Yaghmoor, Rayan B;
(2022)
In vitro Evaluation of Novel Antibacterial Dental Composites.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
The most common cause of failure of dental composites is recurrent caries. This is because of its tendency to accumulate dental biofilms. Moreover, the current recommended treatment for cavitated caries is minimally invasive. A novel material called SMART composites was developed to improve dental composites and follow the minimally invasive technique. Two novel agents were used as additives to the conventional composite filler; antibacterial polylysine (PLS) and remineralising monocalcium phosphate monohydrate (MCPM). A low shrinkage liquid, dimethacrylate phase, consisting of UDMA (bulk monomer) and a diluent monomer (PPGDMA), also was used. To this phase, an acidic functionalised monomer (4-META) (3wt%) was added to promote adhesion and etching effects. This thesis aimed to evaluate the antibacterial properties of the SMART composites containing a fixed MCPM/PLS ratio of 2. The antibacterial activity of PLS was assessed using planktonic cultures of S. mutans (UA159) and recent clinical isolates. This included determining minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and the effect on bacterial growth kinetics. Also, the antibiofilm effect of the SMART composites was evaluated by quantifying the biofilm mass, thickness, and distribution of live-dead bacteria. The findings were correlated with PLS release kinetics quantified by a ninhydrin assay. Additionally, viable bacteria in surface biofilms were counted. The exopolymer matrix was analysed including exo-polysaccharide and extracellular DNA (eDNA) quantification. MIC and MBC showed comparable results for PLS, and the growth kinetics displayed a slowing of growth but no death phase over 24 h. Biofilm mass, thickness and percentages of dead bacteria showed a constant decrease with increasing PLS levels in formulations. The initial PLS release was proportional to the square root of time and levelled after 1, 2, and 3 months for 8-4, 12-6, and 16-8, respectively. Evidence is presented showing that biofilm mass reduction is mainly caused by the decline in exo-polysaccharide quantity. However, with increasing the PLS levels in formulations, a decrease in other biofilm components also contributes to biomass reduction.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | In vitro Evaluation of Novel Antibacterial Dental Composites |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2022. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/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 > 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 |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10158714 |
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