Recording the Occlusion - Replica Technique

Question 1

Define muscular position.

Answer 1

When mandible is raised from rest position by balanced muscle activity and tooth contact is made.

Question 2

How can we fix a protruded mandibular position in complete denture wearers?

Answer 2

1. Establish the correct vertical height/OVD.
2. The mandible may naturally drop down to a more regular occlusal relationship.

• INCREASING THE OVD IN NEW DENTURES MAY CAUSE THE MANDIBLE TO DROP BACK TO A MORE RETRUDED POSITION.

Question 3

Too much freeway space?

Answer 3

Overclosed and sunken.

Question 4

What is the retruded contact position? When is it used?

Answer 4

• The condyle is at the most retruded point in the fossa - REPRODUCIBLE RELATIONSHIP.
• Used when intercuspal position not reproducible.

Question 5

What is freeway space? Normal value?

Answer 5

space between occlusal surfaces when the mandible is at rest.

2-4mm.

Question 6

How are dark spaces of buccal corridor corrected? 2 added advantages?

Answer 6

• Pull the teeth out buccally.
• Prevents posterior crossbite.
• Prevents lower posterior teeth from being too far lingually.

Question 7

What is used to assess if the centre line of the teeth is centered?

Answer 7

• Nose (yet not always centered)
• LABIAL FRENUM.

Question 8

Distance between incisors and lip?

Answer 8

• Incisors should sit AROUND 1MM BELOW THE LEVEL OF THE LIP when the lip is relaxed.
• Hence only the tips of the teeth should be seen when patient is at rest.

Question 9

Formula for determining how TALL a denture should be.

Answer 9

OVD = RVD - FWS

Question 10

What happens if teeth are too far lingual?

Answer 10

Insufficient space for the tongue, hence causing instability when the tongue moves.

Question 11

2 things to consider when examining posteriors of replica denture during occlusion.

Answer 11

1. Position: neutral zone.
2. Occlusal plane: paralel to alar-tragal line.

Question 12

Position of patient when checking OCCLUSION (vertical and horizontal relationships)?

Answer 12

• sitting UPRIGHT with head WELL-SUPPORTED.

Question 13

What is used as a reference to assess if the occlusal plane is level/ there is no run?

Answer 13

• Alar tragal line with Fox’s guide.

Question 14

Where do we want teeth to be?

Answer 14

In the NEUTRAL ZONE.

Question 15

What is done at the end of the occlusion stage for complete dentures (apart from centre line)?

Answer 15

• Shade
• Mould (of anterior and posterior teeth).
• Tooth arrangement (twists, gaps etc).
• Articulator (usually average value).

Question 16

What is used as a reference to assess if the incisors are level/ there is no run?

Answer 16

Inter-pupillary line using Fox’s Guide.

Question 17

Too little freeway space?

Answer 17

• Muscles of mastication become strained and cause pain.

Question 18

Formula for FWS

Answer 18

FWS = RVD - OVD

Question 19

How can severe tooth wear affect jaw position?

Answer 19

• May lead to a PROTRUDED position of mandible (muscular position is PROTRUDED).

Question 20

5 things to consider when examining incisors/ anterior of replica denture during occlusion.

Answer 20

1. Labial fullness. (90 degree angle between base of nose & lip).
2. Incisal plane (inter-pupillary line).
3. Incisal level (1-2mm below upper lip at rest)
4. Centre line (labial frenum).
5. Position (neutral zone)

Question 21

What is used to measure resting vertical dimension?

Answer 21

Willis gauge (base of nose - underside of chin).

Question 22

What is the resting vertical dimension?

Answer 22

Resting face height. The vertical dimension with the mandible in the rest position. Measured from the BASE OF THE NOSE to the UNDERSIDE OF THE CHIN using a Willis gauge.

Question 23

When are master impressions recorded for COMPLETE dentures (conventional or replica) and why?

Answer 23

• Recorded BEFORE occlusion.
• Give a retentive base.
• Any discrepancies caused by impressions in occlusal plane/ vertical heigh can be rectified.

Question 24

4 other terms for retruded contact position.

Answer 24

• Ligamentous position.
• Retruded axis position.
• Terminal Hinge Position.
• Centric relation contact position.

Question 25

What is the rest/ postural position?

Answer 25

The position that the mandible passively assumes when the mandibular musculature is relaxed, and the patient is upright  “TV WATCHING FACE”.

Question 26

When correcting the occlusion in the replica technique, where do we start?

Answer 26

• UPPER DENTURE
• start with HORIZONTAL RELATIONSHIPS (correct INCISORS first, then POSTERIOR TEETH)
• Then consider VERTICAL RELATIONSHIPS.

Question 27

Another term for rest position?

Answer 27

Postural position.

Question 28

5 common characteristics that are modified on replica blocks during the occlusion stage?

Answer 28

When needed:
- Tooth position
- OVD.
- Buccal width/ buccal corridor.
- Incisal level
- Occlusal plane (position/ orientation).

Question 29

Define intercuspal position.

Answer 29

Jaw relationship in which maximum occlusal contact occurs.

Question 30

Relationship between muscular position and intercuspal position in complete denture wearers?

Answer 30

In complete denture wearer, we want the teeth to get maximum tooth contact (intercuspal position) at the position the mandible is naturally raised to (muscular position) without sliding after initial tooth contact.

• MUSCULAR AND INTERCUSPAL POSITIONS SHOULD COINCIDE.

Question 31

What happens if teeth are too far forward?

Answer 31

Lip will bash denture when it moves.