Objective This study aimed to measure the taper and diameter of root canal, as well as the elastic modulus and hardness in the root dentin of maxillary primary anterior teeth. Methods Patients under general anesthesia who needed root canal therapy in the maxillary primary anterior teeth were selected. Silicone impression material was used to take impressions. The impressions were scanned, and the taper and diameter of root canal were measured. Maxillary primary anterior teeth were collected in vitro. The elastic modulus and hardness of root dentin was tested. Results A total of 74 silicone impressions were obtained. The mean tapers of primary incisor teeth, primary lateral incisor teeth, and primary canine teeth were 0.106, 0.185, and 0.098, respectively. The mean diameters of the root canal 5 mm below the cementum-enamel junction (CEJ) were 1.267, 0.860, and 1.429 mm, respectively. The elastic modulus and hardness of root dentin were measured in 10 primary anterior teeth in vitro. The range of elastic modulus was 19.919-25.017 GPa. The range of hardness was 0.867-1.082 GPa. Conclusion The root canal post used in primary anterior teeth can be produced by the following data: taper of primary incisor teeth and primary canine teeth, 0.1; diameters of their tips, 1.2 mm and 1.4 mm, respectively; taper of primary lateral incisor teeth, 0.2; diameter of their tips, 0.8 mm; range of elastic modulus, 20-25 GPa; and range of hardness, 0.87-1.08 GPa.
目的 测量上颌乳前牙根管锥度、直径及根部牙本质的弹性模量和硬度，为用于上颌乳前牙的可吸收根管桩的制作提供参考。方法 选择全身麻醉下进行上颌乳前牙根管治疗的患儿，采用硅橡胶制取上颌乳前牙根管印模，扫描印模后测量根管的锥度和直径。收集10颗离体上颌乳前牙，测量根部牙本质的弹性模量和硬度。结果 本研究共收集了74颗上颌乳前牙的根管模型，其中乳中切牙28颗，乳侧切牙35颗，乳尖牙11颗。乳中切牙、乳侧切牙、乳尖牙的平均锥度依次为0.106、0.185、0.098，釉牙骨质界下方5 mm处平均直径依次为1.267、0.860、1.429 mm。10颗离体上颌乳前牙根部的牙本质弹性模量范围为19.919~25.017 GPa，硬度范围为0.867~1.082 GPa。结论 制作乳牙根管桩时，乳中切牙及乳尖牙根管桩建议取锥度为0.1，尖端直径为1.2、1.4 mm；乳侧切牙根管桩建议取锥度为0.2，尖端直径为0.8 mm；桩的弹性模量范围为20~25 GPa，硬度范围为0.87~1.08 GPa较为适宜。.
Keywords: diameter of root canal; elastic modulus; hardness; primary teeth; root dentin; taper.