Occlusion occurs when the maxillary and mandibular teeth contact during function. Ideal occlusion involves specific patterns of contacts between teeth. Angle's classification describes the relationship between the first molars and canines. Proper tooth positioning and morphology allow for appropriate mastication and protection of supporting structures.

1. Occlusion
Form and Function
CHAPTER 15-16

2. General Information
Occlusion occurs when maxillary and mandibular
teeth contact each other in any functional
relationship
Study of occlusion is concerned with all factors
involved in development, stability, and function of
masticatory system
Occlusion first occurs after the eruption of the
primary dentition

3. Ideal Occlusion
Ideal occlusion implies complete,
harmonious relationship of teeth, as well
as all other mouth structures
Teeth would conform to specific pattern
that includes 138 occlusal contacts on all
32 permanent teeth
This ideal relationship rarely exists

4. Ideal Occlusion
Maxillary teeth facially overlap mandibular by ⅓ and
is distally positioned by ½ tooth length from the
mandibular
Referred to as Interdigitation
Also noted by the positioning of the permanent first
molars and canines

5. Normal Occlusion
Normal occlusion is similar to ideal occlusion with
added common variations
Variations are considered acceptable if there is functional
comfort and stability of alignment
Necessary for each tooth to be able to withstand the biting
force
The biting force for posterior teeth is about 100-170lbs
The first permanent molars are considered key and is the
same as in an ideal occlusion

6. Malocclusion
Any deviation from ideal positioning of teeth
Can be minor in one tooth, severe in several teeth or
the jaws
Based on the relationship of the maxillary and
mandibular first molars and canines
Any variation in this relationship constitutes
malocclusion

8. Occlusal Deviations Involving Several Teeth
 Openbite is existing space between
mandibular and maxillary teeth
Can be anterior or posterior, unilateral or
bilateral
Overbite is a deep or vertical overlap of
maxillary teeth onto mandibular teeth
Exceeds normal or 1/3rd depth of
mandibular incisors

9. Occlusal Deviations Involving Several Teeth
Overjet is a horizontal overlap
creating a protrusion or space
Between the labial surface of the
mandibular incisors and the lingual
surface of the maxillary incisors
Crossbite is facially positioned
mandibular tooth, or teeth
Can be:
anterior or posterior
buccal or lingual

10. Occlusal Deviations Involving Several Teeth
Edge-to-edge or end-to-end is
contacting incisal edges or cusp tips of
opposite arch, rather than interlinking
of cusp and fossae
Actually a crossbite or precrossbite
Underjet is a horizontal relationship
where maxillary anteriors are lingual to
mandibular anteriors

11. Occlusal Deviations Involving Individual Teeth
Labioversion/buccoversion
Tooth positioned more facially than
normal
Linguoversion
Tooth positioned more lingually than
normal
Infraversion
Tooth positioned below plane of
occlusion

12. Occlusal Deviations Involving Individual Teeth
Supraversion
Tooth positioned above plane of occlusion
Torsoversion
Rotated tooth

13. Angle’s Classification of Occlusion
Dr. Angle was first to develop a system to classify
malocclusion
Because mandible is movable, Angle’s classification
relates to anterior–posterior or mesiodistal deviations
in relation to first molar
The first permanent molars are considered the key to
occlusion.
Three classifications

14. Class I: Neutrocclusion (Normal)
Both permanent first molar and canine relationship are
in ideal position
Mesiobuccal cusp of maxillary first molar rests in
mesiobuccal groove of mandibular first molar
Maxillary canine occludes with distal inclined plane of
mandibular canine and first premolar
Can be deviations of the anterior teeth but the molars will
have ideal positioning

15. Class II: Distocclusion
The mandibular first permanent molar and canine are
more posterior
By at the least width of a premolar more than ideal position
Even when molars are in a more distal position, other
deviations can occur
Creating two divisions
Class II, Division I
Class II, Division II

16. Class II: Distocclusion
Division I
Protrusion of incisors or overjet; overbite, crowding,
or labial inclination of maxillary incisors
Division II
Protrusion of maxillary lateral incisors
Retrusion of maxillary central incisors

17. Class III: Mesiocclusion
Permanent mandibular first molar and canine are
more anterior
By at least the width of a premolar more than normal
position
When molars are more mesially located, other
conditions can also occur
Anterior crossbite
Edge-to-edge contact

19. Related Terms
Profiles
 Mesognathic: normal profile
 Prognathic: when mandible protrudes
 Retrognathic: when mandible retrudes
 Centric Occlusion: the most Retruded position of the condyle in the
mandibular fossa
 Functional Malocclusion: occlusal deviation created by habits or
muscular dysfunctions.
 Certain habits such as thumb sucking or revise or deviant swallowing may
cause malocclusion depending on the intensity, duration, and/or age at which
they occur

20. Primary Teeth Occlusion
Spacing of primary teeth plays important part of
occlusion of permanent teeth
The position of the primary second molar is
important determinant of permanent tooth
alignment
If second molars are in Class I position, permanent teeth
will usually be guided into Class I position
The positioning is then referred to as Class I mesial step

21. Primary Teeth Occlusion
Primary molars often show cusp to cusp
relationship called terminal plane
Also considered Class I
Extra space is provided in the area of the molars
allowing for the mesial shift of the permanent
mandibular first molar

22. Primary Teeth Occlusion
B: Mesial Step
• The distal surface of the
mandibular molar is mesial to
that of the maxillary molar,
thereby forming a mesial step.
Most children have this
relationship.
A: straight (flush) terminal plane.
• The distal surfaces of the second
primary molars are on the same
vertical plane. A moderate
number of children have this
relationship.
C: Distal Step
• The distal surface of the
mandibular molar is distal to that
of the maxillary molar, thereby
forming a distal step. Few
children have this relationship.

23. Summary
Occlusion occurs when maxillary and mandibular teeth
are in contact in any functional relationship
Ideal occlusion occurs when teeth conform to specific
pattern of contacts
Angle’s classification used to describe relationship of
first molars and canines

24. General Information
For teeth to masticate food, appropriate position
in arch must be maintained
Correct positioning also necessary to assist
protection of supporting structures which sustain
tooth function
Form and function are concerned with how
position and shape of teeth enable use

25. Proximal Contact Areas
 A small spot on mesial and distal surface of each
tooth that contacts proximal tooth
Every tooth, except last molars in arch, has both distal and
mesial contact area
These areas are generally widest point on the crown of
tooth
Contact areas of the anterior teeth are located more
incisally than the posterior

26. Function of Contact Areas
Proper contact between teeth prevents food
from packing between them
Protects gingiva from food lodged between the
teeth
Stabilize teeth in arch by providing mutual
support

27. Interproximal Spaces
 The area between each tooth normally filled with interdental
papilla
Boundaries form triangle with sides of proximal surfaces of teeth
The base in alveolar crest and apex is contact area
The apex of the interproximal space boundary
Widest point of the crown of the tooth

28. Function of the Interproximal Space
Appropriate width between each tooth (base of the
triangle) is important to
Provide enough space for periodontal structures
Allow ample bone between each tooth for adequate
support
Maintain level of gingival tissue

29. Embrasures
Any curvature, either toward or away from contact
area
Located on incisal, occlusal, lingual, or facial surface
Often referred to as spillways because they assist food
in “spilling” away from tooth

30. Function of the Embrasures
Embrasures or spillways act as an escapement
Keeps food from clinging to teeth or forced into
interproximal spaces
Assists in cleaning tooth and protects gingival tissue
from being irritated by keeping food away from it

31. Compensating Curvatures
Compensating curvatures of the arches account for the
strength, efficiency and stability of teeth
Have no special use other than assist in define occlusion
Main use is construction of dentures or balancing of arches

32. Compensating Curvatures
Curve of Spee
When viewed from a point opposite
the first molars and the teeth are in
normal alignment, a curve forms on
the line of the occlusal plane
Extends from the incisal edge of the
central incisors to the distal buccal
cusp of the second molar
The curve is concave toward the
mandible

33. Compensating Curvatures
Curve of Wilson
A curvature visable when
the arches are viewed from
a frontal position
Concave curvature that
extends from the cusp tip of
the right molar to the cusp
tip of the left molar

34. Summary
Proper proximal contact areas prevent food
from packing between teeth
Embrasures act as spillway so that food does
not cling to teeth
Interproximal spacing allows adequate space
for periodontal structures to support teeth