Ipsilateral interferences and working-side condylar movements § B.-Y. Huang 1 , T. Whittle, C.C. Peck, G.M. Murray * Jaw Function and Orofacial Pain Research Unit, Faculty of Dentistry, University of Sydney, Level 3, Professorial Unit, Westmead Centre for Oral Health, Westmead, NSW 2145, Australia Accepted 20 July 2005 Introduction Natural tooth morphology is often changed during clinical dental practice but with little knowledge of the effects of these changes on the function of the temporomandibular joint. Although a number of studies have shown that changes to natural tooth guidance can alter both working-side 1—3 and balan- cing-side 3,4 condylar movement during a lateral jaw movement (laterotrusion), these studies based their conclusions on the movement of a single condylar point that was not accurately referenced to con- Archives of Oral Biology (2006) 51, 206—214 www.intl.elsevierhealth.com/journals/arob KEYWORDS Computer tomography; Jaw movement; Jaw tasks; Lateral jaw movement; Condylar movement Summary There is limited knowledge of the effects of the occlusion on tempor- omandibular joint function. Aim: The aim was to investigate the influence of a working-side occlusal alteration (OA, i.e. interference) on trajectories of working-side condylar points during stan- dardized lateral jaw movements (laterotrusion) tracked by a jaw-tracking system. Methods: Ten trials of right laterotrusion were repeated under: control 1 (before OA), OA (immediately after placement of a working-side interference) and control 2 (immediately after removal of OA) conditions. Results: During right jaw movement, the paths of the working-side condylar points under OA were significantly more inferior and anterior to those under control at the same amount of mid-incisor-point displacement from the intercuspal position. The OA significantly reduced the rotation of the mandible about the antero-posterior and supero-inferior axes and significantly increased the opening angle. Controls 1 and 2 were not significantly different. Conclusions: A working-side interference has an immediate, significant effect on working-side condylar movement. # 2005 Elsevier Ltd. All rights reserved. § Based on a thesis submitted to the Faculty of Dentistry, University of Sydney, in partial fulfillment of the requirements for the Ph.D. degree. * Corresponding author. Tel.: +61 2 9845 6380; fax: +61 2 9633 2893. E-mail address: gregm@usyd.edu.au (G.M. Murray). 1 Present address: Prosthetic Division, Dental Department, Chang-Gung Memorial Hospital, 199 Tung Hwa North Road, Taipei, Taiwan, ROC. 0003–9969/$ — see front matter # 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.archoralbio.2005.07.006