3D Vertical Alveolar Ridge Augmentation in the Partial Edentulous Anterior Maxilla Using the Split-Bone-Block Technique: A 10-year Clinical Study

PURPOSE: The consecutive clinical study evaluates the long-term results of vertical autogenous bone grafting in the esthetic partial edentulous anterior maxilla according to the Split Bone Block Technique. The first outcome was to evaluate the primary results of the Split Bone Block Technique for vertical bone augmentation in the partially edentulous anterior maxilla, including the healing complication rate and the amount of the vertical bone gain. Among the secondary outcomes, the analysis was conducted for the long-term stability of the vertical bone gain and implant survival. MATERIALS AND METHODS: Autogenous bone blocks were harvested from the mandibular external oblique ridge following the MicroSaw protocol. The harvested bone blocks were split longitudinally according to the split bone block (SBB) technique and grafted for vertical bone reconstruction. Implants were inserted and exposed after every 3 months and prosthetic restoration was performed. Patients were followed up for at least 10 years post operatively. Peri-implant bone loss was assessed using mostly periapical but also panoramic radiographs, depending on data availability. RESULTS: A total of 229 grafted sites in 210 consecutive treated patients were investigated up to 20 years postoperative. Preoperative soft tissue augmentation with a pedicle palatal connective tissue flap was performed in 181 (79%) grafted sites. Early complications with or without bone exposure occurred in 7 sites (3%) leading to loss of graft in one patient (0,4%). Late graft exposure occurred in 4 cases (1,7 %) without negative influence on the clinical result. The average preoperative clinical vertical defect was 8.47 ± 2.07 mm and horizontal width 2.23 ± 0.84 mm. Postoperatively, the average vertical hard tissue gain was 8.33 ± 1.99 mm and horizontal 8.03 ± 0.35 mm. Three months after grafting a total of 322 implants were inserted. Average of peri-implant bone loss after 1 year was 0.53 ± 0.24 mm, after 5 years 0.68 ± 0.19 mm and after 10 years 0.70 ± 0.19 mm. With patient dropout of 21.9% and loss of 2 implants in one patient, average vertically grafted bone was stable at 7.27 ± 1.71 mm after 10 years, corresponding a resorption rate of 8.5%. CONCLUSIONS: The results of this study confirm the predictability and long-term volumetric alveolar stability of using autogenous mandibular bone blocks, grafted according to the split bone block technique, for vertical bone reconstruction in the anterior maxilla. The improvement of the soft tissue quality and quantity using a pedicled palatal connective tissue flap enables reducing dehiscence and ensuring safe healing of the grafted bone, but also increases the volume of the soft tissue for better esthetics.