Vertical Isometric Muscle Forces of the Mandible: A Comparative Study of Subjects with and Without Manifest Mandibular Pain Dysfunction Syndrome

Abstract

The aim of the investigation was to study isometric biting forces at ‘maximal’ as well as at submaximal levels as defined in subjective terms. Special attention was paid to differences between subjects with and without manifest mandibular pain dysfunction syndrome (MPD). Thirty-one female subjects with manifest MPD constituted the patient group and 30 healthy females the control group. The reliability of the measurements was tested and the results obtained in both groups indicated that the discriminating capacity was not affected by the disorder. Except for the lowest force level (approximating the absolute threshold), substantial force differences between the groups were obtained. These differences increased with the force levels, and the patients generally produced only one-half to two-thirds of the forces produced by the control subjects. No significant differences were found between forces produced on the right and left sides respectively in the control group, nor were such differences found in the patient group between forces produced on the disordered or on the non-disordered side. Reasons for this were considered, and a comparison between the vertical and the horizontal forces of the mandible was made and discussed.