牙胶类根管充填材料导热性对根尖封闭的影响

摘要

目的:研究不同牙胶类根管充填材料的导热性及其对根尖封闭的影响.方法:采用差重法分别测量BP、DP、DPP和VP这4种牙胶类根管充填材料的成分,并使用导热系数测定仪测量其导热系数,每种牙胶随机选取20支,其中10支使用System B (200 ℃)距尖端4 mm无压力加热,使用红外热成像仪实时记录牙胶尖的温度变化;另10支用透明根管模型进行热牙胶根管充填,24h后在体视显微镜(×40)下观察距加热端1 mm外和3 mm处的牙胶充填面积比例,使用单因素方差分析(one-way ANOVA)进行比较.结果:DP中无机填料比例(80.90％±1.14％)及导热系数(2.247±0.002)均显著高于BP(79.28％±3.88％;1.179±0.003)、DPP(68.46％±5.09％;0.604±0.001)和VP(78.86％±1.87％;1.150±0.001) (P ＜0.05).在200℃下无压力加热牙胶尖,DP可在1 mm外达到65℃,而BP、DPP、VP仅能在加热端1 mm内测得65℃.热牙胶垂直加压充填后,3组的牙胶充填面积比均有提高,距工作长度3 mm(WL-3)处DP的牙胶充填面积比(96.89％±0.03％)高于BP(95.47％±0.06％)、DPP(95.21％±0.03％)和VP(95.15％ ±0.03％),差异有统计学意义(P＜0.05).结论:4种牙胶类根管充填材料中,DP无机填料多,其导热性好,WL-3处根尖封闭性优于其他种类牙胶.%Objective:To investigate the effect of thermal conductivity on the apical sealing ability of different dental gutta-percha cones during the warm vertical condensation obturation.Methods:Four kinds of dental gutta-percha cones were used in this study:Bio-GP points (BP,B&L,Korea),large-tapered gutta-percha (DP,DENTSPLY,America),PROTAPER Universal gutta-percha points (DPP,DENTSPLY,America) and mtwo gutta-percha points (VP,VDW,Germany).Volume differences method was used to determine the main components and the thermal conductivity determinator was used to measure the thermal conductivity of these dental gutta-percha cones.Furthermore,20 cones randomly selected from each kind of dental gutta-percha cones.And 10 cones of each dental gutta-percha cones,which were cut out the part of 4 mm in length from the apical end,were heated (200 ℃) from the upper end without compression,and the temperature of the gutta perchacones surface was monitored in time by the infrared thermal imager during the whole heating process.In addition,the rest of the 10 cones of each dental gutta-percha cones were used to obturate the root canal in the transparent root canal resin model using warm vertical condensation technique.The cross-sectional surface was observed by stereomicroscope (× 40) at 1 mm and 3 mm from the working length and the gutta-percha obturation area proportion was measured and analyzed.The data were analyzed by one-way ANOVA.Results:The proportion of inorganic fillers (80.90％ ± 1.14 ％) (P ＜ 0.05) and the thermal conductivity (2.247 ± 0.002)of DP was siguificantly higher than BP (79.28％ ± 3.88％,1.179 ± 0.003),DPP (68.46％ 5.09％,0.604 ±0.001),VP (78.86％ ± 1.87％,1.150 ±0.001) (P ＜0.05).During the thermal obturation without compression at the setting temperature (200 ℃),DP could achieve 65 ℃ beyond 1 mm from the heating point,and BP,DPP and VP only reached 65 ℃ within 1 mm.After warm vertical condensation obturation,all the groups showed increased gutta-percha obturation area proportion.At the position of WL-3,DP (96.89％ ±0.03％) showed significantly higher proportion of gutta-percha obturation area than BP (95.47％ ±0.06％),DPP (95.21％ ±0.03％) and VP (95.15％ ±0.03％) (P ＜ 0.05).Conclusion:DP contains more inorganic fillers,possesses higher thermal conductivity,and leads a better apical sealing ability than BP,DPP and VP at the position of WL-3 during warm vertical condensation obturation.