Setting Ortho-lingual Posterior Teeth
Guidelines for Setting Ortho-lingual Posterior Teeth on a 20 Degree Plane
Mandibular Left Set-up
- The anterior teeth are set as previously described.
- Place a small notch in the record base at a point one-half the height of the left and right retromolar pads.
- The occlusal plane is to be set anteriorly from the incisal edge of the mandibular teeth, on a 20 degree inclined anterior-posterior plane, to a point one-half the height of the retromolar pads.
- Place your 20 degree template on the mandibular case. Remove the sufficient occlusal rim wax so that the anterior aspect of the template rests on the incisal edge of the left and right mandibular cuspids and the posterior ends of template are set into the notches in the record bases.
- After softening the wax, set the mandibular left first premolar in light contact with the left cuspid and directly over the rest of the left mandibular ridge. Use the lines previously drawn on the cast to verify this. Place your 20 degree template on the set-up and adjust the occlusal surface of the tooth so that both the buccal and lingual cusps both tough the underside of the template. Don’t forget to re-check the tooth being over the crest of the ridge and in contact with the proximal cuspid.
- Set the mandibular left second premolar and the first molar using the same guidelines.
- As you do your set-up remember to recheck the mesio-distal, bucco-lingual and cervico-occlusal positioning of each tooth.
- All of the left mandibular posterior teeth should have both buccal and lingual cusps touching the 20 degree template. A straight line should be visualized along the central fossae of the mandibular teeth, which in turn should be directly over the crest of the residual ridge. These teeth should exhibit a graceful 20 degree curve when viewed form the facial. The axial inclinations of all of these teeth are straight up and down.
- Carefully heat the wax around each tooth, sequentially assuring the cusp tips are touching the templates, and then chill the wax in order to solidify its positioning. Remove any wax that is on the facial surfaces of the teeth.
Maxillary Right Set-up
- Soften the wax distal to the maxillary left cuspid and place the first premolar in position. Assure that only the lingual cusp touches the central fussa of the mandibular first premolar. The buccal cusp of the maxillary first premolar should be 1-2mm. superior to the buccal cusp of the mandibular first premolar. The buccal cusp of the mandibular first premolar will not be in contact with the central fussa of the maxillary first premolar.
- Unlike natural tooth occlusion, with which you are so familiar, this denture teeth occlusal scheme has only the single lingual maxillary cusp occluding with a rounded-out mandibular occlusal surface.
- Set the maxillary left second premolar and first molar in the same way. Recheck tooth positioning and stability. Cool and remove any wax on the facial surfaces, as was done with the mandibular teeth.
- Set all of the right posterior teeth using the above guidelines.
- Recheck: That there is mesio-distal contact, that the mandibular teeth centered over the ridge, that the mandibular teeth are squarely on the 20 degree curve, that maxillary facial cusps are free of occlusal contact, that all axial inclinations are up right and that no wax is on the facial surfaces of the teeth.
- Teeth must be constantly adjusted to achieve the best result. Never set a tooth and forget it. Refine the tooth position and constantly recheck your guidelines.