Changes in dental age and masticatory performance during the mixed dentition period.

In recent years, the development of masticatory function during growth has become increasingly important. However, only a few studies have objectively evaluated longitudinal changes in masticatory performance during the mixed dentition period. This study aimed to examine the relationship between 1-year changes in dental age and objective masticatory performance in fourth- to sixth-grade elementary school students. The study participants included 434 children (218 boys, age: 9-11 years) in the mixed dentition period (mainly Hellman stages IIIA-IIIC). Oral examinations and masticatory performance measurements were conducted at baseline and at the 1-year follow-up. Oral examinations included assessment of Hellman's dental age (IIIA/IIIB/IIIC/IVA) and the number of permanent and primary teeth. The shearing performance (SP) and mixing performance (MP) were assessed using gummy jellies and color-changing gums, respectively, on a 10-point scale. Statistical analysis was performed using the chi-square, Kruskal-Wallis, and Wilcoxon signed-rank tests. Changes in dental age were observed in 53.5% of the participants, who were classified into nine groups based on the pattern of change (baseline/follow-up). For SP, the IIIB/IVA group showed the greatest increase (p = 0.007), whereas the IIIA/IIIB group showed a decrease, which was not statistically significant (p = 0.053). However, no marked differences in MP were observed between the groups. These results suggest that the changes in masticatory performance over the 1-year period of tooth replacement differ based on the pattern of dental aging, and these changes are influenced by the type of test food used for evaluation.