Homolka Peter, Beer Andreas, Birkfellner Wolfgang, Nowotny Robert, Gahleitner André, Tschabitscher Manfred, Bergmann Helmar
Department of Biomedical Engineering and Physics, University of Vienna General Hospital, Währinger Gürtel 18-20, A-1090 Vienna, Austria.
Radiology. 2002 Jul;224(1):247-52. doi: 10.1148/radiol.2241010948.
To correlate torque forces during insertion of screw-type dental implants with bone mineral density (BMD) values determined preoperatively.
Dental quantitative computed tomography (CT) was performed with simultaneous imaging of five postmortem mandibles and a calibration standard containing defined concentrations of calcium hydroxyapatite. CT numbers were converted to local BMD values by assuming a linear relationship (BMD = a x HU + b), where a and b are calibration coefficients. The a, b, P, and t values, correlation coefficients, and standard errors were calculated. Dental implants (n = 25) were set, and insertion torques were recorded. BMD was determined at the implantation site and correlated with torque forces recorded during implant insertion. Calibration coefficients derived for specimens were compared with those derived for actual patients.
Calibration coefficients (at 120 kV) for the postmortem specimens were a = 0.760 +/- 0.03 (mean +/- SD) and b = 2.8 +/- 3.7 and for the patients were a = 0.804 +/- 0.06 and b = 5.2 +/- 4.2. Calibrated BMD values at the location of dental implants exhibit a significant correlation (R(2) = 0.83, P <.001) with insertion torques on the basis of a second-order model, which yields torque = (0.0055 x BMD + 0.73)(2) for the implants used and the surgical technique applied.
Correlation exists between BMD measured with dental quantitative CT and the insertion torque of dental implants.
将螺旋型牙种植体植入过程中的扭矩力与术前测定的骨矿物质密度（BMD）值进行关联。
对五具尸体下颌骨及含特定浓度羟基磷灰石的校准标准物进行同步成像的牙科定量计算机断层扫描（CT）。通过假设线性关系（BMD = a x HU + b）将CT值转换为局部BMD值，其中a和b为校准系数。计算a、b、P和t值、相关系数及标准误差。植入牙种植体（n = 25）并记录插入扭矩。在植入部位测定BMD，并将其与种植体植入过程中记录的扭矩力进行关联。将为标本得出的校准系数与为实际患者得出的校准系数进行比较。
尸体标本（120 kV时）的校准系数为a = 0.760 ± 0.03（均值 ± 标准差），b = 2.8 ± 3.7；患者的校准系数为a = 0.804 ± 0.06，b = 5.2 ± 4.2。基于二阶模型，牙种植体部位经校准的BMD值与插入扭矩呈现显著相关性（R² = 0.83，P <.001），对于所用种植体及应用的手术技术，该模型得出扭矩 = (0.0055 x BMD + 0.73)²。
牙科定量CT测量的BMD与牙种植体的插入扭矩之间存在相关性。
