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The effect of Monocalcium Phosphate and Polylysine on SMART composite self-bonding to dentine

Saliakelli, Dimitra; (2020) The effect of Monocalcium Phosphate and Polylysine on SMART composite self-bonding to dentine. Doctoral thesis (D.Dent), UCL (University College London). Green open access

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Abstract

Introduction. Despite the great effort made for prevention against caries, this is still a significant public health issue that affects a large number of the population worldwide. Restoration of carious teeth in children can be challenging and often the complex techniques used render the successful completion of the treatment extremely difficult. Aims and objectives. This study investigates the impact that different levels of hydrophilic remineralising Monocalcium Phosphate Monohydrate (MCPM) and antimicrobial polylysine (PLS) agents have on the bond strength of new experimental and potentially self-adhesive composites to ivory and human dentine. Methods. and materials Experimental composite formulations with low versus high levels of MCPM and PLS components were tested. Differences in morphology, mineralisation and caries level of teeth, all affect bond strengths with composites. The great diversity that human teeth exhibit, in addition to the limited supply, has forced the need for model systems. Ivory dentine was therefore used for initial assessment of the bonding strength, of multiple materials under different conditions, before testing optimised formulations in extracted human teeth. For the tests performed in ivory: The experimental composite formulations were placed and light cured in cylindrical cavities drilled fully through ivory blocks (depth 5mm and hole diameter 3mm). Different conditions tested included presence or not of etch and/or bond and storage condition which included or submerged in Simulated Body Fluid (SBF) or artificial saliva. The bond strength was assessed using a push-out test in a Shimadzu machine. In human dentine: Human teeth were cross sectioned into 2mm discs of dentine and the soft caries was removed, but not into hard dentine. The composite restorations were carried out without any tooth conditioning, so that the experiments mimic the way this material may be used. Results. The results in ivory showed that increased levels in both antibacterial and remineralising agents allowed for moderate bonding irrespective of the previous conditioning of dentine. Halving MCPM and PLS simultaneously increased initial (control) bond strength to untreated dentine (from 11 - 8 MPa). Dentine pre-treatment increased this to 14-16 MPa but benefits were minimal with low additive levels. Average bond strength (of all formulations/dentine conditioning/ medium type) halved within 1 week in medium from 11 to 5 MPa, but reached the initial levels of 10 MPa (of when the samples were stored in dry environment for 24 hours) by 30 days. In human teeth, the bond strength following dry storage for 24 hours (control bond strengths) was 7-9 MPa and comparable with those using ivory, but extremely variable following 1 week in Artificial Saliva (9-35 MPa). In 30 days in Artificial Saliva, the bond strength reached magnitudes of 6.5 MPa to 8.0 MPa similar to those of ivory dentine in 30 days in liquid medium. MCPM, PLS and their ratio could affect the bond strength. MCPM / PLS = 2 increased the bond strength to untreated dentine for samples stored in dry storage for 24 hours. Conclusion. Factors affecting bond strength are complex but SMART composites with 4% instead of 2% PLS and MCPM/PLS = 2 can improve bonding.

Type: Thesis (Doctoral)
Qualification: D.Dent
Title: The effect of Monocalcium Phosphate and Polylysine on SMART composite self-bonding to dentine
Event: Eastman Dental Institute - UCL
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Copyright © The Author 2020. Original content in this thesis is licensed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) Licence (https://creativecommons.org/licenses/by/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request.
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
URI: https://discovery.ucl.ac.uk/id/eprint/10089418
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