ORTHOPEDIC JAW MOVEMENT OBSERVATIONS .2. THE ROTATIONAL CAPACITY OF THE MANDIBLE

Using computerized axiography, particularly the electronic mandibular position indicator (EMPI), the mandibular opening movement was measure d in 86 asymptomatic volunteers and temporomandibular joint (TMJ) pati ents. Terminal hinge-axis movement and hinge-axis rotation at maximum- guided mouth opening were recorded. The angle of hinge-axis rotation w as used as a parameter for both movements, in accordance with the neut ral-zero method. This is a well-established technique in orthopedics a nd is the standard tool for quantitative functional analysis of joints . An average group was defined, 50% being volunteers, The interquartil e range for terminal hinge-axis movement in this study was 5.42-degree s-7.41-degrees in the volunteers and 4.73-degrees-7.25-degrees in the patients. The interquartile range for hinge-axis rotation at maximum o pening was from 29.09-degrees-34.87-degrees in the volunteers and from 26.7-degrees-35-degrees in the patients. Computerized axiography is a refined tool for analyzing rotational and translational capacities of the mandible. It is a valid and practical method for orthopedic-diagn ostic evaluation of mandibular movements and gives objective criteria for diagnosis in accident victims.