Factors affecting masticatory performance during the mixed dentition period.

BACKGROUND: During the mixed dentition period, masticatory performance may temporarily decline as deciduous teeth are replaced by permanent teeth. This may lead to an insufficient intake of chewy foods. OBJECTIVES: This study aimed to clarify the characteristics of factors that affect masticatory performance during the dentition exchange period. METHODS: The participants were 229 students in grades 4-6 who were in the lateral dentition exchange period. Shearing performance (SP) was evaluated using gummy jelly, and mixing performance (MP) was evaluated using colour-changing gum. The chewing rate, occlusal force and area, number of teeth, Hellman's tooth age, Rohrer index, grip strength and walking speed were also evaluated. The χ2 test, Mann-Whitney test, Spearman's rank correlation coefficient and a generalised linear model were used for statistical analysis. RESULTS: SP/MP showed a significant positive correlation with occlusal force, occlusal contact area and chewing rate for gummy jelly and gum but there was a difference in the strength of the correlation between boys and girls. Chewing rate for gummy jelly and gum showed a significant relationship with both SP and MP, suggesting that masticatory performance is higher with slower chewing. Maximum occlusal force was selected as a significant independent variable for SP, and Rohrer index was selected as a significant independent variable for MP. When the occlusal force was higher and the Rohrer index was lower, the masticatory performance tended to be higher. CONCLUSIONS: Our results suggest that masticatory performance during the dentition exchange period is higher with slower chewing and a stronger occlusal force, which may be related to obesity.