Single‐ or two‐visits endodontic treatment: Impact of irrigants on surface roughness, microhardness, topography, and fracture resistance of root dentin

This study evaluated the effect of the number of simulated endodontic treatment visits and the type of irrigant on the surface roughness, microhardness, topography, and fracture resistance of root dentin. Bovine roots were distributed into six groups (n = 14) according to the irrigant and number of treatment visits: 0.9% saline solution (single- or two-visits); 2.5% sodium hypochlorite (NaOCl) (single- or two-visits); 2% chlorhexidine (CHX) (single- or two-visits). Next, the roots were embedded in cylindrical acrylic molds for fracture resistance testing and fracture pattern analysis. In addition, dentin blocks were subjected to the same experimental protocols (n = 7) and analyzed for surface roughness, topography, and microhardness. Two-way anova, Tukey's post hoc and Fisher's exact tests were performed. There was no difference between the groups for fracture resistance or failure pattern. For surface roughness, highest values were observed when 2.5% NaOCl was used in combination with two simulated visits, findings that corroborate the dentin erosion observed in the microscopic analysis. For dentin microhardness, 2% CHX resulted in a reduction in this property, whereas the number of visits did not affect the outcome. In conclusion, different irrigants caused microstructural changes in dentin under simulated single- and two-visits treatments, but fracture resistance remained unaffected.