A randomized controlled clinical trial comparing small buccal dehiscence defects around dental implants treated with guided bone regeneration or left for spontaneous healing.

Abstract

The aim of the present randomized controlled clinical study was to test whether small bony dehiscence defects (≤5mm) left to heal spontaneously result in the same clinical and radiological outcome as defects treated with guided bone regeneration (GBR). Twenty-two patients who received at least one implant with a small bony dehiscence defect were enrolled in the study. If the defect height was ≤5mm, the site was randomly assigned to either the spontaneous healing (SH) group or the GBR group. In the SH group, the defect was left without any treatment. In the GBR group, the defects around the implants were grafted with deproteinized bovine bone mineral (DBBM) and covered with a native collagen membrane. Clinical and radiographic measurements were performed 6months after implant placement with a reentry surgery and at the time of crown insertion and the subsequent follow-up appointments at 3, 6, 12 and 18months after loading. For statistical analyses, the mixed linear model was applied for the clinical and radiographic measurements observed around the implants. Simple comparisons of the location of the measurements in the two independent groups are performed with the Mann-Whitney U-test. In addition, the mixed model assumptions were checked. The implant and crown survival rate 18months after loading was 100%, revealing no serious biologic or prosthetic complication. The mean changes of the buccal vertical bone height between implant placement and reentry surgery after 6months revealed a small bone loss of -0.17±1.79mm (minimum -4mm and maximum 2.5mm) for the SH group and a bone gain of 1.79±2.24mm (minimum of -2.5mm and maximum of 5mm) for the GBR group, respectively (P=0.017). Radiographic measurements demonstrated a slight bone loss of -0.39±0.49mm for the SH group and a stable bone level of 0.02±0.48mm for GBR group after 18months. All peri-implant soft tissue parameters revealed healthy tissues with no difference between the two groups. Small bony dehiscence defects left for spontaneous healing demonstrated high implant survival rates with healthy and stable soft tissues. However, they revealed more vertical bone loss at the buccal aspect 6months after implant insertion and also more marginal bone loss between crown insertion and 18months after loading compared to sites treated with GBR.