Assessment of sodium thiosulfate neutralizing effect on micro-hardness of dentin treated with sodium hypochlorite

Abstract

Background: This study aims to evaluate the ability of sodium thiosulfate (STS) to neutralize the adverse effect of sodium hypochlorite (NaOCl) on dentin micro-hardness.Methods: Fifty single-rooted teeth were longitudinally sectioned. The samples divided into a control and four sample groups (n = 20). All the samples were immersed in different solutions as follows, Control: Normal saline for 15 min, G1and G2: 2.5% NaOCl for 15 min, G3: 2.5% NaOCl for 15 min, followed by 5% STS for 10 min, G4: Normal saline for 15 min followed by 5% STS for 10 min. All groups except G1 incubated for one week before the test. The micro-hardness of samples was measured. Data were analyzed using the Kruskal-Wallis test for pairwise comparisons. A p-value < 0.05 was considered significant. Results: All groups showed a significant decrease in the micro-hardness value compared with the control group. NaOCl for one week (G2) reduced the micro-hardness of dentine compared with samples, tested immediately after immersion in NaOCl (G1) (p < 0.05). NaOCl alone (G2) or treated with STS (G3) resulted in a significant decrease in micro-hardness compared with the STS group (G4) (p < 0.05).Conclusions: STS as a neutralizing agent could not prevent the dentin micro-hardness downturn caused by NaOCl.

Does sodium thiosulphate avoid the formation of the brown‐coloured precipitate as an intermediate irrigant between NaOCl and chlorhexidine?

“…In contrast, no coloured precipitate formation was visualised in the group in which sodium thiosulphate was used an intermediate irrigant. The absence of this coloured precipitate may be attributed to the neutralising action of sodium thiosulphate, which is in line with several previous studies that have shown the impact of sodium thiosulphate neutralising NaOCl (22,24,27).…”

“…It is well known that the presence of NaOCl remnants inside the root canals during irrigation with CHX can generate a brown-coloured precipitate, for which one of its main by-products is para-chloroaniline (23). To avoid its formation, several intermediate irrigation protocols, including the use of sodium thiosulphate, have been suggested to neutralise residual NaOCl before the use of CHX (18,24). In this regard, the aim of this study was to evaluate the efficacy of sodium thiosulphate as an intermediate irrigant between the use of NaOCl and CHX to avoid the formation of the brown-coloured precipitate.…”

Effect of Irradiation with 980-nm Diode Laser on the Microhardness of Young and Old Root Canal Dentin after Treatment with Chemical Solutions

“…Moreover, irrigation was used (2ml of 2.6% NaOCl for 1 min), with rotary mechanical preparation of root canals, between each file increasing permeability of the chelating agent to the radicular dentin. This has reduced bacterial count, dissolved collagen, and caused oxidation of the organic portion of radicular dentin (15) . Hence, it was limited to 1 minute as prolonged usage of NaOCl can affect dentinal tissue.…”