ORTHOPEDIC JAW MOVEMENT OBSERVATIONS .3. THE QUANTITATION OF MEDIOTRUSION

The objective of this series is to observe and analyze movements of th e temporomandibular joint (TMJ). With the information from these studi es, orthopedic standards for jaw movements will be established in furt her investigations according to the neutral-zero method used in genera l orthopedics. Any restricted range of motion can thus be defined as a deviation from these standards. Direct interpretation and objective e valuation of joint functions has major practical implications. With th e aid of computerized axiography, mediotrusive movements of 48 asympto matic volunteers and 66 jaw patients were evaluated. The movements per formed were either free or guided. The mean curve lengths, as well as the Bennett angles at 3 mm and al the end point were recorded. An aver age group was defined, containing the Values of 50% of all volunteers. The interquartile range was calculated for lengths of mediotrusive mo vements as well as for Bennett angles. The average range of free medio trusive movement for female Volunteers was 11.06-11.98 mm (mean 11.55 mm) on the right side and 10.47-11.75 mm (mean 11.24 mm) on the left s ide. Male volunteers showed an average range of 10.23- 11.54 mm (mean 11.1 mm) on the right side and 10.24-11.73 mm (mean 11.12 mm) on the l eft side. The values for female patients amounted to 9.95-1.66 mm (mea n 10.8 mm) on the right side and 9.75-11.28 mm (mean 10.55 mm) on the left side. The average range for male patients was 9.06-9.71 mm (mean 9.54 mm) on the right side and 9.17-10.23 mm (mean 9.73 mm) on the lef t side. The average range for Bennett angles at maximum excursion in f ree mediotrusive movement was between 0.41 and 5.89 degrees (mean 4.43 degrees) in the volunteers on the right side and between 2.45 and 10. 07 degrees (mean 6.87 degrees), respectively, on the left side. The va lues for patients amounted to 0.19-12.65 degrees (mean 6.93 degrees) o n the right side and 1.71-14.15 degrees (mean 6.73 degrees) on the lef t side.