A prospective clinical study evaluating the safety and effectiveness of narrow-diameter threaded implants in the anterior region of the maxilla.

The aim of the present study of single-tooth implants was to compare the success rate and marginal bone resorption of a narrow-diameter self-tapping implant placed in less available bone volume with the standard-diameter self-tapping implant placed in a well-dimensioned alveolar process. A new abutment technique and a different permanent abutment design were also evaluated. Fifty-five patients were included in the study; 27 patients received 28 standard-diameter (3.75-mm) implants, and 28 patients received 32 narrow-diameter (3.25-mm) implants replacing either a central or a lateral incisor in the maxilla. In an attempt to create an ideal emergence profile and to regenerate papillae, individual acrylic resin tooth-shaped temporary abutments were fabricated, based on impressions made immediately following implant placement, and connected to the implant after 6 months. A minimum of 2 months were then allowed before definitive restorative procedures were performed. Impressions were always made at the implant level. Follow-up examinations were performed at 6 months after loading and 1, 2, and 3 years after loading. Two narrow-diameter implants were lost after 6 months, but no other failures were subsequently observed in any of the groups after that. In both groups, marginal bone loss followed the same pattern and was recorded radiographically to be a mean of 0.4 mm from the first to the last examination.