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Dental Composites with Calcium / Strontium Phosphates and Polylysine

Panpisut, P; Liaqat, S; Zacharaki, E; Xia, W; Petridis, H; Young, AM; (2016) Dental Composites with Calcium / Strontium Phosphates and Polylysine. PLoS ONE , 11 (10) , Article e0164653. 10.1371/journal.pone.0164653. Green open access

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Abstract

PURPOSE: This study developed light cured dental composites with added monocalcium phosphate monohydrate (MCPM), tristrontium phosphate (TSrP) and antimicrobial polylysine (PLS). The aim was to produce composites that have enhanced water sorption induced expansion, can promote apatite precipitation and release polylysine. MATERIALS AND METHODS: Experimental composite formulations consisted of light activated dimethacrylate monomers combined with 80 wt% powder. The powder phase contained a dental glass with and without PLS (2.5 wt%) and/or reactive phosphate fillers (15 wt% TSrP and 10 wt% MCPM). The commercial composite, Z250, was used as a control. Monomer conversion and calculated polymerization shrinkage were assessed using FTIR. Subsequent mass or volume changes in water versus simulated body fluid (SBF) were quantified using gravimetric studies. These were used, along with Raman and SEM, to assess apatite precipitation on the composite surface. PLS release was determined using UV spectroscopy. Furthermore, biaxial flexural strengths after 24 hours of SBF immersion were obtained. RESULTS: Monomer conversion of the composites decreased upon the addition of phosphate fillers (from 76 to 64%) but was always higher than that of Z250 (54%). Phosphate addition increased water sorption induced expansion from 2 to 4% helping to balance the calculated polymerization shrinkage of ~ 3.4%. Phosphate addition promoted apatite precipitation from SBF. Polylysine increased the apatite layer thickness from ~ 10 to 20 μm after 4 weeks. The novel composites showed a burst release of PLS (3.7%) followed by diffusion-controlled release irrespective of phosphate addition. PLS and phosphates decreased strength from 154 MPa on average by 17% and 18%, respectively. All formulations, however, had greater strength than the ISO 4049 requirement of > 80 MPa. CONCLUSION: The addition of MCPM with TSrP promoted hygroscopic expansion, and apatite formation. These properties are expected to help compensate polymerization shrinkage and help remineralize demineralized dentin. Polylysine can be released from the composites at early time. This may kill residual bacteria.

Type: Article
Title: Dental Composites with Calcium / Strontium Phosphates and Polylysine
Open access status: An open access version is available from UCL Discovery
DOI: 10.1371/journal.pone.0164653
Publisher version: http://doi.org/10.1371/journal.pone.0164653
Language: English
Additional information: © 2016 Panpisut et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Keywords: Science & Technology, Multidisciplinary Sciences, Science & Technology - Other Topics, RESIN-COMPOSITES, IN-VITRO, BONE CEMENTS, CONVERSION, POLYMERIZATION, CHLORHEXIDINE, MECHANISMS, SYSTEMS, RESTORATIONS, CYTOTOXICITY
UCL classification: UCL
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/1519585
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