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Journal ArticleDOI

Polymerization kinetics of resin cements after light activation through fibre posts: an in vitro study.

01 Mar 2015-International Endodontic Journal (Newcastle University)-Vol. 48, Iss: 3, pp 261-267

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.

AbstractAim 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.

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Citations
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Journal ArticleDOI
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

19 citations


Journal ArticleDOI
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.

3 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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Journal ArticleDOI
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.

2 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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Journal ArticleDOI
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.

2 citations


Journal ArticleDOI
TL;DR: Light-cured ERCs containing DPI were efficient for GFP retention to radicular dentin, with similar behaviour to that of dual-curing commercial resin cement.
Abstract: The aim of this study was to analyze the efficiency of experimental light-curing resin cements (ERCs) with a ternary photo-initiator system containing diphenyliodonium hexafluorphosphate (DPI) and different amines on retention of glass-fiber posts to dentin (GFP). ERCs formulations: a 1:1 mass ratio of 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenylpropane and triethyleneglycol dimethacrylate. Camphorquinone was used as initiator. Six experimental groups were established according to the amine used: [ethyl-4-(dimethylamino)benzoate-EDMAB or 2-(dimethylamino)ethyl methacrylate-DMAEMA] and the concentration of DPI (0, 0.5 mol%, 1 mol%). The resin cements Variolink II (dual- and light-cured versions) were used as commercial reference. Eighty recently extracted bovine incisors (n = 10) were selected for this study. The roots were prepared and the fiber posts were cemented with the resin cement specified for each experimental group. Specimens from coronal, middle, and apical thirds of the root were subjected to push-out bond strength test 24 hours after bonding. Data were subjected to split-plot ANOVA and the Tukey test (p = 0.05). ERCs containing DPI showed statistically significant higher bond strengths compared with ERCs without DPI. ERCs containing DPI were statistically similar to VARIOLINK II – dual-cured and superior to VARIOLINK II – light-cured (except for EDMAB – 1DPI in the medium third and DMAEMA – 1DPI in the coronal third). Different amines did not influence post retention. The apical root region showed the lowest bond strength for the groups EDAB-0DPI, DMAEMA-0DPI and VARIOLINK II light-cured. Light-cured ERCs containing DPI were efficient for GFP retention to radicular dentin, with similar behaviour to that of dual-curing commercial resin cement.

1 citations


References
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Journal ArticleDOI
TL;DR: Long-term aging in water caused a reduction in the KIc, independent of composition, but had little effect on other properties, suggesting limited degradation of composites in water.
Abstract: The purpose of this study was to evaluate the long-term effect of aging in water on the physical properties of experimental composites having systematically controlled differences in degree of conversion (DC), filler volume fraction (Vf), and percentage of silane-treated fillers. Composites were made with a 50% Bis-GMA:50% TEGDMA light-cured resin and a 1-2 microm (average size) strontium glass filler (+ 5 wt% SiO2 microfiller). For composites A-E, the DC was varied from 56-66% by changing the curing time; for D and F-I, the Vf was varied from 28-62 vol%; and for D and J-M, the percent of fillers with a silane coupling agent (gamma-MPS) was varied from 20-100%. Fracture toughness (KIc), flexure strength (FS), elastic modulus (E), and hardness (KHN) were tested after soaking in water at 37 degrees C for 1 day, 6 months, 1 year, and 2 years. The KIc was reduced 20-30% for all composites after 6 months, with minimal changes thereafter. The FS was reduced for several composites at 6 months, but only those with poor cure (A and B) were lower at 2 years than they were initially. The E was not reduced for most composites. Hardness was reduced for most composites after 6 months, but many returned to their original levels at 2 years. Long-term aging in water caused a reduction in the KIc, independent of composition, but had little effect on other properties, suggesting limited degradation of composites in water.

559 citations


Additional excerpts

  • ...The base and catalyst of VLII were hand-mixed in a ratio of 1 : 1 as recommended by the manufacturer; however, due to manual dispensing of the materials, there might be variation in the mixing ratio which has been related to the degree of cure (Ferracane et al. 1998)....

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Journal Article
TL;DR: The results of this retrospective study indicated that the Composipost system was superior to the conventional cast post and core system after 4 yrs of clinical service.
Abstract: PURPOSE This retrospective study evaluated treatment outcome of cast post and core and Composipost systems after 4 yrs of clinical service. MATERIALS AND METHODS 200 patients were included in the study. They were divided in two groups of 100 endodontically treated teeth restored with a post. Group 1: Composipost systems were luted into root canal following the manufacturer's instructions. Group 2: Cast post and cores were cemented into root canal preparations with a traditional technique. The patients were recalled after 6 months, 1, 2 and 4 yrs and clinical and radiographic examinations were completed. Endodontic and prosthodontic results were recorded. RESULTS Group 1: 95% of the teeth restored with Composiposts showed clinical success; 3% of these samples were excluded for noncompliance and 2% showed endodontic failure. Group 2: Clinical success was found with 84% of teeth restored with cast post and core. 2% of these samples were excluded for noncompliance, 9% showed root fracture, 2% dislodgment of crown and 3% endodontic failure. Statistical evaluation showed significant differences between Groups 1 and 2 (P < 0.001). The results of this retrospective study indicated that the Composipost system was superior to the conventional cast post and core system after 4 yrs of clinical service.

337 citations


"Polymerization kinetics of resin ce..." refers background in this paper

  • ...Bonded fibre posts are increasingly employed in the restoration of root filled teeth as many laboratory investigations have suggested a modulus of elasticity similar to dentine (Ferrari et al. 2000) and improved bond strengths (Naumann et al....

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  • ...Bonded fibre posts are increasingly employed in the restoration of root filled teeth as many laboratory investigations have suggested a modulus of elasticity similar to dentine (Ferrari et al. 2000) and improved bond strengths (Naumann et al. 2008) compared with conventional posts and cements....

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Journal ArticleDOI
TL;DR: The dual-polymerization resin luting agents tested showed the best combination of mechanical and physical properties combined with the highest setting pH.
Abstract: Statement of problem. New luting agents, particularly with adhesive capability, are being introduced in an attempt to improve clinical success. Independent studies of basic comparative data are necessary to characterize these materials in relation to mechanical and physical properties. Purpose. The purpose of this study was to compare the flexural strength, modulus of elasticity, and radiopacity and pH of representatives of 5 types (categories) of luting agents. Material and methods. The luting agents included a zinc phosphate, a conventional and a resin-modified glass ionomer, 2 dual-polymerizing resins ("photopolymerized" after mixing and "unphotopolymerized" conditions), and an auto-polymerizing resin. The specimens were prepared and the testing was conducted by 1 person to maximize standardization. Flexural strength (MPa) and modulus of elasticity (GPa) were determined on bar-shaped specimens (2 × 2 × 20 mm) at 24 hours and 3 months (n = 8). Radiopacity (mm Al) was measured by exposing 1 mm thick specimens along with an aluminum step wedge (n = 4). pH was measured using a pH electrode immediately after mixing; at 1, 5, 15, 30 minutes; and at 1, 2, 4, 6, and 24 hours (n = 4). The data were subjected to statistical analyses with analysis of variance and Duncan's multiple range test ( P Results. The resin luting agents (64 to 97 MPa) showed higher flexural strength than all other materials tested (7 to 27 MPa), with the "photopolymerized" (83 to 97 MPa) conditions higher than "unphotopolymerized" (64 to 81 MPa) ( P P P P P Conclusion. Within the limitations of this study the data showed a wide variation of material properties. The dual-polymerization resin luting agents tested showed the best combination of mechanical and physical properties combined with the highest setting pH. Photopolymerization of these resin-based materials was necessary to maximize strength and rigidity. (J Prosthet Dent 2003;89:127-34.)

243 citations


"Polymerization kinetics of resin ce..." refers background in this paper

  • ...Dual-cured resin cements have been recommended, but light activation may still be needed and the details of curing behaviour are unclear (Attar et al. 2003)....

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Journal ArticleDOI
TL;DR: No correlation was found between flexural strength and hardness, indicating that other factors besides the degree of cure (e.g. filler content and monomer type) affect theflexural strength of composites.
Abstract: Dual-cured cements have been studied in terms of the hardness or degree of conversion achieved with different curing modes. However, little emphasis is given to the influence of the curing method on other mechanical properties. This study investigated the flexural strength, flexural modulus and hardness of four proprietary resin cements. Materials tested were: Enforce and Variolink II (light-, self- and dual-cured), RelyX ARC (self- and dual-cured) and C & B (self-cured). Specimens were fractured using a three-point bending test. Pre-failure loads corresponding to specific displacements of the cross-head were used for flexural modulus calculation. Knoop hardness (KHN) was measured on fragments obtained after the flexural test. Tests were performed after 24 h storage at 37 degrees C. RelyX ARC dual-cured showed higher flexural strength than the other groups. RelyX ARC and Variolink II depended upon photo-activation to achieve higher hardness values. Enforce showed similar hardness for dual- and self-curing modes. No correlation was found between flexural strength and hardness, indicating that other factors besides the degree of cure (e.g. filler content and monomer type) affect the flexural strength of composites. No statistical difference was detected in the flexural modulus among the different groups.

209 citations


"Polymerization kinetics of resin ce..." refers background in this paper

  • ...In this study, two scans of uncured samples were taken 20 s apart before light activation which showed no noticeable degree of conversion even though the chemical and light-activated elements of dual-curing cements work independently (Braga et al. 2002)....

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Journal ArticleDOI
TL;DR: The results from this study provide the first direct chemical evidence of phase separation in a dentin adhesive and its detrimental effect on the dentin/adhesive bond.
Abstract: To date, the dentin/adhesive (d/a) bond has primarily been studied by morphologic analysis in conjunction with bond strength measurement. Although these analyses have enhanced our understanding, numerous questions about the chemistry have not been answered. The purpose of this study was to determine, at the molecular level, quantitative differences in the composition of the d/a interface formed under "wet" bonding conditions. The occlusal one-third of the crown was removed from 10 extracted, unerupted human third molars. The prepared dentin surfaces were treated, per manufacturers' instructions, with either Single Bond (3M) or One-Step adhesive (Bisco). Three-micron-thick sections of the d/a interface were cut and stained with Goldner trichrome for light microscopy. Companion slabs were analyzed with micro-Raman spectroscopy; the sample was placed at the focus of a 100x microscope objective, and spectra were acquired at 1-microm intervals across the d/a interface. Reference spectra were collected on model compounds of type I collagen and adhesive; the relative ratios of the integrated intensities of spectral features from adhesive and collagen were determined and plotted as a function of wt% adhesive. The same ratios were determined for the interface samples; by comparing these ratios with the calibration curve generated from the model compounds, we determined the percent of adhesive as a function of spatial position across the d/a interface. The relative percent of Single Bond adhesive was or = 50% throughout most of the hybrid. The results from this study provide the first direct chemical evidence of phase separation in a dentin adhesive and its detrimental effect on the dentin/adhesive bond.

198 citations


"Polymerization kinetics of resin ce..." refers background in this paper

  • ...Previ- ous studies have used the aromatic C=C peak at around 1610 cm 1 (Spencer et al. 2000, Faria-e-Silva et al. 2008, Kim et al. 2009), but this peak was absent for VLV, which is likely to be due to the absence of Bis-GMA, therefore ruling out the use of this peak for investigation....

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