Sri Ramachandra Institute of Higher Education and Research, Department of Orthodontics, Chennai, India.
Sri Ramachandra Institute of Higher Education and Research, Department of Orthodontics, Chennai, India.
Int Orthod. 2020 Sep;18(3):468-479. doi: 10.1016/j.ortho.2020.06.006. Epub 2020 Aug 13.
The collum angle that defines the crown root angulation of the single rooted teeth plays an important in treatment planning.
To compare the collum angle (crown root angulation) of maxillary and mandibular anterior teeth in different skeletal malocclusions using Cone Beam Computed Tomography (CBCT).
Sixty subjects were categorized into four groups (fifteen subjects in each group) Class I, Class II division 1, Class II division 2 malocclusion and Class III based on Angle classification, Wits and ANB. The collum angle of maxillary and mandibular anterior teeth was measured using CBCT. One way ANOVA, Post hoc comparison with Tukey HSD and Paired t-test were used to analyse the measured data.
The collum angle of corresponding right and left side teeth were averaged. Thus, the mean and standard deviation of the collum angle (n-30) were generated for maxillary and mandibular central incisors, lateral incisors, and canines. A statistically significant increase was observed in the maxillary central incisors of Class II division 2 and mandibular lateral incisors of class III malocclusion. The collum angle was increased in mandibular canines of Class III malocclusion when compared with class I and Class II division 2 malocclusion. The collum angle was negative in mandibular central incisors of Class II division 2. No statistically significant difference was observed in the mean collum angle between the right and left side anterior teeth in all the four groups.
A variation in Collum angle was observed between the maxillary and mandibular anterior teeth and malocclusions. The effect of these variations in collum angle in torque expression and biomechanics should be kept in mind by the orthodontist before treatment planning especially in Class II division 2 malocclusion.
定义单根牙冠根角的牙颈角在治疗计划中起着重要作用。
使用锥形束 CT（CBCT）比较不同骨骼错牙合畸形上颌和下颌前牙的牙颈角（冠根角）。
60 名受试者分为四组（每组 15 名），根据 Angle 分类、Wits 和 ANB 将其分为 I 类、II 类 1 分类、II 类 2 分类和 III 类。使用 CBCT 测量上颌和下颌前牙的牙颈角。采用单因素方差分析、Tukey HSD 事后比较和配对 t 检验对测量数据进行分析。
对相应的右侧和左侧牙齿的牙颈角进行平均。因此，上颌中切牙、侧切牙和尖牙以及下颌中切牙、侧切牙和尖牙的牙颈角（n-30）的平均值和标准差。II 类 2 分类和 III 类错牙合的上颌中切牙的牙颈角显著增加。与 I 类和 II 类 2 分类错牙合相比，III 类错牙合的下颌尖牙牙颈角增加。II 类 2 分类错牙合的下颌中切牙牙颈角为负。四组中左右侧前牙的牙颈角平均值无统计学差异。
上颌和下颌前牙与错牙合之间存在牙颈角的变化。在治疗计划前，正畸医生应牢记这些牙颈角变化对转矩表达和生物力学的影响，尤其是在 II 类 2 分类错牙合中。
