H. SCHELLER*, L. BORCHERS, N. SCHRÖDER, H. TSCHERNITSCHEK (Dept. of Prosthodontics, Medical University of Hannover)
Healing of malignant disease in oral tissues is often possible only with radical surgery including resection of the jaws. After reconstructive oral surgery there is a reduction in food trituration, the function of the tongue is impaired and xerostomia due to irradiation may further complicate the situation.
To solve these clinical problems after tumor surgery, 243 transmucosal intraoral implants were inserted in 42 patients, 138 were inserted into the residual bone and 105 implants were positioned in autologeous bone grafts. 192 osseointegrated implants were performed by implant retained prostheses. In all cases we used Brånemark implants. 23 patients received local irradiation. The long-term results are described by the cumulative survival rates of the fixtures and the implant retained prostheses using the statistical method of Kaplan and Meier. The influence of implant length, of implant region (residual bone, bone graft) and of irradiation was studied. The difference between the survival rates was tested with the Mantel-Cox test and the Breslow test.
Out of 243 implants we lost 26. This means a cumulative implant survival rate of 86% in 4.4 years. When we analyzed the situation after prosthetic treatment (192 implants) we found a higher cumulative implant survival rate of 94% in 4.4 years. In our statistical analysis, we differentiated with respect implant length and differentiated between implants in irradiated and nonirradiated residual bone. The difference between the survival rates of implant length (18mm 100% in 4.4 years and 7mm 61% in 2.5 years) is significant (p=0.003). In irradiated residual bone we lost 12 out of 74 implants and in nonirradiated residual bone we lost only one implant out of 64 implants. This means a significant difference (p = 0.03) between the cumulative survival rates. By 68 implants inserted in free bone grafts we lost only 2 out of 16 implants in irradiated regions.
The survival rates show, that even implants in irradiated bone give reason to expect long-term success in functional rehabilitation.