Mounted dental casts

Evidence-based dentistry will probably never settle the use of articulators in orthodontics. I was not trained to mount models. One case convinced me to change: an innocent-looking, mild Class II malocclusion in an adult with a deep overbite. After the appliances were placed and the proprioception changed, the mandible repositioned into a borderline surgical case (surgery had not been discussed). I was able to finish the treatment without surgery, but it left a lasting impression on me. I began routinely mounting dental casts in the early 1980s. A superb orthodontist who read this letter commented that he had several similar patients who did require orthognathic surgery.

In deciding about mounted dental casts, ask yourself: can I develop an occlusion at any mandibular (condylar) position and expect the patient to successfully adapt or is there a particular position that I should use as a goal? I believe there is good evidence from the orthopedic literature to support the statement of Okeson : “The criteria for optimal orthopedic stability in the masticatory system would be to have even and simultaneous contacts of all possible teeth, when the condyles are in their most superoanterior position, resting against the posterior slopes of the articular eminences, with the discs properly interposed.” If the orthodontist believes that mandibular position doesn’t matter, would he or she not expect a prosthodontist to use an articulator if full-mouth reconstruction were performed? Drs Rinchuse and Kandasamy argued against the use of articulators in orthodontics based on a lack of evidence that they are effective in diagnosis or treatment of temporomandibular joint disorders. Even if occlusion has nothing to do with temporomandibular disorders, there are valid dental reasons to give our patients a good occlusion. During diagnosis and treatment planning, a mounting allows us to determine where the patient is at that time in relation to the final goal.

I believe the real question is not whether an orthodontist should mount dental casts, but how we should take the bite registration to mount them. Overcoming a patient’s neuromuscular system and capturing centric relation accurately is challenging. My experience has been that, even though a mounting might not be perfect, it still provides more information about the nature of the malocclusion than models trimmed to maximum intercuspation. Articulators have flaws, but they are the best tool we have for diagnosing and planning treatment for our patients to a specific mandibular position at the present.

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Apr 8, 2017 | Posted by in Orthodontics | Comments Off on Mounted dental casts
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