clinical facial analysis for orthodontist and surgeon by almuzian
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UNIVERSITY OF GLASGOW
Clinical Facial Analysis (CFA) For Orthodontists & Maxillofacial Surgeons
2013
Mohammed Al-Muzian
Mohammed Almuzian, University of Glasgow, 20131
Mind map for Clinical Facial
Analysis
Frontal View
Facial type Vertical heights Lip assessment Symmetry assessment
Skeletal base assessment Smile analysis Dental factors
Profile View
Total profile analysis
Angle of convexity
Powell analysis
Analysis of the high midface
Soft tissue glabella
Orbital rim
Cheek bone contour
Analysis of the maxillary area
Nasal base
Nasal projection
AP lip position
Relationship of upper lip to nose
Analysis of the mandible area
AP lip position
Relationship of lower lip to chin
AP chin position
Relationship of chin to
submental plane
Profile View
Total profile analysis
1. Soft tissue nasion to FH
(Sandler 2006)
Maxilla should be approximately 2-3 mm
in front, and the soft tissue pogonion should
lie 2 mm behind this facial plane.
2. Steiner_Kole technique
3.
It is used to determine the convexity of the
dentofacial complex by using SN-MP angle
which is 32 degree.
The face can be classified into divergent,
convergent or normal
Angle of convexity (facial
convexity or facial angle)
Glabella-subnasale-pog 11-30 degree
Powell analysis Nasofrontal angle 160 degree
Nasofacial angle 40 degree
Nasomental angle (Total facial angle)160
degree
Mentocervical angle 100 degree
Analysis of the high midface
Soft tissue glabella 2mm ahead of the soft tissue nasion
Orbital rim 2mm posterior to the eye globe
Check bone contour. smoothly convex from the outer canthus of
the eye through the sub-pupil area to end in
the alar base
Mohammed Almuzian, University of Glasgow, 20132
Analysis of the maxillary area
Nasal base Subnasale is on 0 degree Meridian line
Nasal projection Distance from tip of the nose to TVL 22m
AP lip position The upper lip normally touch the True
Vertical Line TVL
The upper lip should be 4 mm behind E line
The lips should touch S line
H line should touch U lip & bisect the nose.
Relationship of upper lip to nose Naso-labial angle
85–120
Analysis of the mandibular area
AP lip position The lower lip 0.5mm-2mm behind TVL
The lower lip 2 mm behind E line
The lower lip should touch or 1mm ahead of
S line
Relationship of lower lip to chin Labiomental angle
AP chin position Bass aesthetic line touch ST Pog
Soft tissue pog should be 0 ± 2 mm to Zero
Meridian
Holdaway angle (n-pog-ls) 15 degree
Z angle (FH-pog-ls or li) 71-89 degree
Relationship of chin to
submental plane
Lip-chin-submental plane angle: average 90–
110
Submental plane length 40mm
Mohammed Almuzian, University of Glasgow, 20133
Clinical Facial Analysis (CFA) For Orthodontists & Maxillofacial Surgeons
Key articles (Arnnett 1993)
Introduction
Clinical facial analysis (CFA) is a method utilized by clinician for evaluating and
judging the patient‘s face; to define its proportions, volume, appearance, symmetry, and
visible deformities (Biondi, 2005)
Is CFA parameters are standard?
One of the aims of CFA is to assess the facial esthetic of the patient. Facial esthetic
considered a term used to describe the quality of beauty and acceptance. There are
many factors affect the values and the slandered used during CFA steps which
involve:
1. Racial background
2. Cultural difference
3. Gender
4. Personal preference
5. Clinician philosophy
Importance of CFA
McLaughline and Arnnet in their textbook ‘’ Facial and Dental Planning for
Orthodontist & Oral Surgeon’’ in 2004 simply classify the dentofacial deformities
in adult patient into 3 groups:
G1 which can be addressed comprehensively by routine orthodontics
G2 which represent a deformity with mild to moderate skeletal discrepancies
but can be well treated by some dental compensation to achieve a camoflagable
results
Mohammed Almuzian, University of Glasgow, 20134
G3 represent cases with moderate to severe facial imbalance and malocclusion
which should be treated by combined surgery and orthodontics.
It is inappropriate to provide the treatment modalities of G3 to G2 and vice versa. So,
differentiation between these two groups considered one of the main criteria for
treatment success. The way of differentiating between the two groups mainly depends
on the evaluation and assessment of the diagnostic records among this is the clinical
facial analysis (CFA).
To sum up, the main objectives of CFA are:
1. To diagnose and classify the deformities especially for border line cases.
2. To plan the treatment approach that addresses the patient concerns and complaints.
3. To predict the treatment outcomes & prognosis.
To whom CFA might be beneficial?
1. Plastic surgeons,
2. Maxillofacial surgeons,
3. Ophthalmic plastic surgeons,
4. ENT surgeon,
5. Orthodontists,
6. Rehabilitative dentists,
7. Dermatologists
8. For many nonmedical professionals, such as hairdressers, eyeglasses designers
and make-up artists.
When CFA should be performed?
(Biondi, 2005)
1. Initial CFA usually starts
Mohammed Almuzian, University of Glasgow, 20135
During observation stage: From the time of patient entrance to the clinical
practice.
During questionnaire stage. The clinician should have the skill of interpretating
and understanding the body language.
2. During clinical examination stage and should precedes the intraoral
examination
Methods of CFA
1. Direct clinical examination
2. Clinical photographs
3. Non Radiographical 3D imaging methods (with or without the use of metal
marker)
4. Conventional & 3D x-ray imaging.
Steps in CFA
Before commencing any clinical examination the patient should be in:
1. Natural Head Position (NHP)
History: It was developed by Moores, 1958
Technique: Described clearly by Solow and Tallgren in 1971 (walking in the
room for few minutes to relax then looking at 5 feet distance located mirror while
shaking head until a more comfortable position is achieved)
Reproducibility: It has 2 degree reproducibility (Cook, 1988 & Lundstrom,
1992).
2. Centric relation
3. Relaxed lip position , BOWB (Bite Opening Wax Bite) indicated in case of
vertical deficiency that resulted in soft tissue deformity during CO.
4. First tooth contact
Sometime the use of precentric wax bite is essential when there is more than
1mm incoincednce between the RCP and the ICP.
Mohammed Almuzian, University of Glasgow, 20136
If the wax bite cannot be obtained with the condyle in the RCP due to adaptive
changes, it is recommended to us deprogramming splint for 3-6 months. (Arnnet &
McLughlin, 2004)
5. Then the CFA can be started which involve:
A. Frontal view analysis, this should not be underemphasized since the major concern
of the patient viewed frontally.
B. Profile view analysis
C. 45 degree view analysis (to deeply investigate some feature that cannot be fully
assessed by 2 or 3.
D. Other view analysis including face base (bird view), face down or worm view
(submental), nasal base view (subnasal).
Unattractive features of facial appearance
The flowing features of facial appearance are generally rated as unattractive:
1. Little show of vermilion border
2. A very high or very low smile line
3. An upper lip that slopes backwards
4. An everted lower lip
5. Extreme bilabial protrusion
6. Lack of a well-defined labiomental fold
7. Severe class 2 or class 3 malocclusions
So it should be carefully spotted and analyzed.
Frontal facial analysis
Facial type
The facial height (Tr-Me) to width ratio (Zy-Zy)= (Facial index). This gives
the overall facial type, such as ‘long’ or ‘short’ or ‘square’ face. The proportionate
facial height to width ratio is 1.35:1 for males and 1.3:1 for females. (Naini 2008)
Mohammed Almuzian, University of Glasgow, 20137
Bizygomatic facial width, measured from the most lateral point of the soft
tissue overlying each zygomatic arch (zygion), is approximately 70% of vertical
facial height.
Bitemporal width, measured from the most lateral point on each side of the
forehead, is 60 % of vertical facial height.
Bigonial width, measured from the soft tissue overlying the most lateral point
of each mandibular angle (soft tissue gonion), is usually 50% of vertical facial height.
Vertical heights
1. It is important to consider the vertical facial proportions and their balance in relation
to the patient's general build and personality.
2. Facial thirds described by Bell et al 1980, Fish and Epker 1981: upper third from
hairline (trichion) to glabella or midbrow, middle third from glabella to subnasale,
lower third from subnasale to soft tissue menton (62-75 mm).
3. Ricketts et al 1979 divided the face use the middle and lower facial heights only.
4. However the underlying cephalometric proportions of the middle to the lower facial
height are 45:55. This is because the N, ANS and Me points in cephalometric are used
instead of Glasbella, soft tissue nasion and soft tissue menton in soft tiusse analysis.
This might increase the UFH in clinical analysis.
5. Lower anterior facial third is further subdivided into: (Farkus 1984)
a. Upper lip, Subnasale to stomodion superioris
19-22mm
Male>female
Decreased with aging
b. Lower lip and chin, stomodion inferioris to soft tissue soft tissue menton
42-48mm
Increased with age due to submental fat accumulation
It can be subdivided equally into lower lip (stomodion inferioris to soft tissue B) and
the chin area (from soft tissue B to soft tissue soft tissue menton)
Mohammed Almuzian, University of Glasgow, 20138
c. Interlabial gap
Stomodion inferioris-to stomodion superioris
1-5mm,
Female>male because male have longer upper lip.
An increased anterior lower facial height may be due to:
1.Vertical maxillary excess (VME), resulting from excessive inferior development of the
maxilla. This is often accompanied by excessive gingival display at rest and on
smiling, referred to as a ‘gummy smile’. Usually it cause increase in AFH by posterior
rotation of the mandible.
2.Increased vertical chin length.
3.Posterior mandibular rotation.
4.Over eruption of the posterior teeth causing posterior mandibular rotation
Transverse analysis of frontal view
I. Facial midline:
Perpendicular line from glabella to interpupillary line or to true horizontal line if the
pupils are not leveled.
Middle of philtrum of upper lip (Cupid’s bow) and glabella (Naini and Gill 2008) or
centre of the nasal bridge (Arnett and McLaughlin 2004) used to construct facial
midline. If the nasal deviation is significant, the philitrum might be deviated and the
use of vertical perpendicular from Glabella might be used as alternative. (Sheen,
1978).
Postural camouflage can be a problem with the asymmetrical face. The patient with a
marked occlusal Cant habitually tilted the head to level the lip line giving the
impression of orbital dystopia. This was corrected by bimaxillary levelling of the
occlusal plane.
II. ‘Rule of fifths’. Each fifth is approximately the width of an eye.
Mouth width equal to the distance between the medial iris margins 65mm
Mohammed Almuzian, University of Glasgow, 20139
Alar base width equal to the intercanthal distance 34mm.
Skeletal base assessment in frontal view
Mandibular assessment
Chin-Jaw line: It is a line under the surface of the chin at maximum tissue
contact.
This plane should be parallel to inter-pupillary line in the absence of vertical
orbital dystopia otherwise they described as cant.
Mid face and Maxillary assessment
Increased sclera show above the lower eyelid and below the iris is a sign of
midface deficiency.
Paranasal hollowing/flatness is a sign of maxillary hypoplasia. This may be
observed in frontal and profile examination of the face.
Signs of midface deficiency
1.Increased sclera show above the lower eyelid, normally assessed in the frontal facial
examination, is also a sign of midface deficiency
2.Paranasal hollowing is a sign of midface deficiency,
3.Flattened upper lip
4.An obtuse nasolabial angle.
5.Class III problem
6.Upper arch narrow with cross bite and crowding
7.Wide Buccal corridor
Mohammed Almuzian, University of Glasgow, 201310
Lip assessment (LAMP=line, activity, morphology and position) mini-aesthetic
analysis
a. Vertical lip lines level
1. Lower lip should cover incisal third of maxillary incisors.
2. Maxillary incisor exposure at rest: 2–4 mm at rest.
3. Depends on:
Anterior maxillary height,
Upper lip length,
Clinical crown length,
Vertical maxillary incisor inclination
Lip activity during facial animation.
Combinations.
Where the upper lip length is very short then the patient would expect to show more
of the upper incisors. Any attempt to reduce the incisor exposure in relation to a short
upper lip will lead to an unaesthetic reduced middle face height. Similarly, with a
long upper lip, the patient would be expected to show less or no upper incisor, both at
rest and during facial animation.
b. Lip activity
A strap-like lower lip often retroclines incisors (commonly occurs in Class II
division 2 malocclusions). (Mossy 1981)
Flaccid lips are less likely to significantly alter position with anteroposterior
dental movement.
c. Lip morphology
Vermilion show of lower lip 12mm, upper lip 9mm. (Fish & Epker 1981)
Full lips are less likely to significantly alter position with anteroposterior dental
movement.
Thin lips are more likely to ‘flatten’ with incisor retraction.
Mohammed Almuzian, University of Glasgow, 201311
d. Lip posture
Lip competency help to know the etiology of malocclusion and the possible treatment
stability.
Types of lip relationships are:
1. Competent: Lips held together at rest.
2. Lips habitually competent which are held apart at rest by more than 3–4 mm but the
patient tries to posture his/her haw forward to achieve anterior lip seal like in CLII D1
cases.
3. Potentially competent (lips are unable to be held together due to increased inter-
labial space) and the patient exert muscle effort to close them which can be seen in a
form of active mentalis. The features of this condition are puckering of the chin area
and flattening of the LMA.
4. Rolled blind upper lip , means the lip retract on smiling to show more gum.
Lip incompetency is due to:
With aging the lip incompetency is reduced
Short lip
Increased LAFH due to VME
Increased LAFH due posterior growth rotation,
Over-eruption of BS,
AP skeletal malrelationships.
Proclined ULS or LLS
Dental factors
1. Overbite (3mm or 1/3 of the lower incial crown height)
2. Occlusal plane
A. Upper Occlusal plane which subdivided into anterior and posterior (Profitt et al 1980)
B. Lower Occlusal plane which subdivided into anterior and posterior
The posterior Cant represent skeletal problem while anterior represent dental or it
might be secondary to posterior cant.
Mohammed Almuzian, University of Glasgow, 201312
All these plane should be assessed using fox bite or wooden tongue depressor and
should be parallel to interpupillary line in the absence of vertical orbital dystopia
otherwise they described as cant.
In the presence of orbital dystopia, the true horizontal showed be used. In this case a
direct evaluation is difficult and it is better to take a photograph with the patient biting
on the wooden plate and then assess it.
3. Maxillary dental midline
Assessed in relation to middle of philtrum of upper lip (Cupid’s bow) and to facial
midline.
4. Mandibular dental midline
Assessed in relation to midpoint of chin and to the facial midline and in relation to
maxillary dental midline.
Smile analysis
The components of the smile analysis are:
1. The smile arc is defined as the contour of the incisal edges of the maxillary
anterior teeth relative to the curvature of the lower lip during a social smile. For best
appearance, the contour of these teeth should match that of the lower lip. If the lip and
dental contours match, they are said to be consonant.
2. 100% of incisors show (9-11mm at social smile) and 4mm gingival show
(There are two types of smiles: the posed or social smile, and the emotional smile.
The social smile is reproducible, and is the one that is presented to the world
routinely. The emotional smile varies with the emotion being displayed (for instance,
the smile when you're introduced to a new colleague differs from the smile when your
team just won in the year's biggest upset)
3. Width of smile show premolar and narrow Dark ‘buccal corridors’ on Smiling.
4. Upper and lower dental midline in relation to the facial midline, to the chin
and to each other.
Dark ‘buccal corridors’ might increase due to:
Palatally inclined maxillary posterior teeth;
Mohammed Almuzian, University of Glasgow, 201313
Transverse maxillary deficiency;
Anteroposterior maxillary deficiency.
Wide commissure.
The lip incisor relationship in determining smile line depends on a number of
factors including:
1.Soft tissue problems
Upper lip length.
The ‘smile curtain’, defined as the muscular capacity to raise the upper lip. If the
position of the maxilla and maxillary incisors in relation to the face is correct, yet the
patient presents with a ‘gummy smile’ owing to vertical hypermobilility of the upper
lip, the option of ‘Botox’ injections to the levator muscles of the upper lip is available.
Alternatively, the situation may be accepted.
2.Skeletal problems:
The vertical position of the anterior maxilla. The more inferior the position of the
anterior maxilla, the greater the exposure of the maxillary incisors, and vice versa.
The anteroposterior position of the anterior maxilla.
3.Dental problems
The vertical position of the incisor teeth.
The anteroposterior position of the incisor teeth.
The inclination of the maxillary incisor teeth. Retroclination of proclined maxillary
incisors towards the correct inclination increases the incisor exposure,
Maxillary incisor crown length, including the presence of incisal wear.
4.Gingival problem
The vertical level of the gingival margins on the labial surface of the maxillary incisor
crowns.
Profile analysis
Total soft tissue profile analysis
1. Soft tissue nasion to FH
Mohammed Almuzian, University of Glasgow, 201314
An easy assessment of the relative protrusion of the mid third and mandible can be
made by assessing their position relative to the perpendicular to the Frankfort plane
passing downwards through the soft tissue nasion.
With normal facial proportions the soft tissue profile of the maxilla should be
approximately 2-3 mm in front, and the soft tissue pogonion should lie 2 mm behind
this facial plane.
However the face can vary with ethnic norms, giving anterognathic, mesognathic or
posterognathic profiles (Sandler 2006)
2. Angle of convexity (facial convexity) or profile angle
Glabella-subnasale-pog
Described by Burstone 1965.
Class I occlusion presents a total facial angle range of 165° to 175°.' Class II angles
are less than 165°, and Class III are greater than 175°. Skeletal discrepancies
producing Class II angulation
3. Powell analysis (Powell et al 1984) which is made up of:
1. Nasofrontal angle 160,
2. Nasofacial angle 40,
3. Nasomental angle 160
Mohammed Almuzian, University of Glasgow, 201315
4. Mentocervical angle 100,
4. Steiner-Kole technique
It is used to determine the convexity of the dentofacial complex by using SN-MP
angle which is 32 degree.
The face can be classified into divergent, convergent or normal.
Analysis of the high midface
1. Soft tissue glabella 2mm ahead of the soft tissue nasion
2. Orbital rim 2mm posterior to the eye globe (Fish & Epker 1981)
3. Check bone contour should be smoothly convex from the outer canthus of the eye
through the Subpupil area to end in the alar base. (Fish & Epker 1981)
4. Morphology of the ears: if external auditory meati to lie at unequal levels. This
creates an asymmetrical facial artefact and difficulties when taking a facebow
recording for transfer to the articulator.
Analysis of the maxillary area
A. Nasal base
Can be assessed using:
1. Facial vertical from soft tissue nasion, perpendicular to Frankfort position or maxilla
plane (or ideally true horizontal line) with patient in natural head position.
2. Subnasale is on this line (0 degree Meridian line) developed by Gonzales-Ulloa 1966
B. Nasal projection
Distance from tip of the nose to TVL 22m
C. AP lip position
1. The upper lip normally touch the True Vertical Line TVL describer by Arnett
Mohammed Almuzian, University of Glasgow, 201316
2. Esthetic line (E-line). Joins the nasal tip to soft tissue pogonion. The upper lip should
be 4 mm behind this line in adults. This is very dependent on nasal and chin
projection. (Ricketts 1979)
3. Steiner line (S-line). Joins soft tissue pogonion to the midpoint (columella) between
Subnasale and nasal tip (pronasale). The lips should touch this line.
4. Harmony line (H-lines) as introduced by Holdaway. The H-angle is formed by a line
tangent to the chin (pog) and upper lip (Ls) with the soft tissue N-Pog line. Holdaway
said the ideal face has an H-angle of 7° to 15°, which is dictated by the patient's
skeletal convexity. The ideal position of the lower lip to the H line is 0 to 0.5 mm
anterior.
D. Relationship of upper lip to nose
Naso-labial angle is formed by the intersection of the upper lip anterior and columella
at subnasale.
Average value: 85–120. (Fish & Epker 1981)
It can be divided by true horizontal at subnasale point into two angles (upper one
represent nasal angulation 28 degree and lower angle represent upper lip angulation
85 degree.
In general it depends on
1. Columella orientation,
2. Anteroposterior position of maxillary incisors
3. Inclination of ULS
4. Anteroposterior position of the maxilla,
5. The morphology of the upper lip,
6. The vertical position of the nasal tip.
Analysis of the mandibular area
1. Anteroposterior lip position
The lower lip normally 0.5mm-2mm behind the True Vertical Line TVL described
by Arnett in 1993.
Mohammed Almuzian, University of Glasgow, 201317
Esthetic line (E-line). Joins the nasal tip to soft tissue pogonion. The lower lip 2 mm
behind this line in adults. This is very dependent on nasal and chin projection.
Steiner line (S-line). Joins soft tissue pogonion to the midpoint between subnasale
and nasal tip. The lips should touch this line.
2. Relationship of lower lip to chin
Labiomental angle is formed between the lower lip and chin
Average value: 110–130 degree.
It depends on:
A. Thickness of lower lip
B. Mental fat area
C. A prominence of the chin itself
D. AP skeletal relationship as in class III in which there is a loss of upper incisor support
to lower lip
E. The lower incisor inclination
F. Anterior lower face height, a reduced lower anterior facial height may lead to an acute
labiomental angle due to excessive folding of the lower lip after contacting the upper
incisor on occlusion.
G. Lower lip to upper incisor relationship. In case of lip trap the LMA is increase .
3. Anteroposterior chin position
A. Bass aesthetic analysis (Bass, 2003) uses Subnasale (rather than soft tissue
nasion) from which to drop a perpendicular to the true horizontal line with the patient
in NHP. This analysis is useful for planning treatment in mandibular retrognathia,
where the maxillary position is correct.
B. Zero Meridian line: vertical from soft tissue nasion, perpendicular to true
horizontal line with patient in natural head position. Soft tissue pogonion should be 0
± 2 mm to Meridian line.
C. Holdaway angle: angle between the Pog and lip superioris with NPog. 15
degree
Mohammed Almuzian, University of Glasgow, 201318
D. Profile line or Z angle(of Merrifield). A tangent to the chin and vermilion
border of most prominent lips should ideally intersect with FH at 80+9. (Merrifield,
1966)
E. Kole analysis used two lines. The first from prominent part of upper lip
perpendicular to SN. Other from Or perpendicular to SN. The soft tissue Pog should
be in the middle between these two line.
4. Relationship of chin to submental plane
A. Lip-chin-submental plane angle: average 90–110 degree. It is increased in:
Thick lower lip
Increased submental fat are present. (Moshiri et al, 1982)
Mandibular retrognathia,
Retrogenia,
Lower lip projection due to proclined LLS
B. Submental plane length (soft tissue menton to junction of submental plane and
vertical plane of the anterior aspect of the neck). If excessively short, this is a contra-
indication to mandibular setback, which could result in the formation of a ‘double
chin’.
Mohammed Almuzian, University of Glasgow, 201319
Dental Appearance: Micro-Esthetics.
A. Tooth Proportions
1. Golden Proportion
The apparent widths of the maxillary anterior teeth on smile, and their actual mesio-
distal width, differ because of the curvature of the dental arch.
Particularly, only a portion of the canine crown can be seen in a frontal view.
For best appearance, the apparent width of the lateral incisor (as one would perceive it
from a direct frontal examination) should be 62% of the width of the central incisor,
the apparent width of the canine should be 62% of that of the lateral incisor, and the
apparent width of the first premolar should be 62% of that of the canine
2. Height-Width Relationships: Note that the width of the tooth should be about 80%
of its height
3. Gingival Heights, Shape and Contour, Generally, the central incisor has the
highest gingival level, the lateral incisor is approximately 0.5 mm lower and the
canine gingival margin again is at the level of the central incisor. A discripncy in the
gingival height my be due to:
Pd diseases Teeth attrition Ankylosis Canine substitution of lateral Sever crowding Delayed maturation of gingivae.
B. Connectors
The connector includes the contact point and the areas above it. The normal connector
height is greatest between the central incisors, and diminishes from the centrals to the
posterior teeth.
Mohammed Almuzian, University of Glasgow, 201320
Embrasures: Black Triangles
The embrasures (the triangular spaces gingival to the contact) ideally are larger in size
than the connectors, and the gingival embrasures are filled by the interdental papillae
Short interdental papillae leave an open gingival embrasure and these "black triangles"
can detract significantly from the appearance of the teeth on smile.
Current data indicate that lay observers readily detect open gingival embrasures of 3
mm or more and judge them unaesthetic,
Black triangles in adults usually arise from loss of gingival tissue related to periodontal
disease, but when crowded and rotated maxillary incisors are corrected orthodontically
in adults, the connector moves incisally and black triangles may appear, especially if
severe crowding was present. For that reason, both actual and potential black triangles
should be noted during the orthodontic examination, and the patient should be prepared
for reshaping of the teeth to minimize this esthetic problem
Method to treat black triangle
Correct teeth angulation
Relocate contact point by crown contouring or restorative dentistry
Teeth extrusion to relocate alveolar crest more inciso-occlusally
Tooth Shade and Color
The color and shade of the teeth changes with increasing age.
The teeth appear lighter and brighter at a younger age, darker and duller as aging
progresses. This is related to the formation of secondary dentin as pulp chambers
decrease in size and to thinning of the facial enamel, which results in a decrease in its
translucency and a greater contribution of the darker underlying dentin to the shade of
the tooth.
The maxillary central incisors tend to be the brightest in the smile, the lateral incisors
less so, and the canines the least bright. The first and second premolars are lighter and
brighter than the canines, more closely matched to the lateral incisors.
Mohammed Almuzian, University of Glasgow, 201321