This article presents two cases in which different treatments were used for mandibular molars with furcation lesions. In the first case, a conventional amputation treatment of the distal root was performed to save the mesial root as a terminal tooth, which was used as a partial denture abutment. The second case describes a relatively new technique in which a root perforation was filled with graft material (synthetic bioglass) and covered with a resorbable membrane to treat an iatrogenic furcation lesion adjacent to the mesial root. Twelve months after surgery, periapical radiographs of both treated cases showed increased bone density. Follow-up in both cases--30 months in the first case and 12 months in the second--showed no pathological recurrence or clinical dysfunction. Root amputation may provide an alternative to extraction in periodontally involved molars. Synthetic bone replacement materials combined with guided tissue regeneration may also help to correct osseous defects incurred by recent furcation perforations with associated bone loss.