Minimally Invasive Transcrestal Guided Sinus Lift (TGSL): A Clinical Prospective Proof-of-Concept Cohort Study up to 52 Months

Purpose: This study describes a new procedure for sinus elevation using computer-guided planning and guided surgical approach through the use of computer-aided design (CAD)/computer-aided manufacturing (CAM)-generated surgical template in combination with expander-condensing osteotomes thus providing a minimally invasive surgical technique. Materials and Methods: Sixty-six consecutive patients were treated with 136 implants placed by transcrestal-guided sinus floor elevation technique and the patients were followed for at least 3 years in function. The drilling protocol is customized based on the bone density of each implant site to achieve an insertion torque ranging between 45 and 55 Ncm. Titanium temporary abutments were connected to the implants with prosthetic screws tightened to 35 Ncm and an acrylic resin provisional restoration was adapted and delivered immediately. Six months after initial loading, a definitive CAD/CAM-generated restoration was delivered. Outcome measurements assessed were implant and prosthesis survival rate, biological or biomechanical complications, marginal bone level changes, total alveolar ridge bone height before and after procedure, periodontal parameters measured as well as patient's perception of pain levels during recovery period. Results: Mean follow-up was 43.96 (range from 36 to 52) months. Cumulative implant survival rate was 98.53% at 3 years. No biological or mechanical complications were encountered and no prosthetic failures occurred during the entire follow-up period. Mean marginal bone loss (MBL) during the first year of function was 0.33 +/- 0.36 mm, while at the 3-year follow-up, the mean MBL was 0.51 +/- 0.29 mm. The mean residual bone height of the alveolar crest prior to grafting was of 6.7 +/- 1.6 mm (range 5.1-9.2 mm), while, the mean bone height gained was 6.4 +/- 1.6 mm (range 3.2-8.1 mm). All patients reported low levels of pain and found to have normal periodontal parameters. Conclusion: This proof-of-concept study suggests that the use of guided surgery to perform transcrestal maxillary sinus floor elevation for alveolar ridge height augmentation is a successful minimally invasive technique for the short-to medium-term follow-up, thus avoiding the extended treatment time and morbidities associated with maxillary sinus floor augmentation.