Time-frequency analysis of temporomandibular joint (TMJ) clicking sounds using radially Gaussian kernels

Temporomandibular joint (TMJ) sounds and motion were recorded during two clinically-derived movements--simple jaw opening and jaw protrusion followed by opening--from ten patients. A new time-frequency method--radially Gaussian kernel distribution--was applied to classify the TMJ clicking sounds into six groups, type I to type VI, based on the time-frequency patterns of energy distribution. The number of clicks and percentage of each type were examined. Relations between the two movements were examined by the prevalence of each type. A detailed classification of TMJ clicking sounds is provided by time-frequency patterns and may provide a better understanding of temporomandibular disorders.