Although maxillary sinus floor elevation surgery with autogenous bone grafts has become a well established pre&implantology procedure, its effect on the function of the maxillary sinus has not been subject of prospective human studies. In this prospective study the effects of maxillary sinus floor elevation on maxillary sinus performance was evaluated.

17 consecutive patients underwent maxillary sinus floor elevation surgery with an iliac crest autogenous bone graft, agreed to participate in this study. All patients were subject to extensive anamnestic and clinical investigation on sinusitis, con& ventional radiography (Waters, projection) and unilateral endoscopic inspection of the maxillary sinus. This triad of evaluations was performed preoperatively, imme& diately preceding the elevation procedure (maxillary sinus to be inspected endo& scopically was randomly selected), and 3 (at insertion of the implants) and 9 months (at uncovering of implants) post&elevation. 5 out of 17 patients had a history of an impeded sinus clearance, but did not show clinical, or radiological signs of actual sinus pathology preoperatively, neither did the other 12 patients. By contrast, unilateral endoscopic evaluation revealed pre&existing subclinical mucosal pathology in 2 out of 5 patients with a history of sinus clearance impairment and in 1 out of the other 12 patients. 3 months post& elevation, clinical and radiographical examination showed chronic maxillary si& nusitis in 1 non compromised patient. Moreover, serial unilateral endoscopic evaluation revealed subclinical maxillary mucosal pathology in 4 other patients (2 had a history of an impeded sinus clearance), confirmed by Waters, projection in 3 of these 4 patients. Nine months post&elevation, only subclinical maxillary mucosal pathology was detected endoscopically in 2 patients (1 compromised, 1 non com& promised patient), confirmed by Waters, projection in this last patient. 5 implants were lost during the 9 months observation period. As is obvious from this prospective evaluation, the effects of the sinus floor elevation procedure on maxillary sinus performance in patients without signs of maxillary sinusitis are of no clinical significance.