The molars are the teeth that suffer the greatest periodontal destruction in untreated patients. When periodontal disease affects the furcation of a tooth, the chance that it will be lost increases considerably. An increase in the exposed root surface, anatomical peculiarities and irregularities of the furcation surface all favor the growth of bacteria. These problems make it harder for the patient to maintain hygiene, and impede adequate treatment. The treatment of furcations affected by periodontal disease is one of the most difficult problems for the general dentist and periodontist. The motivation of both the attending professional and of the patient are therefore of great importance. No ideal procedure for treating such lesions exists. The present paper reviews those options that are currently available. Long-term research will be needed, along with the development of new techniques, to solve the problem of furcations affected by periodontal disease, possibly including substitution of the affected tooth by an implant.