Hettiarachchi Pilana Vithanage Kalani Shihanika, Olive Richard John, Monsour Paul
Faculty of Dental Sciences, University of Peradeniya, Peradeniya, Sri Lanka; Discipline of Dento Maxillofacial Radiology, School of Dentistry, University of Queensland, Brisbane, Queensland, Australia.
Discipline of Orthodontics, School of Dentistry, University of Queensland, Brisbane, Queensland, Australia.
Am J Orthod Dentofacial Orthop. 2017 Feb;151(2):357-362. doi: 10.1016/j.ajodo.2016.06.044.
The aim of this study was to investigate the relationships between an apical curvature or a hook and the crown/root ratio in subjects with and without palatally impacted maxillary canines.
An experimental group of 44 patients (17 boys, 27 girls; mean age, 13.6 years) with 59 palatally impacted maxillary canines was selected from the records of patients referred to a radiology practice for cone-beam imaging. If a patient had bilateral palatally impacted canines, 1 canine was randomly selected for analysis. The palatally impacted canine group was matched for age and sex with 49 normal subjects (25 boys, 24 girls; mean age, 13.2 years) with 98 canines. Cone-beam DICOM files were imported into In Vivo imaging software (version 5.3; Anatomage, San Jose, Calif) for analysis. The angulations and linear variables of the maxillary canines were measured by using the software measurement tools. Chi-square and independent t tests were used to test for differences between the groups.
The presence of a hook at the apical third and other root curvature were significantly different between the 2 groups (P <0.001 and P <0.05, respectively). Of the 44 palatally impacted canines, 16 (36.4%) had an apical hook and only 1 canine in the control group had an apical hook (1.0%). The mean root length of the palatally impacted canines was 2.66 mm shorter (P <0.001), and the mean crown/root ratio was significantly greater for the palatally impacted canines compared with the nonimpacted group (P <0.001).
Palatally impacted canines have a greater tendency to develop apical hooks and are less likely to develop other root curvatures than are nonimpacted canines. Also, they have shorter roots resulting in larger crown/root ratios compared with the control group.
本研究旨在调查有无腭侧埋伏上颌尖牙患者的根尖弯曲或钩与冠根比之间的关系。
从转诊至放射科进行锥形束成像的患者记录中选取44例患者（17名男孩，27名女孩；平均年龄13.6岁）作为实验组，其共有59颗腭侧埋伏上颌尖牙。若患者双侧尖牙均为腭侧埋伏，则随机选择1颗尖牙进行分析。将腭侧埋伏尖牙组与49名正常受试者（25名男孩，24名女孩；平均年龄13.2岁）的98颗尖牙按年龄和性别进行匹配。将锥形束DICOM文件导入In Vivo成像软件（5.3版本；Anatomage公司，加利福尼亚州圣何塞）进行分析。使用该软件的测量工具测量上颌尖牙的角度和线性变量。采用卡方检验和独立t检验来检验两组之间的差异。
两组在根尖三分之一处存在钩以及其他牙根弯曲情况上有显著差异（分别为P<0.001和P<0.05）。在44颗腭侧埋伏尖牙中，16颗（36.4%）有根尖钩，而对照组中只有1颗尖牙有根尖钩（1.0%）。腭侧埋伏尖牙的平均牙根长度短2.66mm（P<0.001），与未埋伏组相比，腭侧埋伏尖牙的平均冠根比显著更大（P<0.001）。
与未埋伏尖牙相比，腭侧埋伏尖牙更易形成根尖钩，且形成其他牙根弯曲的可能性更小。此外，与对照组相比，它们的牙根较短，导致冠根比更大。
