Purpose: This literature review aimed to investigate the treatment consideration and strategy of mandibular second molar (MM2) comprehensively, which can be of great assistance on managing and solving such a rare disturbance. Methods: Previous studies were identified in PubMed or Embase database using the keywords “orthodontic,” “molar impaction,” and “uprighting molar.” To enrich the contents of every aspect of the topic, other several related articles were also reviewed and included. Results: Forty-six articles were included and systematically discussed in this review, which were arranged according to prevalence, etiology, diagnosis, treatment strategy, and clinical methods. The incidence of MM2 impaction is 0.06%–0.3% worldwide, and it is related to genetics, craniofacial morphology, space problem, obstacles during eruption, abnormal eruption mechanism, or systemic diseases. Impacted MM2 can be diagnosed by a routine panoramic radiograph according to the definition and criteria. Decision-making depends on patient age, root stage and condition of the impacted tooth, with optimal age of 14 and incompletion root formation. Every treatment option has its indication, benefit/shortcoming, and success rate. Among the four treatment options discussed in this review article, surgical exposure and orthodontic uprighting of the impacted MM2 shows better predictability and success rate, with relatively less side effects. The key biomechanism is to provide the distalizing and uprighting force to rotate the MM2 around the center of resistance, presenting a tipback moment. With various uprighting approaches, either conventional methods or skeletal anchorage devices, to provide pushing/pulling force, tipped molars can be easily corrected. Conclusions: Mandibular second molar impaction is a challenging disturbance that requires proper clinical, radiological, biomechanical evaluation, and suitable treatment option and appliance selection for successful treatment result.

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Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.