Abstract：
BACKGROUND: The conicity of the root canals of primary teeth is an important measure for endodontic therapies. However, determining this conicity depends on the methods employed, which requires further investigation.
OBJECTIVE: The aim of this study was to determine the conicity of the root canals of the upper and lower primary second molars using nanotomography (nCT).
METHODS: An in vitro study was performed using nine primary second molars, both upper and lower, subjected to nCT. Comparisons between the diameters of root canals were performed between the thirds (cervical-D0, middle-D5, and apical-D7). The conicity (%) was determined for each root canal from cervical to apical. Data were statistically analyzed with a significance level of 5%.
RESULTS: The conicity ranged from 2% to 8% for the upper primary second molars. Significant differences in root canal diameter between the thirds (D0, D5, and D7 points) were observed in the mesio- and distobuccal roots (p < .05), but not in the palatal roots (p > .05). For the lower primary second molars, the conicity ranged from 2% to 17%, as well as significant differences in root canal diameter between the thirds (D0, D5, and D7 points) were observed in all roots (distal, mesiobuccal, and mesiolingual; p < .05).
CONCLUSIONS: The conicity of the upper primary second molars was different from that of the lower ones, which showed a greater variability.
OBJECTIVE: The aim of this study was to determine the conicity of the root canals of the upper and lower primary second molars using nanotomography (nCT).
METHODS: An in vitro study was performed using nine primary second molars, both upper and lower, subjected to nCT. Comparisons between the diameters of root canals were performed between the thirds (cervical-D0, middle-D5, and apical-D7). The conicity (%) was determined for each root canal from cervical to apical. Data were statistically analyzed with a significance level of 5%.
RESULTS: The conicity ranged from 2% to 8% for the upper primary second molars. Significant differences in root canal diameter between the thirds (D0, D5, and D7 points) were observed in the mesio- and distobuccal roots (p < .05), but not in the palatal roots (p > .05). For the lower primary second molars, the conicity ranged from 2% to 17%, as well as significant differences in root canal diameter between the thirds (D0, D5, and D7 points) were observed in all roots (distal, mesiobuccal, and mesiolingual; p < .05).
CONCLUSIONS: The conicity of the upper primary second molars was different from that of the lower ones, which showed a greater variability.
摘要：
背景：乳牙根管的锥度是牙髓治疗的重要措施。然而,确定这种锥度取决于所采用的方法，这需要进一步调查。
目的：本研究的目的是使用纳米技术（nCT）确定上下主第二磨牙根管的锥度。
方法：使用九颗初级第二磨牙进行了一项体外研究，上部和下部，进行NCT。在三分之二（子宫颈D0，中D5和根尖D7）之间进行了根管直径之间的比较。确定从宫颈到根尖的每个根管的锥度（％）。对数据进行统计学分析,显著性水平为5%。
结果：对于上初级第二磨牙，锥度范围为2％至8％。在近侧根和远侧根（D0，D5和D7点）之间观察到根管直径的显着差异（p<0.05），但不在腭根中(p>.05)。对于下颌第二磨牙，锥度范围从2%到17%，在所有根（远端，近颊,和中舌；p<.05）。
结论：上初级第二磨牙的锥度与下初级第二磨牙的锥度不同，表现出更大的变异性。
目的：本研究的目的是使用纳米技术（nCT）确定上下主第二磨牙根管的锥度。
方法：使用九颗初级第二磨牙进行了一项体外研究，上部和下部，进行NCT。在三分之二（子宫颈D0，中D5和根尖D7）之间进行了根管直径之间的比较。确定从宫颈到根尖的每个根管的锥度（％）。对数据进行统计学分析,显著性水平为5%。
结果：对于上初级第二磨牙，锥度范围为2％至8％。在近侧根和远侧根（D0，D5和D7点）之间观察到根管直径的显着差异（p<0.05），但不在腭根中(p>.05)。对于下颌第二磨牙，锥度范围从2%到17%，在所有根（远端，近颊,和中舌；p<.05）。
结论：上初级第二磨牙的锥度与下初级第二磨牙的锥度不同，表现出更大的变异性。
