目的：这项研究的目的是开发一种新颖的Bonwill®Hawley方法（基于CBCT图像的Bonwill®Hawley弓形式），用于评估牙齿拥挤，并对不同排挤条件下与常规黄铜线和卡尺方法的准确性和合格性进行了研究和比较。
方法：收集60例患者的石膏管座和CBCT数据。所有的演员表都被标记并使用iTero扫描仪转换为数字模型，并导入到OrthoCAD软件中测量所需的空间。使用传统的黄铜线（M1）和卡尺方法（M2），基于数字模型测量和计算了可用空间和牙齿拥挤度，分别。相应地,从CBCT图像中定位并捕获牙弓水平的轴向平面，以绘制Bonwillhawley牙弓形式（M3），用于测量和计算可用空间和牙齿拥挤。对于每种方法，采用类内相关系数(ICC)评估患者内部和检验者之间的可靠性.进行Wilcoxon检验和Kruskal-Wallis检验，以统计分析不同组之间的差异。
结果：对于通过三种方法获得的所有参数，检查内和检查间的可靠性通常都很好，除了使用M1测量的牙齿拥挤（ICC：0.473/0.261）。使用M2测量的牙齿拥挤在轻度，与M1相比，中度和重度拥挤组。然而,在严重拥挤组中，M1和M3之间没有检测到显著差异(上颌骨，p=0.108>0.05；下颌骨，p=0.074>0.05)。随着拥挤状况的恶化，M1和M2或M1和M3之间的牙齿拥挤差异显着降低（上颌骨，M2-M1，温和的VS发球，p=0.003<0.05；上颌骨，M3-M1，温和的VS发球，p=0.003<0.05；下颌骨，M2-M1，温和的VS发球，p=0.000<0.001；下颌骨，M3-M1，温和的VS发球，p=0.043<0.05)。
结论：使用新型Bonwill这两项Hawley方法测量的牙齿拥挤度相对大于卡尺方法，但不超过黄铜线的方法，随着拥挤状况的恶化，其缠绕逐渐接近黄铜丝法。
结论：基于CBCT图像的邦威尔霍利方法被证明是正畸医生分析牙齿拥挤的可靠和可接受的选择。
OBJECTIVE: The purpose of this study was to develop a novel Bonwill⁃Hawley method (Bonwill⁃Hawley arch form based on CBCT image) for the assessment of dental crowding, and to investigate and compare the accuracy and eligibility with the conventional brass wire and caliper methods under different crowding conditions.
METHODS: Sixty patients with the pair of plaster casts and CBCT data were collected. All the casts were marked and transformed into digital models using iTero scanner, and imported into OrthoCAD software to measure the required space. Using the conventional brass wire (M1) and caliper methods (M2), the available space and dental crowding were measured and calculated basing on digital models, respectively. Correspondingly, the axial planes in the level of dental arches were oriented and captured from the CBCT images to draw the Bonwill⁃Hawley arch forms (M3), which were used to measure and calculate the available space and dental crowding. For each method, intra and inter-examiner reliabilities were evaluated with intra-class correlation coefficients (ICCs). Wilcoxon test and Kruskal-Wallis test were performed for statistically analyzing the discrepancy among different groups.
RESULTS: Both intra- and inter-examiner reliability were generally excellent for all parameters obtained by the three methods, except for the dental crowding measured using M1(ICC: 0.473/0.261). The dental crowding measured using M2 were significantly increased in mild, moderate and severe-crowding groups compared with M1. However, no significant difference was detected between M1 and M3 in severe-crowding group (maxilla, p = 0.108 > 0.05; mandible, p = 0.074 > 0.05). With the deterioration of crowding condition, the discrepancy of dental crowding between M1 and M2, or M1 and M3 were significantly decreased (maxilla, M2-M1, mild VS serve, p = 0.003 < 0.05; maxilla, M3-M1, mild VS serve, p = 0.003 < 0.05; mandible, M2-M1, mild VS serve, p = 0.000 < 0.001; mandible, M3-M1, mild VS serve, p = 0.043 < 0.05).
CONCLUSIONS: Dental crowding measured using the novel Bonwill⁃Hawley method was relatively greater than the caliper method, but not exceeding the brass wire method, which wound gradually come close to the brass wire method with the deterioration of crowding condition.
CONCLUSIONS: The Bonwill⁃Hawley method basing on CBCT image proved to be a reliable and acceptable choice for orthodontists to analyze the dental crowding.
