Adjusting Occlusion Rims
Guidelines for Properly Adjusting the Maxillary and Mandibular Occlusion Rims on the Articulator
- If you are using the flat plastic articulator plate, set the incisal pin in place with the rounded end touching this plate. Set the upper arm of the articulator at the zero level, this is the heavy black groove that encircles the incisal pin. Adjust the flat plastic plate block so that the pin touches it at its center.
- If you are using the adjustable metal plate, set the incisal pin in place so that the flat end will touch the incisal plate. Place the incisal plate into the lower member of the articulator with the small screw under the plate in the forward position and the larger screw/foot behind it. Adjust the incisal pin so that the upper arm is at the zero level. Loosening the small screw will allow you to move the plate forward and backward. Adjust the plate so the flat end of the incisal pin touches directly over the black dot in the center of the incisal plate. The incisal pin will now also be inside the black lines down the middle of the plate. Using the side screws be sure that the adjustable lateral wings of the incisal plate are level with the central portion of the plate. When they are, tighten the lock bolts on these adjustment screws. Loosen the larger screw and adjust the incisal plate so that it is at the (o) or horizontal position. The adjustment gauge is on the right underside of the body of the metal plate.
- The following are the articular settings which will be used in this course:
- The condylar inclination is set at 30 degrees
- The Bennett shift movement is set at 5 degrees. Clinically these settings would be determined by the protrusive and lateral excursion recordings.
- Be sure the screws holding the maxillary and mandibular casts onto the articulator are finger tight.
- Viewing the articulated casts, with the incisal pin on the incisal plate, identify a point one half way between the most inferior aspect of the anterior portion of the maxillary cast and the most superior portion of the anterior portion of the mandibular cast. Extend this point visually forward and make a horizontal pencil line on the incisal pin. This line bisects the edentulous intra-maxillary space.
- Place the mandibular record base and occlusion rim on the mandibular cast and close the articulator. Visualize a plane from the line drawn on the incisal pin to the lines drawn on the left and right land areas at half the height of each retromolar pad. Add and/or remove pink base plate wax so that the occlusal flat plane of the wax rim is exactly at the level of the visualized occlusal plane and on a flat plane bucco-lingually.
- Place the transparent ruler over the anterior and posterior land area lines on the right side of the mandibular cast. This will identify the crest of the right residual ridge. Mark a line on the occlusal surface of the occlusion rim along this straight line. Add and/or remove wax on the rim so that this line, on the occlusal plane of the rim, is at the center of the wax. There should be 3.5mm. on each side of the center line in the molar area and 2.5mm. of wax on each side of the center line at the bicuspid area. The width of the wax is 3mm. in the anterior area. Duplicate this procedure on the left side of the mandibular cast.
- Place the maxillary record base and the occlusion rim on the maxillary cast and close the articulator. Add and/or remove wax on this maxillary wax rim so that in the closed position it is in full contact with the lower occlusion rim.
- Add and/or remove wax on the buccal aspect of the maxillary occlusion rim so that there is a horizontal overlap of 2mm. from the cuspid area to the posterior aspect of the rim. Add and/or remove wax so that the occlusion rim is 7mm. wide in the molar area, 5mm. wide in the bicuspid area and 3mm. wide in the anterior area.