The loss of occlusion and its effect on mandibular immediate side shift

Mandibular immediate side shift is a lateral movement of the condyles at the commencement of mandibular laterotrusion. Amount of mandibular immediate side shift has been found to vary among patients and bilaterally within patients. Factors responsible for variance in mandibular immediate side shift have been suggested but not thoroughly investigated. Because of the clinical importance of the mandibular immediate side shift, this study attempted to demonstrate that one suggested factor--the loss of occlusion--would result in increased mandibular immediate side shift. Subjects were placed into one of four groups that had a varied amount of occlusion. Surprisingly, among groups no differences were detected in the amount of mandibular immediate side shift. Therefore loss of occlusion as a suspected cause of an increase in the amount of mandibular immediate side shift was not substantiated. Restorative therapy recommended on the basis of such an assumption will most likely prove inaccurate.