Polymerization kinetics of resin cements after light activation through fibre posts: an in vitro study.
TL;DR: The degree of conversion for VLV reduced after light activation through 9 mm Posts when compared to 3 mm and 6 mm posts, whilst the degree of Conversion for VLII decreased with every increase in post length.
Abstract: Aim
To measure the polymerization of light-cured (Variolink Veneer, VLV) and dual-cured (Variolink II, VLII) resin luting cements after light activation through different lengths of fibre post ex vivo.
Methodology
Degree of conversion after prolonged direct light activation (PLA) [12 min after LED light activation for 3 min] was determined using ATR-FTIR. Models were then produced to allow samples of VLV and VLII (n = 5 each group) to be light-activated through 3, 6 and 9 mm lengths of fibre post (Fiber Lux). Degree of conversion was assessed by ATR-FTIR and expressed as a percentage of the degree of conversion achieved after PLA. Data were analysed using anova and Tukey's test (P < 0.05).
Results
Mean [SD] degree of conversion for VLV and VLII after PLA was 57.97% [1.51] and 54.71% [3.77], respectively. Light activation of VLV through a 3 mm post produced 81.62% of the PLA value, compared with 71.03% for the 6 mm and 46.04% for the 9 mm post. Conversion after activation through 9 mm posts was significantly less than through 3 mm and 6 mm posts (P < 0.05). For VLII, activation through a 3 mm post produced 66.51% of the PLA value, compared with 54.38% for the 6 mm and 41.56% for the 9 mm post. A significant decrease in degree of conversion was noted for VLII as post length increased (P < 0.05).
Conclusions
The degree of conversion for VLV reduced after light activation through 9 mm posts when compared to 3 mm and 6 mm posts, whilst the degree of conversion for VLII decreased with every increase in post length.
Citations
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TL;DR: The use of the Centrix syringe improved the homogeneity of the cement layer, reducing the defects in the layer and increasing adhesive strength values to dentin, even after mechanical cycling.
Abstract: Univ Estadual Paulista, UNESP, Inst Sci &Technol, BR-12245000 Sao Jose Dos Campos, SP, Brazil
20 citations
TL;DR: The addition of 0.5 mol% DPIHFP improved the physical properties of dual‐polymerizing self‐adhesive resin cements and promoted less degradation after immersion in solvent.
Abstract: Statement of problem Dual-polymerizing self-adhesive resin cements present mechanical properties that may adversely affect the clinical performance of luted fiber-reinforced posts. Purpose The purpose of this in vitro study was to evaluate the properties of dual-polymerizing self-adhesive resin cements after the addition of an onium salt. Material and methods The experimental groups were set according to the molar concentration of diphenyliodonium hexafluorphosphate (DPIHFP) (0.5, 1, and 2 mol%). The resin cements were submitted to a push-out bond strength test and assessed for flexural strength (ISO 4049/2009), degree of conversion (Fourier-transformed infrared spectroscopy), depth of polymerization, swelling coefficient, and degradation in solvent. The data were statistically analyzed by ANOVA, Tukey test, Kruskal-Wallis test, Dunn multiple comparison, and paired Student t test (α=.05). Results All the RelyX U100 groups with onium salt showed the highest degree of conversion after 24 hours and 7 days ( P P =.054). The addition of 0.5 mol% DPIHFP increased the push-out bond strength and microhardness of RelyX U100 and promoted less degradation after immersion in solvent. The BisCem control group did not present a statistical difference from the experimental groups in terms of bond strength; the control group and the 0.5 mol% group showed no degradation in solvent. For swelling coefficient and flexural strength, no difference was found between the BisCem groups ( P =.067 and P =.173), and the RelyX U100 2 mol% group presented the lower value ( P P =.048). Depth of polymerization was not statistically different in the experimental groups for either resin cement ( P =.999). Conclusions The addition of 0.5 mol% DPIHFP improved the physical properties of dual-polymerizing self-adhesive resin cements.
9 citations
Cites background from "Polymerization kinetics of resin ce..."
...For intracanal post cementation, light penetration is insufficient for polymerizing the material along the root canal.(5,6) Therefore, the use of dual-polymerizing resin cements is necessary to achieve increased strength in the middle and apical thirds of the canal....
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TL;DR: Surface treatment of fiber post with TiF4 (4 wt/v%-4 min) solution exhibited higher bond strength to resin cement compared with other surface treatments, and flexural properties and microtensile bond strength were determined.
Abstract: This study evaluated the effect of titanium tetrafluoride (TiF4) solution on the bond strength of glass fiber post to resin cement. The specimens were divided into eight groups according to the method of surface treatment performed. Flexural properties and microtensile bond strength (µTBS) were determined. Data were analyzed using two-way ANOVA and Tukey's post hoc tests. The highest µTBS achieved with the TiF4 (4 wt/v%-4 min) group compared with the other groups (p 0.05). Surface treatment of fiber post with TiF4 (4 wt/v%-4 min) solution exhibited higher bond strength to resin cement compared with other surface treatments.
6 citations
TL;DR: A quantitative investigation of the radial transmission of light through different fiber posts and its influence on the Knoop hardness number (KHN) and bond strength (BS) of a dual-cure self-adhesive resin cement at 3 different depths found LT depended on the type of post and on depth.
Abstract: Context: Light transmission (LT) into deeper areas of the dentin root is limited. Aim: The aim of this study is to perform a quantitative investigation of the radial transmission of light (LT) through different fiber posts and its influence on the Knoop hardness number (KHN) and bond strength (BS) of a dual-cure self-adhesive resin cement at 3 different depths. Materials and Methods: Four types of fiber posts (2 translucent and 2 conventional) were used. LT and KHN analyses were performed in a specially designed matrix, which allowed measurements at 3 different depths. LT was measured using a volt-ampere meter while KHN tests were performed in a microhardness tester. For BS analysis, endodontically treated bovine roots were divided into 4 groups, each group receiving one type of post. After cementation, cross sections of the root were tested for resistance to displacement using a universal testing machine. Statistical Analysis Used: Statistical analysis was performed by using this ANOVA and Tukey's test. Results: For LT, translucent posts showed significantly higher values at all depths compared to the conventional ones. For all posts, LT decreased at the deeper depths. The KHN results showed no statistical differences among the different posts, regardless of depth. For BS, a translucent post showed the highest values, and comparative analyses between the different depths of posts also showed statistically significant differences while comparisons among the different depths of the same post showed no differences. Conclusions: LT depended on the type of post and on depth. The type of post did not significantly influence the cement KHN. A translucent post showed higher BS in pooled data.
3 citations
Cites background from "Polymerization kinetics of resin ce..."
...Although studies have revealed unfavorable results concerning the amount of luminous energy transmitted through translucent posts,[10,15,17,23,29,30] some of the manufacturers promise a sufficient transmission of light...
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TL;DR: In this paper, the degree of conversion (DoC) of self-adhesive resin luting cements when irradiated through different fiber post lengths was evaluated with a total reflectance Fourier transform infrared spectroscopy reading.
Abstract: Purpose To evaluate the degree of conversion (DoC) of self-adhesive resin luting cements when irradiated through different fiber post lengths. Methods A total of 60 teeth were sectioned to achieve lengths of 4 mm, 7 mm, and 10 mm, while 60 fiber posts were trimmed to give 3 mm, 6 mm, and 9 mm lengths. Post space was created to accommodate the fiber post and 1 mm of luting cement apically. Two self-adhesive resin luting cements (Multilink Speed and RelyX U200) were used. A total of four cycles of 20 s irradiation was done with an attenuated total reflectance Fourier transform infrared spectroscopy reading between each cycle. Results The mean ± standard deviation DoC achieved with a light-emitting diode and quartz tungsten halogen for Multilink Speed was 67.4 ± 2.7% and 72.4 ± 4.0%, respectively, while for RelyX U200, the corresponding values were 56.5 ± 2.7% and 62.0 ± 3.8%, respectively. For Multilink Speed, there was no significant difference between the control and the 3 mm group, while for RelyX U200, no significant difference was found between the 6 mm and 9 mm groups. All the other groups showed significant differences. Conclusion The DoC reduced as the post length increased.
2 citations
References
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TL;DR: A depth and irradiation time-dependent radical concentration model was developed and it is proposed that the measure of the degree of polymerization in composite materials should be the polymerization of the bottom layer of the sample which is modelled from the number of free radicals generated in the sample.
Abstract: The irradiation time of a visible-light-activated composite necessary to achieve full polymerization throughout the material was studied. Curing-time dependence on the thickness of the material was also investigated. To monitor the visible light-activation effect, the free radical concentration was measured as a function of irradiation time. If the composite sample is less than 0.5 mm thick and exposed to light for a time interval recommended by the manufacturer, full radical concentration is indeed created uniformly. This is not the case in thicker samples. Electron paramagnetic resonance (EPR) was used to monitor the concentration of free radicals in the samples. The number of radicals was monitored as a function of irradiation time during which the radicals were generated in samples 0.5, 0.8, 2.0, 3.0 and 5.0 mm thick. An EPR X-band spectro-meter was used to detect the free radical spectra. The number of free radicals per unit mass as a function of irradiation time shows that 60% of the maximum concentration of radicals in a 1 mm sample is reached in 24 s curing time, while in thicker samples it takes hundreds of seconds. On the basis of the experiments, a depth and irradiation time-dependent radical concentration model was developed. This model shows that a 2.0 mm thick sample is cured at the bottom side if irradiated for 60 s. It is proposed that the measure of the degree of polymerization in composite materials should be the polymerization of the bottom layer of the sample which is modelled from the number of free radicals generated in the sample.
23 citations
"Polymerization kinetics of resin ce..." refers methods in this paper
...1993), electron paramagnetic resonance (Sustercic et al. 1997) and nuclear magnetic resonance (Morgan et al....
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...…et al. 1995), differential scanning calorimetry (Antonucci & Toth 1983), Raman spectroscopy (Shin et al. 1993), electron paramagnetic resonance (Sustercic et al. 1997) and nuclear magnetic resonance (Morgan et al. 2000), have been deployed to determine the degree of conversion of resin…...
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Journal Article•
TL;DR: The translucent fibre posts allowed a significantly higher degree of conversion with dual-cure resin cements than the opaque fibre posts (D.T. White-Posts) because of the light-transmitting property of their optical fibres.
Abstract: OBJECTIVE To evaluate the degree of conversion of dual-cured resin cements applied for luting of translucent and opaque fibre posts. METHODS Two dual-cured resin cements, RelyX ARC and Nexus 2, were used to cement 2 types of tooth-coloured fibre posts, D.T. Light-Post (translucent) and D.T. White-Post (opaque). The degree of conversion for each resin cement was measured. Post-curing polymerization and chemical curing of the cements were also measured. The degree of conversion was measured at various distances (4, 6 and 8 mm) from the tip of the light-curing unit by Fourier transform infrared spectroscopy. The data were analyzed with analysis of variance and post hoc tests (α = 0.05). RESULTS The degree of conversion of the dual-cure cements was significantly higher with the D.T. Light-Posts than with the D.T. White-Posts (p 0.05). The overall degree of conversion decreased linearly with increasing distance from the light-curing tip. Monitoring of post-curing polymerization and chemical curing revealed no further increase in degree of conversion after 5 minutes (p > 0.05). CONCLUSION The translucent fibre posts (D.T. Light-Posts) allowed a significantly higher degree of conversion with dual-cure resin cements than the opaque fibre posts (D.T. White-Posts) because of the light-transmitting property of their optical fibres.
18 citations
"Polymerization kinetics of resin ce..." refers background in this paper
...expected to allow deeper penetration of light and improved conversion (Shadman et al. 2012), but inadequate conversion rates have been reported in middle and apical root thirds (Faria-e-Silva et al....
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...Published by John Wiley & Sons Ltd 261 expected to allow deeper penetration of light and improved conversion (Shadman et al. 2012), but inadequate conversion rates have been reported in middle and apical root thirds (Faria-e-Silva et al. 2008, Kim et al. 2009)....
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