THE EXTRACTION NONEXTRACTION DILEMMA AS IT RELATES TO TMD

Extraction has been a controversial subject for as long as the special ty of orthodontics has existed. Some authors believe that the extracti on of premolars leads to temporomandibular disorders. This occurs, the y say, because the vertical dimension collapses. Concomitantly, over-r etraction and retroclination of the incisors cause the facial profile to flatten, bring about premature anterior contacts, and distally disp lace the mandible and mandibular condyle. Numerous correlation studies in the dental literature do not support this contention. There appear s to be no higher incidence of temporomandibular disorders in patients treated with the extraction of premolars than in nontreated patients or those treated without extractions. Analysis of premolar extraction cases reveals that there is no collapse of the vertical dimension; on the contrary, the vertical dimension is either maintained or slightly opened. Similarly, there is no evidence that premolar extraction cause s undesirable flattening of the facial profile. The facial profile est ablished during treatment is primarily the result of diagnosis and tre atment mechanics. Excessive anterior interferences resulting in possib le posterior condyle displacement are the result of treatment mechanic s. When arches are leveled properly and space closure and overjet redu ction are adequately controlled, there is no reason that such interfer ences should occur.