【摘要】 目的:探讨二维X线根尖片上估算单根牙牙根表面积的可行性。方法:因重度牙周炎无保留价值而拔除的90颗单根牙,拔牙前拍摄X线根尖片,采用根尖片估算法测量牙冠和牙根的长度并计算冠根比例及牙根表面积;拔牙后采用三维激光扫描重建法同样测量牙冠和牙根长度并计算冠根比例及牙根表面积,然后对两种方法进行比较。结果:离体牙上实际测量的冠根比例与根尖片上测量的冠根比例基本一致(t=0.58,P>0.05);下切牙根尖片估算得到的牙根表面积与三维扫描重建所测得的牙根表面积也基本一致(t=0.46,P>0.05);其余单根牙位估算得到的冠1/3、根中1/3和根尖1/3的表面积占牙根总表面积的百分比与实际离体牙测量结果差异无统计学意义(t=0.77,P>0.05),但上颌双尖牙根中三分之一的表面积除外。结论:根尖片(分角线技术投照)上测得的单根牙的冠根比例是相对可靠的;根尖片上估算下切牙的牙根表面积也是相对可靠的,但对于其他牙位的单根牙,可分别估算冠1/3、根中1/3和根尖1/3牙根表面积占牙根总表面积的百分比。更多还原

【Abstract】 Objective:To evaluate the availability of the estimation method of the single-root surface area on periapical radiographs,and to compare with the measured method by 3-dimension laser scanning and reconstructed images.Methods: Ninety single-root teeth with severe periodontitis were selected,periapcal radiographs were taken before teeth extracted.Root lengths and crown lengths were measured on periapical radiographs.The ratio of crown to root of each tooth was calculated.Then the root surface areas were also estimated according to mathematics limit principle on the periapical radiographs.The image of the roots were reconstructed by using a 3D laser scanning,the root surface areas were measured with a CAD/CAM software.Results: No significant difference was found between the measured values of the ratio of crown to root by 3D laser scanning and the estimated values on periapical radiographs(t=0.58,P>0.05).For the lower incisors,no significant difference was found between the measured root surface areas with the 3D laser scanning and the estimated ones on periapical radiographs(t=0.46,P>0.05).The surface area of the root in each tooth was divided into three parts: the coronal 1/3,the middle 1/3 and the apical 1/3.Each part of root surface area was measured and estimated.And then the percentage of each part in total root surface area was calculated.The measured percentage was similar to the estimated one except the middle 1/3 part of the upper premolars(t=0.77,P>0.05).Conclusion: No significant difference was found between the measured ratio of crown to root with 3D laser scanning and the estimated one on periapical radiographs.The evaluated method on periapical radiographs to estimate root surface areas was relatively reliable for the lower incisor.更多还原