Effects of different concentrations and exposure time of sodium hypochlorite on the structural, compositional and mechanical properties of human dentin

Abstract

This study evaluated the effects of sodium hypochlorite (NaOCl) with different concentrations and exposure time on the structural, compositional and mechanical properties of human dentin in vitro. Sixty dentin slabs were obtained from freshly extracted premolars, randomly distributed into four groups (n=15), and treated with 1%, 5%, 10% NaOCl and distilled water (control group), respectively, for a total of 60 min. Attenuated total reflection infrared (ATR-IR) spectroscopy, Raman spectroscopy and X-ray diffraction (XRD) were carried out before, 10 min and 60 min after the treatment. Scanning electron microscopy (SEM) and flexural strength test were conducted as well. The results showed that dentins experienced morphological alterations in the NaOCl groups, but not in the control group. Two-way repeated-measures analysis of variance revealed that the carbonate:mineral ratio (C:M), Raman relative intensity (RRI), a-axis, c-axis length and full width at half maximum (FWHM) with the increase of time and concentration in the NaOCl groups were not significantly different from those in the control group (P>0.05). Nevertheless, the mineral:matrix ratio (M:M) increased and the flexural strength declined with the increase of concentration and the extension of time in the NaOCl groups (P<0.05). Additionally, it was found that the M:M and the flexural strength remained unchanged after 1% NaOCl treatment (P>0.05), and the morphology changes were unnoticeable within 10 min in 1% NaOCl group. These results indicated that NaOCl has no significant effects on the inorganic mineral of human dentin; but it undermines and eliminates the organic content concentration- and time-dependently, which in turn influences the flexural strength and toughness of dentins. In addition, an irrigation of 1% NaOCl within 10 min can minimize the effects of NaOCl on the structural and mechanical properties of dentin during root canal treatment.

Cup-Shaped Tooth Wear Defects: More than Erosive Challenges?

“…The action of loading produced a smear layer on the top surface, mainly composed of grinding debris containing small microcrystalline and organic particles. In order to examine the possible damaged top surface of the affected occlusal surfaces with SEM, the smear layer was removed carefully using NaOCl [Wang et al, 2017]. The specimens were exposed to a 2.5% NaOCl solution for 3 min during constant agitation with a brush.…”

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

“…However, even single use of NaOCl at higher concentrations could affect the MH and FS values of root canal dentin in a time‐dependent manner . Wang et al reported that NaOCl had no significant effect on the inorganic components of dentin but caused a decrease in the organic components, which might influence the FS values of dentin. Considering that the organic component of dentin decreased with age, more prominent effects on FS values after NaOCl irrigation could be observed in young dentin than in aged dentin.…”

“…Besides ageing, root canal irrigants might also affect the structural and mechanical properties of dentin . Different studies, irrespective of age, showed that root canal irrigation solutions had a negative impact on the FS and MH of root dentin .…”

“…[15][16][17][18][19] Different studies, irrespective of age, showed that root canal irrigation solutions had a negative impact on the FS and MH of root dentin. [11][12][13][15][16][17][18][19] In the present study, effects of root canal irrigants as well as ageing on the TA B L E 1 Microhardness values of young and aged coronal dentin pre-and post-treatment MH and FS of coronal dentin were evaluated. Current results indicated that exposure to NaOCl alone or combined with different concentrations of EDTA did not change the MH values of young dentin samples, while these irrigation solutions significantly decreased the MH values of aged coronal dentin as shown previously for the furcal area of mandibular molars.…”

“…5,9 During root canal treatment, used materials that are in contact with the dentin surface, such as root canal irrigation solutions, may affect the mechanical as well as the structural properties of dentin. [11][12][13][14][15][16][17][18][19] Sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid (EDTA) in different concentrations are the most preferred root canal irrigants to provide debridement, lubrication, and destruction of microbes and dissolution of tissues as well as smear layer removal. 20 Throughout irrigation, radicular and coronal dentin sections are exposed to solutions deposited in the pulp chamber.…”