Temporomandibular joint sounds related to orthodontic therapy.

A cross-sectional survey for temporomandibular joint (TMJ) sounds was conducted on 347 orthodontic patients before, during, and after treatment. Those patients who reported joint sounds, or in whom sounds were noted on clinical examination, were subjected to an audiovisual evaluation which was recorded on videotape to identify more precisely the character of the sounds during jaw opening and closing. TMJ sounds were quite common before, during, and after orthodontic treatment. There was a significant association among three variables: joint sounds, age, and treatment. It is not clear, however, whether joint sounds increased due to orthodontic treatment, age, or both. No significant associations were found between TMJ sounds and functional occlusal factors. Significantly more sounds were noted by the examiners than were reported by the patients. Medium or high amplitude sounds were evident in 32.6% of the 135 subjects who underwent the audiovisual examination.