Complete Dentures - Occlusion

Question 1

What does occlusion mean?

Answer 1

Study of how teeth come together when they close and in lateral and protrusive movements.

Question 2

Describe the muscles used on jaw opening and closing.

Answer 2

Jaw opening - digastric muscle and lateral pterygoid muscle cause translation and rotation to cause the jaw to open. This brings the condyle downwards and forwards, and the mandible to move back.

Jaw closing - temporalis muscle causes the jaw to close mostly, and then the masseter provides the force to chew through food.

Question 3

What is the retruded position and RCP?

Answer 3

This is where the condyle seats fully (most superior-posterior position) into the glenoid fossa and this is the most retruded position.
This is the RCP for a patient.

Question 4

What information do we not have for an edentulous patient that makes figuring out occlusion difficult?

Answer 4

We don’t know their ICP or RCP as there’s no teeth.

So we set the patient at retruded position and decide from there and they adapt.

Question 5

What are the compensating curves?

Answer 5

Spee and Monson/Wilson

Question 6

How if the freeway space determined?

What are these determined by?

Answer 6

FWS = RVD - OVD.

RVD is same in patient regardless of edentulous or not. We’re creating the OVD so we have to ensure we make the correct OVD to get the correct freeway space.

Question 7

Why is creating the right OVD and FWS so important?

Answer 7

If it’s too large:

• Overclosure
• Discomfort in chewing
• Little of teeth show

If it’s too small:

• Teeth are always in contact which puts load and soreness on mucosa, TMJ and MoM.
• Teeth clack

Question 8

What info do we need to create OVD? How do we get patients in these positions?

Answer 8

RVD and retruded position.

Retruded position: get patient to curl tongue to back of their mouth in order to seat condyle in most superior-posterior part of glenoid fossa.
RVD: get patients to relax, lips closed (intra-oral vacuum to bring chin up), elasticity of face brings up, while gravity takes it down, reduced pressure/strain on TMJ and patient tries to relax in a straight up sat position and look in the distance. Variable degree of relaxation experienced by patients in dental chair.

OVD = RVD - 3mm.

Question 9

Give a detailed description of how to record the occlusion.

Answer 9

Upper denture:

• Lip support. Make sure it’s correct for naso-labial angle and you can add or remove if needed.
• Incisal level. Make sure it’s not too low. Only 1-2mm of incisor should show.
• Intra-pupillary line parallel to horizontal plane- use Fox’s plane guide.
• Occlusal plane from lateral sides should be parallel to alar-tragal line- use Fox’s plane guide.

Lower denture:
- RVD measured using Willis gauge and 3mm taken off to get the correct OVD.

Both together:

• Place in score lines on midline and premolar teeth.
• Guide patient to retruded position and record bite with Blu Mousse (registration paste).

Question 10

What do you include in your prescription to the lab after this and what do they do?

Answer 10

• Shade of teeth and shape and mould
• Cusps on posterior teeth or cuspless.
• Flange thickness, contoured or stippling.
• Denture base.
• Articulator
• Customisation
• Post-dam
• Incisor relationship

Question 11

What articulator do we use for different things?

What can they replicate?

Answer 11

Simple hinge - for making sure restorations are correct in ICP (unable to simulate lateral movements)
Average value - for partial and complete dentures (based on average pt)
Semi-adjustable - more specific to patient but requires a facebow. When restoring teeth involved in guidance (making sure unwanted interferences aren’t created in lateral or protrusive movements) or modelling changes to occlusion.
Fully-adjustable - more specific

Doesn’t necessarily become more accurate with more but in face more inaccuracies can creep in.