Sub-antral volumetric variation after a modified trephine sinus elevation approach: An 8-month prospective study

Aim To overcome vertical deficiency of atrophic posterior maxilla, sinus floor elevation has been used for several decades either through a transcrestal or a lateral approach. In 1999, Fugazzotto et al. described a modified trephine/osteotome technique for sinus floor augmentation at the time of maxillary molar extraction without implant placement. A trephine was used to create a bone core in the middle of the extraction site and was gently malleted apically. In 2002, Fugazzotto et al. used the same principle to place dental implants in healed maxillary molars sites with limited residual height (RH). This procedure demonstrated a 98.3% implant survival rate at 4 years but lacked radiographic information. The aim of the present study was to assess the efficacy of the modified trephine/osteotome sinus elevation  with implant placement, using a clinical and a radiographic cone beam evaluation. Materials and methods Twenty-one implants were placed in premolar and molar sites with 3≤ RH ≤6mm using the modified trephine/osteotome sinus elevation approach and were evaluated clinically and radiographically at baseline (T1), 3 (T3) and 8 (T8) months. Results Implant survival was 100% at 8 months. Sub-antral volumetric bone gain between T1 and T8 was 20.34%. Linear bone gain was 2.1 ± 1.1 mm buccally; 2.0 ± 1.4 mm palatally; 2.5 ± 1.6 mm mesially; and 1.5 ± 1.5 mm distally. Mean linear bone gain was 2.0±1.1 mm  calculated on the CBCT. Implant stability quotient (ISQ) at T1 was 66.378±7.931, and 67.921±14.369 at T3 without a statistically significant difference between the two measurements. Residual height was positively correlated to vestibular, palatal, and mesial bone gain. Signs of Schneiderian membrane tearing were  noticeable in one case. Conclusion This study demonstrated that sufficient subantral bone formation can be obtained with the modified trephine/osteotome technique with high implant survival rate and low post-operative morbidity.