Worldwide Prevalence and Demographic Predictors of Impacted Third Molars-Systematic Review with Meta-Analysis

Background/Objectives: Impacted teeth are a common phenomenon, in both young and adult populations, as extensively documented in the literature. This study aims to systematically assess the global prevalence of impacted third molars and to analyze their demographic predictors. Methods: The present review adheres to PRISMA guidelines and includes studies published until December 2023. Three databases (MEDLINE, LILACS, Cochrane) were searched, and studies reporting prevalence rates and demographic predictors of impacted third molars were selected for analysis. A meta-analysis was conducted using a random-effects model to calculate pooled prevalence and assess demographic variations. Results: This review yielded 98 studies involving 183,828 subjects. The pooled prevalence of impacted third molars was 36.9% [95% CI: 33.1-40.7%] per subject and 46.4% [95% CI: 36.7-56.1%] per tooth, with the highest rates in Asia (43.1% [95% CI: 34.6-51.7%]) and the lowest in Europe (24.5% [95% CI: 16.1-33.9%]). An odds ratio of 1.173 [95% CI: 1.021-1.347%] indicated a slightly higher likelihood of third molar impaction among women compared to men, and mandibular third molar impaction was more frequent than maxillary impaction. The meta-regression indicated insufficient consistency for the geographic area to be considered a source of heterogeneity in the prevalence of impacted third molars. Conclusions: The present meta-analysis highlights the substantial prevalence of impacted third molars worldwide and underscores the influence of demographic predictors. These findings may inform region-specific clinical guidelines and preventive approaches for managing impacted third molars.