facial landmarks & its role in prosthodontics
TRANSCRIPT
The dentist who is treating a patient
esp. with complete dentures has more
to do with the beauty of the face then
any other person. The appearance of
the entire lower half of the face depends
on the denture.
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- Imaginary line
running between the
two pupils of the eye
when the patient is
looking straight
forward.
- Establishing the
anterior Occlusal
plane of the artificial
teeth of the denture.
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- Imaginary line running
from the Inferior border
of the ala of the nose to
the superior border of the
tragus of the ear.
- Establishing the
posterior Occlusal plane
of the artificial teeth of
the denture.
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- Imaginary line
running from the outer
canthus of the eye to
the superior border of
the tragus of the ear.
- Locating the position
of the condyles
The actions of the zygomatic
muscle in elevating the corner
of the mouth in smiling or
laughing produce the
nasolabial sulcus.
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- Nasolabial fold
become more
prominence with aging
& is restored by:
1- vertical dimension
2- anterior teeth
positioning
3- labial flange
- After extraction of
teeth it becomes
accentuated and
should be restored by
complete denture.
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Marionette lines are the lines which runs from the
angle of mouth towards the chin. Important
landmarks for the general expressions of the face.
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NASOLABIAL
ANGLE It is the angle formed between
lower border of the nose and a
line connecting the intersection
of nose and the upper lip with
the tip of the lip.
This angle is normally 110
degree
It reduces in patients with
proclaimed upper incisors
prognathic maxilla.
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Mentolabial Sulcus
Horizontal groove
midway between
the vermillion
border & the
inferior border of
the chin in the
lower is called
Mentolabial sulcus
or groove.
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- It determines the Angle of
Classification:
1- Angle class [I]: Normal ridge
relationship.
2- Angle class [II[: Retruded mandibular
position.
3- Angle class [III]: Protruded maxillo-
mandibular relation ship.
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Incorrect positioning of the anterior
teeth or supporting base material
complete dentures will alter the normal
appearance of the mentolabial sulcus,
vermillion border, and the philtrum in
edentulous patients.
Extra fullness of the lower lip may be the result of too broad mandibular arch or the the elimination or reduction of the mentolabial sulcus.
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- Diamond-shaped
area between the
centre of the upper
lip and the base of
the nose.
- After extraction of
teeth it becomes
flattened and should
be restored by a
complete denture.
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The drooping corners of the mouth tell the
story of the mishappens and misplaced dental
arch form of the anterior teeth.
- (Angular Chilitis): Inflammation and
ulceration as a result of:
1- Prolonged edentulism.
2- ↓ vertical dimension of complete denture.
3- Vitamin B deficiency.
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Ear lobe
The ear lobes can be used during maxillo-
mandibular relationship registration. This is
commenced by comparing the Fox plane guide
should be equal on both the sides and this is
estimated with the practitioners eyes. Any
discrepancies can be adjusted by adding or
removing from the oclusal rim.
As the ear lobes are important stable landmarks
unlike the moving pupils of the patients.
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• Orbitale (B) - Located by Hanau
facebow with help of orbital pointer.
• Orbitale minus 7 mm (C) - This
plane represents Frankfort plane.
• Nasion (A) - Used with quick mount
facebow (Whip mix)
• Ala of nose (D) - This plane
represents campers plane
• 43 mm superior from lower border
of upper lip (Denar reference plane
locator – Denar facebow uses this
reference point)
Various Anterior Reference Points
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Advantages of anterior reference point
1. Can visualize anterior teeth & occlusion
in the articulator in the same frame of
reference.
2. Determines which plane in the head will
become the plane of reference.
3. Determines the level at which the casts
are mounted to establish a baseline for
comparative studies between patient.
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Posterior reference points
A---Beyron point – 13 mm ant to
post margin of tragus of outer
canthus of eye
B---Gysi – 13mm ant to ant margin
of EAM
C---Snow – 11 -13 mm ant to
tragus
D---Denar’s – 12 mm ant to post
border of tragus and 5 mm inferior
to line from EAM and outer
canthus
Posterior Reference PointsIt helps in determining the position of true hinge axis on either side of the face.
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Facial Profiles
Aesthetics and appearance are very crucially
related to the facial profile of the person
concerned.
Faces come in different forms and are often
classified according to their shape and profile
which represent the front and side views
respectively.
These profiles are used to judge aesthetics
of appearance and analysis of characteristic traits
of a subject by face reading professionals
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The facial profile is examined by viewing the
patient from the side. the facial profile helps in
diagnosing the gross deviation of maxillo-
mandibular relationship. the profile is assessed
by joining the following two reference lines.
1. A line joining the forehead and the soft
tissue point A(deepest point in curvature of
upper lip)
2. A line joining point A and the soft tissue
pogonion(most anterior part of the chin)
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The types of face profiles
are as follows:•
Planar or straight :
In this profile, the person
will have neither the
intentional character of the
concave type or the
demanding nature of the
convex type. Their face is
a moderation between the
two profiles.
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Convex:
Convex profile includes
sloping forehead, slightly
prominent brows and
large slightly curved nose.
Further, people of convex
type have a receding chin
shape.•
This kind of profile occurs
as a result of prognathic
maxilla retrognathic
mandible as seen in class
II div 1
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Concave:
Concave profile comes with a
prominent forehead and
almost flat eyebrows. The
nose is bent or smaller and
straight or slightly curved
inward. There is usually flat
and chin is well formed with
an outward curve.
• This type of profile is
associated with a prognathic
mandible or retrognathic
maxilla as in CLASS III
MALOCCLUSION
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Scientists have found eleven
points to map and analyse fac
ial profiles called “fiducials”.
They are:
1.Forehead,
2.Glabella,
3.Nasion (bridge of nose),
4.Pronasale (tip of nose),
5.Subnasale (base of nose),
6.Labiale superius (top lip),
7.Stomion (middle of lips),
8.Labiale
inferius (bottom lip),
9.Supramenton,
10.Menton (chin) and
11.Throat
It is basically the outline form of face esp., anterior view sometimes described geometrically are as1. Square2. Square tapering3. Tapering4. Ovoid
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Smile line
Smile line refers to an imaginary line along the incisal
edges of the maxillary anterior teeth which should
mimic the curvature of the superior border of the lower
lip while smiling. Another frame of reference for the
smile line suggests that the centrals should appear
slightly longer or, at least, not any shorter than the
canines along the incisal plane.
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This approach is particularly useful in
cases of lip symmetry or extreme lip
curvature during smile formation. Reverse
smile line or inverse smile line occurs
when the centrals appear shorter than the
canines along the incisal plane
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Lip line
Lip line should not be confused with the smile
line. It refers to the position of the inferior border
of the upper lip & the gingival edge of the
maxillary central incisors and thereby
determines the display of tooth or gingiva at this
hard and soft tissue interface
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However a 2mm limit should be
established above and below
the gingival edge, thus
instituting 3 classes
1. High lip line – A 2mm or
above display of gingival
tissues.
2. Medium lip line – Gingival
margin & the lip line is
congruent.
3. Low lip line – A 2mm or
more below the cervical line
of upper central incisors.
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Although Maxillary lip line is evaluated
during smiling
Mandibular low lip line is evaluated
during speech
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Extra oral midline references
Determination of the midline reference line
The best way to assess the symmetry of a face is
through the creation of a reference line in the
center of the face. This reference line is usually
obtained by joining two points of the face:
Glabella and Subnasale . The Glabella (Gl) is the
midpoint between the eyebrows and the
Subnasale (Sn) is the base of the nose.
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The line going through Glabella and Subnasale becomes the reference
line . In a clinical setting, a piece of dental floss may be used to
determine the reference midline. This line will be used to determine the
alignment and symmetry of the facial structures in the transverse
dimension. From this line, the general symmetry of the face will be
assessed. Any noticeable variations should be noted.
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Determination of the upper dental midline
A point is placed between the two central
incisors. If the point is on the reference line, the
upper dental midline is centered. If the point is
located to the left or right of the reference line
then the upper midline is deviated and the
direction and the amount of deviation should be
noted. It is important to differentiate between the
facial (Gl-Subnasale) and the upper dental
midline.
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Evaluation of the mandibular midline
A point is placed on the centre of the chin.
This point is called the soft tissue
Pogonion The Pogonion (Pg) is the most
anterior part of the chin. If the soft tissue
pogonion is aligned with the reference
line, the mandible is centered. If this point
is not on the reference line, the mandible
is deviated in the direction of the point.
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Conclusion
It is vivid from the above discussion that the
prosthesis or smile we create should be
aesthetically appealing and functionally
sound too in respect to normal harmony of
the facial landmarks. It is our duty to
carefully diagnose, analyse and deliver the
best to our patients, taking into account all of
the discussed factors.
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References
• Bouchers book of Prosthodontics 9th edition
• Prosthodontic treatment for edentulous patients Zarb 13th
edition
• Essentials of Complete dentures prosthodontics- Winkler
• Journal of Baghdad College of Dentistry vol 22 no 1 2010
pg 11-12
• Current knowledge & perspectives in prosthodontics
kumar p, kumar a
• Esthetic dentistry in clinical dentistry- Marc geissberger
• Internet
• www.dentalpaedia.ca/orthondontic
• www.academia.edu/facialprofiles
• www.toothbody.com/earlobes