共查询到20条相似文献，搜索用时 46 毫秒
1.
Pong Pongprueksa Jan De Munck Masanao Inokoshi Bart Van Meerbeek 《Dental materials》2018,34(4):684-692
Objective
To evaluate the effect of the kind and concentration of photo-initiator on the degree of conversion (DC) of adhesives on dentin/glass substrates and their mini-interfacial fracture toughness (mini-iFT) to dentin.Methods
We tested the adhesive Clearfil S3 Bond Plus and 4 derived experimental ‘LUB’ (‘Leuven Univesity Bond’) adhesives (all from Kuraray Noritake), namely ‘LUB-CQ/amine_high’, ‘LUB-CQ/amine_low’, ‘LUB-TPO_high’, and ‘LUB-TPO_low’, respectively containing 2.0 wt% camphorquinone (CQ) and 2.0 wt% EDMAB (amine), 0.35 wt% CQ and 0.35 wt% amine, 2.0 wt% TPO, and 0.35 wt% TPO. For DC, each adhesive was applied onto glass or dentin prior to being cured (Bluephase 20i; Ivoclar Vivadent: “high mode”) for 10 s. DC was measured at 5 min, 10 min, 1 h, 24 h and 1 week using micro-Raman spectroscopy (SENTERRA; BrukerOptik). For mini-iFT, each adhesive was bonded to 320-grit SiC-paper ground dentin and covered with composite (Z100; 3 M ESPE). The restored teeth were cut in sticks (1.5 × 2.0 × 16 mm), after which a single-gradient notch was prepared at the adhesive-dentin interface using a 150-μm diamond blade. The micro-specimens were loaded until failure in a 4-point bending test and the mini-iFT in term of KQvM was calculated.Results
DC was higher on dentin than on glass. All adhesives were adequately polymerized at 1 week, except for LUB-TPO_low. DC at 5 min was significantly higher for LUB-TPO_high than for both CQ/amine-based adhesives. The highest and most reliable mini-iFT was measured for LUB-CQ/amine_high, despite its 5-min DC was relatively low. No correlation between DC and mini-iFT was found.Significance
Curing of TPO-based adhesives is faster, but the dark cure of the CQ/amine-containing adhesives is more efficient. The differences in curing profiles do affect the mechanical properties of the resultant interfaces at dentin. 相似文献2.
Pedro Paulo Albuquerque Cavalcanti de Albuquerque Ezequias Costa Rodrigues Luis Felipe Schneider Rafael Ratto Moraes Paulo Francisco Cesar Leonardo Eloy Rodrigues Filho 《Dental materials》2018,34(9):1359-1366
Objective
To determine the influence of benzenesulfinic acid sodium salt 98% (BAS) and the activation mode on the polymerization behavior of experimental self-adhesive resin cements (SARCs) formulated with distinct self-etch methacrylates.Materials and methods
Three catalyst-pastes using different self-etch methacrylates (2MP — bis 2-(methacryloyloxy) ethyl phosphate; 4META — 4-methacryloxyethyl trimellitic acid anhydride; and GDMAP — 1,3-glycerol dimethacrylate phosphate) and four base-pastes were formulated from the incorporation of different amounts of BAS associated to N-N-dihydroxyethyl-p-toluidine (DHPT). BAS/DHPT ratios were blended respectively based on the following final weight (wt%): control (0.0;2.0%), BP1 (0.5;1.5%), BP2 (0.8;1.2%) and BP3 (1.0;1.0%). Real-time polymerization kinetics (KP) was assessed for 10 min by FTIR spectroscopy. Maximum rate of polymerization (Rpmax) was obtained from the first derivative of the curve conversion versus time. Degree of conversion (DC) was determined over 10 min and after 24 h. SARCs were tested in self and dual activation modes. Data of Rpmax and DC 24 h were respectively analyzed by two-way ANOVA followed by Tukey’s method (α = 0.05).Results
All factors and their interactions were statistically significant (p < 0.01). BAS caused an increase in DC in the first minutes of the KP analysis, especially in self-activated groups. After 24 h, all groups showed higher DC than those observed in the first 10 min. In general, the addition of BAS increased the Rpmax. The GDMAP-based materials group showed the highest Rpmax values when exposed to light but self-activated formulations with GDMAP or 2MP showed the lowest Rpmax.Significance
The addition of BAS increased the degree of conversion of SARCs in the first minutes and 24 h after the polymerization reaction. This finding showed the importance of adding this type of salt during resin cement production to achieve better polymerization in the first minutes of the luting procedure specially when light exposure is not possible. 相似文献3.
Lena Rothmund Franz-Xaver Reichl Reinhard Hickel Panorea Styllou Marianthi Styllou Kai Kehe Yang Yang Christof Högg 《Dental materials》2017,33(1):54-62
Objective
An increment layering technique in a thickness of 2 mm or less has been the standard to sufficiently convert (co)monomers. Bulk fill resin composites were developed to accelerate the restoration process by enabling up to 4 mm thick increments to be cured in a single step. The aim of the present study is to investigate the effect of layer thickness on the elution of components from bulk fill composites.Methods
The composites ELS Bulk fill, SDR Bulk fill and Venus Bulkfill were polymerized according to the instruction of the manufacturers. For each composite three groups with four samples each (n = 4) were prepared: (1) samples with a layer thickness of 2 mm; (2) samples with a layer thickness of 4 mm and (3) samples with a layer thickness of 6 mm. The samples were eluted in methanol and water for 24 h and 7 d. The eluates were analyzed by gas chromatography/mass spectrometry (GC/MS).Results
A total of 11 different elutable substances have been identified from the investigated composites. Following methacrylates showed an increase of elution at a higher layer thickness: TEGDMA (SDR Bulk fill, Venus Bulk fill), EGDMA (Venus Bulk fill). There was no significant difference in the elution of HEMA regarding the layer thickness. The highest concentration of TEGDMA was 146 μg/mL for SDR Bulk fill at a layer thickness of 6 mm after 7 d in water. The highest HEMA concentration measured at 108 μg/mL was detected in the methanol eluate of Venus Bulk fill after 7 d with a layer thickness of 6 mm.Significance
A layer thickness of 4 mm or more can lead to an increased elution of some bulk fill components, compared to the elution at a layer thickness of 2 mm. 相似文献4.
Light irradiance through novel CAD–CAM block materials and degree of conversion of composite cements
Diogo Pedrollo Lise Annelies Van Ende Jan De Munck Kumiko Yoshihara Noriyuki Nagaoka Luiz Clovis Cardoso Vieira Bart Van Meerbeek 《Dental materials》2018,34(2):296-305
Objective
To assess light irradiance (LI) delivered by two light-curing units (LCU’s) and to measure the degree of conversion (DC) of three composite cements, when cured through different thicknesses of two novel CAD–CAM block materials.Methods
100-μm-thick films of a dual-curable composite cement (G-CEM LinkAce, GC), a light-curable flowable resin-based composite (RBC) (G-ænial Universal Flo, GC) and a micro-hybrid RBC (G-ænial Posterior, GC) were investigated as luting agents. Two ‘polymer–ceramic’ CAD–CAM blocks (Cerasmart, GC; Enamic, Vita Zahnfabrik) were sectioned in slabs with different thicknesses (1, 3 and 5 mm). LI at the bottom of the specimens was measured using a calibrated spectrometer, while being light-cured through the CAD–CAM block slabs for 40 s with a low- (±500 mW/cm2) or high- (±1,600 mW/cm2) irradiance LCU (n = 5). After light-curing, micro-Raman spectra of the composite films were acquired to determine DC at 5 min, 10 min, 1 h and 24 h. LI data were statistically analyzed by Kruskal–Wallis followed by post-hoc comparisons, while a linear mixed-effect model was applied for the DC analysis. In addition, the CAD–CAM blocks ultrastructure was characterized upon argon-ion slicing using scanning transmission electron microscopy (STEM). Finally, light transmission (LT) through each CAD–CAM block material was assessed using a spectrophotometer.Results
Curing-light attenuation and DC were significantly influenced by thickness and type of the overlying material. LCU only had a significant effect on DC of the micro-hybrid RBC. DC significantly increased over time for all composite cements. CAD–CAM block structural analysis revealed a relatively small and homogenous filler configuration (mean filler size of 0.2–0.5 μm) for Cerasmart, while Enamic contained ceramic grains varying in shape and size (1–10 μm), which were interconnected by the polymer-based network. LT was much higher at a wavelength range of 300–800 nm for Cerasmart than for Enamic.Significance
Light-curable composite cements can be cured through a restoration up to 2.7-mm thickness, depending on the kind of CAD–CAM material. A high-irradiance LCU only has a limited effect on the maximum thickness of the polymer–ceramic CAD–CAM material that can be cured through. 相似文献5.
André L. Faria-e-Silva Andressa dos Santos Angela Tang Emerson M. Girotto Carmem S. Pfeifer 《Dental materials》2018,34(9):1351-1358
Objectives
This study evaluated the efficacy of a thiourethane(TU)-modified silane agent in improving properties in filled composites.Methods
The TU-silane agent was synthesized by combining 1,3-bis(1-isocyanato-1-methylethyl)benzene and 3-(triethoxysilyl)propyl isocyanate with trimethylol-tris-3-mercaptopropionate (TMP), at 1:2 isocyanate:thiol, leaving pendant thiol and alkoxy silane groups. Barium glass fillers (1 μm average particle size) were functionalized with 5 wt% TU-silane in an acidic ethanol solution. Commercially available 3-(trimethoxysilyl)propyl methacrylate (MA-silane) and (3-mercaptopropyl)trimethoxysilane (SH-silane), as well as no silane treatment (NO-silane), were used as controls. Composites were made with BisGMA-UDMA-TEGDMA (5:3:2), camphorquinone/ethyl-4-dimethylaminobenzoate (0.2/0.8 wt%) and di-tert-butyl hydroxytoluene (0.3 wt%) and 70 wt% silanated inorganic fillers. Polymerization stress (PS) was measured using a cantilever beam apparatus (Bioman). Methacrylate conversion (DC) and rate of polymerization (RP) during photoactivation (800 mW/cm2) were followed in real-time with near-IR. Flexural strength/modulus (FS/FM) were evaluated in three-point bending with 2 × 2 × 25?mm. Statistical analysis: 2-way ANOVA/Tukey’s test (α = 5%).Results
DC, Rpmax and E were similar for all groups tested. FS was similar for the TU- and MA-silane, which were statistically higher than the untreated and SH-silane groups. Stress reductions in relation to the MA-silane were observed for all groups, but statistically more markedly for the TU-silane material. This is likely due to stress relaxation and/or toughening provided at the filler interface by the oligomeric TU structure.Significance
TU-silane oligomers favorably modified conventional dimethacrylate networks with minimal disruption to existing curing chemistry, in filled composites. For the same conversion values, stress reductions of up to 50% were observed, without compromise to mechanical properties or handling characteristics. 相似文献6.
William Germscheid Louis Gosse de Gorre Braden Sullivan Catherine O’Neill Richard B. Price Daniel Labrie 《Dental materials》2018,34(9):1367-1377
Objective
To determine the post-curing in six commercial contemporary resin-based composites (RBCs) using axial shrinkage, the degree of conversion, and Vickers hardness.Methods
Five Bulk Fill and one conventional RBCs from three companies were selected with a wide range of filler volume content. The axial shrinkage of samples that were 1.00 mm thick by 9–10 mm diameter was measured using a modified bonded disk method over a time between 15 h and 19 h at temperatures of 26 °C and 34 °C (mouth temperature). The degree of conversion (DC) was collected continuously for 10 min using mid-infrared spectroscopy in the attenuated total reflectance geometry. Vickers hardness was measured at 1 h post-irradiation using a load of 300 gf. For all three tests, the samples were irradiated at five exposure times, 20, 5, 3, 1.5 and 1 s with a light curing unit radiant exitance of 1.1 W/cm2. Three samples (n = 3) were used for each experimental condition.Results
After light exposure, the axial shrinkage and degree of conversion exhibited a functional time dependence that was proportional to the logarithm of time. This suggests an out-of-equilibrium polymer composite glass that is transitioning to thermal equilibrium. At a sufficiently long time and among the RBCs investigated, the shrinkage related physical aging rate was found to vary between 1.34 and 2.00 μm/log(t). The rate was a function of the filler content. Furthermore, 15 h after light exposure, the post-curing shrinkage was estimated to be an additional 22.5% relative to the shrinkage at 100 s for one RBC at T = 34 °C. The hardness in the photo-cured RBC was varied by using different light exposure times. The first two experimental techniques show that the higher the initial DC 10 min after light exposure, the smaller is the post-curing shrinkage related and DC related physical aging rates. A direct correlation was observed between the shrinkage related and the DC related physical aging rates.Significance
Post-curing shrinkage should be evaluated for longer than 1 h. The post-curing shrinkage 15 h after light exposure in dental RBCs can be appreciable. The long-term development of built-in stress within the tooth wall structure may shorten the restoration’s lifespan. 相似文献7.
Purpose
To compare the characteristics and load-deflection graphs of 0.012″ heat-activated NiTi, superelastic NiTi and bent (bends placed at 1, 2 and 3 mm) superelastic NiTi wires, focusing on force at 0.5 mm after deactivation after deflection by 1, 2, 3 and 4 mm.Materials and methods
Three-bracket bending tests using a 10 N load cell with 1 mm/min crosshead speed and 8 mm span were performed at 37 °C. Three groups of wires, 0.012″ heat-activated NiTi wires (HANT), superelastic NiTi wires (S), and superelastic NiTi wires with bends placed at 1, 2 and 3 mm (SB1, SB2 and SB3, respectively) were deflected by 1, 2, 3 and 4 mm. Deactivation forces (N) at 0.5 mm after deactivation were compared using ANOVA.Results
Bent NiTi wires produced lighter forces than superelastic and heat-activated NiTi wires (P < 0.05). Superelastic and heat-activated NiTi wires had linear load-deflection graphs at 1 mm deflection. No bent NiTi wires had linear load deflection graphs; hysteresis was observed after 2, 3 and 4 mm deflection in all NiTi groups. Increasing the number of bends and deflection appeared to inactivate NiTi wires.Conclusions
After any deflection, all bent NiTi wires produce lighter forces at 0.5 mm after deactivation than superelastic NiTi and heat-activated NiTi wires. This study indicates bending a NiTi wire close to a displaced tooth with up to 1 mm deflection can produce an active light deactivation force to level severely displaced teeth. 相似文献8.
Felipe Weidenbach Degrazia Vicente Castelo Branco Leitune Fernanda Visioli Susana Maria Werner Samuel Fabrício Mezzomo Collares 《Dental materials》2018,34(3):427-433
Objective
The aim of this study was to evaluate physicochemical properties, long-term microtensile bond strength and cytotoxicity of methacrylate-based adhesive containing boron nitride nanotubes (BNNTs) as fillers.Methods
A dental adhesive was formulated using BisGMA/HEMA, 66/33 wt% (control). Inorganic BNNT fillers were incorporated into the adhesive at different concentrations (0.05, 0.075, 0.1 and 0.15 wt%). Analyses of degree of conversion (DC), polymerization rate [Rp.(s?1)], contact angle (CA) on dentin, after 24 h and 6 months microtensile bond strength (μTBS-24 h and 6 months) were assessed. Cytotoxicity was performed through viability of fibroblast cells (%) by sulforhodamine B (SRB) colorimetry.Results
DC and max. polymerization rate increased (p < 0.05) after incorporating 0.075 and 0.1 wt% BNNT. The contact angle on dentin increased (p < 0.05) after incorporating 0.15 wt% BNNT. The μTBS-24 h showed no changes (p > 0.05) after incorporating up to 0.15 wt% BNNT comparing to control. After 6 months, μTBS decreased (p < 0.05) for control and 0.15 wt% BNNT and BNNT groups up to 0.15 wt% showed higher μTBS than control (p < 0.05). No difference of fibroblast growth was found among adhesives (p > 0.05) and up to 19% of cell viability was found comparing 0.05 wt% BNNT to positive control group (100%).Significance
Incorporating boron nitride nanotubes up to 0.1 wt% into dental adhesive increased the long-term stability to dentin without decreasing viability of fibroblast cell growth. Thus, the use of BNNTs as filler may decrease failure rate of current dentinal adhesives. 相似文献9.
Gianluca Turco Milena Cadenaro Tatjana Maravić Andrea Frassetto Eleonora Marsich Annalisa Mazzoni Roberto Di Lenarda Franklin R. Tay David H. Pashley Lorenzo Breschi 《Dental materials》2018,34(3):452-459
Objective
The present study evaluated the influence of time, mass and surface area of demineralized dentin collagen matrices on telopeptides release. The hypotheses tested were that the rates of ICTP and CTX release by matrix bound endogenous proteases are 1) not time-dependent, 2) unrelated to specimen mass, 3) unrelated to specimen surface area.Methods
Non-carious human molars (N = 24) were collected and randomly assigned to three groups. Dentin slabs with three different thicknesses: 0.37 mm, 0.75 mm, and 1.50 mm were completely demineralized and stored in artificial saliva for one week. Collagen degradation was evaluated by sampling storage media for ICTP and CTX telopeptidases. Activity of MMPs in the aging medium was evaluated using fluorometric activity assay kit.Results
A statistically significant (p < 0.05) decrease in the release of both ICTP and CTX fragments over time was observed irrespective of the specimen thickness. When data were normalized by the specimen mass, no significant differences were observed. Releases of ICTP and CTX were significantly related to the aging time as a function of surface area for the first 12 h. Total MMP activity, mainly related to MMP-2 and -9, decreased with time (p < 0.05).Significance
Because the release of collagen fragments was influenced by specimen storage time and surface area, it is likely that cleaved collagen fragments closer to the specimen surface diffuse into the incubation medium; those further away from the exposed surface are still entrapped within the demineralized dentin matrix. Bound MMPs can only degrade the substrate within the limited zone of their molecular mobility. 相似文献10.
Mario Alovisi Nicola Scotti Allegra Comba Elena Manzon Elena Farina Damiano Pasqualini Riccardo Michelotto Tempesta Lorenzo Breschi Milena Cadenaro 《Journal of prosthodontic research》2018,62(4):468-472
Purpose
The aim of this in vitro study was to assess conversion degree (DC), micro-hardness (MH) and bond strength of two dual-curing resin cements employed under translucent monolithic zirconia irradiated with different time protocols.Methods
84 square shaped samples of 1 mm thickness were prepared from high translucency zirconia blocks and divided into two groups (n = 24) according to the cement employed: (1) Rely-X Ultimate; (2) Panavia SA. Each group was further divided into 3 subgroups (n = 8) according to the irradiation time: (a) no light; (b) 20 s; (c) 120 s. Light curing was performed 60 s after the sample was placed on the diamond support of a FT-IR spectrophotometer with a high power multiLED lamp. Final DC% were calculated after 10 min. After 24 h, Vickers Test on the cement layer was performed. The same protocol was used to lute composite cylinders in order to evaluate microshear bond-strength test. ANOVA and Bonferroni tests were performed to find differences between MH and bond-strength to zirconia, while for DC% the Scheirer–Ray–Hare two-way test was used.Results
The two cements reached higher DC% in subgroup (b) and (c). As concern MH, statistics showed an increase in curing time was able to improve MH significantly. Bond-strength was not affected by irradiation time only for Panavia SA.Conclusions
The first null hypothesis has to be rejected since DC% and MH of the dual-cements tested were influenced by the curing time. The second null hypothesis is partially rejected since the bond strength was influenced by the curing time only for Rely-X Ultimate. 相似文献11.
Michael Wendler Renan Belli Anselm Petschelt Daniel Mevec Walter Harrer Tanja Lube Robert Danzer Ulrich Lohbauer 《Dental materials》2017,33(1):99-109
Objective
Strength is one of the preferred parameters used in dentistry for determining clinical indication of dental restoratives. However, small dimensions of CAD/CAM blocks limit reliable measurements with standardized uniaxial bending tests. The objective of this study was to introduce the ball-on-three-ball (B3B) biaxial strength test for dental for small CAD/CAM block in the context of the size effect on strength predicted by the Weibull theory.Methods
Eight representative chairside CAD/CAM materials ranging from polycrystalline zirconia (e.max ZirCAD, Ivoclar-Vivadent), reinforced glasses (Vitablocs Mark II, VITA; Empress CAD, Ivoclar-Vivadent) and glass-ceramics (e.max CAD, Ivoclar-Vivadent; Suprinity, VITA; Celtra Duo, Dentsply) to hybrid materials (Enamic, VITA; Lava Ultimate, 3M ESPE) have been selected. Specimens were prepared with highly polished surfaces in rectangular plate (12 × 12 × 1.2 mm3) or round disc (Ø = 12 mm, thickness = 1.2 mm) geometries. Specimens were tested using the B3B assembly and the biaxial strength was determined using calculations derived from finite element analyses of the respective stress fields. Size effects on strength were determined based on results from 4-point-bending specimens.Results
A good agreement was found between the biaxial strength results for the different geometries (plates vs. discs) using the B3B test. Strength values ranged from 110.9 MPa (Vitablocs Mark II) to 1303.21 MPa (e.max ZirCAD). The strength dependency on specimen size was demonstrated through the calculated effective volume/surface.Significance
The B3B test has shown to be a reliable and simple method for determining the biaxial strength restorative materials supplied as small CAD/CAM blocks. A flexible solution was made available for the B3B test in the rectangular plate geometry. 相似文献12.
Yuko Watarai Fumi Mizuhashi Toshihide Sato Kaoru Koide 《Journal of prosthodontic research》2018,62(4):485-489
Purpose
A new method inducing the physiologic rest position of the mandible using the lip contact position with the closed mouth have compared with those obtained using conventional methods of placing the mandible in the physiologic rest position.Methods
The lip contact position with the closed mouth as a method was investigated whether the technique was useful for determining the occlusal vertical dimension. The relationship between the space between the maxillary and mandibular front teeth in the lip contact position with the closed mouth and the areas of the prolabia was also investigated.Results
Median space between the maxillary and mandibular front teeth in the lip contact position with the closed mouth was 1.53 mm, a value intermediate between the value of 2.16 mm in the resting mandibular position obtained by the conventional technique and that of 1.33 mm in the swallowing position. The coefficient of variation of the space in the lip contact position with the closed mouth was significantly lower than those in the resting mandibular position and in the swallowing position. A significant positive correlation was recognized between the space in the lip contact position with the closed mouth and the area of the prolabium of the upper lip.Conclusions
These results clarified that the lip contact position with the closed mouth obtained the excellent reproducibility comparing to the conventional methods. These findings suggested that the area of the prolabium of the upper lip might offer an effective index for individual determination of the correct free-way space. 相似文献13.
Nancy J. Lin Courtney Keeler Alison M. Kraigsley Jing Ye Sheng Lin-Gibson 《Dental materials》2018,34(5):776-785
Objective
Resin-based composites are known to elute leachables that include unincorporated starting materials. The objective of this work was to determine the effect of common dental monomers and initiators on Streptococcus mutans biofilm metabolic activity and biomass.Methods
S. mutans biofilms were inoculated in the presence of bisphenol A glycerolate dimethacrylate (BisGMA), triethylene glycol dimethacrylate (TEGDMA), camphorquinone (CQ), and ethyl 4-(dimethylamino)benzoate (4E) at 0.01 μg/mL up to 500 μg/mL, depending on the aqueous solubility of each chemical. Biofilms were evaluated at 4 h and 24 h for pH (n = 3–8), biomass via crystal violet (n = 12), metabolic activity via tetrazolium salt (n = 12), and membrane permeability for selected concentrations via confocal microscopy (n = 6). Parametric and non-parametric statistics were applied.Results
500 μg/mL TEGDMA reduced 24 h metabolic activity but not biomass, similar to prior results with leachables from undercured BisGMA-TEGDMA polymers. 50 μg/mL BisGMA reduced biofilm biomass and activity, slightly delayed the pH drop, and decreased the number of cells with intact membranes. 100 μg/mL CQ delayed the pH drop and metabolic activity at 4 h but then significantly increased the 24 h metabolic activity. 4E had no effect up to 10 μg/mL.Significance
Monomers and initiators that leach from resin composites affect oral bacterial biofilm growth in opposite ways. Leachables, which can be released for extended periods of time, have the potential to alter oral biofilm biomass and activity and should be considered in developing and evaluating new dental materials. 相似文献14.
Mareike Warkentin Cora Freyse Olaf Specht Detlef Behrend Reinhard Maletz Ralf Janda Peter Ottl 《Dental materials》2018,34(7):1036-1040
Objective
To investigate if Vickers microhardness of dentin and enamel correlated with acoustic velocity c(l) or acoustic reflection from the sample’s top (amplitude).Methods
Eight transversal sections of a sound human tooth were investigated with scanning acoustic microscopy (SAM) and Vickers microhardness measurements. Longitudinal acoustic velocity c(l), amplitude and microhardness MHV were evaluated and for each c(l) test point corresponding amplitude and MHV were linearly interpolated and graphically analyzed. Spearman rank order correlation (rS) was calculated (p < 0.05).Results
c(l) was predominantly 6100–7000 ms?1 in enamel and 3800–4600 ms?1 in dentin and correlated significantly with MHV with 27–420 in enamel and 20–90 in dentin (rs = 0,57). Amplitudes significantly correlated with MHV, too, but even better (rs = 0,77).Significance
Acoustic velocity and amplitudes were appropriate to detect microhardness differences of dentin and enamel and certain value ranges of both could be assigned to certain MHV ranges. Further research is needed to differentiate more precisely between the different hard tooth tissues. 相似文献15.
Stéfani Becker Rodrigues Cesar Liberato Petzhold Douglas Gamba Vicente Castelo Branco Leitune Fabrício Mezzomo Collares 《Dental materials》2018,34(11):1634-1644
Objective
Synthesize and characterize a methacrylamide monomer for adhesive system and evaluate the physicochemical properties of the adhesive resin.Methods
The liquid methacrylamide monomer N,N′,N″-(nitrilotris(ethane-2,1-dyil)tris(2-methylacrylamide) (TMA) was prepared by reaction of methacrylic anhydride and tris(2-aminoethyl)amine with 60% yields. The TMA structure was analyzed by 1H NMR, 13C NMR, ATR-FTIR and UHPLC-QTOF-MS. Experimental adhesive resin containing bisphenol-A glycidyl methacrylate (BISGMA), 2-hydroxyethylacrylamide (HEAA), 2-hydroxyethylmethacrylate (HEMA) and TMA were formulated. Polymerization kinetics of neat TMA and experimental adhesive resin (TMA33%/HEAA66%, TMA50%/HEAA50%, TMA66%/HEAA33%, TMA50%/HEMA50%, BisGMA/HEAA/TMA and BisGMA/HEMA) were evaluated using Differential Scanning Calorimetry. Physiochemical properties for BisGMA/HEAA/TMA and BisGMA/HEMA adhesives were evaluated by cytotoxicity, ultimate tensile strength (UTS), softening in solvent (ΔKHN), contact angle (θ), microtensile bond strength (μTBS) and failure analysis. A primer was also formulated with H2O/HEAA/AMPS (2-acrylamido-2-methylpropane sulfonic acid) and the pH value was verified and compared to commercial primer.Results
Adhesive resin with only HEAA and TMA (TMA33%/HEAA66%, TMA50%/HEAA50%, TMA66%/HEAA33%) showed lower conversion and polymerization rate after 40 s of light activation. Conversion up to 60% was found for BisGMA/HEAA/TMA and BisGMA/HEMA adhesive resin without significant difference between groups, p > 0.05. Cytotoxicity, UTS, μTBS, ΔKHN and θ showed no statistical difference, p > 0.05, between BisGMA/HEAA/TMA and BisGMA/HEMA adhesive resin.Significance
In this study, the proposed synthetic route resulted in a tris(methacrylamide). A new primer composed without acrylates or methacrylates was formulated for 3-step etch-and-rinse adhesive system without the presence of HEMA monomer. Physicochemical properties and cell viability of BisGMA/HEAA/TMA adhesive resin represents an alternative adhesive resin without HEMA monomer. 相似文献16.
Maitê Munhoz Scherer Catina Prochnow Andressa Borin Venturini Gabriel Kalil Rocha Pereira Thiago Augusto de Lima Burgo Marília Pivetta Rippe Luiz Felipe Valandro 《Dental materials》2018,34(8):1134-1143
Objectives
To evaluate the effect of different glass-ceramic surface treatments and aging on the fatigue failure load of a lithium disilicate glass-ceramic adhesively cemented to a dentin analogue material.Methods
One hundred and twenty (120) disc-shaped lithium disilicate specimens (Ø = 10 mm, thickness = 1.5 mm) were produced and randomly allocated (n = 20) into 6 groups, considering 2 study factors: “surface treatment” in 3 levels (SIL—silane application only; HF5+SIL—5% hydrofluoric acid etching and silane application; ME&P—etching with an one-step ceramic primer), and “storage” in 2 levels (baseline—storage for 7 days; aging—storage for 90 days + 12,000 thermal cycles). Ceramic discs were adhesively cemented to discs of a dentin analogue material (Ø = 10 mm, thickness = 2.0 mm) following the manufacturers’ instructions. The fatigue failure load was determined by the staircase approach (250,000 cycles; 20 Hz; initial load = 1050 N [～70% of mean load-to-failure]; step size = 52.5 N [5% of initial load]). Micro-morphologic, fractographic, and atomic force microscope analysis were also performed. Fatigue failure load data were evaluated by one-way ANOVA, Bonferroni and t-tests for independent samples.Results
HF5+SIL presented higher fatigue failure load in both conditions (baseline and aging); ME&P presented intermediary mean values, while the SIL group presented the worst performance. All groups had a statistically significant decrease in the fatigue performance after aging.Significance
Hydrofluoric acid followed by silane application showed the best fatigue performance for an adhesively-cemented lithium disilicate ceramic. Aging negatively influenced the fatigue performance for all tested groups. 相似文献17.
Mireia Haro Adánez Hironobu Nishihara Wael Att 《Journal of prosthodontic research》2018,62(4):397-406
Purpose
This systematic review evaluates the clinical outcome of zirconia implant-associated survival and success rates, marginal bone loss, and implant–restoration complex integrity.Study selection
Using the preferred reporting items for systematic reviews and meta-analysis (PRISMA) guidelines, studies including ≥ 10 patients restored with zirconia implants supporting single crowns (SCs) or fixed dental prostheses (FDPs) prior to January 2017 were identified. Primary outcomes were survival rates and marginal bone loss around one and two-piece zirconia implants and the associated implant–restoration complex integrity.Results
1349 studies were selected; after duplicate removal and title screening, 36 remained for full-text screening. 17 studies met the inclusion criteria: 2 randomized controlled clinical studies, 11 prospective clinical studies and 4 retrospective studies. In total, 1704 implants from 1002 patients were evaluated, including 1521 one-piece and 183 two-piece zirconia implants with follow-up between 1 and 7 years.The mean survival rate was 95 % (95 % CI 91–97 %). The overall mean marginal bone loss was 0.98 mm (95 % CI 0.79–1.18); the mean marginal bone loss after 1 year was 0.89 mm (95 % CI 0.60–1.18). No meta-analysis regarding prosthetic outcomes was possible.Conclusions
Survival and marginal bone loss values after one year for one-piece zirconia implants are acceptable, but long-term studies are required to support their clinical use. No particular restoration material can be recommended; this decision is apparently based on clinicians’ preferences.Results from two-piece implants do not provide sufficient data to support their clinical use and no abutment or cementing materials for two-piece zirconia implants can be recommended. 相似文献18.
Objective
To assess the change in surface roughness of nanohybrid resin composite (Tetric EvoCeram) after antagonist wear against monolithic zirconia and lithium disilicate ceramics through a simulated chewing test using a three-dimensional (3D) profilometer.Methods
A total of 40 Tetric EvoCeram? resin composite specimens against either a Lava? Plus zirconia antagonist (n = 20) or IPS e.max Press lithium disilicate antagonist (n = 20) were prepared for the study. The surface roughness profiles of each resin composite before and after an in-vitro simulated chewing test were analysed using a 3D profilometer and Talymap software. After the simulated chewing, the surface profiles of representative Tetric EvoCeram specimens from each group were analysed using scanning electron microscopy. Independent t-test and paired t-test were used for statistical analysis.Results
For both lithium disilicate and zirconia groups, all surface roughness parameters (Ra, Rt, Sa, Sq,) of Tetric EvoCeram were significantly higher post-chewing compared to pre-chewing (p < 0.05); the post-chewing surface roughness parameters of Tetric EvoCeram for the lithium disilicate group were significantly higher (p < 0.05) than in the zirconia group.Significance
This chewing simulation test showed that Tetric EvoCeram composites exhibited a rougher surface when opposing lithium disilicate ceramic compared to opposing zirconia ceramic. 相似文献19.
C. Parise Gré D. Pedrollo Lise A.P. Ayres J. De Munck A. Tezvergil-Mutluay R. Seseogullari-Dirihan G.C. Lopes K. Van Landuyt Bart Van Meerbeek 《Dental materials》2018,34(11):1679-1689
Objectives
Dentin biomodification using collagen cross-linkers has been proposed as one of the strategies to improve bond durability of adhesives to dentin. However, literature is not very consistent regarding their benefit, in particular when cross-linkers are applied in clinically realistic application times. This study investigated the effect of three cross-linkers on the mini-interfacial fracture toughness (mini-iFT) of four adhesives bonded to dentin following either etch&rinse (E&R) or self-etch (SE) modes.Methods
60 molars were randomly divided in accordance with the three variables: cross-linker, adhesive and bonding mode (n = 5). The cross-linkers glutaraldehyde (5 wt%; GA), proanthocyanidin (6.5 wt%; PA), or UVA-activated riboflavin (0.5 wt%; RB), and distilled water (control) were applied on dentin for 60 s after acid-etching (E&R) or before self-etching (SE). The 3-step E&R adhesive (3E&Ra) OptiBond FL (Kerr), the 2-step SE adhesive (2SEa) Clearfil SE Bond 2 (Kuraray Noritake) and the universal adhesives G-Premio Bond (GC) and Prime&Bond Active (Dentsply), the latter two employed in both E&R and SE modes, were applied following the respective manufacturer’s instructions. Composite buildups (8 × 8 × 8 mm) were made using Filtek Supreme XTE (3M) prior to 1-week storage in artificial saliva. After the teeth were sectioned into mini-specimens (1.5 × 2.0 × 18 mm), a single notch was prepared at the adhesive–dentin interface. Half of the specimens were immediately loaded until failure by 4-point bending to determine the mini-iFT, while the remaining specimen set was tested upon 6-month aging. Data were statistically analyzed with a linear model (p < 0.05).Results
No significant decrease in mini-iFT was noted only for PA (p < 0.05), while the mini-iFT decreased for both other cross-linkers and in quite a similar way as when solely water (Wa) was applied.Significance
The cross-linker proanthocyanidin (PA) applied in clinically relevant conditions was able to maintain a stable mini-iFT after 6-month aging. The incorporation of UVA-activated riboflavin (RB) and glutaraldehyde (GA) in the dentin-bonding protocol appeared not effective to improve the stability of adhesive–dentin interfaces. 相似文献20.
Chinwe O. Uwalaka Natalia Karpukhina Xu Cao Sami Bissasu Rory M. Wilson Michael J. Cattell 《Dental materials》2018,34(10):1566-1577