Occlusion

Question 1

What kind of dental treatments can affect occlusion?

Answer 1

Tooth restoration

Tooth movement

Tooth adjustment

Tooth removal

Question 2

What kind of occlusal issues can patients commonly present with?

Answer 2

Tooth wear (attrition, erosion, abrasion, or abfraction)

Overloading

Fractured cusp or restoration

Question 3

What is the significance of poor occlusion?

Answer 3

Limited evidence suggests that a change in occlusion will precipitate morphological changes in the TMJ

Most likely adaptation occur in teeth and their supporting structures (tooth wear, movement, and fracture)

Question 4

What causes attrition of incisors?

Answer 4

Possible causes include:

Lack of posterior tooth support

Abrasive restorative material

Bruxism

Question 5

What are the features of generalized attrition?

Answer 5

Severe wear, fractured teeth and elongated alveolar processes

Dentoalveolar compensation: Limits vertical space for dental restoration

Question 6

What are splayed teeth?

Answer 6

Outward projection of anterior teeth

Question 7

What are possible causes of splayed teeth?

Answer 7

Loss of posterior teeth

In conjunction with periodontal problems (Reduced PDL supports)

Soreness of anterior teeth precede tooth movement

Over contouring of palatal surface of maxillary incisors or incisal/labial surfaces of mandibular incisors

Question 8

What causes pain on biting?

Answer 8

Compression of the periodontal ligament. This can be caused by premature occlusal contacts or occlusal interferences

Question 9

What causes sensitive teeth?

Answer 9

Could result from occlusal overload. (could be after a poorly finished restoration causing occlusal interferences)

Question 10

What occlusal issues can cause hypermobility?

Answer 10

After poorly finished restoration causing occlusal interferences

All mobile teeth should be assessed to rule out deflective contacts or occlusal overload as a factor in the cause of the mobility

Question 11

What does a fractured cusp eventually cause?

Answer 11

Fracture lines routinely develop when a cusp is loaded with heavy occlusal forces

Can precede split tooth

Results in symptoms of cracked tooth syndrome

Question 12

What are the potential outcomes of poor occlusion?

Answer 12

Incisal wear (attrition)

General attrition

Splayed teeth

Sore teeth (biting sensitivity)

Sensitive teeth (hypersensitivity caused by occlusal overload)

Hypermobility

Fractured cusp

Painful musculature

Question 13

What causes painful musculature as a result of poor occlusion?

Answer 13

Deflective occlusal interferences that cause jaw joints to displace

Unbalanced muscle contraction

Question 14

What is occlusion?

Answer 14

Contacts between teeth

The relationship between the incising or masticating surfaces of the maxillary or mandibular teeth or tooth analogues

Question 15

What are the components of the masticatory system?

Answer 15

Teeth

Periodontal tissues

Articulatory apparatus: Consists of TMJs, Masticatory muscles, and dental occlusion

Question 16

What does the articulatory apparatus dictate?

Answer 16

Mandibular position and movements

Question 17

What is the function of each component of the articulatory apparatus?

Answer 17

TMJ: Guiding system

Dental occlusion: Guiding system

Masticatory muscle: Moving system

Question 18

What are the components of the TMJ?

Answer 18

Condyle head

Articular disc

Glenoid fossa

Provides guidance to the mandible during movement

Question 19

What are the types of motion that the TMJ can undergo?

Answer 19

Hinge movement: Rotation around the intracondylar axis within the glenoid fossa and this provides <2cm of movement.

Translational movement: Gliding against the articular eminence of >2cm

Question 20

What is the function of the masseter?

Answer 20

Primarily elevates the mandible, secondarily protrudes the mandible

Question 21

What is the function of the temporalis?

Answer 21

Elevates and retracts the mandible

Question 22

What is the function of the lateral pterygoid muscle?

Answer 22

Protrudes the mandible. Laterla movements. Depression

Question 23

What is the function of the medial pterygoid muscle?

Answer 23

Primarily elevates the mandible, secondarily protrusion and lateral movements

Question 24

What are the suprahyoid muscles?

Answer 24

Mylohyoid, geniohyoid, stylohyoid and digastric

Question 25

What are the infrahyoid muscles?

Answer 25

Sternohyoid Sternothyroid Thyrohyoid Omohyoid

Question 26

What are the TMJ movements that lead to protrusive movements?

Answer 26

Both condyles are in similar gliding motion

Question 27

What are the TMJ motions responsible for lateral movement?

Answer 27

Working side: Rotational movement around the vertical axis without leaving the glenoid fossa Non - working side: Gliding against the articular eminence forwards downwards and medially

Question 28

What is the angle of downward movement during lateral excursion called?

Answer 28

The condylar angle

Question 29

What is the angle of medial movement during lateral excursion called?

Answer 29

The bennet angle

Question 30

What is the bennett side shift?

Answer 30

The side movement of the body of the mandible on the working side in the horizontal direction

Question 31

What is the difference between static and dynamic occlusion?

Answer 31

Centric occlusion or maximal intercuspation in static. Protrusion in dynamic Centric relation / freedom in centric whereas there is lateral occlusion guidance in dynamic

Question 32

What controls lateral occlusion guidance in dynamic occlusion?

Answer 32

Canine guided Group function Balanced occlusion

Question 33

What is centric relation in static occlusion?

Answer 33

Maxillomandibular relationship in which the condyles articulate with the thinnest avascular portion of their respective discs with the complex in the anterior-superior position against the shapes of the articular eminencies The position is independent of tooth contact and reproducible

Question 34

What is the maximum intercuspation position?

Answer 34

the complete intercuspation of the opposing teeth independent of condylar position: Bite of convenience Habitual bite (position)

Question 35

What is centric occlusion?

Answer 35

If the MIP coincides with CR then this is called centric occlusion.

Question 36

How common is centric occlusion?

Answer 36

In 90% of the population there is a lack of coincidence of MIP with CR

Question 37

When is freedom in centric said to occur? When is it not said to occur?

Answer 37

Freedom in centric occlusion occurs when the mandible is able to move anteriorly for a short distance in the same horizontal and sagittal plane while maintaining tooth contact Alternatively there will be no freedom in centric occlusion if either front teeth or the posterior occlusion do not allow this horizontal movement

Question 38

What is dynamic occlusion?

Answer 38

Refers to occlusal contacts that can be made whilst the mandible is moving relative to the maxilla.

Question 39

What are the criteria for ideal occlusion?

Answer 39

Mandibular stability: Contact of inferior and superior teeth must stabilize the mandible in centric position. Axial load: Occlusal load should be parallel to the long axis of the tooth (load distributed evenly throughout the PDL) During lateral excursions of the mandible there is no interference in the working side. During lateral excursions of the mandible there is no disocclusion in the non-working side. During protrusion there is disocclusion of the posterior teeth.

Question 40

What are the types of guidance?

Answer 40

Canine guided occlusion (dentate) Group function (total or partial) (dentate) Balanced occlusion (bilaterally balanced occlusion) (Edentate)

Question 41

What is canine guided occlusion?

Answer 41

A form of articulation in which the vertical and horizontal overlap of the canine teeth disengage the posterior teeth in the excursive movements of the mandible. (i.e if mandible is moving laterally both canines can touch the whole way through the motion even when posterior teeth have disconnected) Complete disclusion of posterior teeth during lateral movement

Question 42

When is using canine guidance for occlusion not indicated?

Answer 42

Not indicated for teeth that are compromised endodontically or periodontically

Question 43

What is group function occlusion?

Answer 43

Distribution of lateral forces to a group of teeth Multiple contact relations between the maxillary and mandibular teeth in lateral movements on the working side whereby simultaneous contact of several teeth acts as a group to distribute occlusal forces

Question 44

What contacts are seen on lateral movements

Answer 44

On lateral movements, the contacts are on the buccal cusps of the working side The non-working side has no contacts

Question 45

What are the types of interferences that can arise?

Answer 45

Working and/or non-working side interferences

Question 46

Why should interferences be eliminated?

Answer 46

Excessive horizontal and oblique forces will be applied on the restoration or natural teeth causing damage

Question 47

What is balanced occlusion?

Answer 47

Bilateral, simultaneous, anterior and posterior occlusal contact of teeth in centric and eccentric positions At least 3 contact points: 2 posterior and 1 anterior

Question 48

What is balanced occlusion needed for?

Answer 48

Useful for complete denture cases to prevent tipping of the denture Cross arch balanced occlusion is not indicated for natural dentition

Question 49

What happens during protrusion in ideal occlusion?

Answer 49

Protrusive or anterior guidance causes disocclusion of posterior teeth

Question 50

What is mutually protected articulation?

Answer 50

An occlusal scheme in which the posterior teeth prevent excessive contact of the anterior teeth in maximum intercuspation and anterior teeth disengage the posterior teeth in all mandibular excursive movements