Clinical analysis of implant losses in oral tumor and defect patients.

In the period between 1990 and 1996, 279 endosteal dental Bone-Lock implants were placed in 79 patients. Of them 63 have been treated with ablative tumor and reconstructive surgery in the oral cavity, the rest presented with maxillo-mandibular defects of different origin. The circumstances of implant loss were noted down for descriptive analysis concerning age, sex, topography, implant dimensions, loading, time in place and type of superstructure. Failure analysis was done concerning the implants and the patients. Five causes for implant loss could be detected: lacking primary osseointegration, acute inflammation, bone loss, biomechanical overloading and tumor recurrence. No predictive factors for implant loss and no age influence on implant loss could be detected, no specific local implant site and no specific superstructure had an identifiable higher risk. Survival rate of all placed implants in oral tumor and defect patients was 83.5% after 6 years observation. Male tumor patients were found to have a higher risk to lose implants than females. Free iliac bone grafts impaired osseointegration of implants. The mandible offered a better prognosis for the implants than the maxilla. Shorter and thinner implants had a higher risk of being lost. A quarter of all patients (26.3%) had to face implant loss. Clustering of implant loss in several patients was caused by free iliac bone grafting and by prosthetic faults. Chemotherapy had no negative influence on implant survival. Most implants were lost early (76%) before fabrication of the prosthesis. After restoration there was a nearly 100% probability of function. It is concluded that implant treatment can be equally effective for tumor and defect patients as it is known for healthy subjects.