基于CBCT三维重建数据的尖牙冠根形态研究

目的利用CBCT比较Ⅰ、Ⅱ、Ⅲ类矢状骨面型错牙合]患者上下尖牙冠根形态的差异,为正畸的临床治疗提供指导。方法随机选择已拍摄CBCT及X线头颅侧位片的恒牙列期错牙合]患者,按ANB角大小进行矢状骨面型分类:Ⅰ类组、Ⅱ类组、Ⅲ类组。三维重建获得右侧上下尖牙的正中矢状切面图像,以冠根角、冠根偏斜距离、临床冠中心的唇面切线角为指标利用AutoCAD软件进行测量分析。结果上尖牙(F=3.335,P=0.042)、下尖牙(F=3.745,P=0.029)冠根角及上尖牙(F=3.312,P=0.043)、下尖牙(F=3.641,P=0.032)冠根偏斜距离在不同矢状骨面型错牙合]分组中的差异具有统计学意义(P<0.05)。上颌尖牙的Ⅰ类组冠根角大于Ⅱ类组,冠根偏斜距离为负且绝对值大于Ⅱ类组(P<0.05);下颌尖牙的Ⅲ类组冠根角小于Ⅰ、Ⅱ类组,冠根偏斜距离为正且大于Ⅰ、Ⅱ类组(P<0.05)。上下颌尖牙冠唇面切线角在不同矢状骨面型错牙合]分组中的差异无统计学意义(P>0.05)。结论不同矢状骨面型错牙合]患者上下尖牙冠根形态存在差异,上颌尖牙的牙根偏向牙冠唇侧,Ⅰ类组比Ⅱ类组明显;下颌尖牙的Ⅲ类组相比Ⅰ、Ⅱ类组,则牙根更加偏向牙冠舌侧。

Analysis of crown-root morphology in canines based on cone-beam computed tomography

ObjectiveTo compare the morphology of the crown roots of upper and lower canines in patients withskeletal ClassⅠ,Ⅱ,andⅢmalocclusions by CBCT and to provide guidance for the clinical treatment of orthodontics.MethodsRandomly selected patients with permanent occlusal malocclusion who had undergone CBCT and X-rayskull lateral radiographs were Classified according to the ANB angle size:groupⅠ,groupⅡ,and groupⅢ.Three-di-mensional reconstruction was used to obtain the median sagittal section images of the right upper and lower canines.The crown root angle,crown root deflection distance,and lip tangent angle at the center of the clinical crown were usedas indicators for measurement and analysis with the use of AutoCAD software.ResultsThe difference in the crown-root skew distance between different sagittal face types,including upper canines(F=3.335,P=0.042),lower canines(F=3.745,P=0.029)crown root angles and upper canines(F=3.312,P=0.043),and lower canines(F=3.641,P=0.032),was statistically significant(P<0.05).The crown root angle of the maxillary canine in groupⅠwas larger thanthat in groupⅡ,and the deflection distance of the crown root was negative and the absolute value was lager in groupⅠthan in groupⅡ(P<0.05).The deflection distance was positive and greater in groupⅢthan in groupsⅠandⅡ(P<0.05).There was no significant difference in the maxillary canine crown-labial tangent angle between the different sagit-tal facial misalignment groups(P>0.05).ConclusionDifferences in the morphology of canines were found amongsubjects with skeletal ClassⅠ,Ⅱ,andⅢmalocclusions.The root of the upper canine in ClassⅠmalocclusions wasrelatively closer to the labial side of the crown than that in ClassⅡmalocclusions.The root of the lower canine in ClassⅢmalocclusions was the closest to the lingual side of the crown among the three Classes.