The Journal
1) Smile arc
2) Anterior tooth display
3) Gingival display
4) Buccal Corridor
SMILE ARC
It’s an imaginary line drawn along the incisal
edges of the maxillary anterior teeth. In an
esthetic smile, the edges of the maxillary
anterior teeth follow a convex or gull-wing
course matching the curvature of the lower lip.5
In a reverse smile line; the centrals appear
shorter than the cuspids along the incisal plane.
Lip line should not be confused with the smile
line.
The smile arc can be unintentionally flattened
during orthodontic treatment by bracket
positioning or by occlusal plane cant. So the
bracket positions must take the relationship of
the incisal edges to the lower lip curvature for
each individual patient into account.
Smile arc can be reverse, consonant or
nonconsonant (flat). Consonant, the curvature
of the maxillary incisal edges coincides with or
parallels the border of the lower lip in smiling.7
In a “nonconsonant” smile arc; the maxillary
incisal edges are either flat or reversed relative
to the curvature of the lower lip.
ANTERIOR TOOTH DISPLAY
A pleasant smile also depends on the anterior
tooth display. Tooth proportion is one of the
most important elements of anterior dental
esthetics. There is a variation on dental
dimensions that can be considered as normal or
desirable, especially when considering that
there are individuals with different facial
patterns. Orthodontists often face the dilemma
of correcting the disproportionate widths of
anterior teeth.
The rule of golden proportion becomes a savior
in many critical situations.
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An illustration of golden proportion shows that
the ideal tooth width proportions from the frontal
view is: 1.618:1.0:0.618. In an attractive smile,
the apparent width of the lateral incisor is 62%
of the width of Central incisor, width of canine is
st
62% of the width of lateral incisor and 1
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premolar is 62% of the width of canine. This
ratio is an ideal treatment guide and can lead to
naturally attractive and pleasing smile to the
eye.
Part of evaluation of dental esthetics for smile
design also includes choosing tooth shapes for
patients based on their facial characteristics.
When patient represent a longer face, more
rectangular tooth within the esthetic range is
appropriate. For someone with square face, a
tooth with an 80% width-to-length ratio would be
appropriate. 9 A classic study that investigated
dental proportions was that by Gillen et al 10 who
found the following proportions of width among
the upper anterior teeth: a) lateral incisors have
78% of the width of the central incisor (lateral
incisor = central incisor x 0.78); b) lateral incisor
has 87% of the width of the canine (lateral
incisor = canine x 0.87); c) canine has 90% of
the width of the central incisor (canine = central
incisor x 0.90). 10
GINGIVAL DISPLAY
Establishing the correct gingival levels for each
individual tooth is the key in the creation of
harmonious smile. The central incisor has the
highest gingival level, lateral incisor is 1.5 mm
incisal to central incisor and canine is at the
same level as central incisor. A difference of
more than 2 mm in the gingival height is
obvious. 11 The cervical gingival height (position
or level) of the centrals should be symmetrical.
It can also match that of the canines. It is
acceptable for the laterals to display the same
gingival level. However, the resultant smile may
be too uniform and it is preferable to exhibit a
rise and fall in the soft tissue by having the
gingival contour over the laterals located toward
the incisal compared to the tissue level of the
centrals and canines.
Vol. 13
12 No. 1
2
3
May-August
Sept-Dec 2017
Jan-April
2016
2016