Testing Methods to Determine Sealing Ability of Root Filling Materials

OBJECTIVE: Dye penetration is often used to determine the sealing ability of root canal filling materials. There are doubts as to whether the results of these tests are clinically relevant. The aim of this study was to compare a bacterial micro-leakage model and a dye penetration model after sealing root canals with Resilon or Gutta Percha using either cold lateral condensation or System B for obturation. METHODS: The canals of 110 intact single canal teeth were prepared with rotary Profile instruments. Four experimental groups, and a positive and a negative control group were included. Groups one and two were obturated with either GP or Resilon using the System B heat source and groups three and four obturated with either GP or Resilon using a cold lateral condensation technique. Bacterial micro-leakage was tested using the two-chamber method. Thereafter a dye penetration test was performed. The results were subjected to an analysis of variance (ANOVA) and the two tests were compared using Pivot tables and the Chi-squared procedure. A p-value < 0.05 was considered as significant. RESULTS: There was a statistically significant relationship between the results of the two tests for the group as a whole (p=0.0003) and for GP (p=0.0014) and Resilon (p=0.0337) using System B, but not for GP (p=0.6994) or Resilon (p=0.4463) using cold lateral condensation. CONCLUSION: The dye penetration test did not provide results that were comparable to those of the bacterial micro-leakage test in all cases. The bacterial micro-leakage test is probably the closest in vitro replication of the clinical conditions that root canal filling materials could be subjected to.