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The effect of NaOCl and heat treatment on static and dynamic mechanical properties and chemical changes of dentine

Karunanayake, G; Ng, Y; Knowles, JC; Delgado, A; Young, AM; Gulabivala, K; NAZHAT, SN; (2019) The effect of NaOCl and heat treatment on static and dynamic mechanical properties and chemical changes of dentine. Journal of the Mechanical Behavior of Biomedical Materials , 97 pp. 330-338. 10.1016/j.jmbbm.2019.05.042. Green open access

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Abstract

Objectives: To determine the effect of heat on flexural strength (FS), maximum strain (MS), storage modulus (SM), tan delta (TD) and chemical changes through micro-Raman spectroscopy of dentine exposed to 2.5% NaOCl or saline. / Methodology: Dentine bars were randomly allocated to 8 test groups. Half (groups 2,4,6,8) were treated with NaOCl for 20 min; the rest (groups 1,3,5,7) remained in saline. FS/MS were measured in groups 1–4 (n = 15) (3/4 were also heated to 200 °C & re-hydrated in saline). Micro-Raman spectroscopy was performed on bars from groups 1–4. SM/TD were measured in 5-8: in 5/6 (n = 10), repeated after heating (200 °C), then following re-hydration; in 7/8 (n = 3) after heating to 25–185 °C. / Results: Increase in MS on heat and FS/MS on heat + NaOCl was not significant (P > 0.05). SM increased (P = 0.06) after heat treatment but reduced to initial state after rehydration (P = 0.03). TD did not change (P = 0.4) after heat (200 °C) treatment but rehydration increased it compared with pre-treatment state (P = 0.001). For dentine bars pre-treated with NaOCl, SM did not change (P = 0.6) after heat (200 °C) treatment or rehydration but TD significantly increased (P = 0.02) upon re-hydration compared with pre- (P=0.007), or post- (P = 0.03) heat-treatment states. SM and TD varied between 25–185 °C with no consistent trend amongst the NaOCl pre-treated bars. Micro-Raman only detected chemical changes following NaOCl treatment in the mineral phase. / Conclusions: Exposure of dentine bars to heat and NaOCl produced only moderate changes to quasi-static but marked changes to viscoelastic properties, which may be explained by chemical alterations.

Type: Article
Title: The effect of NaOCl and heat treatment on static and dynamic mechanical properties and chemical changes of dentine
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.jmbbm.2019.05.042
Publisher version: https://doi.org/10.1016/j.jmbbm.2019.05.042
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: heat, flexural strength, storage modulus, maximum strain, tan delta.
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Eastman Dental Institute
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Eastman Dental Institute > Biomaterials and Tissue Eng
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Eastman Dental Institute > Restorative Dental Sciences
URI: https://discovery.ucl.ac.uk/id/eprint/10074925
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