Citric acid on coronary smear layer removal of primary teeth

Objectives:This study evaluated the smear layer (SL) removal capacity on 28 pulp chambers of deciduous molars, using as irrigating agents 1% sodium hipochlorite (NaOCl) followed by citric acid at different concentrations. Methods:Roots were removed with diamond discs, chambers were accessed by the occlusal face and the SL was produced on dentin walls with a #1013 diamond bur under refrigeration. The 28 enamel and dentin discs left were randomly divided in four groups, which were irrigated with: 1 ml of NaOCl (10 s), followed by 10 ml of citric acid (30 s) at 4% (G1), 6% (G2), 8% (G3) and 10% (G4) concentrations. Next, they were cleaved longitudinally and the 56 fragments were prepared for SEM observations and evaluated by 3 previously trained examiners (kappa=0,864), according to the criteria: 0 – no SL present; 1 – moderate SL; 2 – dense SL; 3 – dense SL, with no visible dentin tubules. Data were analyzed through Mann-Whitney tests at 5% significance. Results:Results showed predominance of the following scores: G1 – score 0 (50%); G2 – scores 0 and 1 (42,9%); G3 – score 1 (55%); G4 – score 0 (55%). Besides, it was observed that in G4 there was greater peritubular dentin removal. Nevertheless, there was no significant statistical difference between groups (p=0,158). Conclusion: Based on the applied method, it was concluded that lower concentrations of citric acid seem to be effective for removing SL of primary teeth, promoting fewer damages to peritubular dentin.