Relationship between orthodontic anomalies and masticatory function in adults

Introduction: Normal mastication requires the coordinated action of many elements, including teeth, salivary glands, tongue, and masticatory muscles. Dysfunction in any of these areas can result in impaired masticatory function. Few studies dealt with the influence of occlusal conditions on the masticatory function. Our aim in this study was to examine to what extent masticatory function is impaired in subjects with occlusal anomalies. Methods: Masticatory function was studied in 102 untreated adults. They were observed while chewing a standard test food for 20, 30, and 40 chewing strokes. Orthodontic condition was assessed with the index of complexity, outcome, and need (ICON). From the masticatory test, 3 variables were obtained: median particle size (MPS), broadness of the particle distribution (BPD), and masticatory frequency (F). Results: MPS was significantly larger in subjects with ICON scores >43 (definite-need subsample) than in subjects with ICON scores <= 43 (no-need subsample) when the masticatory test was performed with 20, 30, or 40 cycles (P = .05, .03, and .01, respectively). BPD also followed the same trend, but the differences were not significant (P = .33, .16, .14 for 20, 30, and 40 cycles, respectively). Also, the differences in F between the 2 subsamples were not significant (P = .26, .45, .37). Conclusions: The results suggest that, in addition to esthetic considerations, improving a patient's chewing function by improving occlusal relationships could be an indication for orthodontic treatment.