Cleaning of flattened root canals with different irrigating solutions and nickel-titanium rotary instrumentation

The aim of this study was to evaluate the cleaning capacity of Profile .04 files combined with different irrigating solutions in flattened root canals using histological, morphometrical and SEM analyses. Eighty human mandibular incisors were prepared with Profile .04 instruments and randomly divided into 4 groups according to the irrigating solutions used (n=20): G1: distilled water (control); G2: 1% sodium hypochlorite (NaOCl); G3: 1% NaOCl alternated with 17% EDTA, and G4: 1% NaOCl with RCPrep cream. Ten teeth of each group were evaluated with an optical microscope to determine the percentage of root canal debris. The remaining teeth were evaluated under scanning electron microscopy (SEM). Data were analyzed statistically by ANOVA and Tukey's test (alpha=0.01).There was a significant difference (p<0.001) among the groups regarding the percentage of debris left in the canals (distilled water: 18.82 +/- 5.55; 1% NaOCl: 6.29 +/- 5.55; 1% NaOCl + 17% EDTA: 12.47 +/- 6.92; 1% NaOCl + RCPrep: 7.82 +/- 1.91). The SEM analysis showed the best results for 1% NaOCl + 17% EDTA on smear layer removal. It may be concluded that the combination of Profile .04 rotary instrumentation and the tested solutions was not able to totally remove debris and smear layer from flattened root canals.