Risk factors and treatments for impacted permanent second molars

Background/purpose: Impaction of permanent second molar (PM2) is found occasionally. This study tried to explore the risk factors associated with the impacted PM2 teeth and show how to use different treatment modalities to correct the impaction of PM2 teeth. Materials and methods: This study used three cases of PM2 impaction to show how to identify the risk factors of PM2 impaction and how to remove these risk factors to facilitate the eruption of impacted PM2 teeth to the correct occlusal positions. Results: The first and second cases both showed delayed eruptions of two maxillary PM2 teeth. After resection of the dense fibrotic gingival tissues on the tooth eruption pathway, these two impacted maxillary PM2 teeth finally erupted to the normal occlusal positions by their inherent tooth eruption potential. The second case also had mesioangular impaction of two mandibular PM2 teeth. After odontectomy of teeth 38 and 48, the two impacted mandibular PM2 teeth also erupted to the normal occlusal positions by their inherent tooth eruption potential. The third case had impaction of teeth 17, 27 and 47. After extraction of four third molars and four selected premolars, orthodontic mesialization of four permanent first molars, and orthodontic traction using a mini-screw, the three impacted teeth finally erupted to the normal occlusal positions. Conclusion: We conclude that after removing the obstacles on the tooth eruption pathway, the impacted PM2 teeth usually can erupt to their normal occlusal positions by their inherent tooth eruption potential with or without the assistance of orthodontic traction.