Manuals_files/CD Manual 12.pdf - Removable Prosthodontics

Maxillo-mandibular Relationships - 34
e. If the OVD is changed, condylar inclination will not have to be readjusted if an arcon
articulator is used (Celenza)
f. CR is not far from CO at same occlusal vertical dimension (Wilson and Nairn)
Reasons's for NOT using CO in edentulous patients
a. CO may be a dysfunctional position (must palpate muscles, TMJ to ensure no
dysfunction) (Brill et al)
b. The actual position is more difficult to determine - studies have shown it is not as
reproducible. Patients cannot tell where centric occlusion or a habitual position
is with bulky wax rims in position. Basically there is no habitual position with new
wax rims (Crum & Loiselle; Brill et al.)
c. Since CO is not reproducible, the influence of other variables on the centric record
cannot be assessed (Yurkstas and Kapur) e.g.:
- Wax consistency
- Biting force
- Symmetry of guidance
d. CO may lead to dysfunction - no studies to absolutely prove this hypothesis
When to use CR
a. When entire occlusion being restored (i.e. no remaining posterior centric stops)
b. When complete, fixed, or removable partial dentures involve the entire occlusion
c. if a nonpathologic natural occlusion exists (posterior centric stops present), and there
is no valid reason to change it, then restorations should be made in maximum
intercuspation
How to obtain CR
The Dawson method (bimanual manipulation) produces reasonably good results:
1. The patient should be placed in a slightly supine, position
2. Place notches in the occlusion rim to aid in stabilizing the record bases with index
fingers on the rim, and thumbs under symphysis
3. Jiggle the lower jaw – the mandible should freely arc
4. Allow the patient to close the last portion
5. DO NOT PUSH THE MANDIBLE or dislodge the record base
6. The registration media must be dead soft , when the patient close into it