The golden proportion in esthetic treatment planning

The golden proportion in estheticThe golden proportion in esthetic
treatment planningtreatment planning
INDIAN DENTAL ACADEMY
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introductionintroduction
• Beauty is in the eye of the beholder
• Perception of beauty in the brain
• esthetics – the branch of philosophy dealing
with beauty

Fibonacci numbersFibonacci numbers
• Presented 1202 by Filius Bonacci in text
Liber Abaci
• The series is
0,1,1,2,3,5,8,13,21,34,55,89,144…..
• Likened to multiplication of rabbits
• Each no. is 1.618 times the previous no.

Golden sectionGolden section
• Known since 550 B.C. to Egyptians
and Greeks
• Marvellous as it is perceived as
beauty, harmony and balance
• Static symmetry vs. Dynamic
symmetry
• 1.618/1 = 0.618 referred to as Ф after
phidias
• Kepler in 1600 callled it as divine
proportion
• Key to normal morphology
• Natural law of growth of animals and
plants

Clinical application in dentistryClinical application in dentistry
• width of 1┘: 1┐= 1.618
• Lower incisors width :
upper intercanine width =
0.618
• Found in people with most
attractive smiles, faces
and most graceful figures
• Fundamental component
of major biologic plan

Golden rectangleGolden rectangle
• Base of 1.0 and
perpendicular side 1.618
• E.g. playing cards, credit
cards, picture frames, 3”*
5” postcards
• Golden triangle, pentagon,
spirals
• Dynamic: seem to display
some sort of life,
animation
• Golden divider by Robert
M. Ricketts

Why it worksWhy it works
• Face, jaws and teeth as geometric structures
present more esthetics if they align more
with GP
• Referred to as golden to each other
• Smile analysis by several investigators
confirm presence of GP

CompositionComposition
• Study of objects made visible by
contrasts in color , line and texture
• Components
• Unity : oneness, ordering of parts of a
composition to give the individual a
total, whole effect
• Static dynamic
• Regular geometry logarithmic spirals
• Passive, inert dynamic, living

• Cohesive elements : tend to
unify a composition
• Repetition of shape, line and
color
• Unfortunately appear static or
dead
• Arrangement of maxillary ant.
Teeth to a circle
• Segregating elements: introduce
unity with variety
• Hogarth’s line of beauty
• introduced to teeth
arrangement

DominanceDominance
• One shape, color should
dominate
• Others subservient
• E.g the maxillary central incisor
is the most dominant tooth by
virtue of it’s visible size
• Not maxillary cuspid as only
mesial side is visible
• Mouth is the dominant feature
of the face

ProportionProportion
• Golden proportion is ideal guide
• Disadvantages
• Unfortunately applied unilaterally
• Malaligned teeth, overlap, diastemas
• Requires calliper and calculator

Golden percentagesGolden percentages
• Calculated as total sum / individual
ratio i.e.
0.618+1+1.618+1+0.618=6.472/
individual ratio
• 10%-15%-25%-25%-15%-10%
• Does not depend upon lateral
incisors only but the individual
tooth’s contribution to whole
• Teeth with identical width generate
identical %
• Asymmetry clearly identifiable and
quantifiable

Smile analysisSmile analysis
• Repeatable, measurable objective principles can be applied
o improve esthetics
• Consider the following factors in the dentofacial analysis
• Upper lip position – high, average or low
• Upper lip curvature
• Parallelism of maxillary incisal curve with lower lip
• Relation between maxillary anteriors and lower lip
• Number of teeth displayed in a smile
• Midline relation of the central to the philtrum

• Interpupillary line to midline of face
• Midline of teeth to midline of face
• Lip symmetry
• Profile ( influences dominance given to
centrals)
• The negative space
• Buccal corridor

Dental analysisDental analysis
• Width and height of existing teeth
• Proportion
• Parallelism
• Axial inclination, rotation, malposition
• Gingival characteristics

Smile designSmile design
• Age, sex and personality
• Oral health
• Three factors effecting smile design
• Symmetry across midline
• Anterior or central dominance
• Regressive proportion

Treatment planningTreatment planning
• Step 1 – establish facial symmetry and midline
• Interpuppilary line // horizon
• Placement of midline at exact center – artificial
• Eccentric unexaggerated midline – natural illusion
• Maxillary midline and facial /labial frenum midline –
70.4%
• Do not use mandibular midline
• Stable positioning without leanings to left or right

• Step 2 – record the highest lip line
• Height of upper lip at full smile
• Length of centrals
• Amount of visible gingiva
• Photographs or manual
• Ideal smile, gummy smile or long lip smile
• Obvious gingival asymmetry noted
• Postion of lateral incisor

• Step 3 – take photographs
• As viewed from the front
• Lips retracted
• Horizontal frame should // interpupillary line
• Or vertical margin // the facial midline
• 8” from centrals , 1: 2 magnification

Grid analysis systemGrid analysis system
• Given by CK Naylor
• Incorporation of midline axis, incisal plane,
highest lipline, proportionate contact areas forms a
grid
• Provides a method of demonstrate variations from
esthetic arrangement of anterior teeth

• Step 4 – draw the lines on the photograph
• aim to coincide with idealized positions of
• Incisal plane- // upper or lower frame at the position of
idealized incisal edge
• Incisal edge- cornerstone and set to correct level
determined for the pt’s smile
• Visibility at rest and lip mobility
• Incorporated to grid and verified in mock up
• Highest lip line drawn
• Midline axis drawn perpendicular to the incisal plane

• Proportionate placement of contact areas
• Cental incisor to lateral incisor establishes the
former as dominant factor in the composition
• Repeated proportion by Lombardi between CI, LI
and canines
• Most followed is golden proportion
(1/1.618=0.618)
• CI= 9mm → LI = 9*0.618= 5.56mm
• Golden percentages can be used

RED ProportionRED Proportion
• Recurring esthetic dental proportion
• Basically implies not to follow the 62% proportion
• States that proportion of the successive widths of the teeth
as viewed from the frontal should remain constant as one
moves distally dentist can define his own RED proportion
• Several studies have reported mean proportions of 66-78%
for LI: CI

• Step- 5 treatment phase
• Carried out in mouth based on the grid system
• Final result visualized with mock up or
provisionals
• Conventional therapy constituted after patient’s
consent.

ConclusionConclusion
• Golden proportion ids the starting point in
smile design
• Strict adherence to it is questionable but it
serves as useful tool for initial evaluation of
dominance and proportion

The golden proportion in esthetic treatment planning

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