Effect of Heated Sodium Hypochlorite on the Viscoelastic Properties of Dentin Evaluated Using Dynamic Mechanical Analysis

Abstract

Introduction: This study aimed to investigate the effect of immersion of standardised dentin bars in 5% sodium hypochlorite (NaOCl) solutions at 60°C and 80°C on their viscoelastic properties, using Dynamic Mechanical Analysis (DMA). Methods: Eighteen intact teeth were used to produce ninety-nine dentin bars of standard dimensions (12mm×1mm×2mm) and randomly allocated to 6 groups (n=15 each) for immersion in: (1) Saline at 26°C; (2) Saline at 60°C; (3) Saline at 80°C; (4) NaOCl at 26°C; (5) NaOCl at 60°C; (6) NaOCl at 80°C. The bars were individually tested using DMA at baseline and after every 10 minutes of immersion in the test medium, up to 40 minutes. The effects of media, temperature, duration of exposure, and aspect ratio of bars on storage modulus (SM) and tan delta (TD) were investigated using Generalised Estimating Equations. Results: There was significant interaction between test medium and duration of immersion (p<0.05). The SM of specimens immersed in NaOCl at 60°C or 80°C decreased significantly (p<0.0001) over time of exposure, but the changes in other groups were minimal and insignificant. The TD of specimens immersed in saline 80°C (p<0.05), NaOCl at 60°C (p<0.05) or 80°C (p<0.0001) increased significantly over time of exposure but the change in NaOCl at 26°C was minimal. Other groups displayed negligible changes. Conclusions: NaOCl at 60°C or 80°C significantly reduced the elastic behaviour but increased the hysteresis of dentin under cyclic loading.

Effect of sodium hypochlorite temperature and concentration on the fracture resistance of root dentin

“…Previous studies testing the effect of NaOCl on dentin strength have been conducted by immersing specimens in NaOCl solution rather than using NaOCl as a root canal irrigant [ 14 , 15 ]. The results of such studies are clinically irrelevant, as the entire specimen is subjected to NaOCl, rather than just the internal dentinal root canal wall.…”

“…Previous studies have explored the effect of heated NaOCl on the mechanical properties of dentin. In these studies, dentin bars were prepared and totally immersed within the solution [ 14 , 15 ]. This methodology does not replicate the clinical scenario, during which NaOCl irrigation contacts only the internal dentinal surface of the root canal.…”

Root Surface Strain And Cracks Development By Two Reciprocating Nickel Titanium Files

“…Decoronation was done for all teeth to ensure a straight line access during root canal preparation. Sodium hypochlorite was not used as an irrigant in the current study as it negatively affects the mechanical properties and specifically the elastic behavior of dentin (18) . Acrylic tubes were filled with vinyl polysiloxane in order to mimic the physiologic movement of periodontal membrane space during root canal preparation.…”

Heat treatment of Sodium Hypochlorite : A Comprehensive Review

“…It can be heated outside / prewarmed using a beaker on a hot plate, or kettle or with a baby bottle warmer. [20,21,22] and then introduced in the canal. The extraoral heating was ineffective as it could not maintain the rised temperature of the preheated hypochlorite inside the canal and attains the equilibrium within seconds.…”

“…They found that the storage modulus was were reduced by 4.3 -6.8 GPa and 5.1 -9.7 GPa at 60°C and 80°C respectively. [22] Semra Sevimay et al (2010) stated that the surface tension of hypochlorite decreases with an increase in temperature. [41] Ling Zou et al (2010) measured the penetration of hypochlorite at 20°C, 37°C, and 45°C.…”