RESUMEN
PURPOSE: The aim of this multicenter retrospective clinical study was to evaluate the survival rate of implants placed in the posterior maxilla with a residual bone height of <5 mm. MATERIALS AND METHODS: One hundred seventeen patients, recruited from 6 different centers, had 134 implants placed below the maxillary sinus. The patient population consisted of 52 men and 65 women ranging in age from 39 to 78 years (mean age, 53.2 years). Sinus lift procedures were performed following a crestal approach using a specific sequence of drills (Cosci's technique). All implants were submerged. Periapical radiographs were obtained with a paralleling technique and were digitized. The pattern of bone remodeling was subsequently evaluated. RESULTS: The average (±SD) follow-up time was 48.2 months (±29.30 months; range, 24 to 120 months). Of the original 134 implants placed, 5 implants (3.7%) failed. The implant survival rate was 96.3%. The average residual bone height was 3.46 mm (±0.91 mm) at baseline. The average height of the alveolar crest in the treated implant sites was 9.94 ± 2.29 mm. The radiographic bone gain was 6.48 ± 2.38 mm. CONCLUSION: The investigation suggests that this crestal drill approach can be a successful sinus lifting procedure in a severe atrophic maxilla with <5 mm of crestal bone height.