锥形束CT在上颌前牙区牙根位置和牙槽骨三维结构评估中应用价值

Cone-beam CT in evaluating root angle and three-dimensional structure of alveolar bone in maxillary anterior region

目的应用锥形束CT(cone-beam computed tomography,CBCT)评估上颌前牙区牙根与牙槽骨的位置关系及三维结构,分析上颌前牙Kan分类标准矢状面牙根位置(sagittal root position,SRP)4类的CBCT影像特征,为上颌前牙美学区即刻种植提供解剖学依据。方法行CBCT检查者116例,上颌前牙(中切牙、侧切牙、尖牙)影像样本共624个,CBCT影像经重建后,确定牙槽骨长轴、牙根长轴、正中矢状面及横断面,在矢状面上测量牙根角度、唇侧骨高度、腭侧骨高度、根尖区可用骨高度,在横断面上测量唇腭向骨宽度、左侧邻面骨宽度、右侧邻面骨宽度、近远中向骨宽度。依据Kan分类标准进行SRP分类,比较SRPⅠ、Ⅱ、Ⅲ、Ⅳ类上述指标。结果624个上颌前牙影像样本中,SRPⅠ类496个(79.5%),Ⅱ类38个(6.1%),Ⅲ类1个(0.2%),Ⅳ类89个(14.2%)。SRPⅠ类牙根角度[(22.68±9.08)°]、左侧邻面骨宽度[(2.44±0.72)mm]、右侧邻面骨宽度[(2.44±0.71)mm]、近远中向骨宽度[(9.38±1.16)mm]均大于SRPⅡ类[(14.18±7.90)°、(2.07±0.53)mm、(2.07±0.62)mm、(8.63±1.04)mm]、Ⅳ类[(14.74±6.08)°、(2.19±0.56)mm、(2.24±0.47)mm、(8.47±1.14)mm](P<0.05),SRPⅠ类唇腭向骨宽度[(8.45±1.09)mm]大于SRPⅣ类[(7.67±0.97)mm](P<0.05),SRPⅠ类[(8.00±3.32)mm]、Ⅱ类[(7.64±3.76)mm]根尖区可用骨高度小于SRPⅣ类[(9.49±3.10)mm](P<0.05);SRPⅠ类根尖区可用骨高度、唇腭向骨宽度与SRPⅡ类比较差异均无统计学意义(P>0.05),SRPⅡ类牙根角度、唇腭向骨宽度、左侧邻面骨宽度、右侧邻面骨宽度、近远中向骨宽度与SRPⅣ类比较差异均无统计学意义(P>0.05)。结论CBCT评估上颌前牙区牙根与牙槽骨的位置关系及三维结构有一定价值,SRPⅡ类和Ⅳ类牙根角度较小,SRPⅡ类根尖区可用骨高度不足,SRPⅣ类牙槽骨唇腭向和近远中向骨宽度不足,上颌前牙区即刻种植存在初期稳定性不佳的风险。

Objective To evaluate the three-dimensional structure and the positional relationship between the root and alveolar bone in the maxillary anterior teeth area by cone-beam CT(CBCT),and to analyze the CBCT features of four categories of sagittal root position(SRP)of Kan’s classification standard in maxillary anterior teeth in order to provide an anatomical basis for immediate implantation in the aesthetic area.Methods Totally 116 patients undergoing CBCT examination were obtained 624 image samples in the maxillary anterior teeth(central incisors,lateral incisors,canines).After CBCT image reconstruction,the long axis of alveolar bone,long axis of the root,median sagittal plane,and cross-sectional plane were determined.In sagittal plane,the root angle,labial bone height,palatal bone height,and available bone height in apical region were measured;in cross-sectional plane,the labial-palatal width of alveolar bone,left interproximal alveolar bone width,right interproximal alveolar bone width and mesial-distal width of alveolar bone were measured.The root sagittal position was classified according to Kan’s method and the above indexes in SRPⅠ,Ⅱ,ⅢandⅣwere compared.Results Among these 624image samples in the maxillary anterior teeth,496(79.5%)samples were SRPⅠ,38(6.1%)were SRPⅡ,1(0.2%)was SRPⅢ,and 89(14.2%)were SRPⅣ.The root angle[(22.68±9.08)°]was larger,and the left interproximal bone width[(2.44±0.72)mm],right interproximal bone width[(2.44±0.71)mm]and mesial-distal width of alveolar bone[(9.38±1.16)mm]of SRPⅠwere greater than those of SRPⅡ[(14.18±7.90)°,(2.07±0.53)mm,(2.07±0.62)mm,(8.63±1.04)mm]and SRPⅣ[(14.74±6.08)°,(2.19±0.56)mm,(2.24±0.47)mm,(8.47±1.14)mm](P<0.05).The labial-palatal width of alveolar bone of SRPⅠwas greater[(8.45±1.09)mm]than that of SRPⅣ[(7.67±0.97)mm](P<0.05).The available bone height was smaller in apical region of SRPⅠ[(8.0±3.32)mm]and SRPⅡ[(7.64±3.76)mm]than that of SRPⅣ[(9.49±3.10)mm](P<0.05).There were no significant differences in the available bone height in apical region and labial-palatal width of alveolar bone between SRPⅠand SRPⅡ(P>0.05).There were no significant differences in the root angle,labial-palatal width of alveolar bone,left and right interproximal alveolar bone width,and mesial-distal width ofalveolar bone between SRPⅡand SRPⅣ(P>0.05).Conclusions CBCT has a certain value to the prediction of the positional relationship between the root and alveolar bone and the three-dimensional structure in the maxillary anterior teeth area.The root angles of SRPⅡand SRPⅣare small,the available bone height in the apical region of SRPⅡis insufficient,and the labial-palatal width of the alveolar bone and the mesial-distal width of the alveolar bone of SRPⅣare insufficient,therefor there is a risk of poor initial stability in the immediate implantation of maxillary anterior teeth.