Occlusion 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 is occlusion recorded
Need to know what is normal for the patient and keep it the same if it is useful – conforming to occlusion
To facilitate 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
Need to know the position of the teeth in relation to each other
Ensuring loading forces applied correctly to teeth and underlying mucosa/bone
When do we record occlusion
Primary registration
Secondary registration
Framework registration
What is the primary registration stage
When casts cannot be hand articulated and you need to examine the occlusion to design your denture and position rest seats without occlusal interference
How is occlusion checked at the framework trial stage
An occlusal rim added to the framework to record the jaw relationship
If conforming to occlusion ensure that the framework does not interfere with the occlusion
What should be established when recording 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 Plan
(Tooth shade and mould)
What are index teeth
Teeth that contact in the intercuspal position (ICP) and allow easy recording of OVD
A patient may not have many teeth remaining, but they may provide stable occlusal contacts
These tooth contacts should remain the same when the partial denture is in situ – conforming to occlusion
What is absolutely required when replacing anterior teeth and providing metal backings before the framework can be constructed
A tooth trial
What are the steps to conforming to occlusion
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 equipment is used to trim wax blocks
Hot plate
Bunsen and palate knife
What is used to join blocks together
Pink wax or registration phase
What is the disadvantage of using wax to join blocks together
May not get teeth fully closed as wax might not be soft enough
May stick the blocks together where very few teeth present, blockscant be separated
What is the procedure with no occlusal contacts or there is re-organising occlusion
Exact same:
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
When must you determine the OVD and occlusion
If there are not enough index teeth or no stable tooth contacts with a retruded mandible
When do you change 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
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 can be used if ICP is not posible
Centric relation
(the comfortable bite)
What is the retruded contact position
First tooth contact when the condyle of the mandible is in a retruded axis position
Just behind the intercuspal position
Mostly reproducible
What does RVD stand for
Resting vertical dimension
How is the RVD recorded
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 is the OVD recorded
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 = 2-4mm
What is the method to adjusting/trimming the blocks
Adjust the upper occlusal rim
the occlusal and incisal plane is appropriately orientated in relation to the remaining upper natural teeth or the facial reference points
If there is an anterior saddle, ensure that the rim indicates the appropriate incisal level and degree of lip support
Adjust the lower occlusal rim
Remember you are determining the correct OVD and no teeth will be touching
What methods are used to record occlusion when conforming
Occlusal contacts at suitable OVD
Use the ICP
When is ICP used
Sufficient number of index teeth
Stable Occlusion
Variable through life
Usually more anterior than RCP
Simpler to record the occlusion
What is RCP used
Insufficient number of index teeth
Unstable Occlusion
Reproducible position
Usually more posterior than ICP
More challenging to record the occlusion
