Title:
A randomized controlled clinical multicenter trial comparing the clinical and histological performance of a new, modified polylactide-co-glycolide acid membrane to an expanded polytetrafluorethylene membrane in guided bone regeneration procedures.

Abstract:
To compare the clinical and histological outcomes of a resorbable modified polylactide/polyglycolide acid (PLGA) test membrane and a titanium-reinforced expanded polytetrafluorethylene (ePTFE) control membrane used for guided bone regeneration (GBR) around dental implants.
A total of 40 patients with peri-implant dehiscence-type defects were randomly allocated to a GBR procedure using either a modified PLGA test or an ePTFE control membrane. Soft tissue condition, implant integration, adverse events and quality of life were recorded during the 6-month healing period. At re-entry peri-implant bone defect dimensions were measured and compared with values recorded at implant/GBR surgery. A biopsy was retrieved for qualitative and quantitative histological analyses. A comparison between the groups was conducted using non-parametric statistical tests.
Soft tissue complications were observed in five test patients and two control patients. Except for soft tissue complications and incomplete regeneration, no procedure- or device-related adverse events were observed. The vertical bone defect component was, in mean, reduced by-5.1 mm (95% CI -6.8, -3.3) in the test group and -6.9 mm (95% CI -8.2, -5.5 mm) in the control group. The mean residual vertical defect height measured 1.2 ± 2.4 mm in the test group and 0.3 ± 1.1 mm in the control group meaning a mean defect resolution of 81% in the test group and 96% in the control group (P = 0.161). The horizontal bone thickness at implant shoulder level decreased from a mean of 3.2 mm to 1.4 mm (-56%, mean -1.7 mm, 95% CI -2.3, -1.1) in the test group and from 3.3 mm to 2.5 mm (-24%, mean -0.8 mm, 95% CI -1.3, -0.3) in the control group (P = 0.022). Qualitative and quantitative histological analyses did not show significant differences in the tissue composition between groups.
Peri-implant GBR was successfully performed using either of the membranes. The control membrane was able to better maintain the horizontal thickness of regenerated bone and revealed less soft tissue complications. No statistically valid evidence about the superiority of one membrane was found in any other parameters. Soft tissue dehiscences occur with both types of membranes and can impair the amount of regenerated bone.