Correlation between the residual ridge height and the perforation limit of sinus membrane in crestal sinus elevation

Objectives: The residual alveolar bone height at the implant recipient site plays a key role in determination of the risk of sinus membrane perforation during crestal sinus elevation. In this study, we aimed to determine the correlation between residual ridge height and perforation limit of sinus membrane and to examine the safety range for the sinus membrane continuity in crestal sinus elevation. Formalin-fixed cadavers were used for the experiment to observe outcomes. Method and Materials: Crestal sinus elevations were performed on 14 preserved human cadavers' heads. Residual ridge heights were measured using a bone caliper. The physiodispenser was preset to 30 Ncm and sinus floors were elevated by a concave sinus screw with diameter of 4 mm until sinus membrane perforation occurred. The perforations were identified either as Class I or Class II and the portion of the concave sinus screw in the sinus was measured each time using a ruler. Spearman's correlation coefficient was calculated to show the relation between the residual ridge heights and the membrane elevations at the time of perforation of the sinus membranes. Results: In general, the perforation limit of sinus membrane after elevation was higher with greater residual ridge height. A statistically significant correlation was found between residual ridge heights and perforations of the sinus membrane (r = 0.620, P .001). Conclusion: Although it is not always possible to extrapolate results from cadavers to an in vitro clinical setting, it could be considered to have clinical significance. Our findings suggest that higher subsinusoidal elevation may be achieved when the residual ridge bone height increases. The conclusions of this study should be verified with studies of more rigorous design. Keywords: crestal approach, perforation, sinus lift