Potential to induce dentinal cracks during retreatment procedures of teeth treated with “Russian red”: An ex vivo study

The aim of this study was to compare the impact of treatment procedures on roots previously treated with resorcinol–formaldehyde resin and analyze the effectiveness of dye and magnification for the detection of dentin cracks. Distal roots of 80 permanent first mandibular molars with a single canal were sectioned at 3mm and 9mm from the anatomical apex. Two groups were formed according to the method used for root canal penetration: group 1 (K-file and Pro Taper instruments) and group 2 (Ultrasound with Pro Ultra and Pro Taper files). Before and after the completion of procedures, photographs of the roots were taken for examination for cracks or/and infraction lines with two levels of magnification and with or without a dye. In groups 1 and 2, either with dye or without it, there were statistically significant differences (P