Outcome of implant therapy involving localised lateral alveolar ridge and/or sinus floor augmentation: a clinical and radiographic retrospective 1-year study

Aim: To retrospectively evaluate the 1-year outcome of implant therapy involving various types of localised lateral alveolar ridge and/or sinus floor augmentation procedures performed before implant placement. Materials and methods: Forty-seven patients were consecutively treated with oral implants on average 6.5 months after bone grafting. A total of 82 regions were augmented and 151 implants were inserted. All regions were augmented with autogenous bone harvested intraorally. Block grafts (13 regions, 16%), particulate grafts (25 regions, 30%), and a combination of block and particulate grafts (44 regions, 54%) were used. The particulate grafts were sometimes mixed with less than 25% anorganic porous bovine-derived bone mineral (28 regions, 34%). Finally, the grafted areas were in most cases covered by either an expanded polytetrafluoroethylene (e-PTFE) membrane (58 regions, 71%) or a resorbable collagen membrane (11 regions, 13%). The selection of the performed procedure was based upon the experience of the surgeon and thorough evaluation of each case. All surgical procedures were performed by two oral and maxillofacial surgeons with extensive clinical experience with regenerative procedures. The outcome measures were complications related to the augmentation procedure, prosthesis survival, implant survival and peri-implant marginal bone loss. Results: No dropouts occurred. Complications occurred in eight patients (17%) after bone harvesting: temporary paraesthesia (two patients, 4%), membrane exposure (five patients, 11%) and acute sinusitis (one patient, 2%). Membrane exposure was exclusively observed when an e-PTFE membrane was used. However, the subsequent implant placement was not compromised. Regarding the patient with acute sinusitis, the graft was removed and implant/prosthesis placement was not possible. No further prosthesis failures occurred during the 1-year follow-up period. Thus, the prosthesis survival was 99%. The implant survival involving sinus lift, lateral augmentation, and combined sinus lift and lateral augmentation was 91%, 97%, and 100%, respectively. A total of four patients (9%) experienced implant failure. The mean peri-implant marginal bone loss at patient level involving sinus lift, lateral augmentation, and combined sinus lift and lateral augmentation was 0.60 mm (range: 0.31-1.25), 0.31 mm (range: 0.00-0.75) and 0.41 mm (range: 0.00-1.25), respectively. No technical complications were observed. Moreover, no episodes of peri-implant mucositis or peri-implantitis were registered. Conclusions: Localised lateral alveolar ridge and/or sinus floor augmentation performed before implant placement seems to be associated with few complications after 1 year. However, it should be emphasised that all surgical procedures were selected and performed by oral and maxillofacial surgeons with extensive clinical experience in the field of regenerative procedures. Keywords: alveolar ridge augmentation, bone transplantation, dental implants, retrospective study