Regional brain activity during jaw clenching with natural teeth and with occlusal splints: a preliminary functional MRI study.

<bold>Objective: </bold>The purpose of this study was to investigate regional brain activity during jaw clenching with natural teeth and with two types of occlusal splints using functional magnetic resonance imaging (fMRI).<bold>Methods: </bold>Sixteen healthy volunteers were enrolled in this study. Blood oxygenation level-dependent (BOLD) fMRI signals were compared under three conditions: during clenching with natural teeth, with a soft splint, and with a hard splint. For each condition, 30-second jaw clenching followed a 60-second rest, and was repeated three times, with intervening 30-second rests. SPM 8 was used for the fMRI analysis.<bold>Results: </bold>Blood oxygenation level-dependent signals during clenching with natural teeth increased in BA44, 45, and the cerebellum. Blood oxygenation level-dependent signals increased in those areas and in BA17, 18 during clenching with a soft splint. Use of the hard splint increased the BOLD signals in BA6 and BA20, 37 in addition to the areas previously mentioned. Blood oxygenation level-dependent signals in the left BA6, the left BA20, 37, and the right BA44, 45 were significantly higher during clenching with a hard splint than with natural teeth. These regions are associated with motor coordination, memory, and cognition, respectively.<bold>Conclusion: </bold>Jaw clenching with a hard splint caused activity in the widest brain regions, including the associated area with motor coordination. [ABSTRACT FROM AUTHOR]