Tissue dissolution and modifications in dentin composition by different sodium hypochlorite concentrations

Author(s)

Tartari, Talita ; Bachmann, Luciano ; Alves Maliza, Amanda Garcia ; de Andrade, Flaviana Bombarda ; Hungaro Duarte, Marco Antonio ; Bramante, Clovis Monteiro

• Document type: Journal article
• Source: Journal of Applied Oral Science; v. 24, n. 3, p. 291-298, MAY-JUN 2016.
• Web of Science Citations: 10

Abstract

Sodium hypochlorite (NaOCl) remains the most used irrigation solution during root canal preparation because of characteristics such as wide-spectrum antimicrobial activity and organic tissue dissolution capacity. However, these solutions can alter dentin composition and there is no consensus on the optimal concentration of NaOCl to be used. Objectives: To determine the organic matter dissolution and changes in dentin chemical composition promoted by different concentrations of NaOCl over time. Material and Methods: Fragments of bovine muscle tissue were weighed before and after 5, 10, and 15 min of immersion in the groups (n=10): G1- 0.9% saline solution; G2- 1% NaOCl; G3- 2.5% NaOCl; and G4- 5% NaOCl. Bovine dentin fragments were subjected to the same irrigants and absorption spectra were collected by Attenuated Total Reflectance of Fourier Transform Infrared Spectroscopy (ATR-FTIR) before and after 0,5, 1, 2, 3, 5, 8, and 10 min of immersion in the solutions. The ratios of the amide III/phosphate and carbonate/phosphate absorption bands were determined. The tissue dissolution and carbonate/phosphate ratios were submitted to the two-way analysis of variance (ANOVA) with Tukeys multiple-comparison test (alpha<0.05) and to the one-way analysis of variance with Tukeys (alpha<0.05). The amide III/phosphate ratio was analyzed by Friedman test (alpha<0.05) and the Kruskal-Wallis test with Dunns post-hoc (alpha<0.05). Results: The increase in NaOCl concentration and contact time intensified the dissolution of organic matter and dentin collagen with reduction in the amide III/phosphate ratio. Significant differences between all groups (p<0.05) were observed in the dissolution of organic matter at 10 min and in the amide III/phosphate ratio between the saline solution and 5% NaOCl at 5 min. The carbonate/phosphate ratio decreased significantly in G2, G3, and G4 after 0,5 min of immersion (p<0.05), but more alterations did not occur in the subsequent periods (p>0.05). Intergroup differences were not observed in this ratio (p>0.05). Conclusions: The increase in the exposure time and in the concentration of NaOCl solution lead to an increase in the tissue dissolution and dentin collagen deproteination. Furthermore, some carbonate ions are removed from the dentin inorganic phase by the NaOCl. (AU)

• FAPESP's process: 13/19789-3 - Effects of different irrigation regimes in physico-chemical properties of dentin and consequences of changesin the adhesion of microorganisms and AH Plus sealer
• Grantee: Talita Tartari
• Support type: Scholarships in Brazil - Doctorate
• FAPESP's process: 12/02460-6 - Vibrational spectroscopy applied to biological tissues: cancer diagnosis and chemical characterization of laser irradiated dental tissues
• Grantee: Luciano Bachmann
• Support type: Regular Research Grants