Horizontal 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 protrusive, retrusive, and laterotrusive mandibular muscle forces produced at «maximum» as well as at submaximum levels as defined in subjective terms (a simple rating scale). Special attention was paid to differences between subjects with and without manifest mandibular pain dysfunction syndrome (MPD).

31 female subjects with manifest MPD constituted the patient group and 30 healthy females the control group.

The mandibular forces were transmitted via an acrylic splint on the mandibular teeth to a transducer and recorded.

A good reliability of the measurements, especially on high levels, was obtained in both groups. This indicates that the discriminating capacity is unaffected by the disorder.

On low force levels, corresponding to those used in every day life, only small group differences in force were found for all directions studied. On «maximum» levels, however, the forces produced by the patients constantly were only about half those produced by the controls. This seems to be an effect of the higher degree of pain experienced by the patients. In the control group «maximum» laterotrusive forces to the left significantly exceeded those to the right.

Key Words:

• Masticatory muscles
• Muscle contraction
• Temporomandibular joint