LINEAR AND ANGULAR MEASUREMENTS OF THE MANDIBLE DURING MAXIMAL MOUTH OPENING

Purpose: There ave;numerous reports of the translatory movement of the condyle in maximal mouth opening; however, the rotatory movement is l ess well understood. The purpose of this study was to investigate the rotatory condylar movement and the factors associated with it in norma l subjects, Patients and Methods: To study the role of facial morpholo gy in maximal mouth opening, linear and angular measurements of the ma ndible in both the closed and maximal open positions were made by mean s of cephalometry, Dental students, 29 men and 31 women with no functi onal disorders of the masticatory system, were investigated. Results: When the mouth was fully opened, the linear measurement of condylar mo vement was 20.5 +/- 4.0 mm in men and 18.1 +/- 2.5 mm in women, and th e angular measurements of the rotation of the mandibular ramus were 39 .1 +/- 5.9 degrees in men and 36.3 +/- 4.3 degrees in women, These dif ferences were statistically significant (P < .01). Conclusions: During condylar movement and rotation of the mandible, mandibular length and the inclination of the mandibular ramus in the former, and the inclin ation of the mandibular ramus, the mandibular angle and the position o i the condyle in the latter, were important factors.