatatatatatatatatatatathicicicicicicicicicicicicicicicic Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
S rg
r ery
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry; J.C.
C.
C.
C.
C.
C Pos
os
o nicick
F
Maxillary Surgical Change
Horizontal change at incisors
Vertical change at incisors
Midline change at incisors
Cant correction -TOTAL
?2 on right B2 on left
Maxillary plane change -TOTAL
Clockwise - Counterclockwise
Vertical change at T#3 (right) molar
(Base  Cant  Plane)
Vertical change at T#14 (left) molar
(Base  Cant  Plane)
8
2
0
4
2
2 2 2  2
2 2 2  2
E, The planned maxillary repositioning is clarified during the preoperative direct visual
examination. Profile view changes will include vertical lengthening of the incisors (2 mm); horizontal advancement
at the incisors (8 mm); and maxillary clockwise rotation (2 mm). F, The surgical plan for the repositioning of the
maxilla is indicated on the standard orthognathic surgery model-planning data sheet. The data is then relied on to
reorient the maxilla on the articulator with use of the Erickson Model Table. This is accomplished before splint
construction.
• Figure 12-35, cont’d 
Continued

356 SECTION 2  Planning, Surgical Technique, and Complications
G
Cant
correction
Mandibular
straightening
Maxillary advancement
and vertical legthening
Confirm yaw effect
Roll Orientation Correction
H
Yaw
Pitch
Roll
G, Articulated dental casts indicate analytic model planning (see Chapter 13). H, Illustration of roll, yaw, and pitch
orientation. Consideration of reorienting the maxilla in accordance with these parameters is an essential part of planning.
• Figure 12-35, cont’d 
H from Ackerman JL,
Proffit WR, Sarver DM, et al: Pitch, roll, and yaw: describing the spatial orientation of dentofacial traits, Am J Orthod Dentofacial Orthop
131:305–310, 2007.

357
CHAPTER 12  Orthognathic Surgery Treatment Planning
Orth
r ognathic Surg
r ery; J.C. Posnick
Orth
r ognathic Surg
r ery; J.C. Posnick
Orth
r ognathic Surg
r ery; J.C. Posnick
Orth
r ognathic Surg
r ery; J.C. Posnick
I
J
I, Frontal views in repose before and after reconstruction. J, Frontal views with smile before and after
reconstruction.
• Figure 12-35, cont’d 
Continued

358 SECTION 2  Planning, Surgical Technique, and Complications
Orth
r ognathic Surg
r ery; J.C. Posnick
Orth
r ognathic Surg
r ery; J.C. Posnick
Orth
r ognathic Surg
r ery; J.C. Posnick
Orth
r ognathic Surg
r ery; J.C. Posnick
K
L
K, Oblique facial views before and after reconstruction. L, Profile views before and after reconstruction.
• Figure 12-35, cont’d

359
CHAPTER 12  Orthognathic Surgery Treatment Planning
M
Prior to retreatment
Pre surgery
4 years after treatment
N
M, Occlusal views before retreatment, with orthodontic decompensation in progress, and 4 years after treatment.
N, Lateral cephalometric radiographs before and after surgery.
• Figure 12-35, cont’d

360 SECTION 2  Planning, Surgical Technique, and Complications
Assessment for Temporomandibular Disorder
and Current Mandibular Range of Motion
An accurate history of any past and current temporoman­
dibular disorder symptoms and signs should be docu­
mented, including any previous therapy; subjective
complaints; joint noise; mandibular range of motion; any
centric relation–centric occlusion discrepancy; masticatory
muscle tenderness to palpation; and current radiographic
findings. Any active temporomandibular disorder will
require treatment to diminish symptoms and to achieve
adequate range of motion before orthodontic treatment is
initiated (see Chapter 9).
Assessment of the Cervical Spine and Current
Neck Range of Motion
An accurate history of past and current cervical spine symp­
toms and signs should be documented. Individuals with a
dentofacial deformity are at higher-than-average risk for
cervical spine anomalies. If the suspicion of cervical spine
dysfunction exists, consultation with an appropriate special­
ist (i.e., neurologist, orthopedic surgeon, neurosurgeon)
and the obtaining of focused imaging studies (i.e., magnetic
resonance imaging, computed tomography scanning, plain
radiographs) should be carried out. Confirming the safe
range of motion of the neck with the patient awake in the
office setting and understanding any limitations is impor­
tant for safe orthognathic surgery and recovery.
Evaluation of the Lower Facial Skeleton
Confirmation that the upper facial skeleton and the soft-
tissue envelope of the face do not require surgical alteration
and that the neck and mandible have an intact safe range
of motion without significant limitations or discomforts is
essential before focusing on detailed maxillomandibular
surgical planning.142
Qualitative decisions concerning which components of
the maxillomandibular skeleton are asymmetric or dispro­
portionate and thus require surgical repositioning will have
already been discussed with the patient, his or her family,
and other treating clinicians before the initiation of treat­
ment. These details should be reconfirmed by the orthog­
nathic surgeon during the immediate preoperative planning
visit.120,121,130,131,132,152,153,155,170
Assuming that both the maxilla and the mandible
are part of the dentofacial deformity that requires recon­
struction, quantitative (to the millimeter) decisions of
the preferred aesthetic and best functional repositioning
of the upper jaw (at the time of the Le Fort I osteotomy)
must first be made.* When thinking through the details
of maxillary surgical repositioning, it is understood that
the “new” upper jaw position (in two-jaw surgery) will
serve as the platform on which the mandible is to be
placed. Where the lower jaw ends up is important and
will be entirely dependent on the new surgical position
of the maxilla and the orthodontic alignment of the
teeth.159,160,187,195,196,198,205,212,213,214,216-221,235-237,240
Evaluation of Overall Dental
Rehabilitation Needs
Recognizing when a patient who is seeking orthognathic
surgery has additional dental needs beyond standard ortho­
dontics is essential to the achievement of a favorable
outcome. The need for periodontal evaluation and treatment
as well as the need for complex dental restorative work
should be considered for every patient before the initiation
of a coordinated orthodontic and jaw surgical approach.
This is especially true for the individual who has suffered
dental and periodontal sequelae from a longstanding uncor­
rected dentofacial deformity and who may have undergone
camouflage treatment in an attempt to neutralize the occlu­
sion (e.g., orthodontics, occlusal equilibration, restorative
dentistry) (see Chapters 5 & 6).
Detailed Maxillomandibular Surgical
Planning: Eight Critical, Quantitative,
To-the-Millimeter Decisions
1. Assess the current and preferred position of the maxillary
dental midline with reference to the upper face (i.e., yaw
orientation). Anticipate any potential yaw effect of the
new surgical maxillary orientation on the mandible and
the midface (i.e., the cheeks) (see Fig. 12-35, B).
2. Assess for the presence of any maxillary cant (i.e., roll
orientation) with reference to the upper face. Determine
the preferred upper jaw repositioning for cant correction
(see Fig 12-35, B).
3. Assess the current and preferred vertical position of the
maxillary incisor crown with reference to the upper face.
Consider the upper-lip–incisor relationship in both
repose and smile (see Fig 12-35, A and B).
4. Assess the current and preferred horizontal position of the
maxillary incisor crown with reference to the upper face
(see Fig 12-35, D).
5. Assess the current and preferred A-point to B-point rela­
tionship of the jaws (i.e., pitch orientation). When the
face is viewed in profile in the NHP, consider the need
to differentially alter the vertical maxillary height at
the first molars and the incisors (i.e., maxillary plane
change) to achieve specific objectives (see Fig 12-35, D,
E, and F).
6. Assess the baseline pyriform rim, floor of nose, and anterior
nasal spine morphology. Anticipate the location of each
after midface reorientation, including any planned max­
illary plane change. Consider the advantages of the
recontouring of the pyriform rims, the floor of the nose,
*106, 109, 110, 113, 117, 119, 137, 140, 141, 156, 157, 163-165, 167-
169, 170, 175, 176, 179, 182, 183, 188, 194, 224, 230-233, 242, 244,
245

361
CHAPTER 12  Orthognathic Surgery Treatment Planning
Class III on one side and a Class II molar relationship on
the other side. Alternatively, a lateral (side-to-side) shift of
the maxilla would cause a different change in the yaw ori­
entation (see Fig. 12-35, H).
Establishing the correct maxillary dental midline posi­
tion and yaw orientation is especially of concern in cases
that present with moderate to severe three-dimensional
facial asymmetry of multiple bones (i.e., hemifacial micro­
somia). A three-dimensional computed tomography scan
(i.e., from the top of the skull through bottom of the chin)
can be helpful to appreciate where specific mirror-image
dysmorphology exists and how best to manage it (see
Chapter 27 & 28).
During orthognathic surgery, the introduction of yaw
effects may later be visualized as unwanted facial asymmetry
in the following areas:
• The maxillary incisor midline as compared with the upper
facial midline
• The cheek region, with fullness on one side and deficiency
on the other
• The angle of the mandible region, with fullness on one
side and deficiency on the other
Assess for the Presence of Any Maxillary
Cant (i.e., Roll Orientation) with Reference
to the Upper Face
When the decision has been made to surgically reposition
both the maxilla and the mandible (i.e., two-jaw surgery),
no additional risk is encountered when correcting any
observed cant (i.e., roll orientation) of the maxilla. The oper­
ating surgeon is forced to make a conscious decision to
either leave the roll orientation (cant) as is or to alter it and,
if so, by how much. Studies confirm that a 3-degree occlusal
cant is perceived as a noticeable asymmetry by 50% of both
professionals and lay people, whereas a 4-degree cant is
noticeable by 90% of professionals and lay people.
During the preoperative direct planning examination,
the clinician should make an observation when viewing the
patient face to face of whether the maxilla is vertically even
(i.e., from side to side) or, if not, of how much of a deviation
(cant) is present.109,117,141,157,192,231 What is generally consid­
ered a maxillary cant (i.e., vertical height discrepancies of
the maxilla from side to side) may also be viewed from the
perspective of the aesthetic line of the dentition or at the
functional line of the occlusion (see Fig. 12-35, J). Maxillary
cant considerations take into account the upper face (i.e.,
the structures above the maxilla). When the upper face is
basically symmetric, the interpupillary line may be used as
an accurate baseline reference (see Fig. 12-35, B and C).
The presurgical planning visit is a good opportunity for
the surgeon to clarify and discuss directly with the patient
and his or her family both major and minor presenting
facial asymmetries. This can be done by viewing a medical-
quality frontal facial photograph or while the patient is
viewing himself or herself with a handheld mirror. Typical
and the anterior nasal spine to achieve airway and aes­
thetic objectives (see Fig 12-35, D, E, and F).
7. Assess the baseline chin morphology. Anticipate the loca­
tion of the pogonion after jaw reorientation that may
also include mandibular plane change (i.e. pitch orienta­
tion). Consider the advantages of chin reshaping (i.e.,
osseous genioplasty) to achieve the preferred horizontal
and vertical aesthetics and shape of the chin (see Fig
12-35, D, E, and F).
8. Reconfirm the advantage of and need for the segmentation
of the maxilla to achieve the preferred arch form and
occlusion with the mandible (see Fig 12-35, G).
Assess the Current and Preferred Position
of the Maxillary Dental Midline
(i.e., Yaw Orientation) with Reference
to the Upper Face
After the decision has been made to surgically reposition
the maxilla and the mandible (i.e., two-jaw surgery), no
additional risk is encountered by making a change in the
maxillary dental midline position. In fact, the surgeon must
make a conscious decision to either leave the midline as it
is or to adjust it. During the immediate preoperative, direct,
face-to-face examination, the operating surgeon should
consider the preferred location of the maxillary dental
midline.10,117,120,167,176,183 This is a clinical observation when
viewing the patient at conversational distance and closer up.
It is measured in millimeters of variation of the current
maxillary dental midline position (i.e., the point between
the incisors at the incisal edge) in comparison with the
baseline upper facial midline.
Ideally, the midline between the maxillary central inci­
sors should coincide, within 2 mm, with the facial midline.
When the upper face has satisfactory basic symmetry, the
decision of where to position the maxillary dental midline
is generally straightforward (see Fig. 12-35, C). In the pres­
ence of upper face asymmetry—especially in combination
with canting of the maxilla and asymmetry or disproportion
of the mandible (see Chapter 28)—the decision of where
to reposition the maxillary midline becomes more complex.
When the surgeon determines the preferred (new) loca­
tion of the maxillary dental midline, the yaw effect of the
midline change must also be taken into account (see Fig.
12-35, G). For example, the maxilla may be either bodily
moved to one side to correct the incisor midline, or the
maxillary dental midline maybe corrected while leaving the
buttress regions (i.e., side to side) essentially unchanged.
This would require a twisting of the maxilla rather than a
bodily movement so that the posterior maxilla moves slightly
anterior on one side while the other side moves slightly
posterior. This is a similar movement to the twisting open
of a lid on a jar. As stated, a twisting movement of the
maxilla around the vertical axis of rotation (i.e., yaw orien­
tation) results in an incisor midline shift and a simultaneous
anterior-posterior shift at the molars. When twisting the
maxilla, the resulting posterior shift will cause a relative

362 SECTION 2  Planning, Surgical Technique, and Complications
• First molar edge to frontozygomatic suture (millime­
ter distance, left side and right side)
4. Comparison measurements taken directly from the
anthropometric (facial) surface (left side to right side)
• Incisal edge to medial canthus (millimeter distance,
left and right sides)
• Canine edge to medial canthus (millimeter distance,
left and right sides)
• First molar edge to lateral canthus (millimeter dis­
tance, left and right sides)
Assess the Current and Preferred Vertical
Position of the Maxillary Incisor Crown
with Reference to the Upper Face
The relationship between the upper lip and the maxillary
incisors represents a key facial aesthetic land­mark. Ideally,
with the upper lip at rest, several millimeters (i.e., 1 mm
to 3 mm) of the lower aspect to the maxillary incisor
crowns should be seen in frontal view. With a broad smile,
the upper lip elevates and, ideally, the entire maxillary
incisor crown and at least a few millimeters of the gingiva
will be seen. This will vary when evaluating a posed smile (as
for a photograph) versus a dynamic smile (as seen when
laughing).* The aesthetic line of the dentition follows the
surfaces of the maxillary anterior and posterior teeth. The
functional line of occlusion takes into account arch form, arch
width, and symmetry. In the presence of malocclusion—as
a result of distortions in arch width, curve of Spee, and
overall arch form—the functional line of occlusion may not
be even or on a single plane (see Fig 12-35, J). With many
of the typical developmental jaw deformities, the lip-to-
tooth relationship (i.e., the aesthetic line and the functional
line) will show variation from ideal. Affected individuals
will benefit from differential surgical repositioning of the
anterior and posterior maxilla (i.e., intrusion or lengthen­
ing) as part of the surgical correction not only to positively
influence the occlusion itself but also to influence the aes­
thetic line of the dentition and the functional line of
occlusion.
Through a Le Fort I osteotomy with vertical intrusion,
less gingiva with smile and incisor crown height in repose
will be seen. With surgical (vertical) lengthening of the
upper jaw during the Le Fort I osteotomy, more dental show
and gingival exposure are to be expected (see Fig 12-35, I
and J). Unfortunately, even with a pure vertical vector
change of the maxilla, the upper lip soft-tissue response is
generally less than a one-to-one relationship and not entirely
predictable. Soft-tissue predictions become even less accu­
rate in combination with other upper jaw vector changes
(i.e., horizontal, and transverse); in the presence of maxil­
lary asymmetries (i.e., cant and dental midline shifts); when
other procedures are simultaneously carried out (e.g., man­
dible and chin osteotomies, pyriform rim/nasal floor/
minor asymmetries include differences in the height (posi­
tion) and shape of the external ears, the eyebrows, and the
lateral canthi as well as asymmetries in cheek and lip (i.e.,
soft-tissues) elevation during smiling.
The quantifying of any presenting maxillary cant and
the extent of correction planned (to the millimeter) may
be complicated by upper facial skeletal asymmetries; other
directional abnormalities of the maxilla (e.g., transverse,
horizontal, or dental midline to facial midline); and any
asymmetry or disproportion of the mandible. When
present, these compounding factors make it difficult to
accurately predict the most aesthetically pleasing outcome.
Thought is simultaneously given to the yaw orientation
(i.e., rotation around the Y axis) of the presenting maxillary
deformity and the yaw effect at the level of the mandibular
angles and the midface (cheek) regions anticipated as a result
of the (planned) maxillary change (see Fig. 12-35, G). In
complex facial asymmetry cases, the clinician’s ability to
simultaneously analyze the presenting yaw and roll orienta­
tions and the subsequent aesthetic changes of the planned
correction can be augmented with the use of craniofacial
three-dimensional computed tomography scan imaging.
The clinicians’ assessment of the extent of maxillary cant
and the desired correction may be facilitated by the
following:
1. Use of a Fox plane during the direct visual examination.
The placement of a Fox plane directly over the occlusal
surfaces of the maxillary dentition is helpful to judge the
presence and extent of maxillary cant as compared with
the upper face (i.e., the interpupillary reference line).
Soft wax can be added to the deficient side (i.e., wax can
be placed in between the Fox plane and the occlusal
surfaces of teeth) until the cant is corrected. The milli­
meter amount of wax buildup (e.g., at the first molar) is
a measure of the cant. When using a Fox plane, the clini­
cian must also consider the patient’s maxillary arch form.
Often, two separate dentoalveolar planes (i.e., in the
presence of a steep curve of Spee) have been accentuated
by the orthodontic mechanics and will be managed with
segmental osteotomies. How the Fox plane is seated to
the patient’s maxillary occlusal plane is important when
assessing for a cant.
2. Comparison measurements from a posterior-anterior
cephalometric radiograph (left side to right side)
• Incisal edge to nasofrontal suture (millimeter dis­
tance, left and right sides)
• Canine edge to nasofrontal suture (millimeter dis­
tance, left and right sides)
• First molar edge to frontozygomatic suture (millime­
ter distance, left and right sides)
3. Comparison measurements from a three-dimensional cra­
niofacial computed tomography scan (left side to right side)
• Incisal edge to nasofrontal suture (millimeter dis­
tance, left and right sides)
• Canine edge to nasofrontal suture (millimeter dis­
tance, left and right sides)
*References 106, 110, 130, 131, 137, 140, 152, 173, 179, 194, 209, 218,
220, 230, 233, 244, 250

363
CHAPTER 12  Orthognathic Surgery Treatment Planning
anterior nasal spine recontouring); and in the presence of a
hypotonic upper lip (e.g., longstanding skeletal Class III
malocclusion) or an immobile scarred upper lip (e.g., fibro­
sis after cleft lip repair).
Nevertheless, with thoughtful planning, a favorable aes­
thetic outcome involving the relationship of the incisor ver­
tical position to the upper lip should be achieved for the vast
majority of orthognathic patients (see Fig. 12-35, I and J).
As a general rule, it is best to prevent too little maxillary
incisor and gingival show in relationship to the upper lip,
because this will result in an edentulous, aged, or sad look.
Remember that, with age, the upper lip lengthens as a result
of a loss of muscle tone. As long as excess lip separation at
rest and mentalis strain with closure are avoided, erring on
the side of more rather than less incisor show is generally
the preferred aesthetic objective.
NOTE:  I prefer to make final decisions regarding the
exact aesthetic vertical position of the maxillary incisors
during operation after the maxilla is secured to the
mandible through the intermediate splint. At this point,
with the condyles seated in the terminal hinge position,
all other vector changes for the maxilla are
predetermined. The maxillomandibular complex is
rotated, the vertical height is measured (i.e., medial
canthus to incisor height), and the final vertical incisor
position is determined.
Assess the Current and Preferred Horizontal
Position of the Maxillary Incisor Crown with
Reference to the Upper Face
The “ideal” aesthetic horizontal (sagittal) position of the
maxilla is not an exact millimeter number but rather a
narrow range of what will be considered proportionate
within the overall face. For each specific developmental jaw
growth pattern (e.g., long face or short face growth pattern,
maxillary deficiency with relative mandibular excess, cleft
maxilla), the needed directional horizontal surgical change
of the maxilla should be clear at the initial consultation.
This will be reconfirmed during the preoperative planning
examination by the operating surgeon. The preferred
horizontal (millimeter) change at the maxillary incisors can be
gauged through a combination of analyses:
1. Cephalometric analysis. A lateral cephalogram of the
patient is taken in (or adjusted to) the NHP, in centric
relation, and with the lips relaxed.
2. Andrews’ analysis. A lateral facial photograph of the
patient is taken in (or adjusted to) the NHP, in centric
relation, with a broad smile (i.e., exposing the maxillary
incisors) and with the exposure of the forehead skin (i.e.,
with the hair pulled back).
3. Anthropometric surface analysis. A direct visual examina­
tion of the patient’s face is made by viewing him or her
in the NHP from various perspectives, both in repose
and with a smile.
COMMENT:  Normative cephalometric
measurements (e.g., the sella-nasion-A point angle)
generally underestimate but may also overestimate the
preferred horizontal aesthetic projection of the maxilla
and therefore cannot be relied on. Alternatively, an
Andrews’ analysis of how much to advance the maxilla
in the sagittal plane can be a useful aide to the clinician
when evaluating a patient with a dentofacial deformity.
Spending time with an experienced orthognathic
surgeon is a valuable way for a clinician in training
to gain the hands-on knowledge required to make
consistent favorable aesthetic judgments of the
preferred three-dimensional reorientation of the maxilla
during the operation.
As stated, Andrews’ analysis can be a helpful tool to assess
the preferred horizontal (sagittal) projection of the maxilla
in the patient with a dentofacial deformity. This author’s
application of Andrews’ “Element II of Orofacial Harmony”
is illustrated in Figure 12-36. A step-by-step outline of how
to do so is also given here:
• View a photograph of the individual’s head and neck in
profile. The photograph is best taken in the NHP and
with a broad smile so that the labial surfaces of the maxil­
lary incisors are fully visualized. The forehead skin up to
the hairline must also be exposed, so the hair should be
pulled back, if necessary. There should be a calibration
scale on the facial photograph to confirm that it is life size
(i.e., 1 to 1) so that accurate measurements can be made.
• Identify the trichion: This is the junction of the forehead
skin and the anterior hairline. It is considered the most
superior aspect of the forehead when the forehead
contour is relatively flat.
• Identify the superion: This is typically considered the
most superior aspect of the clinical forehead. This is the
point used when the forehead is either rounded or
angular in contour.
• Identify the glabella: This is the most anterior projection
of the lower forehead.
• Draw a line that connects the superion and the glabella
(assuming that the patient has an angular or rounded
forehead).
• Identify the midpoint between the superion and the
glabella: This is called the forehead anterior point (FA
point).
• Locate and drop a vertical line through the FA point.
This line should be perpendicular to the floor when
viewing the patient’s photograph in the NHP. This is
called the forehead anterior limit line (FALL).
• Measure the angle at the superior forehead between
these two lines. This angle is a measure of forehead
inclination.

364 SECTION 2  Planning, Surgical Technique, and Complications
A
B
Face in profile (NHP)
Calibration for 1 to 1 measurements
Trichion
(Junction of anterior
hairline and forehead)
Superion
(Superior limit of
clinical forehead)
Glabella
(Most anterior
projection of forehead)
C
D
Line connecting the 2 points
identify midpoint (called FA point)
Line through FA point and perpendicular to
floor with patient in NHP
Midpoint
(FA point)
Superion
Glabella
FALL
(Forehead
Anterior
Limit Line)
• Figure 12-36  Patient viewed in profile in the natural head position (NHP). He is shown as a case example to demonstrate
application of Andrews’ “Element II of Orofacial Harmony.” (See text for explanation.)

365
CHAPTER 12  Orthognathic Surgery Treatment Planning
• Locate and drop a second vertical line that is anterior
and parallel to the FALL. This second line is called the
goal anterior limit line (GALL). The location of this line
is measured in millimeters anterior to the FALL in accor­
dance with the following standard formula: (Forehead
inclination angle − 7) × 0.6 = _____ mm.
• Locate and drop a third vertical line that is parallel to
both the FALL and the GALL. This line is called the
dental anterior limit line (DALL). The line runs through
the anterior surface of the maxillary incisors. The differ­
ence (in mm) between the GALL and the DALL is the
Forehead
inclination
Angle  18°
E
F
GALL  (187)  0.6  6.6 mm
GALL is 6.6 mm anterior to FALL
GALL (Goal Anterior Limit Line)
G
H
DALL  Line through anterior surface of
maxillary incisor
GALL to DALL  Desired maxillary AP
advancement  11 mm
11 mm DALL
GALL
DALL (Dental Anterior Limit Line)
FALL
• Figure 12-36, cont’d 
NOTE:  If the GALL is anterior to the glabella, then
locate and drop a fourth vertical line (through the
glabella) that is parallel to the others. This represents the
maximum horizontal position for the incisor to achieve
preferred midface aesthetics (i.e., rather than the GALL).
“recommending” distance that the maxilla should be
horizontally (sagittally) advanced to improve midface
aesthetics in the patient with a maxillary deficiency. This
is assuming that Andrews’ Element I is correct (i.e., that

366 SECTION 2  Planning, Surgical Technique, and Complications
for an individual with maxillary deficiency in combination
with relative mandibular excess who presents with a Class
III negative overjet malocclusion (see Fig. 12-35, I and J).
The improvement of the smile aesthetics in the patient with
a maxillary deficiency are often accomplished through a
combination of maxillary arch expansion, horizontal
advancement, and the adjustment of the vertical height.
the proper arch shape-positioning of the maxillary teeth
[roots] over basal bone is correct).
Additional Considerations to Andrews’ Standard Analysis
• I have found that Andrews’ analysis for the preferred
maxillary incisor position (i.e., Element II) is best suited
for Caucasian patients. When applying Andrews’ formula
to Asian, African, or Indian morphology, caution is war­
ranted. Facial variations in forehead, nasal, and midface
morphology are characteristically influenced by race.
• I have found that variations in skin thickness can have a
significant effect on the preferred aesthetic sagittal posi­
tion of the maxilla. This is an additional factor that
should be taken into account when reorienting the
maxilla in conjunction with a Le Fort I osteotomy. For
example, the individual with a thick soft-tissue envelope
(e.g., a patient with obstructive sleep apnea and an ele­
vated body mass index) may handle a greater horizontal
advancement than Andrews’ analysis indicates. The
opposite may be true for the individual with a thin soft-
tissue envelope.
• Andrews points out that midface aesthetics in profile are
highly dependent on the ideal positioning of the maxillary
teeth within the arch (i.e., Element I). An example of this
is seen in the patient with a maxillary deficient and rela­
tive mandibular excess growth pattern. If maxillary
bicuspid extractions are not carried out (when required)
to provide space for the orthodontic retraction of the
incisors toward a normal inclination, then midface aes­
thetics will be negatively affected. Unless Element I has
first been achieved, the procumbent maxillary incisors
will negatively affect the nasolabial angle in repose, the
draping of the upper lip with a smile, and the baseline
nasal base aesthetics.
The achievement of a favorable smile is influenced by
several factors, including but not limited to: 1) the quality
of the perioral soft tissues 2) the vertical position of the
maxilla 3) the horizontal position of the maxilla 4) the
maxillary arch width and 5) the inclination of the anterior
teeth within the arch (see Fig. 35, I and J). The smile arc is
analyzed in the frontal view by evaluating parallel lines that
represent the lower lip and the upper dentition. The ideal
smile arc (i.e., the consonant smile line) is characterized by
the curvature of the lower lip line parallel to the curvature
of the maxillary incisal edges. A consonant smile line is felt
to project a happy and youthful appearance. The buccal
corridor is the space that is created between the buccal sur­
faces of the posterior teeth and the inner aspect of the oral
commissure when the individual is smiling. Those with
excessive buccal corridors (i.e., negative space) are generally
rated as having less attractive smiles than those with smaller
buccal corridors. When the maxilla is narrow and horizon­
tally retrusive, the visual appearance of dark buccal corridors
reduces the attractiveness of the smile. Smile aesthetics are
enhanced when the display zone is filled with the maxillary
teeth. This concept is best appreciated when viewing pho­
tographs of the smile before and after orthognathic surgery
NOTE:  Decisions regarding where to position the
maxillary incisor vertically and horizontally at the time of
Le Fort I osteotomy will greatly affect smile aesthetics.
When determining the preferred horizontal (surgical)
repositioning of the maxilla, an important facial aesthetic
consideration is the interrelationship of the anterior maxil­
lary wall (i.e., above the alveolar process), the ocular globes,
and the lower eyelids (see Fig. 12-35, D). Horizontal
advancement and clockwise rotation of the upper jaw (after
Le Fort I osteotomy) for individuals who present with max­
illary deficiency and relative mandibular excess are typically
required to achieve and maintain favorable periorbital aes­
thetics (i.e., a positive vector relationship; see Chapter 20).
William Hogarth was an artist during the mid 1700s
who published an analysis of facial beauty.188 He docu­
mented the aesthetic importance of establishing an unbro­
ken convex contour from the lower eyelid to the cheek (see
Fig 12-35, L). He felt strongly that this convex shape, also
called the midface ogee curve, was fundamental to a youthful
and attractive midface. Dr. John Little further characterized
the ideal midface ogee curve when viewing the individual
at conversational distance.170 This can also be appreciated
on a medical-quality, high-resolution, oblique facial photo­
graph. Little suggested that the surgeon use the midface
ogee curve as an aesthetic reference standard when attempt­
ing to rejuvenate an aging face.
A lack of this youthful cheek region is often seen in indi­
viduals with either a long face Class II mandibular deficiency
anterior open-bite growth pattern (see Chapter 21) or a
maxillary deficiency relative mandibular excess growth
pattern (see Fig. 12-35, D). Projecting the midface forward
and appropriately rotating the maxillary plane (i.e., pitch
orientation) as part of the orthognathic correction is often
useful to recreate the natural attractive curvatures and
NOTE:  Some cosmetic surgeons attempt to
camouflage the individual’s maxillary deficiency either
with the excess injection of subcutaneous soft-tissue
fillers (e.g., fat grafts, collagen) or with the placement of
hard implants (e.g., Silastic, porous polyethylene) rather
than using an orthognathic approach (see Chapter 40).
I believe that a surgical camouflage approach is
counterproductive in most cases; it will result in a less
favorable facial appearance as compared with a biologic
orthognathic approach, and it runs the risk of leaving
the patient with an unnatural and “operated” look.

367
CHAPTER 12  Orthognathic Surgery Treatment Planning
aesthetic analysis, then the image should first be rotated to
establish NHP (see Fig. 12-35, D). From this position, a
perpendicular line may be dropped (e.g., from the nasion,
the soft-tissue glabella or from subnasion) as a vertical refer­
ence line from which to assess the A-point to B-point rela­
tionship, the horizontal jaw projection, and the effects on
the overlying soft tissues. The clinician should then consider
the need for operative rotation (i.e. pitch alteration) of the
maxillary and mandibular planes as part of the orthognathic
correction. This is to bring the A-point just in front of the
B-point and to bring both of them in correct proximity to
the vertical reference line (which is perpendicular to the
NHP) to achieve enhanced facial projection.
The establishment of a favorable A-point to B-point
relationship is an important part of approximating Euclid­
ian proportions and of recreating the natural attractive cur­
vatures and contours of the face (see Chapter 40). Achieving
the preferred A-point and B-point relationship will influ­
ence the relative position of the skeletal structures above
(i.e., the anterior wall of the maxilla, the pyriform rims, and
the anterior nasal spine) and below (i.e., the pogonion) (see
Fig. 12-35, L and N). The position of these superior and
inferior skeletal structures will then be reflected through the
overlying facial soft-tissue envelope. This includes the soft
tissues of 1) the lower eyelids (i.e., improvements in the tear
trough and the negative vector); 2) the cheeks (i.e., improve­
ments in the nasolabial folds); 3) the nose (i.e., improve­
ments in depressed nasal sills and a plunging tip); 4) the lips
(i.e., improvements in turned-down oral commissures and
marionette lines); 5) the chin (i.e., the prevention of ptosis);
and 6) the neck (i.e., improvements in an obtuse neck angle
and a double chin).
The surgical repositioning of the jaws to improve the
A-point to B-point relationship is also carried out with
consideration of its effects on the relative inclination of the
maxillary and mandibular incisors (see Fig 12-35, N). The
rotation of the maxillary plane can improve the relationship
of the maxillary smile arc to make it consonant with the
lower lip. With respect to incisor inclination, when the max­
illary plane is surgically rotated clockwise, the relative
incisor inclination decreases. When the maxillary plane is
surgically rotated counterclockwise, the incisors become
more procumbent. When the mandibular plane is rotated
clockwise, the incisors become more proclined. When the
mandibular plane is rotated counterclockwise, the incisors
become more retroclined. These effects must be considered
during the presurgical orthodontic phase and again at the
time of detailed preoperative planning.
Assess the Baseline Pyriform Rims, Floor of
Nose, and Anterior Nasal Spine Morphology:
Anticipate the Location of each after
Maxillary Reorientation
The satisfactory surgical positioning of the A-point and the
B-point (i.e., pitch orientation) will generally result in more
pleasing aesthetics at the pyriform aperture (paranasal)
regions154,178,198,205,212-217 (see Fig. 12-35, L and N). However,
contours of the otherwise deficient midface (see Fig. 12-35,
L). This generally requires counterclockwise rotation for the
long face growth pattern and clockwise rotation for the maxil­
lary deficient relative mandibular excess growth pattern.
Assess the Current and Preferred A-Point
to B-Point Relationship of the Jaws
(i.e., Pitch Orientation)
The facial aesthetic advantage of achieving an ideal
A-point to B-point relationship has been discussed
by contemporary orthodontists and orthognathic sur­
geons.109,161,162,187,198,205,212-217 The individual who presents
with a dentofacial deformity will frequently have a dishar­
monious A-point to B-point relationship, which results in
negative influences on facial aesthetics (see Fig. 12-35, D).
This deviation from ideal, when viewed in profile and in
the NHP, tends to be predictable in accordance with the
specific pattern of developmental jaw deformity (e.g., long
face growth pattern, maxillary deficiency with relative man­
dibular excess, primary mandibular deficiency).
For most patients with dentofacial deformities, the
achievement of preferred facial aesthetics requires the
planned operative rotation of the maxillary and mandibular
planes (i.e., pitch orientation) to correct A-point to B-point
disproportion (see Fig. 12-35, L and N). This may require
clockwise or counterclockwise rotation of the maxillary and
mandibular planes, but it rarely requires a true lengthening
or shortening of the posterior facial height.198,205,212-217
When using sagittal split ramus osteotomies, the
unchanged proximal segment of the mandible establishes
the posterior facial height, whereas any plane change carried
out occurs in the distal segment. The height of the proximal
segment (i.e., the posterior facial height) does not change with
either clockwise or counterclockwise rotation of the distal
segment in conjunction with a sagittally split ramus osteotomy
(see Chapter 15).
When establishing the preferred A-point to B-point rela­
tionship and achieving full midface projection and ideal
anterior vertical height through orthognathic techniques,
the upper airway will also improve.
The assessment of the profile aesthetics should be made
with the patient in the Natural Head Position with the teeth
in centric relation and then with the normal freeway space.
The lips are first relaxed (i.e., not pursed together) and then
also assessed with full smile (see Fig. 12-35 A, B, and D).
Individuals who present with a jaw discrepancy frequently
have an altered mode of respiration and tend to rest their
heads in positions that an experienced evaluator will view
as involving either neck extension or flexion or a head tilt.
The adjustment of the individual’s head position by the
clinician to the NHP is required to accurately assess the
profile.
Oftentimes, the patient’s lateral facial photograph and
lateral cephalometric radiograph are not taken with the
patient’s head in the NHP. If the profile photograph,
the three-dimensional computed tomography scan, and the
lateral cephalometric radiograph are to be used for facial

368 SECTION 2  Planning, Surgical Technique, and Complications
at the time of Le Fort I osteotomy, the recontouring of the
pyriform rims, the floor of the nose, and the anterior nasal
spine region to correct baseline skeletal deformities may also
be beneficial (see Chapter 15). The advantage of these
recontouring procedures to the upper lip and tooth relation­
ship and the aesthetics of the base of the nose should always
be considered during preoperative planning.
Riola’s textbook of cephalometric measurements con­
firms that the normal mean vertical height of the anterior
nasal spine down to the maxillary incisal edge is 30 mm
(±3 mm) for females and 33 mm (±3 mm) for males.209 At
the time of the Le Fort I osteotomy, the patient’s specific
measurements can be confirmed with a caliper. This is useful
information to guide nasal floor reconstruction. For
example, with the long face growth pattern, a patient who
is undergoing Le Fort I osteotomy with vertical intrusion
to reduce a gummy smile will frequently have an average
height of between 38 mm and 45 mm. At the time of
LeFort I osteotomy, recontouring and lowering the floor of
the nose and the anterior nasal spine toward 30 mm is
useful to normalize anatomy. In so doing, the nasal airway
and the nasal aesthetic unit will be favorably enhanced (see
Fig. 16-19).
Assess the Baseline Chin Morphology:
Anticipate the Location of the Pogonion
after Jaw Reorientation
An individual’s lateral cephalometric radiograph when
viewed in the NHP is useful to assess the 1) anterior facial
heights, 2) any baseline bony chin dysmorphology, 3) the
maxillary and mandibular incisor inclination and 4) the
A-point to B-point relationships (see Fig. 12-35, N).
Riola’s table of normative mandibular cephalometric
values confirms that the mean vertical height of the chin
(i.e., from the mandibular incisal edge to the menton) is
approximately 42 mm (±2.7 mm) for females and 49.4 mm
(±2.9 mm) for males.210 These measurements can be a
useful benchmark from which to judge the preferred vertical
height of the chin.
The effective alteration of the A-point to B-point
relationship at the time of orthognathic surgery will in
itself generally have a positive effect on the chins appear­
ance.198,205,212-217 Additional direct surgical alteration of the
chin (i.e., osseous genioplasty) is also frequently beneficial to
achieve enhanced facial aesthetics (i.e., vertical lengthening
or shortening, midline shifts, horizontal advancement or in
some cases recontouring of the chin surface anatomy; see
Chapter 37).
These morphologic details should be considered during
the immediate preoperative face-to-face patient examina­
tion and discussed with the patient and his or her family.
A plan for chin management is agreed to and then executed
at the time of orthognathic surgery, with the goals of further
improving aesthetics, lip function, and possibly breathing
(e.g., genioglossal advancement in the individual with
obstructive sleep apnea).
Reconfirm the Advantage of and Need for the
Segmentation of the Maxilla
The advantage of segmentation of the maxilla should be
considered before the initiation of orthodontic treatment.
Maxillary segmentation is often a necessary procedure to
achieve favorable long-term occlusal stability and periodon­
tal health. It may also be required to achieve an 1) ideal
curve of Spee, 2) arch width, 3) incisor inclination and
4) successful closure of dental gaps.
Segmentation is generally performed as either a “two-
piece” osteotomy, with an interdental osteotomy between
the incisors and then parasagittally through the hard palate,
or as a “three-piece” osteotomy, with interdental osteotomies
between the lateral incisor and canine on each side and then
down the parasagittal midline on one or both sides (see
Chapter 15).
The segmentation of the upper jaw is not an excuse for
poor orthodontic preparation. It does provide an opportu­
nity to correct skeletal issues through the basal bone rather
than through orthodontic compensation that would other­
wise position the teeth outside or on the edge of the alveolar
process (see Chapter 17). An orthodontic compensation
(i.e., dental camouflage) approach will likely be unstable for
the occlusion and the periodontium in the long run (see
Chapters 6 and 17).
These decisions (i.e., plans for maxillary segmentation)
should be agreed upon before the initiation of orthodontic
treatment, reconfirmed at the time of immediate presurgical
model planning, demonstrated on the articulated dental
models, registered on the prefabricated acrylic splints, and
then executed during surgery (see Fig. 12-35, G).
Conclusions
From a patient and family perspective, facial aesthetic
aspects are of significant importance to the correction of a
dentofacial deformity. The most attractive faces will always
incorporate a consistent symmetry of proportions in which
the golden ratio can be found.
An in-depth visual facial analysis, the use of radiographic
and photographic imaging, meticulous analytic model plan­
ning, and experienced surgical execution remain the impor­
tant components of successful orthognathic surgery. There
is much to be said for both the scientific and artistic aspects
and a methodical approach to accomplish facial aesthetic
objectives, the restoration of dental health, and improved
head and neck function (i.e., breathing, swallowing,
chewing, and speech) through the reconstruction of a den­
tofacial deformity. The ultimate objective is the creation of
Euclidian facial proportions by attempting to reach the
Kanon of beauty as described by Polyclitus and as visualized
by the nautilus found in nature.
For the correction of a dentofacial deformity, the iden­
tification and then the reconstruction of key landmarks of
the face are the objectives. In the past, simple but practical
tools such as the compass and the square were used to

369
CHAPTER 12  Orthognathic Surgery Treatment Planning
establishment of ideal facial aesthetics. When analyzing the
Mona Lisa, academicians still disagree about Leonardo’s
intent and the meaning of his work vis-à-vis the golden
ratio. Nevertheless, with a working knowledge of the golden
ratio and of its fascinating impact on the arts and architec­
ture as well as in nature, the clinician’s aesthetic sense of
harmony and symmetry is enhanced for the benefit of his
or her patients.
accomplish these goals. These are similar to the instruments
that the 15th-century mathematician Luca Pacioli used to
create geometric images and that are used for architecture
constructions. The orthognathic surgeon now supplements
these tools with computer software programs, three-
dimensional imaging, and locating techniques.
In current clinical practice, we can take some solace in
knowing that even Leonardo da Vinci was not entirely able
to articulate the link between theory and practice for the
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374

13
Standard Analytic Model Planning
for Orthognathic Surgery
JEFFREY C. POSNICK, DMD, MD
• Controversies Surrounding Model Planning
for Orthognathic Surgery
• Standard Facial Records for Orthognathic
Surgery
• Key Measurements Obtained via Direct Visual
Examination to Define Planned
Maxillomandibular Surgical Change
• Face-Bow Registration and Transfer to the
Semi-Adjustable Articulator
• Use of the Erickson Model Table to Define the
Spatial Orientation of an Articulator-
Mounted Maxillary Unit
• Use of the Erickson Model Table to Define the
Spatial Orientation of an Articulator-
Mounted Mandibular Unit
• Separation of the Maxillary Cast from the
Articulator Base
• Segmentation of the Maxilla
• Use of the Erickson Model Table
Measurements to Reorient the Maxillary Cast
• Intermediate Splint Construction for the
Positioning of the Maxilla During Operation
• Reorientation of the Mandibular Cast to
Register the Final Occlusion
• Final Splint Construction for the Positioning
of the Mandible During Operation
• Finishing of the Prefabricated Acrylic Splints
• Accuracy of the Described Analytic Model
Planning Technique: Review of Study
• Conclusions
Unlike most surgical procedures, orthognathic surgery
involves not just the thorough medical assessment of the
patient but also precise preoperative dental, radiographic,
and facial aesthetic planning. The surgeon must carry out a
detailed face-to-face examination of the patient to deter­
mine variations from normal (Fig. 13-1).
Immediate presurgical records include the following:
1) dental impressions of the maxilla and mandible 2) an
accurate bite registration in centric relation (CR) 3) a face-
bow recording of maxillary orientation in relationship to
the condyles and the upper face and 4) the measurement of
specific facial landmarks that includes deviations from
normal (Figs. 13-2 and 13-3).
The maxillary model is mounted on a semi-adjustable
articulator in accordance with the face-bow recording. The
mandibular model is occluded to the mounted maxillary
cast with the use of the CR bite1,2,14,17,18,21,30,52,62,63 (Fig.
13-4). The mounted dental casts are then used to complete
model planning12,50 (Figs. 13-5 through 13-8). Splints made
of acrylic are fabricated and used intraoperatively to further
ensure the reliable execution of predetermined facial aes­
thetic and functional objectives (Figs 13-9 through 13-11).
Although clinical decision making regarding the pre­
ferred aesthetic reorientation and repositioning of the jaws
in the operating room remains both an art and a science
(see Chapter 12), the technical aspects of planning should
be precise and consistent. Analytic model planning and the
use of prefabricated splints continue to represent the stan­
dard of care for bimaxillary and segmental maxillary
osteotomies.8,9,15,16,22,26,44,55,77,78,80,85,86
Despite the benefits of this time-honored approach,
there is the potential to introduce error. For example, during
bimaxillary surgery, if an inaccurate bite registration is
obtained from the patient preoperatively in the clinic
setting, this will be transferred to the articulated models;
this leads to inaccurate splint construction and then to
intraoperative errors when the splints are relied on during
surgery. The surgeon’s ability to obtain an accurate and
reproducible bite registration in CR during the immediate
Text continued on p. 405

375
CHAPTER 13  Standard Analytic Model Planning for Orthognathic Surgery
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• Figure 13-1  A 19-year-old man of Asian descent presented with a maxillary deficient and relative mandibular
excess growth pattern. He has an Angle Class III anterior open bite with negative overjet malocclusion as well as
a lifelong history of obstructed nasal breathing. The maxillofacial dysmorphology causes difficulties with speech,
chewing, swallowing, breathing, and lip closure/posture, and it also negatively affects his facial aesthetics. The
upper facial skeleton is symmetric and proportionate; the soft-tissue envelope is distorted but not malformed. There
is a good range of motion of the neck and mandible without temporomandibular disorder. After evaluation, a
comprehensive orthodontic and surgical approach was discussed and approved. Orthodontic (dental) decompen­
sation required 10 months of active treatment. No extractions were required. Six weeks before surgery, the patient
returned for a direct visual examination and the taking of records that included alginate impressions of the maxilla
and mandible, centric bite registration, face-bow registration, and the transfer of the data to a semi-adjustable
articulator. Decisions were made regarding critical measurements for the surgical repositioning of the jaws. The
procedures carried out included the following: a Le Fort I osteotomy in segments (horizontal advancement, cant
correction, arch expansion, and clockwise rotation); bilateral sagittal split ramus osteotomies (mandibular adjust­
ment); osseous genioplasty (minimal vertical shortening and horizontal advancement); and septoplasty and inferior
turbinate reduction. A, Frontal view in repose and occlusal views before treatment. B, A Panorex radiograph. This
is useful to assess basic condylar morphology and to look for mandibular and dental pathology, including root
resorption.
Continued

376 SECTION 2  Planning, Surgical Technique, & Complications
C
Assess intranasal anatomy
• Septal deviation? “Yes”
• Inferior turbinate hypertrophy? “Yes”
• Tight nasal inlet? “Yes”
• Elevated nasal floor? “No”
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o nicicicicicicicicicicicick
D
C, The patient’s history of lifelong nasal obstruction—in combination with an intranasal
speculum and a sinus computed tomography scan examination—confirms a deviated septum (bone and cartilage)
and hypertrophic inferior turbinates. Both of these conditions required surgical correction to improve the airway.
D, Frontal view with smile and occlusal views with orthodontic decompensation in progress.
• Figure 13-1, cont’d

377
CHAPTER 13  Standard Analytic Model Planning for Orthognathic Surgery
Continued
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Maxillary Surgical Plan
Frontal View:
Maxillary midline
No change needed
Cant correction 2 mm
Anterior vertical No change needed
1 mm (L)
1 mm (R)
E
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F
3mm
5mm
3mm
Maxillary clockwise rotation (3 mm) to enhance profile aesthetics
E, A frontal facial view confirms that the maxillary midline matches the upper facial midline; that
there is a satisfactory lip–tooth relationship in repose and with smile; and that there is canting of the maxilla at the molars
(2 mm) as compared with the upper face. F, Analysis of the facial profile and the lateral cephalometric radiograph before
surgery provides useful information about facial height, incisor inclination, A-point to B-point relationship, maxillary and
mandibular projection, and chin morphology.
• Figure 13-1, cont’d

378 SECTION 2  Planning, Surgical Technique, & Complications
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Orththththththththththththtr ogn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gnatatatatatatatathicicicicicicicic Su
Su
Su
Su
Su
Su
Surg
r ery
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry; J.C.
C.
C.
C Pos
os
os
os
os
os
os
os
os
os
os
os
os
os
os
os
os
os
os
os
osnicicicicici k
G
Maxillary Surgical Plan
Profile View:
Anterior vertical
no change
Posterior vertical 3-mm intrusion
Horizontal
5-mm advance
Maxillary clockwise rotation (3 mm) to enhance profile aesthetics
H
Measurements are used to spatially reposition the maxilla. The
mandible is then set into occlusion with the repositioned maxilla.
Maxillary Surgical Change
Horizontal change at incisors
Vertical change at incisors
Midline change at incisors
Cant correction -TOTAL
↑
1 on right ↓
1 on left
Maxillary plane change -TOTAL
Clockwise - Counterclockwise
Vertical change at T#3 (right) molar
(Base
Cant
Plane)
Vertical change at T#14 (left) molar
(Base
Cant
Plane)
5
0
0
2
3
0
1
3
4
0
1
3
2
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Orththththththththththththtr ogn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gnatatatatatatatathicicicicicicicic Su
Su
Su
Su
Su
Su
Surg
r ery
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry; J.C.
C.
C.
C Pos
os
os
os
os
os
os
os
os
os
os
os
os
os
os
os
os
os
os
osnicicicicick
G, The direct visual examination of this patient in profile as well as Andrew’s analysis
confirms the following: an advantage of horizontal advancement at the maxillary incisors (5 mm); no need for vertical
change at the maxillary incisors; an advantage of 3-mm clockwise rotation of the maxillary plane (3-mm intrusion
at the first molars); and no need for horizontal change at the mandibular incisors. Note that 5-mm horizontal
advancement at the incisors will correct the negative overjet and that 3-mm clockwise rotation of the maxillary
plane (intrusion at the first molars) will be helpful to restore profile aesthetics and to overcome maxillary incisor
procumbancy. H, The planned maxillary surgical change is recorded on the orthognathic data sheet. These mea­
surements will be used to spatially reposition and reorient the maxilla first on the articulator for intermediate splint
construction and then at the time of Le Fort I osteotomy. During surgery, through sagittal split ramus osteotomies,
the mandible will then be set into occlusion with the repositioned maxilla.
• Figure 13-1, cont’d

379
CHAPTER 13  Standard Analytic Model Planning for Orthognathic Surgery
Or
Or
Or
Or
Or
Or
Or
Or
O ththththth
r ogn
gn
gn
gn
gn
gn
gn
gn
gn
gn
g atathicicicicic Su
Su
Su
Su
Su
Su
Surg
r ery
ry
ry
ry
ry
ry; J.C.
C.
C.
C Pos
os
os
os
o nicicici k
Or
Or
Or
Or
Or
Or
Or
Or
Orthththththththththth
r ogn
gn
gn
gn
gnatatatatatathicicicicicicicicic Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
S rg
r ery
ry
ry
ry
ry
ry
ry; J.C.
C.
C.
C.
C Pos
os
os
os
os
os
o nicicicicicici k
A
“Chin-point guidance” technique for centric relation
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
O ththththththththththththththththththththththth
r ogn
gn
gn
gn
gn
g atatatatatatatatatatatatatatatatatatata hicicicicicicicic Su
Su
Su
Su
Su
Su
Su
Surg
r ery
ry
ry
ry
ry
ry
ry
ry; J.C.
C.
C.
C.
C.
C.
C.
C Pos
os
os
os
os
os
os
os
osnicicici k
Or
Or
Orthththtr ogn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
g atatatatatatatatatatatathicicicicicicicicicicicic Su
Su
Su
Su
Su
Su
Su
Su
Su
Surg
r ery
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry; J.C.
C.
C.
C.
C.
C.
C.
C.
C.
C.
C.
C.
C Pos
os
os
os
os
os
os
os
os
os
os
os
o nicicicicicicicicicicicicick
B
“Chin-point guidance” technique for centric relation
• Figure 13-2  The chin-point guidance technique is used to capture (register) the centric relation bite.
The patient is seated upright and in the natural head position. The chin-point guidance technique is
accomplished by using one hand to apply pressure to the subject’s chin and the other hand to apply
counter pressure to their occiput. This allows the clinician to apply posterior and superior “vectored” force
on the anterior aspect of the mandible. By doing so, the condyles will be seated in a superior-anterior
location within each glenoid fossa (i.e., centric relation). A, The registration of the patient’s maxillary occlu­
sion into soft wax. B, Applying pressure to the chin with the patient’s muscles relaxed. The condyles are
seated, and the mandible is rotated up until the teeth first occlude. It is essential to avoid a shift (slide)
from the centric relation into a centric occlusion. This may occur in a patient with malocclusion if he or
she is allowed to fully clench the teeth together.
Continued

380 SECTION 2  Planning, Surgical Technique, & Complications
C
Centric relation (CR) bite (wax)
Wax wafer
Bite registration
C, Wax wafer before and after bite registration.
• Figure 13-2, cont’d 
A
Register spacial orientation between
Condyles/ear canals
Maxilla/maxillary occlusal plane
Skull base/facial plane
For transfer of relationships to articulator
Face-bow registration
• Figure 13-3  A, Bite fork with soft wax placed on the upper side is demonstrated. The face-bow apparatus is shown from both
the bird’s-eye view and the worm’s-eye view.

381
CHAPTER 13  Standard Analytic Model Planning for Orthognathic Surgery
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
O ththththththththththththththth
r ogn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
g atatatatatatatatatatatatatatathicicicicicicicicicicicicicicic Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Su
Surg
r ery
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry
ry; J.C.
C.
C.
C.
C Pos
os
os
osnicicicick
Even pressure
of ear prongs
Thumb screws
Temporal bars
Approximating infra-orbital rims (profile)
Consistent with NHP (profile)
Parallel to pupils (frontal)
C
Or
Or
O thth
r ogn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
g atatatatatathicicicic Su
Su
Su
Su
Surg
r ery
ry
ry
ry; J.C.
C.
C.
C.
C.
C.
C.
C.
C.
C. Pos
os
os
os
os
os
os
os
os
o nicicicicicicicicicick
Or
Or
Or
Or
Or
Orththththth
r ogn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
g atatatatatatathicicicici Su
Su
Su
Su
Su
Su
Su
Surg
r ery
ry
ry
ry
ry
ry
ry
ry; J.C.
C.
C.
C.
C.
C.
C. Pos
os
os
os
os
os
os
os
os
os
os
o nicicicicicicicicicicicick
B
Register patient’s maxillary occlusion into soft wax on bite fork
B, The patient’s maxillary occlusion is registered into soft wax on the bite fork.
C, The face bow apparatus is held in place through even pressure of the ear prongs in each ear canal.
The three thumbscrews are then tightened.
• Figure 13-3, cont’d 
Continued

382 SECTION 2  Planning, Surgical Technique, & Complications
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
Or
O ththththththththththtr ogn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
gn
g atatatatatatatathicicicicicicicic Su
Su
Su
Su
Su
Su
Su
Su
Surg
r ery
ry
ry
ry
ry; J.C.
C.
C.
C.
C.
C.
C.
C Pos
os
os
os
os
os
os
os
osnicicicicicicicick
Even pressure
of ear prongs
Thumb screws
Temporal bars
Approximating infra-orbital rims (profile)
Consistent with NHP (profile)
Parallel to pupils (frontal)
D
E
Ear prongs
Thumb screws secure ear prongs
(once the face bow is in place)
D, The temporal bar is set parallel with the interpapillary line and consistent with the natural head posi­
tion. E, A close-up view is shown of the thumbscrews that secure the ear prongs in place.
• Figure 13-3, cont’d

383
CHAPTER 13  Standard Analytic Model Planning for Orthognathic Surgery
T-screws
F
Vertical rod
Temporal bar
T-screws secure bite fork to vertical rod of face bow
Orth
r ognathic Surg
r ery; J.C. Posnick
G
Face-bow apparatus removed from patient
Ready to place on semi-adjustable articulator
F, T-screws secure the bite fork to the vertical rod of the face-bow apparatus. The T-screws are turned clockwise
to secure the face bow after confirming that the temporal bar extensions are parallel to the interpupillary line (frontal view) and consistent
with the natural head position (profile view). G, With the T-screws tight, the thumbscrews are loosened to release the face-bow apparatus
from the patient. The face bow is now ready to place on the articulator.
• Figure 13-3, cont’d 
Continued

384 SECTION 2  Planning, Surgical Technique, & Complications
H
Alginate impressions of mandible and maxilla
Use vibrator to
limit air bubbles
Pour up alginate impressions in green dental (die) stone
I
H, Impression trays are selected to fit the patient’s arch form. The alginate is mixed, placed in the
trays, and then taken to the maxillary and mandibular arches, in turn. Negative impressions of the dentition are recorded
in the alginate. I, The alginate impressions are “poured up” in green dental (die) stone. The use of a vibrator during this
process will limit air bubbles.
• Figure 13-3, cont’d

385
CHAPTER 13  Standard Analytic Model Planning for Orthognathic Surgery
J
Base forms are helpful
Incorporate at least 30 mm of stone base
K
Trim each model
First molar cusp tip
Canine cusp tip
Central incisor cusp tip
Measure (25-30 mm) down from
J, Base formers are useful when incorporating additional dental stone to achieve at least 30 mm of height for each
dental cast. K, After the die stone is set (≈30 min), the models can be trimmed to achieve a consistent 25-mm base on the maxillary cast
and a 30-mm base on the mandibular cast.
• Figure 13-3, cont’d

386 SECTION 2  Planning, Surgical Technique, & Complications
Bite fork
support
Base plate
Mounting maxillary cast on articulator using white plaster
bite fork support prevents sagging
A
Plaster
Maxillary cast secured to base plate with plaster
Bite fork
support
Base plate
B
Add plaster
With maxillary unit dry – turn articulator upside down
Use CR wax bite to occlude mandibular cast to maxillary unit
CR wax bite
Base plate
Mandibular
cast
C
• Figure 13-4  A, The trimmed dental casts are
then mounted on the semi-adjustable articulator
with the use of the face-bow apparatus. The tem­
poral arms of the face bow are maintained parallel
to the upper aspect of the articulator and the
counter top. Base plates for the maxillary and
mandibular units are secured to the articulation. A
bite-fork support is useful to prevent the sagging
of the face-bow apparatus when mounting the
maxillary cast. B, The plaster is mixed and added
in between the maxillary dental cast and the
base plate. C, With the maxillary unit initially set
(≈15 min), the articulator is turned upside down.
The centric relation wax bite is occluded to the
maxillary cast. The trimmed mandibular cast is
then occluded to the other side of the wax bite.

387
CHAPTER 13  Standard Analytic Model Planning for Orthognathic Surgery
D
Mandibular and maxillary casts secured to articulator
E
Remove maxillary and mandibular units from articulator, trim each independently on grinder
F
Prior to trimming
After trimming
D, With the base plate secured to the
articulator, the space that separates the mandibular dental cast
from the base plate is filled with white plaster. E, The maxillary
and mandibular units are removed from the articulator and
taken to the grinder for trimming. F, The mounted dental casts
are shown on the semi-adjustable articulator before and after
trimming.
• Figure 13-4, cont’d

388 SECTION 2  Planning, Surgical Technique, & Complications
A
Placement of maxillary unit horizontal reference lines
- 1st reference line in green stone
- 2nd reference line (15-20 mm down) in white plaster
C
Between central incisors
Perpendicular to horizontal lines
B
Placement of maxillary unit vertical reference lines
At mesiobuccal groove of each first molar
Perpendicular to horizontal lines
• Figure 13-5  Marking horizontal and vertical reference lines on the articulated dental casts. A, The maxillary unit horizontal reference lines
are placed parallel to the base plate. The first horizontal reference line is placed entirely in the green stone. The second is placed entirely in
the white plaster, with 15 mm to 20 mm of separation between the lines. B, A maxillary unit vertical reference line is placed at the mesiobuc­
cal groove at each first molar, perpendicular to the horizontal lines. C, The next maxillary unit vertical reference line is placed between central
incisors, perpendicular to the horizontal lines.

389
CHAPTER 13  Standard Analytic Model Planning for Orthognathic Surgery
E
Posteriorly at tuberosity regions
2 reference lines on each side – at alveolar ridge
D
Placement of maxillary unit vertical reference lines
At cusp tip of each canine
Perpendicular to horizontal lines
A
Erickson Model Table – Measurements
Mark four spacial reference points on maxilla
T#3
T#8
T#9
T#14
D, Additional maxillary unit vertical reference lines are placed at the cusp tip of each canine, perpendicular
to the horizontal lines. E, Vertical maxillary unit reference lines are also placed posteriorly in the tuberosity regions. Two reference
lines are generally placed on each side, adjacent to the alveolar ridges. Similar horizontal and vertical reference lines are placed
on the mandibular unit.
• Figure 13-5, cont’d 
• Figure 13-6  The Erickson Model Table (EMT) is used to register the baseline
maxillary orientation in all three planes in space. The baseline measurements
are then used to assist with the accurate repositioning and reorienting of the
maxilla in accordance with clinical requirements. A, With a Sharpie marking
pen, a reference dot is placed at the mesiobuccal cusp tip of each maxillary
first molar and the midpoint of each maxillary central incisor.
Continued