Theoretical Distribution of Gutta-percha within Root Canals Filled Using Cold Lateral Compaction Based on Numeric Calculus

This study aimed to present a new method based on numeric calculus to provide data on the theoretical volume ratio of voids when using the cold lateral compaction technique in canals with various diameters and tapers. Twenty-one simulated mathematical root canal models were created with different tapers and sizes of apical diameter, and were filled with defined sizes of standardized accessory gutta-percha cones. The areas of each master and accessory gutta-percha cone as well as the depth of their insertion into the canals were determined mathematically in Microsoft Excel. When the first accessory gutta-percha cone had been positioned, the residual area of void was measured. The areas of the residual voids were then measured repeatedly upon insertion of additional accessary cones until no more could be inserted in the canal. The volume ratio of voids was calculated through measurement of the volume of the root canal and mass of gutta-percha cones. The theoretical volume ratio of voids was influenced by the taper of canal, the size of apical preparation and the size of accessory gutta-percha cones. Greater apical preparation size and larger taper together with the use of smaller accessory cones reduced the volume ratio of voids in the apical third. The mathematical model provided a precise method to determine the theoretical volume ratio of voids in root-filled canals when using cold lateral compaction.

3种根管充填技术体外模型充填密度的对比

目的体外比较3种根管充填技术充填后的密度。方法选取60个模拟30°弯曲根管的透明树脂块,随机分为3组,每组20个。采用Protaper手动镍钛锉和冠向深入法预备模拟根管。A组使用冷牙胶侧方加压技术充填根管,B组使用E-Q立体热熔牙胶根管充填技术充填根管,C组使用Obtura-Ⅱ高温热塑牙胶注射充填技术充填根管。收集所得数据进行统计学分析。结果B组(11.693±0.766)和C组(11.900±0.384)牙胶团的重量明显高于A组(9.614±0.601)(P<0.05),但B、C两组牙胶团的重量无显著差异(P>0.05)。结论与传统冷牙胶侧方加压充填技术相比,E-Q立体热熔牙胶根管充填技术和Obtura-Ⅱ高温热塑牙胶注射充填技术在根管充填致密性方面有着显著的优越性,但二者之间无差别。