Self-curing Mode Research Articles

The Effect of a Dual Cure Activator on Self-Adhesive Resin Cements and Zirconia Shear Bond Strength

This study examines the impact of a dual cure activator (DCA) when applied in combination with self-adhesive resin cements on the zirconia. Sixty zirconia were prepared in compliance with the manufacturer’s directions. The specimens were randomly assigned to each group under the dark condition, following DCA and self-adhesive resin cements [RelyX universal resin cement (RXS); Maxcem elite chroma (MAC); Panavia SA cement multi (PSM)]; group 1, RXS; group 2, MAC; group 3, PSM; group 4, DCA + RXS; group 5, DCA + MAC; and group 6, DCA + PSM. The resin composite was fixed to the zirconia, surface-treated, and maintained in a dark container for 30 min. The specimens were kept in an incubator at a temperature of 37 degrees Celsius for 24 h. The universal testing device was employed to compute the shear bond strength (SBS). A stereomicroscope was used to analyze the fractured types. The data were analyzed employing the one-way ANOVA and Tukey’s test. Group 2 had the lowest SBS (4.93 ± 0.53 MPa). Group 1 (11.17 ± 0.86 MPa) and group 3 (11.48 ± 1.17 MPa) were not significantly different in SBS. Group 6 (15.61 ± 0.68 MPa) had the highest SBS but was not significantly different from group 4 (15.45 ± 1.20 MPa). The findings show that treating the zirconia surface with DCA before using the self-curing mode of self-adhesive resin cements is the best way to improve the bond between the zirconia and resin cement.

Influence of luting strategies on dentin bond performance of self-adhesive resin luting cement in combination with a universal adhesive.

This study aimed to evaluate the dentin bond performance of various resin luting cement (RLC) systems combined with universal adhesives in different luting strategies. Three self-adhesive resin luting cements (SRLCs) were used with universal adhesives as primers. Twelve specimens per group were prepared to measure shear bond strength (SBS) under distinct luting strategies in etch-&-rinse and self-etch modes. Regarding luting strategies, the bonded specimens were categorized into four groups based on tooth primer application and the curing mode of the SRLC paste: (i) with light irradiation of the tooth primer (wL) + dual-cure mode (DC) of the SRLC paste, (ii) wL + self-cure mode (SC) of the SRLC paste, (iii) without light irradiation of the tooth primer (woL) + DC mode of the SRLC paste, and (iv) woL + SC mode of the SRLC paste. Specimens were also subjected to different storage conditions: 24h in water (baseline condition) and 10,000 cycles of thermal cycling. Luting strategy, storage condition, and SRLC system type significantly influenced dentin SBS values in both etching modes. Notably, certain SRLCs exhibited significantly higher dentin SBS when the primer was light-irradiated compared with no primer irradiation. Most SRLCs demonstrated higher dentin bond strength with light-irradiated primers, suggesting potential enhancement of dentin bond performance via primer light irradiation.

Degree of conversion of dual-cured composite luting agents: The effect of transition metal-based touch-cure activators

PurposeThe aim of the study was (a) to assess the effect of universal adhesives and tooth primers with novel touch-cure activators on the conversion of dual-cured resin composite luting agents (RLAs) polymerized under the self-curing mode, and (b) to investigate the source of the catalytic effect exerted by the activators. Materials and MethodsThe materials selected were the adhesive RLAs Panavia V5/Tooth Primer (PV5/TP5), Variolink Esthetic DC/Adhese Universal DC (VLE/ADC), and the self-adhesive RLAs GCem ONE/AE Primer (GCO/AEP), RelyX Universal/Scotchbond Universal Plus (RXU/SUP) and Panavia SA Universal/Clearfil Universal Bond Quick (PSU/CUQ), the later serving as a control with an aryl-sulfinate activator. Coronal dentin specimens were prepared (n = 5/material), treated with the corresponding primers/adhesives (non-irradiated) and covered with a 100 μm-thick RLA layer (SC+A group). Three specimen series were additionally prepared (n = 3 × 5/material): A self-cured without the primers/adhesives (SC group), a dual-cured (20 s irradiation) with the corresponding primers/adhesives (DC+A group) and a dual-cured without primers/adhesives (DC group). All specimens were stored for 15 min (37 °C/dark/60 %RH). After demolding the degree of C = C conversion (DC%, top RLA surfaces) was measured by ATR-FTIR spectroscopy. The primer/adhesive liquids were further analyzed by ICP-MS and the microbrush tips of ADC by SEM-EDS. ResultsThe touch-cure activators increased the DC% in all self-cured RLAs but failed to reach the values of the corresponding dual-cured RLAs. The effect of the activators in dual-cured specimens was negligible. The ICP-MS analysis showed the presence of V (AEP, TP5, ADC) and Cu (SUP) transitional metals in the activators, with V been located at the free ends of ADC tip bristles. The V activators demonstrated the highest DC% improvement in self-cured specimens. ConclusionThe new touch-cure activators significantly increased the conversion of the self-cured RLAs. Therefore, this step should be considered as universally applicable and not selective, as currently proposed for the self-adhesive luting agents by the manufacturers.

Influence of dual-cure resin-cement curing modes on gingival cytotoxicity and inflammatory responses

Background/purposeDual-cure resin-cements are used for various dental restorations. However, whether the curing modes of these resin-cements influence gingival inflammation remains unclear. Hence, herein, we evaluated the effects of dual-cure resin-cement curing modes on gingival cytotoxicity and inflammatory responses. Materials and methodsSpecimens were prepared using two dual-cure resin-cements—RelyX Unicem 2 (RU) and G-CEM ONE (GO)—by light-cure or self-cure modes. Degree of conversion (DC) and monomer elution of the resin-cements were measured using Fourier-transform infrared spectroscopy and high-performance liquid chromatography, respectively. Human gingival fibroblasts (GFs) and macrophages were cultured on resin-cements, and inflammatory cytokine levels, intracellular reactive oxygen species (ROS) generation, and mitogen-activated protein (MAP) kinase activation were evaluated. ResultsLight-cured (LC) resin-cements exhibited significantly higher DC and lower monomer elution than did self-cured (SC) resin-cements. Triethyleneglycol dimethacrylate (TEGDMA) and urethane dimethacrylate (UDMA) were substantially eluted from RU and GO, respectively. Neither LC resin-cement exhibited cytotoxicity and enhanced pro-inflammatory cytokine expression in GFs and macrophages. However, both SC resin-cements significantly decreased cell numbers and promoted cellular inflammatory responses. SC generated higher intracellular ROS levels compared to that seen with LC, and different patterns of MAP kinase activation were observed between SC–RU and SC–GO. ConclusionCompared with LC dual-cure resin-cements, SC dual-cure resin-cements show stronger cytotoxicity and elicit greater inflammatory responses in gingival cells owing to residual monomers (e.g., TEGDMA and UDMA) by activating MAP kinases in GFs and macrophages. Clinicians should ensure adequate light irradiation during prosthesis cementation and make efforts to remove the excess cement.

Elution from direct composites for provisional restorations.

Purpose To assess elution from direct composite materials for provisional restorations and compare them with elution from direct restorative composites for permanent restorations.Methods Two dual-cure (Integrity Multi-Cure and Tempsmart DC) and two self-curing composites (Protemp 4 and Structur 3) were used, with Essentia serving as a reference. Cylindrical specimens (n=20) were cured according to the manufacturer's instructions; the dual-cure materials were prepared in both self- and dual-curing modes. Elution experiments were performed using water and absolute ethanol. The samples were incubated at 37 °C for either 24 h or four weeks; the extraction solvents were refreshed weekly. The eluted BisEMA (-3 / -6 / -10), BisGMA, CQ, UDMA, and TEGDMA were quantified using UHPLC-MS/MS.Results Monomer elution was detected in all provisional composites at 24 h and four weeks, but the amounts released did not exceed those released by the reference composite. When prepared in self-curing mode, Integrity Multi-Cure exhibited significantly higher elution of BisEMA-3, -6, and -10 in ethanol both after 24 h and cumulatively after four weeks. Self-cured Tempsmart DC released significantly more CQ, TEGDMA, and UDMA in both water and ethanol after immersion for 24 h and four weeks, along with significantly more BisGMA in ethanol both after 24 h and four weeks comparison to dual-cured Tempsmart DC (two-way ANOVA, post-hoc Tukey, P < 0.05).Conclusions Provisional composite materials did not elute higher amounts of monomers than a restorative composite. Dual-cured materials, prepared in the self-curing mode, show a trend towards higher monomer elution.

Residual stresses in glass crowns generated by polymerization and water sorption of resin cements.

This study investigated residual stresses in glass crowns cemented with resin cements. Glass caps were cemented to cylindrical cores using a conventional resin composite cement, a self-adhesive resin cement, or a methyl methacrylate (MMA)-based cement in dual-cure or self-cure mode. The cemented caps were stored in 37°C water for 28 days, and stresses on the cap surface were repeatedly measured. The water sorption, water solubility, and elastic modulus of the cements were also measured. Polymerization of the cements initially generated compressive stresses on the surfaces. Dual-curing or a greater modulus yielded greater initial stress. The stresses gradually decreased over time and lingered on the surfaces at 28 days with all the cements. Greater sorption tended to lead to greater stress reduction; however, the MMA-based cement exhibited less stress reduction despite exhibiting the greatest sorption. The use of a resin composite cement or dual-curing is recommended to reinforce crown restorations.

Touch-cure activation by marketed universal resin luting cements of their associated primer to dentin.

The aim of this study was to investigate the dentin shear bond strength (SBS) and bonding interface of three recently developed "universal" resin luting cements based on different modalities. The dentin SBS and interfacial analysis of three recently launched "universal" resin luting cements, namely, G-Cem One, RelyX Universal and Panavia SA cement universal, were studied. All bonding protocols, including the previous use of their dedicated primer or universal adhesive in touch-cure mode or light-cure mode were performed. Variolink Esthetic LC used in conjunction with Scotchbond Universal Plus was used as a control group. For each group (n = 9), 10 specimens were tested for dentin SBS and two were examined by scanning electron microscopy. SBS were analyzed by two-way ANOVA followed by Dunnett's test. SBS values showed that the three "universal" resin luting cements tested exhibit different adhesive behaviors. G-Cem One with its touch-cure activated primer had a greater SBS to dentin (25.5 MPa) than that of the control group (22.1 MPa). "Universal" resin luting cements have variable efficacy when used in self-curing mode. The touch-curing mode is also of concern but may show high potential for some formulations.

In vitro shear bond strength over zirconia and titanium alloy and degree of conversion of extraoral compared to intraoral self-adhesive resin cements

ObjectiveEvaluation of the Shear bond strength over zirconia and titanium alloy and degree of conversion of extraoral compared to intraoral self-adhesive resin cements.Materials and methodsNine bonding protocols were carried out on zirconia 4Y-TZP and titanium alloy (Ti-6Al-4V). Seven resin cement (one extraoral and six intraoral) were tested in the shear bond strength test and the degree of conversion measurements.ResultsThe significantly highest value was obtained for Monobond Plus + Multilink Hybrid Abutment, the extraoral resin cement for both titanium alloy (35.1 MPa) and zirconia (32.9 MPa). For each resin, significantly higher DC values were obtained for the dual-cure mode compared with the self-cure mode. Regardless of the cure mode, Nexus Universal reached the highest DC (78.4%).Discussion/ConclusionsIn this study, the extraoral self-curing resin cement showed the higher bond strength values on zirconia and titanium alloy when associated with a universal primer. Some intraoral dual-cure resin cements showed closed performances when used with universal primers. There is no direct correlation between the degree of conversion of the resin cement and the shear bond strength obtained on the prosthetic materials tested.

A Comparative Study of the Repair Bond Strength of New Self-Adhesive Restorative Materials With a Resin Composite Material.

The aim of the present study is to compare the repair bond strengths (RBSs) of Cention-N (light-cure and self-cure modes), Equia Forte HT Filand a nanohybrid resin composite. Equia Forte HT Fil (GC, Tokyo, Japan), Cention-N (Ivoclar Vivadent, Schaan, Liechtenstein) and Filtek Z550 (3M ESPE, St Paul, MN, USA) were used in this study.EquiaForte HT Fil(EQF), Cention-N self-cure (CSC), Cention-N light-cure (CLC) and Filtek Z550 (Z550) groups were formed.A total of 40 samples were prepared; 10 samples in each group (n = 10).After the polymerization was completed according to the manufacturer's instructions, the samples were polished with OptiDisc (Kerr Corporation, Orange, USA) for 5 s each, from extra-course to extra-fine. After all samples were stored in 37°C water for 24 h, 10,000 cycles of brushing simulator and thermal cycles were applied to the samples.The samples were prepared in accordance with the selected repair protocol, and microshear bond strength (µSBS) test was performed. Fracture analysis on debonded surfaces was visualized by scanning electron microscopy. The conformity of the data to normal distribution was analyzed by the Shapiro-Wilk test. Multiple comparisons were performed using Dunn's test. Z550 showed significantly higher µSBS as compared to the other three groups. There is no differencebetween CSC, CLC and EQF. The use of Cention-N's self-cure or light-cure mode did not affect the RBSvalues. The RBS values of Cention-N and Equia Forte HT Fil materials are lower than those of the composite resin material.

Effect of polymerization mode on shrinkage kinetics and degree of conversion of dual-curing bulk-fill resin composites

ObjectivesTo assess the behavior of dual-cure and conventional bulk-fill composite materials on real-time linear shrinkage, shrinkage stress, and degree of conversion.Materials and methodsTwo dual-cure bulk-fill materials (Cention, Ivoclar Vivadent (with ion-releasing properties) and Fill-Up!, Coltene) and two conventional bulk-fill composites (Tetric PowerFill, Ivoclar Vivadent; SDR flow + , Dentsply Sirona) were compared to conventional reference materials (Ceram.x Spectra ST (HV), Dentsply Sirona; X-flow; Dentsply Sirona). Light curing was performed for 20 s, or specimens were left to self-cure only. Linear shrinkage, shrinkage stress, and degree of conversion were measured in real time for 4 h (n = 8 per group), and kinetic parameters were determined for shrinkage stress and degree of conversion. Data were statistically analyzed by ANOVA followed by post hoc tests (α = 0.05). Pearson’s analysis was used for correlating linear shrinkage and shrinkage force.ResultsSignificantly higher linear shrinkage and shrinkage stress were found for the low-viscosity materials compared to the high-viscosity materials. No significant difference in degree of conversion was revealed between the polymerization modes of the dual-cure bulk-fill composite Fill-Up!, but the time to achieve maximum polymerization rate was significantly longer for the self-cure mode. Significant differences in degree of conversion were however found between the polymerization modes of the ion-releasing bulk-fill material Cention, which also exhibited the significantly slowest polymerization rate of all materials when chemically cured.ConclusionsWhile some of the parameters tested were found to be consistent across all materials studied, heterogeneity increased for others.Clinical relevanceWith the introduction of new classes of composite materials, predicting the effects of individual parameters on final clinically relevant properties becomes more difficult.

Shear Bond Strength of Resin Luting Materials to Lithium Disilicate Ceramic: Correlation between Flexural Strength and Modulus of Elasticity.

This study investigates the effect of the curing mode (dual-cure vs. self-cure) of resin cements (four self-adhesive and seven conventional cements) on their flexural strength and flexural modulus of elasticity, alongside their shear bond strength to lithium disilicate ceramics (LDS). The study aims to determine the relationship between the bond strength and LDS, and the flexural strength and flexural modulus of elasticity of resin cements. Twelve conventional or adhesive and self-adhesive resin cements were tested. The manufacturer's recommended pretreating agents were used where indicated. The shear bond strengths to LDS and the flexural strength and flexural modulus of elasticity of the cement were measured immediately after setting, after one day of storage in distilled water at 37 °C, and after 20,000 thermocycles (TC 20k). The relationship between the bond strength to LDS, flexural strength, and flexural modulus of elasticity of resin cements was investigated using a multiple linear regression analysis. For all resin cements, the shear bond strength, flexural strength, and flexural modulus of elasticity were lowest immediately after setting. A clear and significant difference between dual-curing and self-curing modes was observed in all resin cements immediately after setting, except for ResiCem EX. Regardless of the difference of the core-mode condition of all resin cements, flexural strengths were correlated with the LDS surface upon shear bond strengths (R2 = 0.24, n = 69, p < 0.001) and the flexural modulus of elasticity was correlated with them (R2 = 0.14, n = 69, p < 0.001). Multiple linear regression analyses revealed that the shear bond strength was 17.877 + 0.166, the flexural strength was 0.643, and the flexural modulus was (R2 = 0.51, n = 69, p < 0.001). The flexural strength or flexural modulus of elasticity may be used to predict the bond strength of resin cements to LDS.

In vitro evaluation of a silane containing self-adhesive resin luting agent.

To investigate the setting characteristics, wettability and bonding capacity with a lithium disilicate ceramic of a silane containing self-adhesive resin luting agent (Panavia SA Universal-PU). The degree of conversion (DC %) and extent of acid neutralization (SY %) of PU were measured on dual- (DC) and self-cured (SC) specimens after 10, 30 and 60 min storage by ATR-FTIR spectroscopy, whereas the presence of silanols was traced by curve-fitting the 60 min spectra, using the silane-free analog (Panavia SA Plus-PS) as a control. The role of a dedicated adhesive (Clearfil Universal Bond Quick-CU) in assisting the early DC % in PU-SC was investigated on 10 min-stored specimens. The water contact angles on polished and HF acid-etched lithium disilicate surfaces (IPS e.max Press), were assessed before and after silanization by unset PU or a silane primer (Ultradent Silane-SL). Finally, the shear strength of PU-DC specimens bonded to the acid-etched ceramic surfaces was determined before and after SL treatment. The DC % was higher in DC than SC (PU, PS; all time intervals), in PU-SC than PS-SC (30, 60 min) and in the CU assisted PU-SC group. The SY % was lower in DC than SC (PU, PS) and higher in PS-SC than PU-SC groups. Silanols were found only in unset PU and PU-DC groups. SL treatment provided higher water contact angles on polished and acid-etched ceramic surfaces and higher shear bond strength on acid-etched ceramic surfaces than PU (p < 0.05 for all comparisons). Although the degree of conversion of the silane containing luting agent was improved in the self-curing mode, especially in the adhesive assisted group, it was still inferior to light-curing. Acid-neutralization and presence of silanols were affected by the setting modes. The use of a silane primer enhanced the hydrophobicity and bond strength of the silane containing luting agent with the etched ceramic substrate.

Effect of curing mode on polymerization kinetics, mechanical properties, and dentin adhesion of self-adhesive and conventional resin cements

Objectives The objective was to evaluate the effect of curing mode on polymerization kinetics, biaxial flexural strength (FS) and modulus (MO), and dentin bond strength (BS) of self-adhesive and conventional resin-based cements. Materials and methods Two materials were evaluated: one self-adhesive G-Cem LinkAce (GC) and one conventional resin cement RelyX Ultimate (RU). Polymerization kinetics was followed by infrared spectroscopy (n = 5). Disc specimens of light-activated or self-cured materials were tested for FS and MO (n = 10). Extracted human molars were divided into 4 groups (n = 10) according to resin cement, curing mode, and evaluation time (24 hs and 1 year). Composite discs were used to simulate indirect restoration which bonded to occlusal dentin with the resin cements, and light-activated or allowed to self-cure, and restored teeth were tested for microtensile BS. Data were submitted to statistical analysis at 5% significance level. Results A rapid rise in conversion was observed when materials were light-activated. When self-cured, RU demonstrated a slower polymerization rate and lower conversion than GC. Dual curing yielded higher FS, MO, and BS than self-curing mode to RU cement, while no significant differences were observed for GC. Conclusions Light-activation influences polymerization kinetics of resin-based cement, but it did not influence the mechanical properties and adhesion of the self-adhesive cement tested (GC).

Effect of Translucency and Curing Mode of Four CAD/CAM Materials on Polymerization Efficiency of Light and Dual Cure Resin Cements.

To determine the effect of translucency of four CAD/CAM materials and different curing modes on the degree of conversion of resin cements. Disks were fabricated from IPS e.max CAD, Vita Suprinity, Vita Enamic, and DD Cube X². Translucency was measured using a spectrophotometer. The degree of conversion of two resin cements Variolink Esthetic DC and LC were measured using a Fourier transform infrared spectrometer. For Esthetic DC, the degree of conversion was determined in self-cure and dual cure modes. ANOVA, Tukey HSD test, and /Linear Regression R2 were used to statistically analyze the data. There was a significant difference in the translucency of the four materials (P ⟨ 0.0001). The mean translucency of Vita Suprinity was significantly higher, followed by Vita Enamic, DD Cube X², and IPS E.max CAD. Degree of conversion of resin cements cured under DD Cube X² had the highest values (25.22%), whereas those cured under Vita Suprinity showed the lowest values (17.86%). The self-cure mode had the lowest degree of conversion values (16.22%) and dual cure mode showed the highest values (26.12%). A negative linear relationship was found between degree of conversion and translucency of the CAD/CAM materials.

Comparison of physical and mechanical properties of three different restorative materials in primary teeth: an in vitro study

Physical and mechanical properties of three different (Ketac Molar Easymix, Dyract XP, Cention N (CN)) restoratives with different ingredients were evaluated. Four groups were obtained; Group 1: CN LightCure, Group 2: CN SelfCure, Group 3: Ketac Molar Easymix and Group 4: Dyract XP. Disk-shaped samples (n = 10) were prepared and evaluated for the surface roughness test using a profilometer. For the flexure strength test, 2 × 2 × 25mm bar-shaped samples (n = 10) were prepared, and a three-point bending test was applied to the samples. After preparing cavities for microleakage tests, teeth were restored with restoratives, immersed in dye, and microleakage was assessed. For the microtensile bond strength (µTBS) test, ten sticks were obtained for each group and were stressed under tension. According to surface roughness tests, CN SelfCure showed the lowest value (0.13μm), while Ketac Molar Easymix showed the highest value (0.28μm), and significant differences were found between the groups. In flexural strength tests, the highest values were seen in CN SelfCure (82.94MPa), with statistically significant differences between the groups. When CN SelfCure was applied with an adhesive, the teeth showed statistically decreased leakage than other groups on the gingival side. Higher leakage values were seen on the gingival side than the occlusal side in most groups, and the SelfCure groups showed decreased leakage than the LightCure groups. According to µTBS tests, the highest value was obtained in CN SelfCure-Adhesive group, while the lowest was in CN LightCure-Non-adhesive group. When µTBS was evaluated regardless of adhesive use, the SelfCure groups showed higher µTBS values than the LightCure groups. As a result of the µTBS and microleakage test, the difference between the use of CN with and without adhesive, regardless of the polymerization type, was found to be significant (p < 0.05). Cention N showed better properties in SelfCure mode, compared to the rest materials tested, but further in vitro and in vivo studies are needed to investigate the effect of different polymerization modes and the oral environmental conditions.

Long-Term Assessment of Contemporary Ion-Releasing Restorative Dental Materials.

The objective was to evaluate new commercially available ion-releasing restorative materials and compare them to established anti-cariogenic materials. Four materials were tested: alkasite Cention (Ivoclar Vivadent) in self-cure or light-cure mode, giomer Beautifil II (Shofu), conventional glass-ionomer Fuji IX (GC), and resin composite Tetric EvoCeram (Ivoclar Vivadent) as a control. Flexural strength, flexural modulus, and Weibull modulus were measured one day, three months, and after three months with accelerated aging in ethanol. Water sorption and solubility were evaluated for up to one year. Degree of conversion was measured during 120 min for self-cured and light-cured Cention. In this study, Beautifil II was the ion-releasing material with the highest flexural strength and modulus and with the best resistance to aging. Alkasite Cention showed superior mechanical properties to Fuji IX. Weibull analysis showed that the glass-ionomer had the least reliable distribution of mechanical properties with the highest water sorption. The solubility of self-cured alkasite exceeded the permissible values according to ISO 4049. Degree of conversion of light-cured Cention was higher than in self-cure mode. The use of alkasite Cention is recommended only in the light-cure mode.

O5 - Self-Adhesive Luting Composites: Effect of Curing-Mode and Storage on KIc

The aim of the present study was to investigate the influence of curing-mode (dual or self-curing) and storage time (24 h, 14 d, 60 d) on the fracture toughness (KIc) of self-adhesive luting composites (SALCs). The KIc of four different SALCs (RXU2, RelyX Unicem 2, 3 M ESPE; GCLA, G-Cem LinkAce; GC-Corporation; iCEM, iCem Self Adhesive, Kulzer; PAN, Panavia SA Universal Cement, Kuraray Noritake) was measured using the Chevron-Notched Beam method. From each material, 30 samples were prepared in dual-curing mode (20 s @ 1200 mW/cm2, 8 mm light-tip) and 30 samples in self-curing mode (curing-time according to manufacturer). All specimens were stored in artificial saliva in the dark at 37 C. KIc was measured after 24 h, 14 and 60 d (n=10 per material, curing-mode and storage time). Statistical analysis was performed with a t-test of independent samples and a single factor ANOVA (alpha=0.05). The curing mode had a significant influence on KIc, within the same material and storage time (p<.05), with exception of RXU2, GCLA and iCEM after 60 d. In general, the KIc of dual-cured specimens was significantly higher, except for RUX2 in self-cure mode after 24 h (p>.05). After 60 d of storage all materials, independently of the curing-mode, had a significant decrease in KIc (p<.05). Only PAN had any decrease in KIc. Under the same curing-mode and storage time, GCLA showed the significantly highest KIc (p<.05), whereas iCEM the lowest, with exception of the its 24 h dual-cure group. Within the limits of this study, it can be concluded that the mechanical stability of the SALCs under investigation, in terms of KIc, is influenced by curing-mode and storage time. The extent of mechanical deterioration is material dependent. The in-vitro measured decays in KIc could lead in-vivo to deterioration of the adhesive interface and in consequence to restoration loss or fracture. The long-term resilience to water degradation and chemical curing of SALCs show potential of improvement.

Degree of Conversion and Mechanical Properties of Modern Self-Adhesive Luting Agents

New self-adhesive resin composite luting agents have currently been developed, claiming improved properties. The study aimed to evaluate the composition, degree of conversion, and mechanical properties of Panavia SA Plus (PSP), Panavia SA Universal (PSU), SpeedCem Plus (SPC) and TheraCem Ca (THC), with the resin luting agent Panavia V5 (PV5) serving as a control. The structure of the materials was studied by FTIR spectroscopy and SEM/EDX spectrometry. Disk-shaped specimens were prepared from each material under dual- and self-curing modes (n = 5/mode and material). After a 3-week storage period (dark/37 °C/80%RH) the Martens hardness, indentation modulus, elastic index, and creep were determined by instrumented indentation testing (IIT), while the degree of conversion was assessed by FTIR spectroscopy. Statistical analysis was performed by 2-way ANOVA and post-hoc testing (α = 0.05). All materials were based on aromatic monomers, except for SPC. Fillers with potentially bioactive Ca-glasses were identified in SPC and THC, which showed the highest P/Si ratio. The dual-curing mode demonstrated superior performance in all properties. Differences between materials within each curing mode were limited to SPC, THC (highest conversion) and PSA, PSU, SPC (highest elastic index) for dual-curing, and THC (lowest hardness and elastic index). The results confirmed a lower self-curing conversion in these materials, which may affect some of the mechanical properties tested.

Evaluation of Cements Curing Modes Regarding Microleakage During Cementation of E-max Laminate Veneers

Purpose: The aim of this study is to investigate the effect of the curing modes of two adhesive resin cements (Light cure mode of the Variolink Veneer, the self-cure mode and dual cure mode of the Multilink Automix) on the marginal leakage of lithium disilicate ceramic laminate veneers. Methods: A total number of forty eight extracted natural central incisors were prepared to receive ceramic laminate veneers, constructed using E-max ceramic divided into three groups cemented using three curing modes of two adhesive resin cements {light-cure mode of Variolink Veneer, self-cure mode of Multilink Automix and dual-cure mode of Multilink Automix adhesive resin cements} . Die penetration test was done using the methylene blue stain {qualitative assessment} for testing the die penetration along the tooth/ceramic interface. Results: Descriptive statistical analysis revealed that the self-curing mode recorded the significantly least degree of leakage compared to the light and dual cure modes. The self-cure mode recorded (0.1±0.3) which was significantly lower than light cure (1.2 ±0.9) and dual cure mode (1.2 ±0.4), there was no statistical significant difference between the later two curing modes. The self-cure mode of the resin cement is considered a more effective method for having the least marginal leakage at the tooth/ceramic interface. There was no difference between the light cure mode and the dual cure mode.

Effect of curing mode on the conversion and IIT-derived mechanical properties of core build-up resin composites

The aim of the study was to evaluate the degree of conversion and the mechanical properties of five composite core build-up materials polymerized in dual-curing and self-curing modes. The materials tested were: Clearfil DC Core Plus (CF), Gradia Core (GC), Luxacore-Z Dual Smartmix (LX), Multicore Flow (MC) and Paracore (PC). Disk-shaped specimens were prepared from each material; half the specimens were light-cured, whereas the rest were only self-cured. After a 3-week storage period (dark/dry/37 °C) the Martens Hardness, Indentation Modulus, and Elastic Index were determined by instrumented indentation testing (IIT), while the degree of conversion was assessed by ATR-FTIR spectroscopy. Statistical analysis was performed by 2-way ANOVA and post-hoc testing (α = 0.05). The dual-curing mode resulted in statistically higher Martens Hardness and Elastic Index than the self-curing mode in most materials but showed insignificant differences in Indentation Modulus. MC and PC demonstrated significantly higher degree of conversion in both curing modes. Overall, the self-curing mode was inferior to the dual-curing in conversion and mechanical properties for most products, despite their differences in monomer composition and filler loading.