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Evaluation of the split bone technique for lateral ridge augmentation: A retrospective case-control study.

PURPOSE
The aim of this retrospective case-control study was the evaluation of the split bone technique with regard to the occurrence of early complications, implant survival rate, and peri-implant bone resorption. The effect of patient-related factors (gender, age, tobacco consumption), implant location, and the implant system used on bone resorption was analyzed.


MATERIALS AND METHODS
Patients treated by means of the split bone technique with autologous bone blocks from the external oblique line in a two-stage grafting procedure were observed for up to 5 years after implant placement. The control group was a randomly selected group of patients with implants inserted without any augmentation procedures. Vertical bone resorption was measured radiographically, implant survival was calculated by means of the Kaplan-Meier procedure, and complications were recorded numerically.


RESULTS
A total of 194 augmentations in 164 patients were performed in the 10-year period. One graft was lost due to exposure and infection of the recipient site, and in four cases, severe resorption of the graft prior to implant placement made a second augmentation necessary. Eighty-seven patients with 100 grafts and 173 implants in the study group and 91 patients with 173 implants in the control group participated in the follow-up. Implant survival was 100% in the study group and 98.5% in the control group (P = .262; log-rank test). The median vertical peri-implant bone resorption after 5 years was 0.7 mm in the study group and 0.6 mm in the control group (P = .371; Mann-Whitney U test). In the study group, the difference between male (0.4 mm) and female (0.9 mm) patients was significant at the end of the follow-up period (P = .022). Significant differences were also found between smokers (2.8 mm) and nonsmokers (0.6 mm) after 5 years (P = .002).


CONCLUSION
The split bone technique using autogenous bone represents a reliable therapy method with a very low complication rate and an implant survival rate of 100% after 5 years. The technique did not result in any increase in peri-implant bone resorption during the follow-up period. Smoking and gender may negatively influence peri-implant bone resorption when using this technique.