Effects of Endodontic Irrigation in Primary Teeth: Micro-mechanical Analysis

Objectives: To verify the effects of endodontic irrigants, auxiliaries of instrumentation, and chelating agent on the microhardness of the pulp chamber dentin in primary teeth. Methods: Fifty anterior teeth were selected. The roots were sectioned at the cementoenamel junction and discarded. The crowns were sectioned longitudinally in the mesiodistal direction to expose the pulp chamber. Dentin surfaces were prepared for microhardness test by grinding and polishing. The specimens were randomly distributed in ten groups: saline solution, 1.0% NaOCl, 1.0% NaOCl+urea peroxide cream, 1.0% NaOCl+17% EDTA, 17% EDTA, 2.0% chlorhexidine gel, 2.0% chlorhexidine gel+17% EDTA, 5.25% NaOCl, 5.25% NaOCl+urea peroxide cream, 5.25% NaOCl+17% EDTA. The teeth were irrigated simulating chemical preparation for 30 minutes. Dentin microhardness was measured with a Vickers diamond microhardness tester (50g/5s) in Vickers hardness number (VHN) before and after the irrigation. Statistical comparisons among the test groups were performed using ANOVA and Bonferroni tests. Before and after the irrigation treatment data were submitted to paired t test (p<0.05). Results: The microhardness data indicated a statistically significant difference between the VHN values within groups before and after irrigation and for the differently treated groups (p<0.05). The results indicated that all test groups except saline solution and chlorhexidine significantly decreased the microhardness. For EDTA groups, after the treatment, the microhardness could not be measured. Saline solution (23.146) and chlorhexidine (20.490) showed the highest VHN values compared to 5.25% and 1.0% NaOCl (11.724/11.462, respectively). 5.25% and 1.0% NaOCl+urea peroxide cream (15.573/14.742, respectively) showed intermediate results with no significant difference in relation the others groups. Conclusions: It could be concluded that the use of EDTA resulted in the maximum decrease in dentin microhardness, since it could not be measured. In addition, both 5.25% and 1.0% NaOCl significantly reduced the microhardness of pulp chamber dentin in primary teeth.