Membranes over the lateral window in sinus augmentation procedures: a two-arm and split-mouth randomized clinical trials

ObjectiveThis study evaluates whether or not, among other factors, membrane-coverage of antrostomy defects improves implant survival in sinus augmentation procedures. Materials and MethodsWe performed a two-arm and split-mouth randomized controlled clinical trial on 104 and 5 patients respectively. In the two-arm study, antrostomy defects were membrane-covered in 66 procedures and uncovered in 69, before placing a total of 265 implants that were followed up for 1year. In the split-mouth study, following bilateral sinus augmentation, antrostomy defects were membrane-covered on one side and left uncovered on the contra-lateral. Bone biopsies from each sinus were histologically analysed 6months later. ResultsIn the two-arm study, implant survival rates were similar (p=0.08) in the membrane-covered (96.1%) and uncovered (94.2%) groups. In the split-mouth study, bone augmentation was similar in both groups (p=0.52). Delayed implant placement (p=0.04), thick Schneider's membrane (2mm) (p<0.01), treatment for hypertension (p=0.04) and non-smoking (p=0.01) seemed to be associated with lower risk of implant failure. ConclusionsImplant survival in sinus lifting procedures could be influenced significantly by timing of implant placement, Schneider's membrane thickness, antihypertensive treatment and smoking habits, but not by antrostomy membrane coverage.