Nocturnal masseter muscle activity and the symptoms of masticatory dysfunction

Summary This study evaluated the level of nocturnal masseter activity and the symptoms of jaw dysfunction in eighty‐five subjects who varied with respect to degree of jaw dysfunction. A combined jaw dysfunction index was employed which evaluated both the patients subjective report of pain as well as the clinical examination evidence of jaw dysfunction. Using this combined index, a significant correlation was found between the level of nocturnal masseter activity and the signs and symptoms of jaw dysfunction. Tooth wear was also related to signs and symptoms of jaw dysfunction as well as high levels of nocturnal masseter muscle activity (bruxism).