Smallest detectable difference in outcome variables related to painful restriction of the temporomandibular joint

The smallest detectable difference is the smallest statistically significan t change in measurement results. In the field of temporomandibular disorder s, the smallest detectable difference is not a commonly used concept. Most outcome studies are based on comparisons of group means, although this does not provide information about individual changes or about the clinical rel evance thereof. The smallest detectable difference for maximal mouth openin g was calculated from previously published reliability coefficients and the standard deviations of different samples of healthy subjects and patients with complaints of the temporomandibular joint. The smallest detectable dif ference of pain intensity measured with different visual analogue scales wa s calculated from the reliability coefficients and standard deviations of a heterogeneous group of pain patients. The smallest detectable difference o f function impairment was calculated for a group of patients with complaint s of the temporomandibular joint. For maximal mouth opening in healthy subj ects, the smallest detectable difference was 5 mm. Repeated measurements im proved it to 3 mm. The smallest detectable difference on a visual analogue scale was 28 mm for actual pain intensity and 22 mm for minimal pain as wel l as for maximal pain intensity. For total function impairment of patients with complaints of the temporomandibular joint, the smallest detectable dif ference was 8 units on a 0 to 68 scale.