Clinical and radiographic intrasubject comparison of implants placed with or without guided bone regeneration: 15-year results

Aim: To test whether implants placed with simultaneous guided bone regeneration (GBR) differ from implants placed without GBR regarding survival rate, interproximal marginal bone level (MBL), and dimensions of buccal bone and mucosa. Material and Methods: Twenty-three patients treated 15 years earlier were included. Machined implants had been inserted following one of the two procedures: (i) with simultaneous GBR, which involved grafting with particulate deproteinized bovine bone mineral (DBBM), autogenous bone (AB), or a mixture of the two and defect covering with a native collagen membrane (CM) (GBR group) and (ii) standard implant placement without GBR (control group). One GBR and one control implant in each patient were selected for analysis. At 15 years, the dimensions of buccal bone and mucosa were measured with cone beam computed tomography. The interproximal MBL was evaluated at 5 and 15 years on periapical radiographs. Results: The 15-year survival rate amounted to 95.6% for GBR implants and to 94.1% for control implants. At 15 years, interproximal MBL measured 1.44 +/- 0.84 mm for the GBR group and 1.69 +/- 0.84 mm for the control group. From the 5-to the 15-year examination, the loss of interproximal MBL reached 0.23 +/- 0.70 mm for the GBR group and 0.28 +/- 0.63 mm for the control group. At 15 years, buccal MBL measured 1.98 +/- 0.98 mm for GBR implants and 2.19 +/- 1.29 mm for control implants. None of these values reached statistical significant differences between the groups. In cases in which GBR involved grafting with DBBM, GBR implants achieved approximately 0.3-0.4 mm higher mean values in buccal bone dimensions and mucosal level in comparison to control implants. In contrast, when GBR was performed by grafting with AB without DBBM, implants rendered less favourable results in buccal bone and mucosa dimensions than the control implants. Conclusions: Implants placed with simultaneous GBR using particulate DBBM and/or AB in combination with CM did not significantly differ from implants completely placed into pristine bone with respect to 15-year implant survival, interproximal bone levels, and dimensions of buccal bone and mucosa. The machined-surface implants placed both into native bone and sites augmented by GBR exhibited stable interproximal bone levels.