Influence of Maxillary Sinus Membrane Thickness on Sinus Floor Elevation

Objectives: Many patients with edentulous posterior maxilla confront the vertical bone reduction because of bone resorption and continued pneumatization of the maxillary sinus after tooth loss. The transcrestal approach for sinus floor elevation (SFE) could effectively increase the vertical bone height in a less invasive way. Nevertheless, the thickening sinus membrane might have an effect on being separated from the sinus floor, maintaining the space and the perforation of the sinus membrane.
Objectives: (1) estimate the formation of new bone by measuring the vertical bone height on the cone beam computed tomography; and (2) analyse the relevance between the perforation of sinus membrane and its thickness.
Methods: 117 transcrestal SFE procedures was selected. CBCT was taken before the procedure (T0), immediately after the procedure (T1) and after the bone healing period (T2). The sites of procedure were divided into 4 groups based on membrane thickness: group A (<1mm), group B (1-2mm), group C (2-4mm) and group D (>4mm). The sinus membrane thickness (SMT), residual bone height (RBH) and elevated bone height was measured.
Results: The average SMT was 2.16±2.54 mm. The formation of new bone decreased from group A (3.78±2.48 mm) to group D (3.14±1.89 mm) in general, but there was no significant correlation between SMT and the formation of new bone (P>0.05). There was no statistics difference between the perforation rate and SMT (P>0.05) either. But the formation of new bone when the sinus membrane had perforated (n=8) was 2.38±2.34 mm, which was evidently less than 3.62±2.12 mm of the non-perforation group (P=0.114).
Conclusions: The thickening membrane would not decrease the formation of new bone or improve the perforation rate which was mainly blamed on the anatomic factors. The perforation of sinus membrane significantly reduces the formation of new bone.