Occlusion for Partial Dentures

Question 1

What is occlusion?

Answer 1

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

Question 2

What is ICP? (tooth position)

Answer 2

The complete intercuspation of the opposing teeth independent of condylar position
-> sometimes referred to as the best fit of the teeth regardless of the condylar position (can change with extractions and age)

Question 3

What is RCP? (Condylar position)

Answer 3

Guided occlusal relationship occurring at the most retruded position of the condyles in the joint cavities (fixed)

Question 4

How do we get the patient into RCP?

Answer 4

 Move jaw far back as possible then will reach limit (most reproducible position)
 Ask patient to touch roof of mouth with tip of tongue (think loose and floppy)
 Manipulate- slacken then push back and bite up (might be a bit less accurate)

Question 5

What must we remember about RCP and ICP?

Answer 5

They can be the same

Question 6

What are index teeth?

Answer 6

Contacting facets in ICP
 Measure of quality of dentition- more index teeth means more stable occlusion
 If not enough- choose RCP

Question 7

Key points of ICP:

Answer 7

Need sufficient index teeth to use

Stable occlusion

Can vary through life

Is dependent on tooth relationships

Usually more anterior than RCP

Question 8

Key points of RCP:

Answer 8

Can be used if insufficient index teeth

Unstable occlusion

Reproducible position
-> Condylar position

Usually more posterior than ICP

Question 9

When is a conforming approach opted for? What position is used?

Answer 9

In stable occlusion with sufficient index teeth
-> record in ICP

Question 10

What is a potential pitfall to be aware of when using conformist approach?

Answer 10

Ensure prothesis does not alter the occlusion
-> if it has it indicates there has been an error when recording the occlusion

Question 11

When may an occlusion be changed? What position is used?

Answer 11

In unstable occlusion and insufficient index teeth
-> record in RCP (more difficult to achieve)

Question 12

When may occlusion not need to be recorded?

Answer 12

If there is sufficient teeth and it is obvious how they meet

-> obtaining an inter-occlusal record will always be more accurate even in these situations

Question 13

What are the options for taking an interocclusal record

Answer 13

Bite registration paste – usually silicone paste
-> Jetbite- polyvinyl siloxane

Wax wafer – modelling wax

Modified wax wafer – eg alminax
-> easier to mount casts as it doesn’t spring

Question 14

What else can alminax be useful for?

Answer 14

Facebow registrations when reorganising occlusion

Question 15

When are record blocks required for recording the occlusion?

Answer 15

When there is insufficient index teeth
-> more complex to record

Question 16

What are the types of record blocks?

Answer 16

Wax

Wax with wire strengthener- prevents distortion

On Co/Cr framework (preliminary jaw reg required prior)

Shellac- good for complete dentures

Question 17

What is the function of record blocks?

Answer 17

Give stability posteriorly to make it easier to transfer relationship to articulated casts

Question 18

What can be used to modify height or Record Blocks?

Answer 18

Hot plate

Bunsen

Spatula

Wax knife

Question 19

How can occlusion be recorded using record blocks?

Answer 19

Trim to desired height
-> Cut squares in opposing record blocks and syringe bite reg paste into with patient occluding together (push cheeks in and get patient to use tongue)