Mandibular flexure associated with muscle force applied in the retruded axis position

The object of this study was to measure any mandibular flexure occurring in the horizontal plane, when R.A.P. recordings were made with an 'anterior jig' (Lucia, 1964), chin-point guidance and patient-applied muscle force. The rationale for the experimental method was that any arch-width change noted at the tooth level reflected a flexure of the mandible. Ten subjects participated and the mean lateral flexure of the mandible in the horizontal plane was 0.073 +/- 0.028 mm. As a corollary to the study, mean medial flexure of the mandible in wide opening movements was found to be 0.093 +/- 0.044 mm, which was consistent with earlier workers' results. On the basis of the results obtained, restorations constructed to muscle-R.A.P. recordings could conceivably present as occlusal interferences and, indeed, articulators may require modification so as to allow for mandibular resilience.