Aspects of maxillary sinus reconstruction with endosseous implants

Abstract: This study of maxillary sinus reconstruction in conjunction with insertion of endosseous implants included 99 patients. Two separate surgical methods were applied; a one-staged strategy (n=49) and a two-staged strategy (n=50). The aims were to compare two different strategies concerning implant and prosthetic construction survival. Differences in positioning and angulation of the inserted implants between the two separate strategies were compared. Osteomorphometry and standard histological analysis were performed to evaluate bone morphology from biopsies taken from the alveolar process at different time intervals and from the iliac crest. Bone quality was also assessed by osteometry. Further, influence of patients general medical health status, smoking habits and long lasting medication on implants survival was investigated. Patients assessment of function, phonetics and esthetics of the final outcome of the treatment was performed using a questionnaire. The surgical treatment was performed either as a one-stage or a two stage procedure using cortico-cancellous bone grafts harvested from the anterior iliac crest. In the first method the implants were inserted at the time of bone grafting while in the second method the implants were insterted during a second operation after a healing period of 9-12 months. Mean follow-up time was 30 months (range 9-48 months). Implant survival rate for the two separate strategies was 81.5% and 79.5% respectively. Additionally, differences in implant survival were identified between implants placed in the sinus inlays for both methods (81% and 84% respectively) and the anterior adjacent grafted or non-grafted alveolar process (81% and 75% respectively). Permanent bridge survival was 100% for both methods. The option for optimal implant positioning was in favour of the two-stage strategy. Low bone mineral density (BMD%) assessed by osteometry displayed a significant negative influence on implant survival. Histological analysis of serial bone biopsies showed bone revitalization which well support the planned healing time between bone grafting and implant insertion applied in this study. Osteomorphometry did not seem to be a useful tool for prognostic evaluation of future implant survival. Patients assessment of the final outcome of the treatment concerning estetics, phonetics and function showed a high degree of acceptance with the final result and which also correlated well with the surgery-prosthodontic teams´ evaluation of the same parameters. In conclusion, this investigation showed a rate of implant and bridge survival which well matched other studies on grafted and non-grafted materials. Bone quality measurements by osteometry proved to be a useful tool for prognostic evaluation of increased risk of implant failure in patients with decreased bone mineral density. The 99 patients treated seemed to be most satisfied with the prosthetic rehabilitation accomplished after treatment with a one- or two- stage surgical strategy.