Reliability of mandibular movement assessments depending on TMD.

OBJECTIVE: This study determines the effect of temporomandibular disorders (TMD) on the reliability of mandibular movement assessments.

METHODS: The vertical and horizontal jaw movements, as well as overjet and overbite, were measured twice in 56 consecutively recruited adult subjects with TMD according to the RDC/TMD and 29 controls without TMD diagnosis by experienced dentists utilizing a millimeter ruler. The reliability was determined by intraclass correlation coefficient (ICC).

RESULTS: Neither statistically nor clinically relevant differences in the repeatability between both subgroups could be detected (all p ≥ 0.077). The mouth opening and overjet proved an excellent reliability (ICC 0.85-0.92). Overbite and laterotrusion showed good to excellent reliable results (ICC 0.74-0.82). The second measurement of the vertical jaw movement resulted in systematically higher values (p < 0.003).

DISCUSSION: The assessment of the mandibular movement with a millimeter ruler is a reliable procedure irrespective of TMD. To decrease the variances in the mouth opening measurements, the patient should be asked beforehand to practice this movement.