Lecture 10 - Optimal Functional Occlusion II Premature Contacts and Interferences

Question 1

what are the types of occlusal interferences

Answer 1

-centric interferences
- working side interferences
- non working side interferences
- protrusive interferences

Question 2

define occlusal interference

Answer 2

an unwanted or premature interocclusal contact

Question 3

what is another name for centric interference

Answer 3

premature contact

Question 4

what is centric interference

Answer 4

a premature contact that occurs when the condyles are manipulated into CR

Question 5

how many teeth contact in centric interference

Answer 5

only one, maybe two teeth

Question 6

what happens to the mandible when centric interference occurs

Answer 6

the mandible moves forwards and upwards into MIP

Question 7

where does centric interference occur

Answer 7

on the mesial inclines of the maxillary teeth and the distal inclines of the mandibular teeth

Question 8

describe contacts on working side ideally

Answer 8

-on lateral excursion there is anterior guidance on the working side
- no other teeth on the working or non working side should contact

Question 9

where do working side interferences occur and what can they affect

Answer 9

between maxillary and mandibular posterior teeth on the working side as the patient makes a lateral movement
- if heavy enough can disclude the anterior teeth and interfere with the movement of the NWS condyle

Question 10

on what inclines do working side interferences occur

Answer 10

• between the outer incline of the mandibular buccal cusp and the inner inclines of the maxillary buccal cusp and/or
• between the outer inclines of the maxillary lingual cusps and the inner inclines of the mandibular lingual cusps

Question 11

what is the difference between group function and working side interferences

Answer 11

-contacts further distal to the MB cusps of the first molars are WS interferences
- contacts on the WS that prevent the canines from guiding are WS interferences

Question 12

what are non working side interferences

Answer 12

any contact between the maxillary and mandibular teeth on the non working side during a lateral movement

Question 13

what are the most destructive interferences and why

Answer 13

non working side because they change the lever system of the mandible and place considerable stress on the TMJ joints

Question 14

what inclines do non working side interferences occur

Answer 14

on the NW side between the inner inclines of the maxillary lingual cusps and the inner inclines of the mandibular buccal cusps

Question 15

what are protrusive interferences

Answer 15

any contact between the posterior teeth as the mandible moves forward in protrusion
- if interferences is severe it will prevent contact between the anterior teeth

Question 16

why are protrusive interferences destructive

Answer 16

because they are positioned close to the fulcrum (TMJ) and the resulting source of power (muscles) are large and destructive forces

Question 17

what inclines do protrusive interferences occur

Answer 17

• between posterior teeth
• between the mesial inclines of the mandibular cusps and the distal inclines of the maxillary teeth