Registration: Stage II intermaxillwry Relation Flashcards
What happens if there is an error in recording the intermaxillary jaw relation
Dentures will be uncomfortable or unwearable and may even have the potential to produce lasting damage to many elements of the stomatognathic system
What are the three elements to be recorded at the intermaxillary relation record stage
Vertical relationship Horizontal plane (antero posterior relationship) Coronal plane (lateral relations of the jaw)
What is the first of the intermaxillary relationship records
Vertical relationship
Establishes the amount of jaw separation
What is the RVD
Resting vertical dimension
What does resting vertical dimension mean
FWS = RVD - OVD
What is the FWS
Individuals that have their natural dentition demonstrate a space between the occlusal surfaces of the teeth and the opposing Jaws when they are at rest and with the head upright
What is another name for the FWS
Interocclusal distance
What is the FWS determined by
A balance between the elevator and depress or muscles attached to the mandible and the elastic nature of the sorrounding soft tissue in a natural dentition
How is the FWS measured
Indirextly by noting the difference between the resting vertical dimension of the face using a Willis gauge and subtracting from this the vertical dimension of occlusion with the teeth in occlusion
How is the RVD measured
Willis gauge
Is the RVD a stable measurement
The RVD may differ in a pt after they become edentulous compared to when teeth were present. RVD is not a stable position throughout life for a given individual
Is RVD the starting point
Yes. This measurement can also be used to determine the appearance of the denture wearing pt
Why is head position important when measuring RVD
Tilting the head backwards pulls the mandible away from the maxilla and a forward inclination pushes the mandible and attached structures closer to the maxilla
How is the RVD measured? What reference points are required?
Two measuring points are required in the midline of the face - one related to the nose, and one to the chin
What is important about the two points required on the chin and nose when measuring the RVD
The points must be on sites of minimal influence from the muscles of facial expression to avoid skin movement and should be chosen only after careful observation of the patient seated normally in the dental chair with the head erect
How is the RVD measurement made? At what stage?
The measurement is made with the pt in a relaxed and comfortable position while wearing the previously developed upper base and rim.
What might help in recording the RVD? What can you ask the pt to do?
It may be helpful if the pt moisten the lips with his or her tongue and brings them into light contact prior to recording the measurement.
Asking the pt to swallow and relax the Jaws is also a useful method.
Verification of the measured value can be attempted by asking the pt to say the letter m and to hold the facial expression whilst the measurement is made.
Carefully observe
What might be observed if the upper and lower base and rim are placed in the mouth and there is excessive OVD
Orbicularis iris muscle group straining to effect a seal
What can an insufficient OVD look like
Ageing effect on the pt
How can you establish the height of the lower rim?
- The relative height of the upper and lower rim should be considered
- An element of reasonable balance between the two rims is desirable
- Excessive height of the lower rim can have the effect of walling in the tongue causing a resultant unstable lower denture
- On the other hand, deficient depth of the lower rim can result in poor aesthetics and further may result in tongue biting.
- The occlusal plane should be below the dorsum of the tongue at rest
What effect will excessive reduction in. The height of the lower rim have?
‘walling in’ the tongue
Causing a resultant unstable lower denture
What effect will a deficient depth of the lower rim result in?
Poor aesthetics
Tongue biting
Should the occlusal plane be below the dorsum of the tongue at rest
Yes
Should the RVD be established first, before the upper and lower rims are placed in the mouth?
Yes
Do you mould the upper rim first?
Yes
How is the OVD established?
- Mould upper rim
- Reduce lower rim height until it contacts evenly the upper rim at VDO 2-4 mm less than the established RVD
- Ensure FWS of 2-4mm
What may be the consequences of excessive OVD
- Increased risk of trauma to the tissues underlying the Dentures as the absence of a freeway space effectively causes continuous clenching of the teeth
- Painful mucosa over the denture bearing areas and muscle soreness, particularly associated with the masseter muscle
- Teeth are liable to contact (causing clicking during speech)
- Difficulty in bringing the lips together for p b m sounds
- Poor aesthetics
- Tmjd
Is clicking of the teeth a manifestation of insufficient or excessive OVD
Excessive OVD may cause clicking as the teeth are liable to contact during speech and the pt will have difficulty with other softer sounds p b m
What trauma may result to the pt due to excessive OVD
Absence of freeway space effectively causes continuous clenching
Painful mucosa over the denture bearing areas and muscle soreness
What may be the results of insufficient OVD
Lack of support of the angles of the mouth
Causes dribbling and possible angular Cheilitis may be present
Reduced masticatory efficency
Poor aesthetics lack of adequate support of the lips and cheeks may be seen
Chin protrusion on closure of the Jaws
What should be remembered about the FWS
FWS is an average value
Pt dependent
Some pts may require a larger or smaller value
Eg where atrophic mucosa exists in middle aged adult an increased FWS might prevent or redu e trauma to the residual mandibular tissues