Implant beds with an insufficient amount of cortical bone or a loss of cortical bone can result in the initial instability of a dental implant. Thus, the objective of this study was to evaluate the effect of bone cement grafting on implant initial stability in areas with insufficient cortical bone.

Two different circumferential defect depths (2.5 mm and 5 mm) and a control (no defect) were prepared in six bovine rib bones. Fourteen implants of the same type and size (4 mm×10 mm) were placed in each group. The thickness of the cortical bone was measured for each defect. After the implant stability quotient (ISQ) values were measured three times in four different directions, bone cement was grafted to increase the primary stability of the otherwise unstable implant. After grafting, the ISQ values were measured again.

As defect depth increased, the ISQ value decreased. In the controls, the ISQ value was 85.45±3.36 (mean±standard deviation). In circumferential 2.5-mm and 5-mm defect groups, the ISQ values were 69.42±7.06 and 57.43±6.87, respectively, before grafting. These three values were significantly different ( P <0.001). After grafting the bone cement, the ISQ values significantly increased to 73.72±8.00 and 67.88±10.09 in the 2.5-mm and 5.0-mm defect groups, respectively ( P <0.05 and P <0.001). The ISQ value increased to more than double that before grafting in the circumferential 5-mm defect group. The ISQ values did not significantly differ when measured in any of the four directions.

The use of bone cement remarkably increased the stability of the implant that otherwise had an insufficient level of stability at placement, which was caused by insufficient cortical bone volume.