Assessment of the degree of conversion in light-curing orthodontic resins with various viscosities

Araujo, Lorenna Oliveira Fernandes de; Barreto, Osmar; Mendonça, Adriano Augusto Melo de; França, Rodrigo

doi:10.1186/s40563-015-0055-z

Cited by 15 publications

(21 citation statements)

References 26 publications

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“…These results are in line with previous investigations that determined the conversion upon light curing of Activa, which was described as poor [ 41 ]. When comparing results achieved with VF in previous studies, their final conversion values were inferior to what was found in this study [ 42 , 43 ]. Differences may be explained by material thickness and peak selection variability, confirmed with this study.…”

Section: Discussioncontrasting

confidence: 99%

Methacrylate peak determination and selection recommendations using ATR-FTIR to investigate polymerisation of dental methacrylate mixtures

Delgado

Young

2021

PLoS ONE

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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.

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Section: Discussioncontrasting

confidence: 99%

Methacrylate peak determination and selection recommendations using ATR-FTIR to investigate polymerisation of dental methacrylate mixtures

Delgado

Young

2021

PLoS ONE

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“…Ideally, light curing of resin-based materials would result in a completely polymerized sample with no unpolymerized material remaining [ 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. However, even when using experimental adhesives, the highest DC values reached we Please explain each mark re around 80% [ 20 , 21 ].…”

Section: Discussionmentioning

confidence: 99%

Degree of Conversion and Oxygen-Inhibited Layer Effect of Three Dental Adhesives

et al. 2016

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This study investigated the effect of the oxygen-inhibited layer on the degree of conversion (DC) of three dental adhesives, comparing two different protocols. Quartz–tungsten–halogen (QTH) light curing and light-emitting diode (LED) were used to cure three adhesives: OptiBond All in One (OAIO), Adper Easy Bond (AEB) and ExciteF (EXF). The DC was calculated utilizing Fourier Transform infrared spectroscopy (FTIR) (n = 12). The two protocols used were as follows: (i) prevent the oxygen-inhibited layer using a Mylar plastic strip pushed onto each bonding adhesive; and (ii) polymerize samples without a plastic strip. The data was analyzed statistically by a three-way ANOVA, and Tukey Test (a = 0.05). The presence of an oxygen-inhibited layer reduced the DC of the adhesives by 64% for EXF, 46% for AEB and 32% for OAIO. This study suggests that there are differences among the oxygen-inhibited layers present for the adhesives tested.

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“…Thus, orthodontic bonding materials should have optimal physicochemical and mechanical characteristics as well as sufficient bond strength to withstand masticatory forces [36]. Different composites have been suggested for bonding orthodontic brackets [37], including both restorative and orthodontic bonding materials. However, the two major properties of these dental composites that still require improvement are their polymerization shrinkage and the related polymerization stress [13,24].…”

Section: Discussionmentioning

confidence: 99%

Evaluation of shear strength of brackets with different dental composites and enamel roughness

et al. 2016

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Assessment of the degree of conversion in light-curing orthodontic resins with various viscosities

Cited by 15 publications

References 26 publications

Methacrylate peak determination and selection recommendations using ATR-FTIR to investigate polymerisation of dental methacrylate mixtures

Methacrylate peak determination and selection recommendations using ATR-FTIR to investigate polymerisation of dental methacrylate mixtures

Degree of Conversion and Oxygen-Inhibited Layer Effect of Three Dental Adhesives

Evaluation of shear strength of brackets with different dental composites and enamel roughness

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