title: Unexpected TMJ responses to functional jaw orthopedic therapy.
abstract: The activator, the Bionator, the Fränkel, and, more recently, the Herbst appliances have enjoyed increasing popularity. Although an increase in mandibular growth has not been shown to be clinically consistent or always significant, the popularity of these appliances continues. Another clinical goal of these functional jaw orthopedic (FJO) appliances is to correct, maintain, or protect the integrity of the TMJ--specifically, to prevent posterior condylar displacement and/or anterior disk displacement. Because all FJO appliances anteriorly reposition the condyle during treatment, it is hoped that internal derangement problems may be resolved during treatment. Even though a single TMJ radiograph is not diagnostic in itself, multiple radiographs are helpful in monitoring the net changes in the condylar position during treatment. The relative (or net) change in the condylar position may provide clues to what occurred during treatment. However, TMJ responses are not always predictable during FJO treatment. Three case histories are presented that illustrate unexpected TMJ responses in which the condyles were still posteriorly displaced in spite of FJO treatment. Only 2% to 3% of the author's practice responds in this manner and no physiologic mechanism is suggested. These findings point out the complexity of the TMJ and its treatment, regardless of the appliance, and emphasize that no one approach to TMJ treatment will always be efficacious.
mesh_terms: D000202:Activator Appliances / Q000009:adverse effects*; D002648:Child; D006801:Humans; D004204:Joint Dislocations / Q000000981:diagnostic imaging / Q000209:etiology*; D008297:Male; D008335:Mandibular Condyle / Q000000981:diagnostic imaging; D009968:Orthodontic Appliances, Removable / Q000009:adverse effects*; D011859:Radiography; D013704:Temporomandibular Joint / Q000000981:diagnostic imaging