Occlusion and Partial Dentures Flashcards
What is occlusion?
The static relationship between the incising or masticating surfaces of the maxillary or mandibular teeth or tooth analogues;
Why do you need to record occlusion?
- Need to know what is normal for the patient and keep it the same if it is useful in denture design
- To help the technician mount the casts and set-up the teeth
- To ensure the denture is stable and is not dislodged in function – articulation: think of types of articulator
- If you are planning to “re-organise” the occlusion
- Ensuring loading forces applied correctly to teeth and underlying mucosa/bone
When is occlusion important to record in the primary registration stage?
When casts cannot be hand articulated and you need to examine the occlusion to design your denture and position without occlusal interference
What componments are important when recording the occlusion?
- Inter-occlusal relationship to allow technician to articulate casts (and therefore set-up the teeth)
- Occlusal vertical dimension
Index teeth
Re-organising occlusion - Buccal/labial contours of wax record block
Lip support
Incisal Plane
Occlusal Plane - (Tooth shade and mould)
What are index teeth?
Teeth that contact in the intercuspal position (ICP) and allow easy recording of OVD
What should be done before patient arrives?
Check the work is for the correct patient
Check the correct work has been done
Disinfect the record block(s) (perform)
What is the difference between reorganising and conforming?
conforming = enough index teeth to provide stable occlusion
re-organising = OVD not clear, no occlusal contacts
What is the procedure outline?
- Adjust the upper record block then the lower record block
- Record the occlusion
- Check the registration fits to the casts
- Disinfect
- Select tooth shade and mould
- Instructions to the laboratory
What materials are used to record the occlusion with record blocks?
join the record blocks using;
pink wax
registration paste
What should you check on the blocks with the wax/paste?
block heels are not touching and altering occlusion
What happens if there are not enough index teeth>
You will have to decide what the occlusion and OVD should be.
If you are lucky there may be stable tooth contacts when the mandible is in a retruded position
What happens if there is no stable tooth contacts when the mandible is in a retruded position?
change the OVD
This should always be planned and not done by accident
* You use the record blocks to establish the OVD you want
* Frequently done when treating patients with tooth wear using the Dahl principle
What are advantages of increasing OVD?
- Increasing the OVD can provide space to place restorations
- If patients are over closed and having TMJ problems or persistent angular cheilitis
- Increasing the OVD reduces creasing and pooling of saliva at the commisures
What is posselts envelope?
Extremes of mandibular movement
Border movements of the mandible in the Sagittal Plane
What is retruded contact position and why is it useful?
First tooth contact when the condyle of the mandible is in a retruded axis position
Just behind the intercuspal position Mostly reproducible
How can you record the resting vertical dimension (RVD)? (2 methods)
Two dot method
Choose point on nose and chin with minimal movement
Jaw relaxed, lips just touching, space between posterior teeth
Use dividers to measure distance between dots Distance between divider arms = RVD
Willis Bite Gauge
Jaw relaxed, lips just touching, space between posterior teeth
Fixed arm nasio labial position
Sliding arm under chin
Distance between sliding and fixed arms = RVD
How can you record the occlusal vertical dimension (OVD)? (2 methods)
Two dot method
Choose point on nose and chin with minimal movement
Teeth in inter-cuspal position
Use dividers to measure distance between dots
Distance between divider arms = OVD
Willis Bite Gauge
Teeth in inter-cuspal position
Fixed arm nasio labial position
Sliding arm under chin
Distance between sliding and fixed arms = OVD
What is the free way space and how is it calculated?
The space between the occluding surfaces of the maxillary and mandibular teeth when the mandible is in physiologic resting position
Free Way Space = RVD-OVD
What is the range of values for the free-way space?
2-4mm
For primary registrations, what will the lab send back after occlusal recordings?
special trays
For secondary registrations, what will the lab send back after occlusal recordings?
try-in with wax
What other position can you use if ICP is not available?
Centric relation / occlusion
“The comfortable bite”
“The habitual bite”
“The bite of convenience”
Compare ICP with RCP
Intercuspal Position ICP
Sufficient number of index teeth
Stable Occlusion
Variable through life
Usually more anterior than RCP
Simpler to record the occlusion
Retruded Contact Position Insufficient number of index teeth
Unstable Occlusion
Reproducible position
Usually more posterior than ICP
More challenging to record the occlusion
When is RCP used?
RCP gets used if there is no consistent centric relation.
