Dataset Information

Ageing of Dental Composites Based on Methacrylate Resins-A Critical Review of the Causes and Method of Assessment.

ABSTRACT: The paper reviews the environmental factors affecting ageing processes, and the degradation of resins, filler, and the filler-matrix interface. It discusses the current methods of testing materials in vitro. A review of literature was conducted with the main sources being PubMed. ScienceDirect, Mendeley, and Google Scholar were used as other resources. Studies were selected based on relevance, with a preference given to recent research. The ageing process is an inherent element of the use of resin composites in the oral environment, which is very complex and changes dynamically. The hydrolysis of dental resins is accelerated by some substances (enzymes, acids). Bonds formed between coupling agent and inorganic filler are prone to hydrolysis. Methods for prediction of long-term behaviour are not included in composite standards. Given the very complex chemical composition of the oral environment, ageing tests based on water can only provide a limited view of the clinical performance of biomaterial. Systems that can reproduce dynamic changes in stress (thermal cycling, fatigue tests) are better able to mimic clinical conditions and could be extremely valuable in predicting dental composite clinical performance. It is essential to identify procedure to determine the ageing process of dental materials.

SUBMITTER: Szczesio-Wlodarczyk A

PROVIDER: S-EPMC7240588 | biostudies-literature | 2020 Apr

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Ageing of Dental Composites Based on Methacrylate Resins-A Critical Review of the Causes and Method of Assessment.

Szczesio-Wlodarczyk Agata A Sokolowski Jerzy J Kleczewska Joanna J Bociong Kinga K

Polymers 20200410 4

The paper reviews the environmental factors affecting ageing processes, and the degradation of resins, filler, and the filler-matrix interface. It discusses the current methods of testing materials in vitro. A review of literature was conducted with the main sources being PubMed. ScienceDirect, Mendeley, and Google Scholar were used as other resources. Studies were selected based on relevance, with a preference given to recent research. The ageing process is an inherent element of the use of res ...[more]

PMID: 32290337

Similar Datasets

Project description:ObjectivesThe susceptibility of methacrylates to hydrolytic and enzymatic degradation may be a contributing factor limiting the clinical lifespan of resin composite restorations. The elimination of labile ester bonds is a potential advantage of methacrylamides, which have been shown to produce more stable restorative interfaces. The rationale of this study is to design hydrolytically and enzymatically stable adhesive monomers, with the added benefit of being able to form crosslinked networks. The objective of this study was to synthesize difunctional, hybrid methacrylate-methacrylamide monomers, and evaluate them as potential monomers for dental adhesives.Materials and methodsHEMA, TEGDMA (controls) or secondary methacrylamides (HEMAM - commercially available, 2EM and 2dMM - newly synthesized) either bearing a hydroxyl group or a methacrylate functionality (Hybrids-Hy), were added at 40mass% to bisGMA. The photoinitiator system consisted of 2-dimethoxyphenyl acetophenone (DMPA) and diphenyl iodonium hexafluorophosphate (DPI-PF6) at 0.2 and 0.4mass%, respectively. Polymerization kinetics were followed in real-time by near-IR spectroscopy during light activation at 630mW/cm2 for 300s. Water sorption and solubility (WS, SL) were measured according to ISO 4049. Storage modulus in shear (G') for 300s was obtained by oscillatory rheometry. For the microtensile bond strength (μTBS), fully formulated adhesives containing 40vol% ethanol were used to restore caries-free human third molars. Bonded specimens with 1mm2 cross-sectional area were tested after 48h and 6 months storage in water at 37°C. Single bond (SB) was tested as a commercial control. Data were analysed with one-way ANOVA and Tukey's test and Student's t-test (α=0.05).ResultsIn general, hybrid versions showed lower polymerization rate and degree of conversion, whereas the methacrylate controls, HEMA and TEGDMA, showed the highest values. The hybrid versions showed lower values of WS and SL than their monofunctional versions. HEMAM Hy showed the highest values of G' and TEGDMA, 2EM, and 2dMM-Hy the lowest. The μTBS values between 48h and 6 months were statistically reduced only for the HEMA and both 2dMM materials. The formulation containing the monofunctional methacrylamide (HEMAM) showed only 9% reduction in μTBS after 6 months of aging, while the other groups showed a decrease ranging between 18% and 33%.ConclusionOverall, hybrid monomers showed lower reactivity than their analogous monofunctional versions, but had markedly lower water sorption. Shear storage modulus was affected differently by the addition of the second functionality. HEMAM-containing systems were able to maintain stable long-term dentin bond strength, which demonstrates that bonding stability is a result of the complex interplay among the factors studied.Clinical significanceThe novel monomers showed here are potential alternatives to the current methacrylate adhesives, with selected formulations presenting greater bond stability.

Project description:Cellulose nanocrystals (CNCs) derived from renewable plant-based materials exhibit strong potential for improving properties of polymers by their dispersal in the polymer matrix as a composite phase. However, the hydrophilicity and low thermal stability of CNCs lead to compromised particle dispersibility in common polymers and limit the processing conditions of polymer-CNC composites, respectively. One route that has been explored is the modification of CNCs to alter surface chemistry. Acrylic materials are used in a broad class of polymers and copolymers with wide commercial applications. Yet, the available methods for adding groups that react with acrylics to enhance dispersion are quite limited. In this work, a versatile chemical modification route is described that introduces acryloyl functional groups on CNCs that can in turn be polymerized in subsequent steps to create acrylic-CNC composites. The hydroxyl group on CNC surfaces was reacted with the isocyanate moiety on 2-isocyanatoethyl methacrylate (IEM), a bifunctional molecule possessing both the isocyanate group and acryloyl group. The resulting modified CNCs (mCNCs) showed enhanced hydrophobicity and dispersibility in organic solvent relative to unmodified CNCs. Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy, solid-state 13C nuclear magnetic resonance (NMR) spectroscopy, and elemental analysis verified the surface modification and allowed an estimation of the degree of modification as high as 0.4 (26.7% surface hydroxyl substitution CNC). The modified CNCs were copolymerized with methyl methacrylate, and the composites had improved dispersion relative to composites with unmodified CNCs and enhanced (104%) tensile strength at 2 wt % CNC when compared to the neat poly(methyl methacrylate) (PMMA), indicating a benefit of the reactive acryloyl groups added to the CNC surface. Overall, the modification strategy was successful in functionalizing CNCs, opening possibilities for their use in organic media and matrices.

Project description:Investigation of polymerisation kinetics using ATR-FTIR systems is common in many dental studies. However, peak selection methods to calculate monomer-polymer conversion can vary, consequently affecting final results. Thus, the aim of this study is to experimentally confirm which method is less prone to systematic errors. Three commercial restorative materials were tested-Vertise Flow (VF), Constic and Activa Bioactive Restorative Kids. Firstly, Attenuated Total Reflectance Fourier Transform Infra-Red (ATR-FTIR) (Spectrum One, Perkin-Elmer, UK) spectra of monomers were acquired-10-methacryloyloxy decyl dihydrogen phosphate (10-MDP), bisphenol-A glycidyl dimethacrylate (Bis-GMA), 2-hydroxyethyl methacrylate (HEMA), triethyelene glycol dimethacrylate (TEGDMA) and urethane dimethacrylate (UDMA) to investigate proportionality of methacrylate peak heights versus concentration. Spectral changes upon light exposure of 2 mm discs of the restorative materials (irradiated for 20 s, LED curing unit 1100-1330 mW/cm2) were assessed to study polymerisation kinetics (n = 3), with continuous acquisition of spectra, before, during and after light exposure. Peak differences and degrees of conversion (DC %) were calculated using 1320/1336, 1320/1350 and 1636/1648 cm-1 as reaction/reference peaks. Inferential statistics included a MANOVA and within-subjects repeated measures ANOVA design (5% significance level). Proportionality of methacrylate peak height to concentration was confirmed, with the 1320/1352 cm-1 peak combination showing the lowest coefficient of variation (8%). Difference spectra of the polymerisation reaction showed noise interference around the 1500-1800 cm-1 region. Across the different materials, DC % results are highly dependent upon peak selection (p<0.001), with higher variability associated to the 1636 cm-1. Significant differences in the materials were only detected when the 1320 cm-1 peak was used (p<0.05). Within the same materials, methods were significantly different for Constic and Activa (p<0.05). It is possible to conclude that the 1320 cm-1 peak is more adequate to assess polymerisation of methacrylates and is therefore recommended.

Dataset Information

Ageing of Dental Composites Based on Methacrylate Resins-A Critical Review of the Causes and Method of Assessment.

Publications

Ageing of Dental Composites Based on Methacrylate Resins-A Critical Review of the Causes and Method of Assessment.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure