下颌下腺窝解剖形态锥形束CT分析

CBCT evaluation of posterior sub-mandibular fossa

目的 应用锥形束CT(Cone beam computed tomography,CBCT)评估磨牙为健康的成年患者下颌骨磨牙区舌侧骨性倒凹横断面结构特征,以评估磨牙区横断面形态对即刻种植的风险。方法 选取2019年-2021年就诊于某医院放射科进行CBCT检查的病例资料,共108例。将纳入研究下颌第一、第二磨牙横断面形态进行分类;对存在下颌下窝病例,对下颌下窝相关参数进行测量分析;包括下颌下窝最深点(C)相对下颌神经管的分布率、下颌下腺窝高度(Vb)、倒凹深度(D)、下颌下腺窝角(Ca),按照牙位及性别进行比较分析;对所有病例进行中相关参数测量:包括测量管嵴距(H)、从根尖到下颌神经管上缘的距离(RAC)、牙槽嵴内倾斜角(A),下颌骨横断面上下宽之差(W1-W2),按照横断面分类、牙位以进行比较分析。结果 在三种不同横断面形态分类中,U型结构是最常见的62.96%,差异存在显著性(P=0.019);第一、第二磨牙倒凹最深点(C)点在ABC区中分布频率无显著差异(P=0.802);第一、第二磨牙对下颌下窝深度D值、下颌下腺窝角(Ca角)存在统计学差异(P <0.01,P=0.032),第一、第二磨牙下颌下腺窝高度(Vb)无同显著差异(P=0.639)。所有病例中第一、第二磨牙管嵴距(H值)、从根尖到下颌神经管上缘的距离(RAC)、牙槽嵴内倾斜角(A角)的差异有统计学意义(P <0.01,P <0.0001,P <0.018),第一、第二磨牙横断面上下宽之差(W1-W2)无显著差异(P=1.54)。各横断面形态间下颌骨横断面上下宽度差(W1-W2)以及牙槽嵴内倾斜角(A角)差异有统计学意义(P <0.01,P=0.007),横断面形态管嵴距(H值)、从根尖到下颌神经管上缘的距离(RAC)的差异无统计学意义(P=0.96,P=0.926)。结论 锥形束CT能够较好重建下颌下窝解剖形态,CBCT对下颌磨牙即刻种植术前评估和设计有重要的指导意义。

Objective To evaluate the anatomical formation of sub-mandibular area using cone-beam computed tomography(CBCT), to evaluate the risk of immediate dental implantation in adults with different cross sectional patterns. Methods CBCT images of 108 healthy patients were studied retrospectively, the cross-sectional shapes of the posterior mandible were categorized into threetypes. Then the dimensional parameters of lingual concavity(angle, height, depth)of patients with sub-mandibular undercut were determined by the measurement of selected anatomic landmarks, the relationship between the most concave point and the inferior alveolar canal(in zones A, B, C), distance from root apex to the inferior alveolar canal(RAC)were also evaluated. Results On CBCT images,Among the three different cross-sectional morphology, the U-shaped structure was the most common in all examined images which accounted for 62.96%, The difference was significant(P = 0.019). In the U-type shapes, the most concave point of the sub-mandibular fossa were further divided into areas A, B, and C. There were no significant differences in the frequency of the most concave point(point C)between the first and second molars in the A, B, C area(P = 0.802). The depth of the sub-mandibular undercut of the first molar and second molar were 3.17 ± 1.0, 4.52 ± 1.42, respectively. The depth(D)of the sub-mandibular undercutandthe concave angle(Ca)among the different tooth types were of significantly difference(P < 0.01, P = 0.032). The canal ridge distance(H value)at the first and second molars, the distance from the root to the upper edge of the mandibular canal(RAC), and the inclination angle of the alveolar ridge(A angle)had statistically significant differences amongall cases,(P < 0.01, P < 0.0001, P < 0.018). There was no significant difference between the upper and lower sections of the first and second molars(W1-W2)(P = 1.54). The difference of upper and lower width of mandibular cross section(W1-W2)and angle of inclination of alveolar ridge(Angle A)among different cross section morphology was statistically significant(P < 0.01, P = 0.007), there were no statistically significant differences in the length of tubular cristae(H value)and the distance from root tip to the superior edge of mandibular neural tube(RAC)(P = 0.96, P = 0.926). Conclusion The results demonstrate that CBCT can better show the critical anatomical structures in the sub-mandibular area, the evaluation using CBCT before the immediate dental implant procedure is of great significance.