The document discusses the relationship between tooth form and function. It explains how characteristics like root size and shape, crown size, contact areas, and embrasures are proportional to each other and related to jaw movements. Tooth form directly influences jaw morphology and movements. For example, humans have more complex tooth anatomy and jaw movements compared to animals with simpler conical teeth. The positions of contact areas, contours, embrasures, and occlusal curves are adapted for functions like mastication, protection of tissues, and self-cleansing of teeth.

1. DR MONIKA NEGI
Oral Pathology Microbiology and
Forensic Odontology

2. Form follows Function
Explains the inter –
relation of the shape of
some part and its
function .

3.  Size of crown and root ,root form
 Tooth form and jaw movements
 Proximal contact areas
 Interproximal spaces
 Embrasures (SPILLWAYS )
 Facial and lingual contours of teeth :mesial and distal
 Curvature of the cervical line (CEJ )
 Occlusal curvatures

4.  Should be proportional to each other
and to jaw .
 Reflects the function of teeth .
 Example :
 Canine : long roots (extra size and
length of root ensures enough
anchorage and support for canine
teeth bear shear forces .)
 Molars :Multiple roots( withstand
masticatory forces )
 Developmental depressions
(enhance anchorage in the alveolar
bone )

5.  Tooth form have direct influence on the jaw movements
.
 Example :
 In animals teeth are conical ,have simple opening and
closing type of jaw movements without lateral
movements .
 Because of interlocking conical form of teeth ,TMJ
morphology ,equal sized jaw and lack of muscles to
carry out lateral movemnts .

6.  In humans ,jaws are not of same size
 Maxilla overlaps mandibular arch labially and bucally
in horizontal plane .
 TMJ is specialized in humans as the occlusal anatomy
of teeth is complex .
 INCREASING COMPLEXITY OF JAW MOVEMENT IS
ASSOCIATED WITH COMPLEXITY OF OCCLUSAL
ANATOMY OF TEETH .

8.  From labial and lingual –Teeth are narrower at cervix
mesiodistally than they are towards the occlusal surface .
 Triangular or pyramidal shaped space between the
approximating teeth just cervical to contact area is created .
 BASE –Alveolar process between adjacent teeth
 Triangle are formed by proximal surface of teeth and the
apex of the triangle is at the contact area of the two teeth .
 ACCOMMODATE AND PROTECT INTERPROXIMAL
SPACES .
 Gingival tissue that fills the interproximal space is
called the gingival papilla/ interdental papilla .

9.  Base=alveolar bone
 • Sides=prox. surfaces of teeth
 • Apex=proximal contact area
 • These triangular shaped areas are
normally filled with gingival
tissues

10.  Gingiva covers alveolar process of jaw bones
(ATTACHED GINGIVA ) ,extends around the neck of
tooth to form gingival crevice (free/marginal gingiva )
and fills the interdental space .(gingival/interdental
papilla )
 Mucogingival line marks the junction between
attached gingiva and alveolar mucosa .
 The part of interdental gingival tissue that lies below
the contact area and extends faciolingually is called col

11.  Col is non keratinized and vulnerable to trauma
during mastication and invasion by bacteria .
 Tight contacts and proper interproximal spaces
between adjacent teeth help to protect the col and
interproximal gingival tissue .
 BUCCALLY /LINGUALLY – Roots of teeth taper from
cervix to apices creating enough space between the
roots of adjacent teeth .
 Allows sufficient alveolar bone between one tooth to
another ,so that the teeth are securely anchored in the
jaws .

13.  Proximal Contact Areas • All
teeth contact adjacent teeth at a
proximal contact area except: –
distal of the last tooth In the
arch – diastemas – pathology.
 CONTACT AREA- it is formed
because of wear of one proximal
surface against another during
physiologic tooth movement.
 MAXILLARY AND
MANDIBULAR CENTRAL
INCISORS ARE THE ONLY
TEETH HAVING MESIAL
SURFACE FACING EACH
OTHER .

14.  – Ensures food will not be packed between teeth
causing inflammation to the supporting tissues
thereby causing gingivitis & periodontitis
 – It helps stabilize the dental arches by the combined
anchorage of all the teeth in either arch in positive
contact with each other (exception - third molars.)
 – Each tooth is individually supported by these
contact areas.

15.  CONTACTS are OBSERVED
from 2 views
 • Labial /buccal aspect
demonstrates the
cervicoincisal/cervico -occlusal
position
 • Incisal /occlusal aspect
demonstrates the facio-lingual
position

16.  • Anterior teeth have
contacts that are generally
centered faciolingually
when view from the incisal
 • Posterior teeth have
contacts that are generally
located buccal to the center
of teeth when viewed from
the occlusal

17.  HEIGHT OF CROWN DECREASES FROM INCISOR –
MOLAR
 MORE CERVICALLY POSITIONED WHEN MOVING
AWAY FROM THE MIDLINE .
 DISTAL CONTACT AREA IS MORE CERVICALLY
PLACED THAN MESIAL .
 EXCEPT – mand 1ST PREMOLAR (mesial more
cervically )
 Mand CI ( both at same )

20.  1. Contact area move cervically
from anterior to posterior in
each quadrant
 2. On individual teeth the
distal contact is more cervically
located then the mesial contact
 3. Contacts increase in size
from anterior to posterior 2
**Note: Contacts on incisors in
incisal1/
 3, Where as contacts on molars
in middle /3

21.  Mandibular Teeth:
Contact their class
counterpart and the tooth
mesial •
 Maxillary Teeth: Contact
their class counterpart
and the tooth distal

24.  The curvature formed
by two adjacent teeth in
an arch form a spillway
space that is called an
embrasure
 Note the Symmetry of
the embrasure of the
central incisors

25.  Embrasures are named
relative to the contact
area
 – Facial or lingual
views show the
occlusal/ incisal
embrasures and
cervical/ gingival
embrasures
 – Occlusal views show
the buccal/ labial and
lingual embrasures

26.  Facial or lingual aspects:
 – The incisal / occlusal
embrasures increase in
size from anterior to
posterior
 – The cervical embrasure
decreases in size from
anterior to posterior
 – The incisal embrasure
of the maxillary
lateral/canine =greatest
or longest
 – The incisal embrasure
of the maxillary
canine/premolar= widest
angle

27.  Embrasures
 • Mandibular posterior area
occlusal view
 • Arrows denote the facial and
lingual embrasure areas
 • The lingual embrasures are
larger than the facial embrasures,
because of lingual convergence of
the crown.

28.  • Serves as a spillway for food material during
mastication
 • Prevents food from being forced through the contact
area and injuring the periodontal tissues.
 • Also, Enhances the self-cleansing process of the
tooth by exposing the surfaces to oral fluids,
mechanical cleansing, and friction from the tongue,
lips, and cheeks

29.  It is a line encircling a
tooth In more or less
horizontal plane,
representing its greatest
circumference.
 The facial and lingual
contours:
 • Protect the gingiva by
the deflection of foods
and help prevent trauma
Buccal Lingual

30.  Buccal Lingual The
height of contour on
both the facial and
lingual surfaces of
anterior teeth is located
in the cervical third.

31.  The height of contour of the buccal
surfaces of posterior teeth is located
in the gingival third
 • The height of contour of the lingual
surface of posterior teeth is located
in the middle or occlusal third
 • The average curvature is around
0.5mm, with mandibular posterior
having a lingual curvature of 1 mm. •
Mandibular anteriors having
curvature of less than 0.5mm.

34.  The CEJ is a stable line whose
curvature is related to the
widths and lengths of the
crown and the location of the
contact areas interproximally
The extent of the curvature
depends on
 • Height of the contact area
above the crown cervix
 • Diameter of the crown
labiolingually.

35.  The CEJ is curved toward the
apical on the facial and lingual
surfaces of teeth
 • The CEJ is curved toward the
incisal or occlusal surfaces on
the proximal surfaces of teeth
 • The depth of the curvature is
greater on the mesial than on
the distal aspect
 • The depth of curvature on the
CEJ on all surfaces is greater on
anterior teeth and decreases
toward the posterior

36.  CURVE OF SPEE
 CURVE OF WILSON
 CURVE OF MONSON

38.  OCCLUSAL CURVATURES
Curve of Spee
 Curvature which begins at
the tip of canines & follows
buccal cusp tips of premolars
& molars posteriorly, when
viewed from their facial aspect

39.  Curve of Wilson
 The medio-lateral curvature of
the occlusal plane of posterior
teeth.
 Two dimensional & approax.
right angles to that of the Curve
of Spee.
 Complement paths of condyles
during movements of mandible.

40.  The crowns of mandibular
posterior teeth must incline to
lingual, while crowns of maxillary
posterior teeth must incline toward
buccal
 This curve becomes deeper
posteriorly, so that molars
inclination is greater than that of
premolars

41.  Because of this curve &
associated tooth inclinations,
buccal cusps of mandibular
molars & lingual cusps of
maxillary molars usually appear
to be longer

42.  It is a curve obtained by
extending the curve of spee
and curve of wilson to all
cusps and incisal edges .