Radiographic evaluation of dental implants placed using an osteotome technique

Background: The osteotome technique has been successfully used for implant placement when a limited vertical height is available at posterior maxilla. However, it is not clear if new bone is formed at the apical portion of the implant placed by this technique without any bone graft. The aim of this study was to radiographically evaluate bone formation around dental implant surfaces exposed to the space created at the sinus floor without the presence of any graft material. Methods: Forty patients (21 male, 19 female; mean age 46.7 years) who received a total of 75 dental implants together with indirect sinus lifting procedure were included. Initial and 6-month postoperative panoramic films were scanned and analyzed using a commercially available software program. Implants were divided into two groups: initial alveolar bone height < 9 mm or >= 9 mm. This helped determine the effect of available bone and exposed implant surface on bone formation in a system where the shortest implant was 8 mm. Results: The mean implant length placed at locations with < 9 mm initial bone height (mean 7 +/- 1.3 mm, N = 29 implants) was 11 +/- 1.7 mm; gain in bone height was 3.9 +/- 1.9 mm. At locations where minimum bone height was 9 mm (mean 10.4 +/- 0.7 mm), 44 implants were placed with a 13.5 +/- 1.06 mm mean length. Mean gain in bone height was 2.9 +/- 1.2 mm at these sites. Two implants were lost at stage 2 surgery. The success rate after 25 months of loading was 97.3%. Conclusions: It is possible to radiographically observe a gain of approximately 3 to 4 mm of bone from the sinus floor to the implant apex. The amount of initial alveolar bone height, presence of sinus membrane perforation, and the amount of exposed implant surface appear to play a role in the presence or absence of radiopacity within the elevated sinus floor, following 6 months of healing.