锥形束CT与导板引导微创开髓精确性的体外研究

Accuracy of using cone-beam computed tomography and guided templates for minimally invasive endodontic cavity preparation:an in vitro study

目的研究锥形束CT(CBCT)与三维打印导板引导微创开髓造成的偏移距离与偏移角度,探讨该操作的精确性。方法收集40颗人离体单根双根管上颌第一前磨牙,开髓前进行CBCT扫描。对所有样本进行编号,通过随机数字表法将样本分为A、B两组,每组20颗牙,包括40个根管。微创开髓洞型采用“Truss”开髓洞型的设计。其中A组为三维打印导板引导开髓组,根据CBCT图像制作导板;B组为CBCT引导开髓组,根据CBCT图像确定牙合面开髓的位置与方向,于样本标记后直接开髓。两组样本开髓后,在CBCT图像中测量并计算各开髓孔在牙合面与髓角平面的面积、颊腭向与近远中向的偏移距离及偏移角度,使用SPSS 20.0软件进行统计学分析。结果各组数据不满足正态分布及方差齐性,故采用Mann-Whitney U 检验分析。开髓孔在牙合面平面的面积分别为A组(1.34 ± 0.18)mm^2、B组(1.30 ± 0.15)mm^2,差异无统计学意义(U =0.876,P =0.393)。髓角平面的面积分别为A 组(1.74 ± 0.20)mm^2、B 组(1.67 ± 0.24)mm^2,差异无统计学意义(U = 1.290,P =0.194)。B组牙合面近远中偏移距离[(0.37 ± 0.26)mm]小于A组[(0.52 ± 0.30)mm],差异具有统计学意义(U =2.237,P =0.024)。两组的牙合面颊腭向偏移距离、髓角颊腭向偏移距离、髓角近远中偏移距离、颊腭向偏移角度及近远中偏移角度间差异均无统计学意义(P>0.05)。结论单独使用CBCT可精确引导常规根管解剖形态患牙的微创开髓,CBCT结合导板对引导微创开髓的精确性与单独使用CBCT相比无显著提高,且两种引导方法对微创开髓洞型的大小无明显影响。

Objectives The aim of this study was to investigate the accuracy of minimally invasive endodontic cavity preparation with the guidance of cone-beam computed tomography(CBCT)and three- dimensional printed templates through analyzing distance deviation and angle deviation. Methods Forty extracted human single-rooted maxillary first premolars with double root canals were selected. Preoperative CBCT scanning of all specimens was used for designing access cavities. All teeth were numbered and assigned into two groups according to the random number table. There were twenty teeth including forty root canals in each group. The minimally invasive endodontic cavity was designed as“Truss”access cavity. Preparation for access cavities in group A was guided by three-dimensional printed templates which were fabricated according to the CBCT images. Access cavities in group B were prepared according to the marks on occlusal surface after the analysis of CBCT images. Distance deviations and angle deviations in buccopalatal and mesiodistal directions as well as the areas of access cavities at occlusal and pulp horn levels were measured and calculated in the CBCT images. Statistical analysis for the data was performed by SPSS 20.0. Results The data were analyzed with Mann-Whitney U test,since they were not satisfied with the normal distribution and the homogeneity of variance. No statistic difference was observed between the two groups in the areas of access cavities at occlusal level[group A:(1.34 ± 0.18)mm^2,group B:(1.30 ± 0.15)mm^2;U = 0.876,P = 0.393]or at pulp horn level[group A:(1.74 ± 0.20)mm^2,group B:(1.67 ± 0.24)mm^2;U =1.290,P =0.194]. The mesiodistal distance deviations at occlusal level in group B[(0.37 ± 0.26)mm]were less than that in group A[(0.52 ± 0.30)mm],which had significant difference(U = 2.237,P =0.024). There was no significant difference between the two groups in the buccopalatal distance deviations of occlusal level[group A:(0.45 ± 0.40)mm,group B:(0.41 ± 0.28)mm;U = 0.385,P = 0.697],the buccopalatal distance deviations of pulp horn level[group A:(0.32 ± 0.25)mm,group B:(0.41 ± 0.30)mm;U = 1.290,P = 0.199],the mesiodistal distance deviations of pulp horn level[group A:(0.38 ± 0.24)mm,group B:(0.35 ± 0.26)mm;U = 0.905,P = 0.500],as well as the buccopalatal angle deviations[group A:(4.76 ± 3.04)°,group B:(4.72 ± 3.61)°;U = 0.404,P = 0.679]or the mesiodistal angle deviations[group A:(3.04 ± 1.97)°,group B:(3.05 ± 2.45)°;U = 0.467,P = 0.637]. Conclusions CBCT scanning was able to accurately guide the preparation of the minimally invasive endodontic cavities for the teeth with normal root canal anatomy. The guidance of CBCT scanning with templates did not significantly enhance the accuracy of access cavities,compared to that of CBCT scanning alone. Moreover,no significant difference was detected in the actual sizes of“Truss”access cavities prepared with the guidance of the two approaches.