Occlusion of Teeth Question And Answers

Occlusion

Question 1. Describe in detail the occlusal relationship of maxillary and mandibular teeth.
Answer:

• The arch form of the maxilla tends to be large than that of the mandible.
• Asa result, the maxillary teeth overhang the mandibular teeth when the teeth are in centric occlusion.
• When the teeth of one jaw come into occlusal contact with their antagonists in the opposite jaw, curved surfaces come into contact with curved surfaces.
• These surfaces may be convex or concave

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• Lingual surfaces of maxillary incisors present some concave surfaces where convex portions of the incisal ridges of mandibular incisors come into occlusal contact.
• Pointed cusps contact marginal ridges on the posterior.
• Deeper portions of sulci and grooves over posteriors provide escapement of food.
• Each tooth has two antagonists, the loss of one still leaves one antagonist remaining.
• This keeps the tooth in occlusal contact with the opposing arch and keeps it in its own arch relation at the same time.
• This prevents elongation and displacement through the lack of antagonism.

Contacts:

• The lingual cusps of the maxillary posterior teeth and the buccal cusps of the mandibular posterior teeth are supporting cusps.
• Areas of occlusal contact that a supporting cusp makes with opposing teeth in centric occlusion are centric stops.

List of occlusal contacts (total 138):

• Lingual surfaces of maxillary incisors and canines – 6
• Labial surfaces of mandibular incisors and canines – 6
• Triangular ridges of maxillary buccal cusps of premolars and molars – 16
• Triangular ridges of mandibular lingual cusps of premolars and molars – 16.
• Buccal embrasure of mandibular premolars and molars – 8
• Lingual embrasure of maxillary premolars and molars 1- 0
• Lingual cusp points of maxillary premolars and molars – 17
• Buccal cusp points of mandibular premolars and molars – 16
• Distal fossae of premolars – 8
• Central fossae of the molars – 12
• Mesial fossae of the mandibular molars – 6
• Distal fossae of the maxillary molars- 6
• Lingual grooves of the maxillary molars – 6
• Buccal grooves of the mandibular molars – 6

Question 2. Centric relation and centric occlusion
Answer:

Centric relation:

• It is the relation of the mandible to the maxilla when the condyles are in the uppermost superior position in their glenoid fossa with the articular disc properly interposed.

Centric occlusion:

• It is the position of the mandibular condyle when the teeth are in maximum intercuspation.

Question 3. Leeway space.
Answer:

• The combined mesiodistal width of premolar and permanent canines is less than that of deciduous molars and canines.
• This is called leeway space.
• Value: Maxillary arch – 1.8 mm
• Mandibular arch-3.4 mm

Question 4. Occlusion.
Answer:

• It is the normal relation of the occlusal inclined planes of the teeth when the jaws are closed.
• It is the contact relationship of the teeth in function or parafunction.

Question 5. Overjet and overbite.
Answer:

Overjet:

• It is the horizontal overlapping of the maxillary and mandibular anterior.
• Value: 1.4-2 mm

Overbite:

• It is vertical overlapping of maxillary and mandibular interiors.
• Value: 1.5-2 mm.

Question 5. Mesial drift.
Answer:

• It describes the migration of teeth in a mesial direction.

Causes:

• Transaction of transseptal fibers.
• It is an active mechanism
• Forces of mastication
• Tongue pressure
• Occlusal forces.
• It is the passive mechanism of Closure of proximal tooth contacts.