Sex Differences in Oral Hygiene, Masticatory Performance and Chewing Habits of Japanese Schoolchildren: A Cross-Sectional Study From the Osaka MELON Study.

Background: Sex differences in oral health behaviours and function during childhood may affect long-term oral and general health. However, large-scale studies of Japanese children are limited.

Objectives: To clarify sex differences in oral hygiene, masticatory performance, and chewing habits of Japanese schoolchildren.

Methods: This cross-sectional study included 1400 fourth-grade children (686 boys and 714 girls) from public elementary schools in Osaka City. Oral examinations assessed dental plaque, gingival inflammation, and caries experience (DMFT/dmft indices). Masticatory performance was evaluated using a colour-changeable chewing gum test. Chewing and toothbrushing habits were assessed by questionnaires. Logistic regression analyses were conducted to examine associations between sex and oral health outcomes, adjusting for dental development stage and caries indices.

Results: Boys had higher prevalences of dental plaque and gingival inflammation, higher masticatory performance scores, and were more likely to eat fast and eat with the mouth full than girls. On multivariate analyses, boys were more likely to have dental plaque (odds ratio (OR) = 1.31, 95% confidence interval (CI): 1.02-1.68), gingival inflammation (OR = 1.49, 95% CI: 1.04-2.13), eat fast (OR = 3.11, 95% CI: 2.48-3.91), and eat with the mouth full (OR = 2.43, 95% CI: 1.93-3.07), and less likely to have lower masticatory performance (OR = 0.70, 95% CI: 0.55-0.90).

Conclusions: Significant sex differences were observed in oral hygiene, masticatory function, and chewing behaviour of Japanese schoolchildren. These findings highlight the need for sex-specific strategies in oral health, particularly targeting boys with poorer oral hygiene and chewing habits.