Manuals_files/CD Manual 12.pdf - Removable Prosthodontics

Maxillo-mandibular Relationships - 35
What type of registration media to use
1. Never use wax if you can use something else! Waxes produce the least accurate
interocclusal records. Numerous studies with dentate patients have even shown that the
most accurate mountings are achieved when NO MATERIAL is used with DENTATE
casts where the patient has stable contacts (i.e. no rocking when placed together - you
need to remove all positive bubbles to check for this). Alternatively, for dentitions that
do not have stable contacts, elastomeric materials produce more accurate interocclusal
records than wax. For best records for complete or removable partial dentures:
a. Use no material for tooth borne RPD’s with stable occlusal contacts.
b. Use elastomeric bite registration material (e.g. Memoreg) with record bases and
wax rims for CD’s & most RPD’s. Record the entire occlusal surface for stability.
Use small ‘V’ shaped notches on the occlusal rim surface.
Procedure for recording the centric position and mounting the mandibular cast:
1. Place 3 widely separated marks between the maxillary and mandibular wax rims as you
did previously and check that the record base heels do not touch
2. Place two sharp ‘V’-shaped notches in the wax in the premolar and molar areas of the
maxillary and mandibular rims (1-2mm deep). Make sure there are no undercuts in the
rims or the ‘V’-shaped notches
3. Place the record bases and occlusion rims intraorally and rehearse making the centric
position record without recording media.
4. Place a thin layer of elastomeric registration material
over the entire arch of the mandibular rim.
5. Stabilize the mandibular record base using index
fingers on the flange (or in a recess in the occlusion
rim) and the thumbs under the symphysis.
6. Ask the patient to open, relax, and slowly close
7. You should be able to gently arc the mandible in a hinge like motion - without translation
of the mandible, without much splinting
8. The patient slowly closes, and the operator uses tactile input to ensure the mandible does
not move suddenly forwards or to the side
9. The patient should close until the occlusion rims are almost touching ( l mm apart). Ask
the patient to stop as soon as this position has been reached, or as soon as they feel they