Abstract:

Objective To compare the apical sealing of two kinds of warm gutta-percha filling techniques under two root canal preparation concepts. Methods One hundred and eight extracted permanent premolars were collected and stochastically divided into six groups, two control groups (n=12) and four experimental groups (A, B, C and D groups, n=21). Groups A and C were prepared to 50#02 as the master apical file; groups B and D were prepared to 25#08 as the master apical file. Then groups A and B were obturated with the traditional warm gutta-percha filling technique; groups C and D were obturated with modified warm gutta-percha filling technique. Six samples were randomly selected from each experimental group to prepare sections at 1, 3, and 5 mm, and the interfacial gap between the filling material and the dentin wall was observed. The apical microleakage of the rest of the teeth was observed with dye penetration and transparent teeth technique under a stereomicroscope. Results The microleakage value of the modified type was smaller than that of the traditional warm gutta-percha filling,and the difference was statistically significant (P<0.05). The microleakage value of preparation with 25#08 as the master apical file was smaller than that of preparation with 50#02, and the difference was statistically significant (P<0.05). The average value of dye leakage was group B < group C < group D < group A, and the differences were statistically significant between group A and each group, group B and group D (P<0.05), while the differences among remaining groups were not statistically significant. In the statistics of single and double root canals, the average value of dye leakage was still group B < group C < group D < group A, and the difference was statistically significant between group A and each experimental group, while the difference was not statistically significant between group B and group D. There was no statistically significant difference in the interfacial gap between groups and within groups, but a relatively small gap was found at 3 mm, and a large gap was found in groups C and D. Conclusion The traditional warm gutta-percha filling with 25#08 as the master apical file is better, which is as good as the modified warm gutta-percha filling with 50#02 as the master apical file. In the interface observation, it is easy to produce a large gap when using the modified warm gutta-percha filling.

Key words: warm gutta-percha filling technology, root canal preparation, dye penetration method, microleakage