Premature Contacts and Intereferences

Question 1

first goal of occlusal diagnosis and treatment planning

Answer 1

occlusal stability

Question 2

to be healthy, the teeth must be maintained without (3)

Answer 2

excessive wear, hypermobility or migration out of an acceptable alignment

Question 3

the five requirements that must be fulfilled if an occlusion is to function with optimum stability are

Answer 3

1. stable stops on all teeth when the condyle-disk assemblies are properly aligned in their most superior-anterior positron against the eminentiae (CR)
2. an anterior guidance that is in harmony with the border movements of the envelope of function
3. discussion of all posterior teeth in protrusive movements
4. discussion of all posterior teeth on the non-working side
5. non interference of all posterior teeth on the working side with either the lateral anterior guidance or the border movements of the condyles

Question 4

3 reasons for stable centric stops

Answer 4

1. the more teeth in contact in CR, the less stress will be exerted on any contacting tooth
2. the more teeth that contact correctly in CR, the less wear will occur on each contracting surface
3. a correct centric holding contact on each tooth prevents supraeruption

Question 5

2. an anterior guidance that is in harmony with the border movements of the envelope of function

Answer 5

F THE ANTERIOR GUIDANCE IS IN HARMONY WITH
THE ENVELOPE OF FUNCTION THERE WILL NOT BE A
TENDENCY FOR DESTRUCTIVE NONFUNCTIONAL
MOVEMENTS.

Question 6

3. discussion of all posterior teeth in protrusive movements

Answer 6

WHEN THE MANDIBLE IS PROTRUDED, THE ONLY
TEETH IN CONTACT SHOULD BE THE ANTERIOR
TEETH. THERE IS NO NEED FOR POSTERIOR TEETH TO
TOUCH DURING INCISING.

Question 7

4. discussion of all posterior teeth on the non-working side

Answer 7

NONWORKING SIDE INTERFERENCE S ARE
CONSIDERED TO BE ONE OF THE MOST DESTRUCTIVE
TYPES OF INTERFERENCES BECAUSE:

Question 8

5. non interference of all posterior teeth on the working side with either the lateral anterior guidance or the border movements of the condyles
   IDEALLY, THE LATERAL GUIDING INCLINES OF THE
   WORKING SIDE SHOULD BE FOUND ON THE —
   TEETH. THE — ARE USUALLY IN THE PRIME
   POSITION OF IMPORTANCE FOR LATERAL GUIDANCE

Answer 8

ANTERIOR

CUSPIDS

Question 9

MIP and CR are coincident=

Answer 9

when the teeth meet in MIP, the condyles are in the CR position

Question 10

“ideal occlusion”

“mutually protected occlusion” (4)

Answer 10

MIP and CR are coincident= when the teeth meet in MIP, the condyles are in the CR position
the patient has multiple, bilateral, even and simultaneous contacts in MIP/CR
the patient has “light contacts” on the anterior teeth in MIP/CR
the patient has anterior guidance in protrusion and lateral excursive movements

Question 11

types of occlusal interferences (4)

Answer 11

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

Question 12

occlusal interference

Answer 12

an unwanted or premature interocclusal contact

Question 13

centric interference, also called

Answer 13

premature contact

Question 14

a premature contact that occurs when the

Answer 14

condyles are manipulated into CR

Question 15

in general, how many teeth will contact

Answer 15

one or two

Question 16

once this centric interference occurs,

Answer 16

the mandible moves forwards and upwards (and usually slightly laterally) into MIP

Question 17

centric interferences occur on the (2)

Answer 17

mesial inclines of the maxillary teeth and

distal inclines of the mandibular teeth

Question 18

ideally on lateral excursion, there is — on the working side

Answer 18

anterior guidance (canine guidance

no other teeth on the working or nonworking side should contact

Question 19

working side interferences occur between

Answer 19

maxillary and mandibular posterior teeth on the working side as the patient makes a lateral movement

Question 20

these contacts may be heavy enough to disclude the anterior teeth and interfere with the smooth harmonious movement of the — condyle

Answer 20

NWS

Question 21

on which inclines do these interferences occur (2)

Answer 21

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 22

what is the difference between group function and working side interferences (3)

Answer 22

• different philosophies (canine guidance vs group function)
• contacts further distal to the MB cusps of the first molars are WS interferences
• contacts on the WS that prevent the canines fro guiding are WS interferences

Question 23

non-working side interferences (3)

Answer 23

• any contact between the maxillary and mandibular teeth on the non-working side (side opposite to which the mandible moves) as the patient makes a lateral movement
• they are the most destructive of all interferences
• they change the lever system of the mandible and place considerable stress on the TMJ joints

Question 24

on which links do these interferences occur?

Answer 24

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

Question 25

protrusive interferences (2)

Answer 25

• any contact between the posterior teeth as the mandible moves forward in protrusion
• sometimes the interference is so severe it will prevent contact between the anterior teeth

Question 26

protrusive interferences

Answer 26

protrusive interferences are very destructive, because they are positioned close to the fulcrum (TMJs) and the results source of power (muscles) is large and destructive forces

Question 27

on which includes do these interferences occur? (2)

Answer 27

between the posterior teeth

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