Factors Related to Masticatory Rhythm in Patients with Oral Tumors.

Background: Older adults who have undergone surgery for oral tumors are at increased risk of impaired masticatory rhythm. This study investigated the correlations between masticatory rhythm, objective masticatory performance, and subjective masticatory performance as well as factors related to masticatory rhythm. Methods: The participants were 44 adults (24 men, 20 women; age range 42~90 years old) who had undergone maxillectomy, mandibulectomy, or glossectomy and were rehabilitated with a maxillofacial prosthesis. The number of functional contact teeth pairs was confirmed by intraoral examination. Chewing rate, cycle duration, coefficient of variation (CV) for cycle duration (reflecting the stability of masticatory rhythm), and mixing ability were measured simultaneously using a mastication movement rhythm tracking device during gum chewing. Maximum occlusal force was measured using the dental prescale system. Patients' perception of chewing ability was rated using a questionnaire. Results: The Spearman's rank correlation test revealed that mixing ability, patient-rated masticatory scores, cycle duration, CV for cycle duration, and maximum occlusal force showed significant correlations with chewing rate. Multiple linear regression analysis identified mixing ability and the CV for cycle duration as significant predictors of masticatory rhythm. Conclusions: Factors associated with a faster chewing rate were higher mixing ability and masticatory scores, greater maximum occlusal force, shorter cycle duration, and smaller CV for cycle duration. Stable masticatory rhythm and mixing ability are significant predictors of chewing rate. Poor masticatory performance and unstable masticatory rhythm can result in slower chewing and thus a higher risk of inadequate dietary intake.

Gender differences in masticatory movement path and rhythm in dentate adults.

PURPOSE: The purpose of this study was to clarify whether there might be a gender difference in masticatory movement path and rhythm in dentate adults. METHODS: Thirty healthy males and 30 healthy females were asked to chew softened chewing gum on their habitual chewing side for 20 sec, and the movement of the mandibular incisal point was recorded using mandibular kinesiograph. For 10 cycles from the fifth cycle, the spatial and temporal parameters (spatial: amounts of vertical and lateral movements; temporal: opening, closing, occluding, and cycle times) of masticatory movement path and rhythm and the parameters representing the stability of masticatory movement path and rhythm were calculated and compared between males and females. RESULTS: The values of the spatial parameters were significantly greater for males than for females. The values of the temporal parameters were smaller for males than for females, and significant differences were found in all parameters except occluding time. However, there was no statistically significant difference in the parameters representing the stability of masticatory movement path and rhythm. CONCLUSION: From these results it was suggested that although there were no differences in the stability of masticatory movement path and rhythm between genders, there were gender differences in the spatial and temporal parameters of masticatory movement path and rhythm.

Relationship between masticatory rhythm, body mass and mandibular morphology in primates.

OBJECTIVE: It has been proposed that rhythmic movements such as locomotion and respiration have a period proportional to body mass(1/4). Mastication basically consists of rhythmic alternation of jaw-closing and jaw-opening movements. We studied the relation between masticatory rhythm and body mass in primates, and masticatory rhythm and mandible morphology. METHODS: We measured the chewing cycle duration (CCD), mandibular length, mandible height, mandible width and distance from the condylar process of mandible to the centre of gravity of the mandible. Body mass was quoted from the literature. RESULTS: The CCD is related to mandible morphology and was found to be proportional to body mass(1/6). CONCLUSION: These findings suggest that masticatory rhythm is correlated with body mass and mandibular morphology, and that scaling rate of masticatory rhythm to body mass is slower than for the other rhythms.