Dental Occlusion

1. Occlusion
Dr Laila Amin
DrLaila Amin

2. Objectives:
 Define centric occlusionfunction
 Illustrate supporting/guiding cusps
 Enumerate key of occlusion
DrLaila Amin

3. Objectives :
 Enumerate angles classification
 Relate importance of proper
occlusion with the clinical practice
 Classify mandibular movement
DrLaila Amin

4. Centric Occlusion
maximum
inter-
cuspation
most retrusive unstrained position
of condyles in glenoid fossa
GLENOID
FOSSA
TOOTH –TO- TOOTH RELATIONSHIP
1
DrLaila Amin

5. 7-Occlusal contact and intercusp Relations
of all Teeth in One Arch with those in the
Opposing Arch in Centric Occlusion.
a
b
c
a) Supporting cusps. b) guiding cusps
c) centric stop
DrLaila Amin

6. Supporting cusps: the cusp that makes contact with
a centric stop in the opposing tooth
Centric stops: areas of contact that a supporting cusp
makes with opposing teeth
DrLaila Amin

7. Supporting cusps:
1)Maintain the distance
between max, man
2)Support the vertical
dimension
3)Play the major role in
masticationDrLaila Amin

8. DrLaila Amin

9. DrLaila Amin

10. Guiding Cusps: the cusps that
are free of contact during
centric occlusion
1)Minimize tissue impingement
2)Maintain the food bolus on
occlusal table
3)Guide the mandible during
movement
DrLaila Amin

11. key of occlusion
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12. 1.First permanent teeth to erupt
in the oral cavity.
2.Occupy a central position in the jaw
(antro-posteriorly).
Key of Occlusion:
Maxillary & mandibular
1st permanent molars
serve as “Key of
occlusion”:
Why?
DrLaila Amin

13. 3- Their positions in the jaws
are guided by the presence
of the deciduous molars
preceding them.
4- Their eruption is not disturbed as
they have no predecessors.
5- 6 is considered more accurate than
6 as it is attached to a bone fixed to
the base of the skull.
DrLaila Amin

14. Key of occlusion : 6
6
Key of occlusion
means:
• in normal jaw relation,
• normal sized teeth ,
•teeth in correct position,
MB cusp of upper 6
occlude in the MBG of lower
6, this normal relation of
these two teeth is called
key of occlusionDrLaila Amin

15. Angle’s
Classification:
Class I:
• Normal
Class II: Retrognathic
• Retruded profile
• Deficient in chin length
Class III: Prognathic
• Protruded profile
• Excessive in chin length
DrLaila Amin

16. MB cusp 6
MB groove 6
Classification of Occlusion
Class I :
Centric occlusion:
Angle’s Classification:
MB
MB groove
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17. Class II malocclusion
Retrognathic profile
Classification of Occlusion
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19. Class III malocclusion
Anterior cross bite
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21. Class I
Class II
Class III
Angle’s Classification:
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22. The centric relation of the teeth in
centric occlusion
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23. Centric Occlusion of Permanent Teeth
Each tooth in a dental
arch occludes with two
teeth in
the opposing arch ,
except:
the mandibular central
incisor
the maxillary third molar.
1
1 2
5
5
4
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24. The centric relation of the teeth
in centric occlusion
The median plane is coincident in two jaws
Upper tooth has labial relation to lower incisor in
centric relation
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25.  Incisal ridges is free of contact , labial relation to
labioincisal portion of lower central & lateral incisor
 Cingulum above the lingual embrasure of 1&2 lower
incisor
 Mesial outline is in line with the mesial outline of lower 1
incisor
 distal outline is centered above labial surface of lower 2
incisor
Upper central incisors:
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26. Upper lateral incisors
 MOL: above the labial surface of lower 2
 DOL: above the labial surface of lower 3
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27. Lower 1, 2
Lower 1
LI R: contact 1 at junction
incisal and middle third
MOL: with midline
DOL: below mesial 23 1
Lower 2
LIR: contact 1,2 at junction of
incisal , middle third
MOL: below distal 13 of 1
DOL: below 2
DrLaila Amin

28. Lower 3Upper 3
Below lingnal embrasure 2,3above labial embrasure lower
3,4
Cusp
Free, below ling embrasure 2,3Free, above ling embrasure 3,4Cingulum
Below lingual surface 2Above the cusp tip lower 3MOL
Below ling surface 3Above lower 4 (BC)DOL
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29. Facial relation premolarsmolars in centric
occlusion
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30. lingual relation of premolarsmolars in
centric occlusion
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33. SUMMARY STATEMENTS:
1. ML cusp of each maxillary
molar occludes in the central
fossa of the opposing
mandibular molar.
2. MB cusp of each mandibular
molar occludes on the MMR of
the opposing maxillary molar.
DrLaila Amin

34. 3- Functional cusps:
B cusps of mandibular posterior teeth.
L cusps of maxillary posterior teeth.
DrLaila Amin

35. Centric occlusion relation of the deciduous teeth:
At age 3 years the child has centric
occlusion similar to permanent teeth
DrLaila Amin

36. DrLaila Amin

37. 8-The Occlusal Contact and Intercusp
Relations of all the Teeth During the Various
Functional mandibular movements.
Mandibular movements are: (rotating movement )
A.Symmetrical bilateral movements:
• Depression.
• Elevation.
• Protrusion.
• Retrusion.
B.Asymmetrical bilateral movements:
• Right lateral movements.
• Left lateral movements.
DrLaila Amin

38. Rest position of the mandible :
•When the mandible is at rest lower teeth are not in contact
with the upper teeth as there is a space of 2 mm in-between
the two arches freeway space .
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39. functional relations of mandibular
movements:
Protrusive occlusal relation.
Retrusive occlusal relation.
Right occlusal relation.
Left occlusal relation
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40. •The mandibular arch
bears a forward,
anterior relation to its
centric relation with the
maxillary arch.
•Biting or shearing food
material
1) Protrusive occlusal relation:
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41. •Retrusion of the mandible,
•the mandibular teeth will
have posterior relation to
centric occlusion with the
maxillary arch.
•Very limited and non
functional movement.
2)Retrusive occlusal relation:
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42. •The mandibular dental arch is
placed in a right or left lateral
relation to centric occlusion with
the maxillary arch.
3) Right and left lateral occlusal relation:
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43. The masticatory cycle of posterior
teeth:
•The working side shows the buccal cusps
of maxillary and mandibular teeth to be in
contact.
•The balancing side shows contact of
lingual cusps of the maxillary teeth with
the buccal cusps of mandibular teeth.
•Then both sides move to centric occlusion.
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44. Working side Balancing side
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46. The masticatory cycle of anterior teeth:
• In bitting
• the functioning side is located at the
anterior teeth
• the balancing side at the posterior teeth.
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49. The term key of occlusion refers to the
relationship of the
1.Buccal cusps of the mandibular molars to the
central fossae of the maxillary molars
2.Maxillary and mandibular canines
3.Mesiobuccal cusp of the maxillary first molar
to the mesiobuccal groove of the mandibular
first molar
4.Mandible and maxilla
DrLaila Amin

50. When the mandible is in its physiologic rest
position, there is
1.Premature contact of teeth
2.No contact of teeth
3.Maximum contact of teeth
4.Slight contact of teeth
DrLaila Amin

51. When a permanent mandibular canine is
located distal to the maxillary canine during
full closure of the mandible, this is regarded
as a
1.Class I occlusion
2.Class II occlusion
3.Class II occlusion
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52. Class III malocclusion is very often when
1.The maxillary arch is larger than the mandibular
arch
2.Maxillary and mandibular arches are proportion to
each other
3.The maxillary arch is smaller than the mandibular
arch
DrLaila Amin

53. DrLaila Amin