To assess the therapeutic approaches for impacted mandibular second molar (M2M) impaction and summarize the success of surgical, surgical-orthodontic and orthodontic treatments available.

A search strategy was performed following the PRISMA guidelines across 5 databases. The inclusion criteria incorporated both non-randomized and randomized trials. Case studies, case series with fewer than 5 patients, and reviews were not considered. Methodological quality assessment employed the Newcastle–Ottawa scale for non-randomized trials and the Cochrane Collaboration tool for randomized trials. The study focused on three outcomes: (1) treatment success rate (i.e. the relocation of impacted M2M in the dental arch with a normal functional occlusal connection and periodontal condition); (2) time-to-repositioning; and (3) complications.

Three methods were used to determine the treatment success differences: orthodontic (uprighting/orthodontic traction), surgical (surgery/strategic extractions), and surgical-orthodontic (surgical + orthodontic techniques) as the exposure variable.

A quantitative analysis distinguished the success rates with the third molar removal as the secondary predictor variable. Statistical heterogeneity (I2) was determined using the χ2 test.

Out of a total of 1,102 articles retrieved, 16 were included, encircling the analysis of 1008 M2Ms. Nine studies demonstrated fair quality, six showed good quality, and one had an unclear risk of bias. Managing impacted second molars exhibited a moderate-to-high success rate (i.e. 66.7-100%). Notably, significant differences favoring surgery over orthodontic treatment were observed for M2M uprighting [odds ratios (OR)= 4.97; confidence intervals (CI): 1.49 to 16.51; P = .01]. No noteworthy differences were noticed when comparing surgical and surgical-orthodontic therapy or orthodontic and surgical-orthodontic therapy. There was no substantial correlation observed for third molar removal with M2M uprighting.

Clinicians have the flexibility to opt for either orthodontic or surgical approaches in managing impacted M2M, indicating that both options are viable for the majority of cases.