Knösel Michael, Attin Rengin, Kubein-Meesenburg Dietmar, Sadat-Khonsari Reza
Department of Orthodontics, Center of Dentistry, University Hospital, Göttingen, Germany.
J Orofac Orthop. 2007 May;68(3):199-209. doi: 10.1007/s00056-007-0635-z.
Estimating incisor inclination cephalometrically by reference lines NA and NB puts the orthodontist in the difficult position of relating these axial inclination data to the bracket's third-order prescription which refers to a perpendicular to the occlusal plane. Purpose of the present study was to evaluate the relationship between the cephalometrically-assessed incisor inclination (using the lines NA and NB for reference) and the third-order angle (syn.: torque angle, TA) according to Andrews' description, and moreover to investigate the correlation between incisor inclination data and skeletal-sagittal and skeletal-vertical findings.
The lateral cephalograms and corresponding dental casts of 67 subjects between 10 and 25 years of age (regardless of skeletal and dental relationships) were considered in the study. All subjects were Caucasian, and none had undergone orthodontic therapy. Upper (U1) and lower (L1) incisor angulations were cephalometrically assessed in reference to the NA and NB lines and compared to third-order angles obtained from dental cast measurements with an incisor inclination-recording appliance. Incisor inclination data from the two measurements were correlated to craniofacial sagittal (angles SNA, SNB, ANB) and vertical (angles NSL-NL, NSL-ML, ML-NL) findings from the radiographs.
The third-order angles in the upper arch measured on the dental casts were a mean of 16.2 degrees (SD = 5.3 degrees) smaller than the axial inclination according to the NA line; the lower incisor third-order data were less than those of the axial inclination according to the NB line by a mean of 27.8 degrees (SD = 4.75 degrees). In this sample, there was a range of 42.7 degrees for the U1TA variable (mean = 5.6 degrees, SD 9.73 degrees) and 47 degrees for U1NA/ degrees variable (mean = 21.71 degrees, SD = 8.67 degrees). The L1TA variable showed a range of 29 degrees (mean = -2.95 degrees, SD = 7.17 degrees), the radiographic L1NB/ degrees range was 23 degrees (mean = 24.91 degrees, SD = 5.8 degrees). We observed a highly significant correlation (r(NA) = 0.84***, r(NB) = 0.76***) between the Andrews' angle and the inclination estimated in reference to the NA and NB lines. No significant correlation between incisor inclination and craniofacial measurements was detected.
Dental cast measurements seem to be more precise and more valid than lateral radiographs. The method we describe enables clinicians to get a good idea precisely and quickly of how much torque potential remains in the brackets and archwires during treatment. The inclination of the incisors can also be calculated using the regression equations provided, making additional lateral cephalograms unnecessary.
通过参考线NA和NB对头影测量法评估切牙倾斜度，这使得正畸医生难以将这些轴向倾斜度数据与托槽的三阶处方相关联，三阶处方是指与咬合平面垂直的方向。本研究的目的是根据安德鲁斯的描述，评估通过头影测量法评估的切牙倾斜度（以NA和NB线为参考）与三阶角（同义词：转矩角，TA）之间的关系，此外还研究切牙倾斜度数据与骨骼矢状向和骨骼垂直向测量结果之间的相关性。
本研究纳入了67名年龄在10至25岁之间的受试者（不考虑骨骼和牙齿关系）的头颅侧位片和相应的牙模。所有受试者均为白种人，且均未接受过正畸治疗。通过头影测量法，参照NA和NB线评估上（U1）、下（L1）切牙的角度，并与使用切牙倾斜度记录装置从牙模测量中获得的三阶角进行比较。将两种测量方法得到的切牙倾斜度数据与头颅侧位片中的颅面矢状向（角度SNA、SNB、ANB）和垂直向（角度NSL-NL、NSL-ML、ML-NL）测量结果进行相关性分析。
在牙模上测量的上牙弓三阶角比根据NA线测量的轴向倾斜度平均小16.2度（标准差=5.3度）；下切牙的三阶数据比根据NB线测量的轴向倾斜度平均小27.8度（标准差=4.75度）。在这个样本中，U1TA变量的范围为42.7度（平均值=5.6度，标准差9.73度），U1NA/度变量的范围为47度（平均值=21.71度，标准差=8.67度）。L1TA变量的范围为29度（平均值=-2.95度，标准差=7.17度），头颅侧位片上L1NB/度的范围为23度（平均值=24.91度，标准差=5.8度）。我们观察到安德鲁斯角与参照NA和NB线估计的倾斜度之间存在高度显著的相关性（r(NA)=0.84***，r(NB)=0.76***）。未检测到切牙倾斜度与颅面测量之间存在显著相关性。
牙模测量似乎比头颅侧位片更精确、更有效。我们描述的方法使临床医生能够准确、快速地了解治疗过程中托槽和弓丝中剩余的转矩潜力。也可以使用提供的回归方程计算切牙的倾斜度，无需额外的头颅侧位片。
