The total area of periodontal ligament around the abutment teeth in 60 fixed bridges, inserted in patients treated for advanced periodontal disease, was calculated and compared with the total "periodontal ligament area" of the teeth replaced by pontics. The calculations revealed that only in 8% of the bridge restorations did the periodontal ligament area of the abutment teeth equal or exceed that of the replaced teeth. In 57% of the bridge material the periodontal ligament area of the abutments was less than 50% of the anticipated normal ligament area of the pontics. Despite the fact that the periodontal support for the restorations was dramatically reduced, all bridges have functioned properly for 8-11 years and the periodontal tissues around the abutment teeth have not suffered further loss of attachment during the period of maintenance care.