采用锥形束CT测量健康上前牙唇侧骨板形态及牙长轴倾角的变化

Cone-beam computed tomography digital for measuring the inclination angle to the long axis of healthy maxillary anterior teeth and morphologically characterizing their labial bone plates

目的采用锥形束CT(CBCT)图像数字化测量的方法,测量健康上前牙唇侧骨板厚度、釉牙骨质界(CEJ到骨嵴顶距离及牙长轴倾角,并探讨可能的影响因素。方法分析由Newtom VGI■CBCT机拍摄获得的345例CBCT影像,使用NNT软件分别在上颌中切牙、侧切牙和尖牙的正中矢状平面上测量CEJ下4 mm、根中点和根尖水平的唇侧骨板厚度,CEJ距骨嵴顶距离和牙长轴倾角,记录各牙位CEJ下4 mm水平唇侧骨板厚度≥1 mm的例数。结果1)中切牙的牙长轴倾角,CEJ距骨嵴顶距离,CEJ下4 mm、根中点和根尖水平的骨板厚度均值分别为15.2°±6.2°、(1.5±1.0)mm、(0.8±0.4)mm、(0.6±0.4)mm和(1.3±0.7)mm;侧切牙和尖牙的上述5项测量值分别为16.2°±8.8°、(1.6±1.0)mm、(0.7±0.5)mm、(0.4±0.6)mm和(1.1±0.7)mm;19.0°±6.2°、(1.8±1.0)mm、(0.9±0.6)mm、(0.4±0.6)mm和(1.2±0.7)mm。2)345例患者中,中切牙、侧切牙和尖牙CEJ下4 mm水平骨板厚度≥1 mm者分别占28.3%、25.8%和42.7%。3)中切牙、侧切牙和尖牙CEJ到骨嵴顶距离与年龄高度相关,相关系数分别为0.42、0.50、0.62(P<0.01)。结论健康上前牙唇侧骨板厚度较薄,CEJ到骨嵴顶距离随着年龄的增加而增加,牙长轴较牙槽突长轴舌倾,充分考虑这些特点有利于提高相关口腔治疗方案的安全性和预后。

Objective We aim to determine the thickness of the labial plate,the distance between the cement-enamel junction(CEJ)and alveolar crest,and the inclination angle of the long axis of healthy maxillary anterior teeth by using conebeam computed tomography(CBCT).Methods A total of 345 CBCT volumes obtained by Newtom VGI?CBCT were analyzed by using the NNT software.The digital measurements of the labial bone plate thickness at level 4 mm below the CEJ,the midpoint of tooth root and the radiological tooth apex,the distance between the CEJ and alveolar crest,and the angle between the long axis of the teeth and the long axis of alveolar process were obtained from the mid-sagittal planes of maxillary incisors and canines.Plate thickness 4 mm below the CEJ was measured,and values below≥1 mm were recorded.Results In the central incisor,1)the angle between the long axis of the teeth and alveolar bone was 15.2°±6.2°,the distance between the CEJ and alveolar crest was(1.5±1.0)mm,labial bone plate thick ness at 4 mm below the CEJ was(0.8±0.4)mm,the midpoint of tooth root was(0.6±0.4)mm,and the radiological tooth apex was(1.3±0.7)mm;in the lateral incisor,16.2°±8.8°,(1.6±1.0)mm,(0.7±0.5)mm,(0.4±0.6)mm,and(1.1±0.7)mm,respectively;and in the canine,19.0°±6.2°,(1.8±1.0)mm,(0.9±0.6)mm,(0.4±0.6)mm,and(1.2±0.7)mm,respectively.2)The frequencies of plate thickness≥1 mm were 28.3%,25.8%,and 42.7%in the central incisor,lateral incisor,and canine,respectively.3)The distance between the CEJ and alveolar crest was positively correlated with age.The correlation coefficients was 0.42(P<0.01)in the central incisor,0.50(P<0.01)in the lateral incisor,and 0.62(P<0.01)in the canine.Conclusion The thickness of labial bone plate is thin,the distance from CEJ to alveolar crest increases with age,and the long axis of the teeth is more inclined than the long axis of alveolar process.Knowledge of these special morphological characteristics can improve the safety and result for many dental procedures.