Effectiveness of Chemical Agents on Smear Layer and Root Permeability

Objective: To evaluate the effects of chemical agents on the removal of the smear layer and permeability in the primary root dentin. 

Method: Fifty primary roots were distributed in 6 groups: 5.25% Sodium Hypochlorite, 5.25% Sodium Hypochlorite + 17% EDTA, 2% Chlorhexidine, 2% Chlorhexidine + 17% EDTA, 17% EDTA, and Saline Solution. The canals were instrumented and irrigated. The roots were dyed, washed, sectioned and the permeability index was measured. The hemisections were prepared for scanning electron microscopy evaluation. The amount of smear layer was scored in: 1 = no smear layer; 2 = moderate smear layer; and 3 = heavy smear layer. Data were submitted to ANOVA, Kruskal-Wallis, Student-Newman-Keuls and t tests (p<.05).

Result: Significant differences were observed for the cervical and apical thirds for the 2% Chlorhexidine (p=0.03), 2% Chlorhexidine + 17% EDTA (p=0.027), Saline Solution (p=0.038) and 5.25% Sodium Hypochlorite (p=0.0008) groups. The Saline Solution group showed heavy smear layer in all thirds. Root canals treated with 5.25% Sodium Hypochlorite + 17% EDTA showed great cleaning in the cervical, middle and apical thirds.

Conclusion: Sodium hypochlorite associated with EDTA produces the best root canal cleaning and the highest permeability in all thirds for primary teeth.