Assessing Occlusal Plane/Midline Cant ProblemsBy Robert Winter on June 12, 2013 | 3 comments
At the time you try-in a patient's final restorations, if there is a cant to the occlusal plane or midline, you can follow these steps to assess or rectify the situation.
- Evaluate the restorations on the mounted cast. Place the restorations on the master cast, which has been mounted on the articulator.
- Determine if the occlusal planes and/or midline are canted or level to horizon. If it is level on the mounted cast but not intraorally, an error was made in the facebow transfer.
1. Evaluate the restorations intraorally.
- Try-in all the restorations individually and confirm the proper marginal integrity.
- Try-in the restorations two at a time to check and adjust interproximal contacts. A frequent cause of canted restorations or poor marginal integrity, are tight interproximal contacts.
- Evaluate the occlusal plane and midline with the patient standing in front of you.
2. If there is a cant that needs to be corrected in the laboratory:
- Temporarily seat the restorations.
- If the restorations are crowns, seat them with a very small amount of Mock 2 (or Mock Slow if you require more time for this procedure). If they are veneers, you may need to use a temporary cement to lightly secure the restorations to the tooth.
- Take a facial photograph of the restorations with the patient standing in front of a horizontal line, lips retracted, level interpupillary line, teeth slightly apart (1-2 mm) so the maxillary and mandibular occlusal planes can be seen. Align the lens of the camera at the level of the maxillary arch. This photograph must show the cant which needs to be corrected.
- Take a new facebow with the restorations temporarily secured to the teeth. Be certain to level the facebow with the patient standing. Photograph the facebow transfer with the level line behind the patient.
- Return all of the original information and casts to the laboratory along with the new facebow transfer and photographs.
- Fill out a new prescription identifying the corrections needed including completing the diagram of the occlusal planes and midline relative to the interpupillary line and horizon.
Using the new facebow transfer, the laboratory mounts the original master cast with the restorations in position. If the new mounting and photographs all accurately represent the clinical situation, the laboratory and the dentist can both be confident in the corrections that are made.
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