[Study of dental apex sealing effects after post space].

PURPOSE: To evaluate the sealing ability of three different lengths of root canal fillings after post space and two different obturation techniques by using a glucose leakage test, and provide theoretical basis for clinical selection of best collocation of root canal filling methods and residual root canal filling materials. METHODS: One hundred and thirty-two extracted single-root teeth were randomly divided into 6 experimental groups(n=20 each), positive(n=6)and negative controls(n=6). After root canal preparation, different treatments were performed in different groups. Group A: lateral compaction and 4 mm length of root canal fillings after post space. Group B: lateral compaction and 6 mm length of root canal fillings after post space. Group C: lateral compaction and 8 mm length of root canal fillings after post space. Group D: warm gutta vertical compaction and 4 mm length of root canal fillings after post space. Group E: warm gutta vertical compaction and 6 mm length of root canal fillings after post space. Group F: warm gutta vertical compaction and 8 mm length of root canal fillings after post space. Group G: random root canal filling. Group H: no root canal filling. A glucose leakage model was used for quantitative evaluation of the coronal to apical microleakage. SPSS 19.0 software package was used for statistical analysis. RESULTS: Lateral compaction showed significantly more leakage than warm gutta vertical compaction at all observation times, regardless of the length of the root canal fillings. The shorter the length of root canal fillings after post space, the worse the effect of the apical sealing for the same filling method. There was significant difference between 4 mm and 6 mm (P<0.05), but no significant difference between 8 mm and 6 mm (P>0.05). CONCLUSIONS: Warm vertical compaction shows a better sealing result than cold lateral compaction of gutta-percha. The shorter the length of root canal fillings after post space, the worse the effect of the apical sealing. 6 mm may be the proper residual root filling material length after post space preparation.