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

OBJECTIVE: This study evaluates whether or not, among other factors, membrane-coverage of antrostomy defects improves implant survival in sinus augmentation procedures.

MATERIALS AND METHODS: We 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 1 year. 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 6 months later.

RESULTS: In 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 (≥2 mm) (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.

CONCLUSIONS: Implant 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.