The influence of sinus membrane thickness upon membrane perforation during transcrestal sinus lift procedure.

OBJECTIVES: Schneiderian membrane perforation is one of the main complications during sinus augmentation. The reasons may be associated with surgical technique, septum, inadequate ridge height, and membrane thickness. However, reports that used cone-beam computed tomography (CBCT) to quantify the thickness of sinus membrane were limited. The aims of this retrospective study were: to study the correlation between membrane thickness and perforation rate during transcrestal sinus lift and to propose a classification system of sinus membrane thickness based upon CBCT data. MATERIAL AND METHODS: One hundred and twenty-two subjects who received dental implant restorations over posterior maxilla with a total of 185 transcrestal sinus lift procedures between years 2010 to 2013 were selected consequently. Each patient selected had to have taken CBCT in the initial examination and immediately after surgery. The membrane thickness, perforation rate, residual bone height, and elevated bone height were recorded and processed for statistical analysis. RESULTS: The mean thickness of the Schneiderian membrane was 1.78 +/- 1.99 mm. There was a significant correlation between membrane thickness and perforation rate (P < 0.05), and the perforation rate was higher in thicker (>/=3 mm) and thinner membrane (</=0.5 mm). Among the thickness group, Class B (between >/=1 and <2 mm) had the lowest perforation rate. No significant difference was between the perforation and the membrane morphology. A negative relationship between residual bone height and membrane thickness was found. Trend showed that in the thicker and the thinner residual bone height, the higher the perforation rate would be. CONCLUSIONS: There was a significant correlation between membrane thickness and perforation rate. The perforation rate was lowest when the thickness was 1.5-2 mm.