Intra- and interobserver variability in the assessment of signs of disorder in the stomatognathic system.

The observer variability in the assessment of signs of disorder in the stomatognathic system within a 3-hour period was investigated in 19 subjects. The clinical examination comprised measurement of maximal mouth opening capacity, sagittal distance between the retruded position (RP) and the intercuspal position (IP), vertical overbite, horizontal overjet and palpation for tenderness of masticatory muscles. The clinical dysfunction score and index (Helkimo 1974) were also calculated. The observer variability in the measurement of maximal mouth opening was quite low, while the relative variability in the measurement of the sagittal distance between RP and IP was high. The intra-observer variability of the nonparametric variables clinical dysfunction score and clinical dysfunction index was within accept able limits, while the interobserver variability was unacceptably high for all the non-parametric variables.