Managing Mandibular Second Molar Impaction: A Systematic Review and Meta-Analysis

Mandibular second molar (M2M) impaction is a serious eruption disorder. The purpose of this systematic review was to analyze the therapeutic approaches for M2M impaction. The objective of the meta-analysis was to summarize the success of the surgical, surgical-orthodontic, and orthodontic treatment.A PRISMA-guided search strategy was conducted by 2 authors in 5 databases up to January 2023. Randomized and nonrandomized clinical trials were considered. Case reports, case series with<5 patients, and reviews were excluded. Methodological quality was assessed using Newcastle-Ottawa scale and Cochrane Collaboration tool for nonrandomized and randomized clinical trials, respectively. Outcomes were as follows: 1) treatment success rate defined by the repositioning of impacted M2M in the dental arch with normal functional occlusal relationship and periodontal health; 2) time-to-repositioning as time-to-event analysis; and 3) complications. Meta-analysis examined treatment success differences with 3 approaches: orthodontic (uprighting maneuvers/traction), surgical (surgical procedures/strategic extractions), and surgical-orthodontic (combined surgical and orthodontic procedures) as the exposure variable. The quantitative analysis also compared the success rate using third molar removal as the secondary predictor variable. The χ2 test determined the statistical heterogeneity (I2); a cut-off of 70% was used to select the common or random effects model. Odds ratio (OR) and 95% confidence interval (CI) were recorded.A total of 1,102 articles were retrieved. After full-text reading, 16 articles were included and 1008 M2Ms were analyzed. Nine studies had fair quality, 6 studies had good quality, and 1 had unclear risk of bias. Managing impacted M2Ms showed a moderate to high success rate (66.7 to 100%). Significant differences favoring surgical treatment over orthodontic treatment were observed for M2M uprighting (OR = 4.97; CI: 1.49 to 16.51; P = .01).No differences were detected comparing surgical and surgical-orthodontic treatment (OR = 1.00; CI: 0.03 to 37.44; P = .99), or orthodontic and surgical-orthodontic treatment(OR = 4.14; CI: 0.43 to 40.14; P = .22).Third molar removal showed no significant correlation with M2M uprighting (OR = 1.98; CI: 0.24 to 16.03; P = .5).Despite study limitations, both orthodontic and surgical management of impacted M2M can be effective suggesting that clinicians are able to choose best treatment for most cases.