2. OUTLINE
Definition of occlusion
Normal occlusion
Line of occlusion
Ideal occlusion
Static and dynamic occlusion
Anterior and posterior determinant of occlusion
Classification of occlusion
Conclusion
3. DEFINITION OF OCCLUSION
"The relationship of
maxillary and mandibular
teeth when they are in
functional contact during
the activity of the mandible"
ANGLE defined occlusion
as the normal relation of the
occlusal inclined planes of
the teeth when the jaws are
closed.
4. NORMAL
OCCLUSION
Defined from two characteristics:
1. Alignment of the teeth within each arch along
a “line of occlusion”.
2. Occlusion, with the mesiobuccal cusp of the
maxillary first molar occluding with the central
fossa of the lower first molar.
If the teeth were arranged on a smoothly curving line of
occlusion and this molar relationship existed, then normal
occlusion would result.
5. LINE OF OCCLUSION
The line of occlusion is a smooth
curve passing through the central
fossa of each upper molar and
across the cingulum of the upper
canine and incisor teeth.
The same line runs along the buccal
cusps and incisal edges of the lower
teeth, thus specifying the occlusal as
well as inter-arch relationships once
the molar position is established.
6. IDEAL OCCLUSION
" Anatomically perfect arrangement of
teeth".
Angle’s concept was that if the buccal
occlusal line of the mandibular dental
arch was coincident with the central
fossae line of the maxillary dental
arch and the teeth were well aligned,
ideal occlusion would result.
7. STATIC VS DYNAMIC OCCLUSION
The term occlusion has both static and dynamic aspects.
DYNAMIC
Dynamic occlusion is the contacts
between the teeth when the mandible
is moving. The working side is the
side of the mandible towards which
the mandible is moving.
STATIC
Static occlusion refers to
the contact between the teeth
when the jaw is closed and
stationary.
8. DYNAMIC
OCCLUSION
The pathways along
which the mandible
moves are determined
by the muscles of
mastication and two
guidance systems.
9. POSTERIOR DETERMINANT OF
OCCLUSION
TMJ-
Temporomandibular
joint.
Bony surfaces.
Posterior guidance
This is provided by the TMJ.
The mandible moves along
this guidance pathway as the
heads of the condyles move
downwards and forwards in
the glenoid fossae and on to
the articular tubercle.
10. ANTERIOR DETERMINANT
OF OCCLUSION
TEETH:
1. Incisors
2. Canines
3. Premolars
4. Molars
Any teeth that are touching during protrusive or lateral
movements of the mandible are providing anterior guidance.
Provide vertical stops
Guide mandible to the Centric Occlusion
Guide mandible in protrusive, retrusive and lateral
excursions
11. Classification of occlusion
Based on mandibular position
Based on the organisation
Based on pattern
CENTRIC
ECCENTRIC
BILATERAL BALANCED
UNILATERAL
BALANCED
MUTUALLY
PROTECTED
CUSP TO FOSSA
CUSP TO EMBRASURE
13. CENTRIC
OCCLUSION
Centric occlusion is that position of the
mandiblular condyle when the teeth are in
maximum intercuspation.
It is also called inter-cuspal position or
convenience occlusion.
It is the occlusion of opposing teeth when
the mandible is in centric relation.
14. The centric relation is the
relation of the mandible to the
maxilla when the mandibular
condyles are in its most
anterior superior position
in the glenoid fossa with
the articular disc
properly interposed.
It is important to understand
that centric relation is not an
occlusion and has nothing to
do with teeth, it is instead a
jaw relationship.
The head of the condyle lies against the
most superior part of the distal facing
incline of the glenoid fossa.3
15. ECCENTRIC OCCLUSION
Eccentric occlusion is the contacting of opposing occluding
surfaces of the teeth when the jaws are in any other relation
than centric relation.
It can be of two types:
1. Functional occlusion
2. Non-functional occlusion
17. LATERAL EXCURSIONS
Lateral excursions are a form of dynamic occlusion
which occurs when the mandible moves left or right
with teeth in contact. They can be described as:
CANINE GUIDED GROUP FUNCTION
18. Canine guided
occlusion
The canine-guided occlusion is a
mutually protected occlusion
where the vertical and horizontal
overlap of the canine teeth
causes disengagement of the
posterior teeth in the lateral
movement of the mandible
19. GROUP FUNCTION or
GROUPED LATERAL
OCCLUSION
It is defined as the multiple contact
relationship between the maxillary
and mandibular teeth, in lateral
movements, on the working-side,
whilst the rest of the teeth
become discluded. Simultaneous
contact of several teeth acts as a
group to distribute occlusal forces.
20. PROTRUSIVE MOVEMENT
This is the forward sliding of the mandible to come to an edge
to edge incisal relationship.
Ideally, the palatal surfaces of the anterior teeth provide the
guidance and at the point of protrusion, all of the posterior
teeth should disclude, protecting the posterior teeth from wear
and fracture.
21. ORGANIZATION OF OCCLUSION
There are three recognized concepts that describe
how teeth should contact in various mandibular
positions:
1. Bilateral balanced occlusion
2. Unilateral balanced occlusion ( Group function)
3. Mutually protected occlusion ( Canine protected)
22. 1. Bilateral balanced
occlusion
It dictates that a maximum
number of teeth should contact in
all excursive positions of the
mandible.
23. 2. Unilateral balanced occlusion
It requires teeth on the working side to be in contact in
lateral excursion and teeth on the non-working side are free
of any contact.
24. 3. Mutually
protected
occlusion
Anterior teeth overlap
prevents the posterior
teeth from making
any contact on either
the working or non-
working sides during
mandibular
excursions.
25. BASED ON
PATTERN
CUSP FOSSA OCCLUSION
In this type of occlusion, the stump
cusp of one tooth occludes in a single
fossa of a single opponent. This is
tooth-to-one-tooth relation.
CUSP-EMBRASURE
OCCLUSION
In this type of arrangement, occlusion
of one supporting cusps into a fossa
and the occlusion of another cusp of
the same tooth into the embrasure
area of two opposing teeth. This is a
tooth-to-two-teeth relation.
26. Terminologies used in occlusion
PHYSIOLOGIC OCCLUSION:
The occlusion that shows no sign of occlusion related pathosis. It
may not be an ideal occlusion but it is devoid of any pathological
manifestations in the surrounding tissues.
TRAUMATIC OCCLUSION:
An occlusion judged to be causative factors in the formation of
traumatic lesions of disturbances in the orofacial complex.
THERAPEUTIC OCCLUSION :
It is a treated occlusion employed to counteract structural
interrelationship related to traumatic occlusion.
27. CONCLUSION
The study of occlusion is an important aspect of
dentistry.
The orthodontist should know what constitutes a
normal occlusion in order to be able to
recognize abnormal occlusion.
28. BASED ON RELATIONSHIP OF
TEETH
Normal occlusion: Normal (Class I) molar relationship, teeth on line of
occlusion
Class I malocclusion: Normal (Class I) molar relationship, teeth crowded,
rotated, and so on
Class II malocclusion: Lower molar distal to upper molar, relationship of
other teeth to line of occlusion not specified
Class III malocclusion: Lower molar mesial to upper molar, relationship of
other teeth to line of occlusion not specified
29. FEATURES OF IDEAL OCCLUSION
At a tooth level
• Multiple simultaneous contacts in CO
• Forces directed down along the long axis of posterior
teeth
• Cusp to fossa contacts as opposed to cusp to incline
contacts
• Smooth and shallow guidance contacts
At a system level
• Absence of posterior and non-working side
interferences
• Centric occlusion equals centric relation
• Freedom in centric occlusion
• Canine guidance rather than group function
• Protrusive movement with guidance from anterior teeth,
which cause immediate disclusion of posterior teeth
At a patient level
• An occlusion within the neuromuscular tolerances of
the patient, which is determined using an occlusal hard
plastic splint
