Association of anterior crossbite and open bite with the number of remaining teeth: A cross-sectional study from the Tohoku medical megabank cohort.

OBJECTIVES: Malocclusion, particularly anterior crossbite and open bite, contributes to abnormal occlusal stress distribution, potentially leading to tooth loss. We examined the association between anterior malocclusions and tooth loss-related outcomes in a large-scale, community-based sample of Japanese adults. MATERIALS AND METHODS: This cross-sectional study targeted 17,349 participants aged ≥ 40 years from the Tohoku Medical Megabank Cohort Study (2013-2017). Based on overjet and overbite, participants were classified into normal occlusion (n = 16,790), anterior open bite (n = 177), anterior crossbite (n = 348), and combined malocclusion (n = 34). Outcomes included ≤ 19 remaining natural teeth and posterior tooth loss. Adjusted prevalence ratios (PRs) and 95% confidence intervals (CIs) were calculated using modified Poisson regression models. RESULTS: The crossbite group demonstrated a higher prevalence of ≤ 19 remaining teeth (PR, 1.48; 95% CI, 1.04-2.10) and posterior tooth loss (PR, 1.14; 95% CI, 1.07-1.20) than the normal group; the open bite group exhibited a lower prevalence of posterior tooth loss (PR, 0.79; 95% CI, 0.69-0.90). Heatmap analysis revealed lower molar tooth retention in the crossbite group and higher retention in the open bite group. CONCLUSIONS: Anterior crossbite is associated with increased posterior tooth loss, whereas open bite shows a weaker association. These findings suggest that specific anterior malocclusions may be linked to reduced tooth retention. CLINICAL RELEVANCE: Identification of anterior malocclusion types, particularly anterior crossbite, may help identify individuals at higher risk for tooth loss. Orthodontic management of anterior crossbite might support posterior dentition preservation and long-term oral function.