HORIZONTAL RIDGE AUGMENTATION USING GBR WITH NATIVE COLLAGEN MEMBRANE AND 1:1 RATIO OF PARTICULATE XENOGRAFT AND AUTOLOGOUS BONE: A 5-YEAR PROSPECTIVE CLINICAL STUDY

PURPOSE. To report the 5-year clinical and radiographic data of patients who underwent a two-stage guided bone regeneration (GBR) procedure to reconstruct severe horizontal bony defects (<4 mm) in the posterior areas. MATERIALS AND METHODS. This study was designed as a prospective single-cohort study. Cawood and Howell class IV horizontal bony defects were augmented seven months before implant placement using a resorbable collagen membrane to protect a 1:1 mixture of anorganic bovine bone mineral (ABBM) and particulated autogenous bone. Patients were followed up for five years after definitive prostheses fitting. Implant and prosthesis survival rates and complications were the primary outcome measures. Secondary outcome measures were horizontal and volumetric dimensional changes, peri-implant marginal bone loss, and periodontal parameters. RESULTS. Eighteen consecutive patients were enrolled, and 55 implants were inserted. Five years after loading, one patient dropped out. None of the implants or prostheses failed during the entire follow-up. Three minor surgical complications occurred early on in three patients (16.7%). In all of these cases, the collagen membrane was exposed rou-ghly two weeks after augmentation. Two of these patients were moderate smokers (P = 0.559). At initial examination, the mean horizontal alveolar ridge width was 3.07 ± 0.64 mm. At the 7-month follow-up examination, the mean bone width was 8.09 ± 2.16 mm. The mean bone gain was 5.03 (95% CI, 4.13-5.92 mm). The difference was statistically significant (P < 0.001). The mean volume of the grafted bone, calculated using the superimposition technique, was 1.12 (95% CI, 1.01-1.23 CC). Five years after loading, the mean marginal bone loss from implant placement was 1.29 (95% CI, 1.18-1.40 mm), PI was 13.1% ± 3.9% (95% CI, 9.6%-16.6%) and BoP was 6.2% ± 2.8% (95% CI, 4.1%-8.3%). CONCLUSIONS. Within the limitations of the study, good and stable bone augmentation and high implant survival rate up to 5 years seem to validate the use of resorbable colla-gen membranes with a 1:1 mixture of particulate ABBM and autogenous bone.