Micro-computed tomographic evaluation of smear layer and accumulated hard tissue debris removal

The isthmus and irregularities present in the root canal system are potential areas for debris accumulation areas and therefore the seach for devices and solutions to improve cleaning of these areas is of utmust importance. This study evaluated, by micro-computed tomography, the efficiency of 37% phosphoric acid solution with that of 17% EDTA in the removal of smear layer and accumulated hard tissue debris (AHTD) after canal preparation.

Twenty-six mesial roots of mandibular molars were subjected to microtomographic scanning using the SkyScan 1173 X-ray microtomograph at a resolution of 14,97 µm. The canals were prepared using Reciproc R40 instruments, 6% NaOCl and EndoVac System® to irrigation/aspiration. After instrumentation, the specimens were divided into two groups: 37% phosphoric acid solution or 17% EDTA.

The results demonstrated that 37% phosphoric acid was significantly more effective in removing smear layer and AHTD than 17% EDTA (Mann-Whitney, P <0.05). It was shown that both 37% phosphoric acid and 17% EDTA are effective agents in the removal of smear layer and debris, but better results were obtained with the use of 37% phosphoric acid.

The results suggest that this solution can be a potential alternative to remove smear layer after root canal preparation.