Methodological considerations concerning the use of Bruxcore Plates to evaluate nocturnal bruxism.

The purpose of this study was to evaluate the Bruxcore Plate (BP) as a dependent measure of nocturnal bruxing activity. As part of a bruxism treatment study, we evaluated 100 nocturnal bruxers for bruxing activity before, during, and immediately after treatment and again at a six-month recall. The first 40 subjects wore both a BP and an EMG (electromyographic) unit for every night of each 14-night evaluation period (baseline; post-treatment; six-month recall). During the treatment period, these subjects wore the EMG unit but no Bruxcore Plates. Another 40 subjects wore the EMG unit and never used Bruxcore Plates. We evaluated a 20-subject no-treatment control group by two methods. Ten control subjects were evaluated with the EMG unit and the BP and another ten with the EMG unit alone. We hypothesized that the BP would not measure the same construct as an accepted EMG measure of bruxing activity, and that the BP would effect changes in EMG measured nocturnal bruxing activity. The results supported the conclusions that the BP did not measure the same construct as the EMG measure, and that the BP did effect changes in nocturnal bruxing activity. Correlations of BP scores with EMG data for equivalent measurement periods were low or non-existent. For the control group and the massed practice (negative practice) treatment group, there were significant interaction effects for EMG-measured bruxing episodes per hour for BP vs. no-BP Groups, with respect to measurement periods (time). Interpretation of these results indicated that BP evaluation of nocturnal bruxing activity was confounded with measurable treatment effects.