Effect of synthetic and natural-derived novel endodontic irrigant solutions on mechanical properties of human dentin

Abstract

This study aimed to evaluate the effects of different synthetic and natural-derived root canal irrigants (6% sodium hypochlorite [NaOCl], 6% calcium hypochlorite [Ca(OCl)] and 6.5% grape seed extract [GSE]) on dentin mechanical properties (flexural strength, ultimate tensile strength [UTS] and fracture resistance). Rectangular-shaped beams and hourglass-shaped sections obtained from mid-coronal and root dentin were treated with 6% NaOCl, 6% Ca(OCl) or 6.5% GSE for 30 min. The irrigant solutions were replaced every 5 min. Then, the dentin specimens were rinsed with distilled water (DW) followed by incubation with 17% EDTA for 1 min, and thoroughly rinsed with DW again. Specimens from the control group were tested without prior irrigation. After treatment with the irrigants, dentin beams were used to assess the flexural strength (n = 10) while UTS was evaluated using the root dentin hourglass-shaped sections (n = 10). Similarly, roots with 1 mm of dentinal wall thickness were obtained from human teeth and treated with the same irrigant solutions (n = 10). A compressive loading was applied to the coronal surfaces of roots until fracture. The values of each mechanical test were statistically analyzed individually by one-way ANOVA followed by Tukey HSD test (P < 0.05). NaOCl significantly reduced the mechanical properties of dentin in all mechanical tests (P < 0.05) and no statistical difference was found among Ca(OCl), GSE and control group (P > 0.05). It can be concluded that Ca(OCl) and GSE may be alternative irrigant solutions, since they do not negatively affect the dentin mechanical properties.

Influence of different irrigation protocols on microhardness and flexural strength values of young and aged crown dentin

“…Therefore, root canal irrigants must be used carefully considering their concentration, amount, usage sequence and duration of irrigation. Although there were differences between nanohardness, Young's modulus and mineral density of coronal and radicular dentin, previous studies reported that higher concentrations of irrigants and longer irrigation duration caused irreversible changes in the structure of radicular and coronal dentin . Higher concentrations of NaOCl decreased the MH and FS of root dentin in a time‐dependent manner.…”

“…Studies indicated that longer irrigation periods and higher concentrations of irrigation solutions are reported to have an adverse effect on the mechanical and morphological properties of dentin. [11][12][13][14][15][16][17][18][19][23][24][25]35 Therefore, using lower concentrations of irrigation solutions with shorter irrigation periods during root canal irrigation might preserve MH and FS values of coronal dentin and contribute to the success of post-endodontic treatment.…”

“…As human lifespan is prolonged, the need for geriatric endodontic practices is likely to increase, particularly in the elderly population. In the light of the aforementioned information, data are limited regarding the effect of root canal irrigation solutions on the mechanical properties of coronal dentin, irrespective of age . In previous studies, the effect of irrigation solutions and ageing on the MH and FS of dentin were evaluated separately.…”

“…Although there were differences between nanohardness, 21 Young's modulus 21 and mineral density 22 of coronal and radicular dentin, previous studies reported that higher concentrations of irrigants and longer irrigation duration caused irreversible changes in the structure of radicular 11,13,[17][18][19]23 and coronal dentin. 12,14,24,25 Higher concentrations of NaOCl decreased the MH 18 and FS 17,19 of root dentin in a time-dependent manner. Besides, NaOCl, 17% EDTA alone or 17% EDTA prior to 2.5% NaOCl also resulted in the maximum decrease in dentin MH.…”

“…In the light of the aforementioned information, data are limited regarding the effect of root canal irrigation solutions on the mechanical properties of coronal dentin, irrespective of age. 14,24,25 In previous studies, the effect of irrigation solutions and ageing on the MH and FS of dentin were evaluated separately. Combining these parameters might be advantageous to evaluate the combined effects of ageing and irrigation with 2.5% NaOCl and different concentrations of EDTA on the MH and FS values of coronal dentin.…”