Based on these preliminary data, canal shaping appears to cause apical microcracks regardless of the type of rotary instrument motion. Contrast-enhanced micro-CT was able to identify microcracks in roots.

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The aims of this study were to investigate the effects of hesperidin, a citrus flavonoid, on human root dentin demineralization and collagen preservation, and compare it with chlorhexidine and grape seed extract. Specimens were assigned to different treatment groups: hesperidin, chlorhexidine and grape seed extract. Specimens were subjected to pH cycling by demineralization for 14 h, incubation in testing solutions for 2 h and remineralization in presence of bacterial-derived collagenase for 8 h, for 8 days. Calcium release was measured by means of an atomic absorption spectrophotometer, and degraded collagen matrix was investigated by hydroxyproline assay. Specimens were assessed longitudinally with transverse micro-radiography to investigate lesion depth and mineral loss. In hesperidin and grape seed extract groups, demineralization was reduced when the collagen matrix was preserved. The hesperidin group showed the lowest value in lesion depth and mineral loss, indicating that hesperidin inhibited demineralization and probably enhanced remineralization even under fluoride-free conditions.

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This study aimed to evaluate the effect of phytic acid (IP6), used as etchant, on resin-dentin bond strength, smear layer removal, and the viability of pulpal cells. Flat dentin surfaces with smear layer were etched with 1% IP6 for 60, 30, or 15 s; in the control group 37% phosphoric acid (PA) was used. Dentin surfaces were rinsed, blot-dried, and bonded with an etch-and-rinse adhesive, followed by composite build-ups. The specimens were subjected to tensile testing after 24 h of water storage at 37°C, and failure modes were determined using scanning electron microscopy. The effectiveness of IP6 to remove the smear layer was observed using scanning electron microscopy. To evaluate the effect on pulpal cells, solutions of 0.1 and 0.01% IP6 and of 3.7 and 0.37% PA were prepared and rat pulpal cells were treated with these solutions for 6 and 24 h. Cell viability was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The results demonstrated that all application times of IP6 produced bond-strength values that were significantly higher than that of the control. Phytic acid effectively removed the smear layer and plugs, thus exposing the collagen network. Phytic acid had a minimal effect on pulpal cells, whereas PA resulted in a marked decrease in their viability.