Correlation Between Angular Position and Pathological Changes in Impacted Lower Third Molars: A Systematic Review and Meta-Analysis

Abstract

Background: The extraction of impacted third molars presents anatomical challenges and surgical risks, prompting debate over prophylactic removal, particularly for impacted lower molars. Studies highlight associated pathologies and complications that influence treatment decisions. Objective: This study aims to systematically review and analyze the correlation between the angular positions of impacted lower third molars and their association with pathological changes, including periodontal defects, alveolar bone loss, and cystic degeneration. Methods: This systematic review was conducted according to PRISMA guidelines, including studies from 2000 to 2024. Studies reporting the angular position and associated pathologies of impacted lower third molars were included. The Newcastle-Ottawa Scale (NOS) was used to assess the risk of bias. A meta-analysis of the proportion of pathological changes related to specific angular positions was performed. Results: Of the 2943 studies initially identified, six studies (including 2222 patients and 3276 impacted lower third molars) met the inclusion criteria and were included in the review, while four studies were included in the proportional meta-analysis. The most common angular positions observed were mesioangular (34.0-66.1%), followed by vertical (12.8-48.3%), horizontal (8.1-23.4%), and distoangular (3.2-14.0%). Pathological changes were reported in 8.1-75.0% of cases, with horizontal impactions demonstrating the highest correlation (41.1%, 95% CI: 20.9-63.0). Conclusions: The angular position of impactions of the lower third molars significantly influences the risk of pathological changes. Horizontal impactions exhibit the highest associated with pathological changes, whereas distoangular impactions show the lowest prevalence of complications. Standardized diagnostic and reporting practices are needed to improve clinical decision-making. Further research should focus on long-term outcomes and the impact of clinical management strategies.

Keywords: alveolar bone loss; impacted third molars; mesioangular position; meta-analysis; pathological changes.

Figure 1

Workflow diagram depicting the systematic selection of studies for inclusion in the meta-analysis [26].

Figure 2

Proportional meta-analysis of included studies with pathological changes in the angular position of impacted lower third molars [(A) mesioangular, (B) horizontal, (C) vertical, and (D) distoangular] [23,24,25,26]. Aggregate percentage of patients with different frequent causes of symptoms. Markers represent grouped effects. The position of the diamond represents the estimated effect size, and the width of the diamond reflects the precision of the estimate. Output generated by MedCalc 14.8.1 software.