Dentofacial perspective / cosmetic dentistry course

DENTOFACIAL PERSPECTIVEDENTOFACIAL PERSPECTIVE
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

In our modern competitive society, a pleasing
appearance often means the difference between
success and failure in both our personal and
professional lives.
An acceptable cosmetic effect in any dental
restoration has always been regarded as important
to good dentistry. A well-made prosthesis will fail
if it is deficient in this respect.

 Esthetics includes the appreciation and response
to the beautiful in art and nature.
 Esthetics has been given many definitions in
dentistry but according to Young. “It is apparent
that beauty, harmony, naturalness and
individuality are major qualities” of esthetics.

The dentist must visualize esthetics in relation to
the patient and then translate that visualization
into an acceptable esthetic result.
The success of his efforts depends upon his
artistic ability, his powers of observation and his
experience

 Dentofacial perspective concentrates on the oro-
facial landmarks consisting of highly vascu-
larised lips with the teeth acting as a gateway to
the oral cavity. The emphasis here is to analyse
the lips in relation to the anterior maxillary sex-
tant.
 The deeper colour of the lips compared with
lighter coloured teeth creates a colour con-trast
to add interest to this arrangement.

 The dento-facial composition encompasses
both the frontal and sagittal planes in two
muscular positions:
 Static
 Dynamic.

STATIC POSITIONSTATIC POSITION
 The static position is when the lips are slightly
parted and the teeth are out of occlusion with
the perioral muscles relatively relaxed.
 This position is typically achieved following
utterance of the letter ‘M’.

Sagittal view of the static position
of the dento-facial composition with
relaxed orofacial muscles
Frontal view of the static position of
the dento-facial composition with
relaxed orofacial muscles

 In this tranquil position, four factors influence
tooth exposure:
lip length
age,
race and
sex,
also known as the acronym LARS.

LIP LENGTHLIP LENGTH
 The length of the upper lip varies from 10-36mm,
and individuals with long maxillary lips show
more mandibular rather than maxillary teeth.
 The amount of tooth exposure at rest is predomi-
nantly a muscle-determined position.

Maxillary lip length in relation to anterior tooth exposure
Maxillarylip
classification
length (mm)
Exposure of Exposure of
upper central lower central
incisor incisor (mm)
(mm)
Short 10-15 3.92 0.64
Medium 16-20 3.44 0.77
Medium 21-25 2.18 0.98
Long 26-30 0.93 1.95
Long 31-36 0.25 2.25

The LARS factor to
determine the amount of
tooth exposure at rest.
Lip length: the linear
measurement of the
upper lip. The patient
depicted has a medium
maxillary lip length

AGEAGE
 Age is the second part of the LARS factor, which is
a similar way to lip length, influences the amount of
tooth visibility.
 The amount of maxillary tooth displayed is
inversely proportional to increasing age whereas the
amount of mandibular teeth is directly proportional
to increasing age.

 There-fore, a young person will display more
maxillary than mandibular teeth, whereas an older
individual will show more mandibular, rather than
maxillary teeth:
Maxillary incisor tooth visibility (inversely
proportional to age)
Mandibular incisor tooth visibility (directly
proportional to age).

Young females display a greater degree
of the upper anterior teeth due to
pronounced tonicity and shorter
maxillary lips
Elderly males show little, or no,
upper teeth but more lower teeth
due to tegumental laxness and
longer maxillary lips

The LARS factor to
tooth exposure at rest. Age:
an elderly individual
showing only the lower
incisors

 People age at differing rates because ageing
is a multi-factorial phenomenon described
by the three Ps:
programmed,
pathological, and
psychological ageing.

PROGRAMMED {OR} PHYSIOLOGICPROGRAMMED {OR} PHYSIOLOGIC
AGEINGAGEING
 During youth the process of destruction and
formation of cells is in equilibrium. With advancing
years the balance shifts in favour of increased
destruction and reduced replacement of body
tissues.
 This change is called programmed or physiological
ageing, and is triggered by an internal ‘biological
clock’. Why and when this change occurs is still
unknown.

PATHOLOGICALAGEINGPATHOLOGICALAGEING
 Pathological ageing is due to diseases of the oral
environment leading to accelerated tissue
degradation.
 For example, if anterior teeth are lost due to
refractory periodontitis, premature formation of
nasolabial grooves is evident.

PSYCHOLOGICALAGEINGPSYCHOLOGICALAGEING
 Finally, when feelings of fatality prevail over
those of existentialism, due to emotional and
personal traumas, changes in the psyche are
observed.
 These psychosomatic changes manifest
themselves as psychological ageing.

 The result of the three
Ps of ageing is reduced
tonicity of the orofacial
muscles and laxness of
tegumental relief in the
lower third of the face
resulting in formation
of the labial, nasolabial
and mental grooves and
ridges.
An edentulous 50-year-old woman
showing pathological ageing due to
premature loss of all her dentition in
her twenties, resulting in
development of the nasolabial
grooves and ridges

 The loss of elasticity of the upper lip, with
decreasing tooth support by the gingival
2/3 of the maxillary incisors, accounts for
less maxillary and more mandibular incisor
tooth display.

RACERACE
 A decreasing amount of
maxillary, and an increasing
amount of mandibular tooth
visibility, is seen from
Caucasians to Asians to
Blacks,
The LARS factor to determine the amount of tooth
exposure at rest. Race: black individuals reveal
less maxillary teeth than Caucasianswww.indiandentalacademy.com

 Males generally have longer maxillary lips
than females, leading to an average maxillary
tooth display of 1.91 mm for men and 3.40
mm for women.
 Consequently, gender differ-ences account for
females displaying nearly twice the amount of
maxillary teeth compared with men.
SEXSEX

The LARS factor to
tooth exposure at rest.
Gender: females show
nearly twice the amount
of upper teeth than men

 Before the amount of tooth exposure at rest is
prescribed for the proposed prostheses, each
patient should be assessed according to the LARS
factor.
 An increased maxillary tooth exposure is
indicated for young females, and the opposite for
elderly males.

THE DYNAMIC POSITIONTHE DYNAMIC POSITION
 The second constituent of dento-facial compo-
sition is the dynamic position, typically char-
acterised by a smile.
 The extent of tooth expo-sure during a smile
depends on skeletal make-up, degree of
contraction of the facial muscles, shape and size
of the dental elements and shape and size of the
lips, which vary from extremely thin to full and
thick.

Frontal view of the dynamic position
of the dento-facial composition with
contracted orofacial muscles during
a relaxed smile
Sagittal view of the dynamic
position of the dento-facial
composition with contracted
orofacial muscles during a relaxed
smile

 According to Rufenacht’s
morphopsychological
concepts, individuals with
thin and taut lips should be
provided with teeth which
confer delicacy and fragility.
Frontal view of woman with thin,
taut lips

 Conversely, patients
endowed with thick or
voluptuous lips require
teeth which display
dominance and
boldness
Frontal view of woman with
thick, voluptuous lips

SYMMETRYSYMMETRY
 Whereas in the facial composition horizontal
symmetry is the most important factor, in the
dentofacial view it is radiating symmetry that
takes precedence.
 Radiating symmetry is defined as an object having
a central point, from which the right and left sides
are mirror images.

 In this view, the fulcrum, or central point is the
maxillary dental midline, and the right and left
upper anterior teeth are balanced mirror images.
 However, due to differing wear patterns of the
incisal edges, this ideal is uncommon. Lack of
radiating symmetry is not crucial, so long as there is
balance on the right and left sides of the anterior
dental segment.

COHESIVE FORCESCOHESIVE FORCES
 Cohesive forces, as in the
facial composition, add
interest to the dentofacial
composition.
 These are created by
parallelism of the incisal
(lime green) and
commissural (blue) lines,
with the segregative force
of the dental midline
(yellow) intersecting at 90
degrees. www.indiandentalacademy.com

 Placement of the dental midline has evoked
considerable controversy in dental literature.
 One school of thought states that the maxillary
dental midline should coincide exactly with the
labial fraenum and the facial midline, as it does
in 70% of the population.

 The opposing view is that placing the midline
exactly in the centre may contribute to a sense
of artificiality.
 The choice of where to place this midline
should be determined after aesthetic appraisal.

 If a dominant central point of focus exists, e.g. a
maxillary median diastema, then the midline
should be placed with this focal point as the
fulcrum.
 Another reason for placing a vertically aligned
midline precisely in the centre is to detract attention
from asymmetries and disharmonies of the face.

 Opticians and the cosmetic industry, with dramatic
visual effect, exploit this concept of guiding the eye
to a particular point of focus on the face to mitigate
blemishes or undesirable facial features.

Lack of coincidence of the facial
midline (red) with the maxillary
dental midline (yellow) is not a
prerequisite for aesthetic
approval
Alternatively, a slightly off
centre placement of the dental
midline in relation to the
facial midline is not
detrimental to aesthetic
approval.

THE SMILE LINETHE SMILE LINE
 The smile line is an imaginary line running from the
incisal edges of the maxillary incisors and
coinciding with the curvature of the lower lip.

 When the incisal plane is not parallel with the curvature of
the lower lip then flat, eccentric or reversed smile lines are
evident.
Flat incisal plane due to short
crowns on the central incisors
and lack of anterior-posterior
incisal embrasure progression
revered incisal plane in
relation to the mandibular lip
curvature

 This coincidence between the incisal table and
the mandibular lip is often lost due to
wear by abrasion,
erosion or attrition,
periodontitis,
altered patterns of eruption

Altered eruption patterns of maxillary
teeth resulting in an eccentric incisal
plane, not parallel with the
mandibular lip curvature
Lack of parallelism of the maxillary
incisal plane with curvature of the
mandibular lip due to pronounced wear
of the maxillary teeth

Periodontitis leading to over-eruption
of the lateral incisors leading to
disruption of the incisal plane in
relation to the mandibular lip
curvature
Dento-facial view of patient
showing disharmony of the
maxillary incisal plane in relation to
the mandibular lip curvature

Wear on acrylic teeth of
removable full denture lacking
parallelism with mandibular lip
curvature
Replacement of removable full
denture with restitution of
incisal plane, which is parallel
with mandibular lip curvature

 The anterior and lateral negative spaces act as a
border to the dental elements, with the lips
representing the picture frame.
 These negative spaces provide cohesiveness to the
dentofacial composition, and are also in the Golden
proportion to the anterior dental segment.

 Anterior negative space is
evident during both
speech and laughter.
 while bilateral negative
spaces should be evident
during a relaxed smile.

CASE STUDYCASE STUDY
Anterior dental aesthetics: DentoFacial perspective:
Ahmad: BRITISH DENTAL JOURNAL VOLUME
199 NO. 1 JULY 9 2005
This case study highlights some of the points discussed,
and how these concepts can be used to achieve optimum
dental aesthetics.

A 60-year-old lady attending the practice sought aesthetic
improvement of her maxillary anterior segment.
The preoperative views showed unsightly composite
fillings in teeth 13, 12, 11, 21 and 22. The left canine was
the anteri-or abutment of a defective three-unit fixed par-
tial denture.

The dentofacial composition revealed an undulating
(roller-coaster) incisal plane, in conflict with the lower
lip curvature, which was neither parallel to the
commissural line, nor the gingival exposure line.
Undulation, ‘roller-coaster’
incisal plane
Incisal plane (lime) is neither parallel
to commissural (blue), nor gingival
(white) lineswww.indiandentalacademy.com

The treatment plan to resolve these aesthetic anomalies
consisted of porcelain laminate veneers on teeth 13, 12
and 22, full coverage ceramic crowns on the maxillary
centrals, and a new three-unit ceramo-metal fixed partial
denture with teeth 23 and 25 as abutments and 24 as the
pontic.

The ceramic veneers and crowns blended impeccably with the fixed partial denture,
with optimal gingival health depicted by formation of the gingival groove, knife edge
gingival margins and stippling of the attached gingiva.

The maxillary incisal
plane is now parallel
with the curvature of
the mandibular lip and
to the commisural and
gingival exposure
lines.

Pre- and post-operative facial views showed the
transformation and rejuvenation of the patient from
being dejected and forlorn to a vivacious and
confident persona.

 To summarise, there is no such thing as a perfect
smile, however for the sake of defining guidelines
for prosthodontics, the constituents of an ideal smile
are when:
 The upper anterior teeth coincide with the cur-
vature of the mandibular lip during a relaxed smile.
 The corners of the lips are elevated to the same height
on both sides (termed smile symmetry)

 Bilateral negative spaces are evident, separat-ing
the teeth from the corners of the lips.
 Additionally, the contact points of the anterior
dental segment should also coincide with the incisal
edges and with the curvature of the lower lip, thus
enhancing the cohesiveness of the dentofacial
composition.

BIBLIOGRAPHY
 Anterior dental aesthetics: DentoFacial perspective:
Ahmad: BRITISH DENTAL JOURNAL VOLUME 199
NO. 1 JULY 9 2005
 Anterior dental aesthetics: Facial perspective: Ahmad:
BRITISH DENTAL JOURNAL VOLUME 199 NO. 1
JULY 9 2005
 Anterior dental aesthetics: Historical perspective:
Ahmad: BRITISH DENTAL JOURNAL VOLUME 199
NO. 1 JULY 9 2005

Dorfman WM. How to design smile styles for cosmetic
dentistry. Dent Today 1995 Oct;14(10):68-9
Solomon EGR: Esthetic consideration of smile; J of
IPS 1999: 10(3&4); 41-471)
Singer BA. Principles of esthetics. Curr Opin Cosmet
Dent 1994;:6-1
Messing MG. Smile architecture: beyond smile
design. Dent Today 1995 May;14(5):74, 76-9

Treatment planning for the management of selected
dento-facial abnormalities: C. G. MURRAY: Journal
of Oral Rehabilitation, 1979, Volume 6, pages 89-99
Van Zyl I, Geissberger M. Simulated shape
design. Helping patients decide their esthetic ideal.
J Am Dent Assoc 2001 Aug;132(8):1105-9

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Dentofacial perspective / cosmetic dentistry course

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Dentofacial perspective / cosmetic dentistry course