A prospective clinical trial of endosseous screw-shaped implants placed atthe time of tooth extraction without augmentation

THIS PROSPECTIVE CLINICAL TRIAL EVALUATED 134 implants in 81 patients. The implants were placed at the time of tooth extraction and were not augmented with barrier membranes or graft materials. The implants were placed into g ood jaw bone anatomy and quality and were restored by dentists familiar wit h the implant system. Forty-seven implants were followed between 4 to 5 yea rs with a cumulative success rate of 93.3%. Marginal bone levels were measu red for 61 patients with 108 implants. The average mesial-distal measuremen ts for maxillary implants at abutment connection were 1.02 mm (SD +/- 0.59) and 1.36 mm (SD +/- 0.78) at an average of 32 months follow-up. These diff erences were not significant. The average mandibular mesial-distal measurem ents at abutment connection were 1.05 mm (SD +/- 0.92) and 1.54 mm (SD +/- 0.91) at follow-up. These differences were statistically significant (P = 0 .0027). Removal of one patient (5 implants) with advanced marginal bone los s from the data provided a marginal bone level of 1.20 mm (SD +/- 0.94) at abutment connection and 1.30 mm (SD +/- 0.87) at follow-up. These differenc es were not significant. The results of this study indicate that implants p laced at the time of extraction without augmentation or grafting have excel lent long-term cumulative success rates.