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1.
Linyong Song Xueping Ge Qiang Ye Kyle Boone Sheng-Xue Xie Anil Misra Candan Tamerler Paulette Spencer 《Dental materials》2018,34(11):1652-1660
Objectives
The objective of this study was to explore the effect of lysine integration to dental adhesives with respect to the polymerization kinetics, neutralization capacities in the acidic microenvironment, dynamic mechanical properties, and thermal properties.Materials and method
Lysine was incorporated into liquid resin formulations at 2.5 and 5.0 wt % with additional water/ethanol co-solvents. The co-monomer system contained 2-hydroxyethyl-methacrylate (HEMA) and Bisphenol A glycerolate dimethacrylate (BisGMA) with a mass ratio of 45/55. The kinetics of photopolymerization, neutralization capacities, lysine-leaching, dynamic mechanical properties and thermal properties of the control and experimental adhesives were analyzed.Results
The degree of conversion of the experimental adhesive was increased substantially at 2.5 wt% lysine as compared to the control. The experimental polymers provided acute neutralization of the acidic microenvironment. Approximately half of the lysine was released from the polymer network within one month. Under dry conditions and physiologic temperatures, the incorporation of lysine did not compromise the storage modulus. Comparison of the thermal properties suggests that the more compact structure of the control adhesive inhibits movement of the polymer chains resulting in increased Tg.Significance
Incorporating lysine in the adhesive formulations led to promising results regarding modulating pH, which may serve as one aspect of a multi-spectrum approach for enhancing the durability of composite restorations. The results provide insight and lay a foundation for incorporating amino acids or peptides into adhesive formulations for pH modulation or desired bioactivity at the interfacial margin between the composite and tooth. 相似文献2.
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3.
Yuncong Li Xiaoyi Hu Yang Xia Yadong Ji Jianping Ruan Michael D. Weir Xiaoying Lin Zhihong Nie Ning Gu Radi Masri Xiaofeng Chang Hockin H.K. Xu 《Dental materials》2018,34(9):1310-1322
Objectives
A nanoparticle-doped adhesive that can be controlled with magnetic forces was recently developed to deliver drugs to the pulp and improve adhesive penetration into dentin. However, it did not have bactericidal and remineralization abilities. The objectives of this study were to: (1) develop a magnetic nanoparticle-containing adhesive with dimethylaminohexadecyl methacrylate (DMAHDM), amorphous calcium phosphate nanoparticles (NACP) and magnetic nanoparticles (MNP); and (2) investigate the effects on dentin bond strength, calcium (Ca) and phosphate (P) ion release and anti-biofilm properties.Methods
MNP, DMAHDM and NACP were mixed into Scotchbond SBMP at 2%, 5% and 20% by mass, respectively. Two types of magnetic nanoparticles were used: acrylate-functionalized iron nanoparticles (AINPs); and iron oxide nanoparticles (IONPs). Each type was added into the resin at 1% by mass. Dentin bonding was performed with a magnetic force application for 3 min, provided by a commercial cube-shaped magnet. Dentin shear bond strengths were measured. Streptococcus mutans biofilms were grown on resins, and metabolic activity, lactic acid and colony-forming units (CFU) were determined. Ca and P ion concentrations in, and pH of biofilm culture medium were measured.Results
Magnetic nanoparticle-containing adhesive using magnetic force increased the dentin shear bond strength by 59% over SBMP Control (p < 0.05). Adding DMAHDM and NACP did not adversely affect the dentin bond strength (p > 0.05). The adhesive with MNP + DMAHDM + NACP reduced the S. mutans biofilm CFU by 4 logs. For the adhesive with NACP, the biofilm medium became a Ca and P ion reservoir. The biofilm culture medium of the magnetic nanoparticle-containing adhesive with NACP had a safe pH of 6.9, while the biofilm medium of commercial adhesive had a cariogenic pH of 4.5.Significance
Magnetic nanoparticle-containing adhesive with DMAHDM and NACP under a magnetic force yielded much greater dentin bond strength than commercial control. The novel adhesive reduced biofilm CFU by 4 logs and increased the biofilm pH from a cariogenic pH 4.5–6.9, and therefore is promising to enhance the resin–tooth bond, strengthen tooth structures, and suppress secondary caries at the restoration margins. 相似文献4.
Yasaman Delaviz Mitchell A. Nascimento Michael W. Laschuk Timothy W. Liu Meilin Yang J. Paul Santerre 《Dental materials》2018,34(5):711-725
Objective
Two leading causes contributing to dental restoration replacement are the marginal breakdown at the composite/dentin interface and secondary caries mediated by bacteria. The objective of the present study was to synthesize oligomers which incorporated enhanced bio-stability but would also be able to generate antimicrobial function if they underwent degradation.Methods
Stability was incorporated into the oligomers by generating structural features that would physically hinder the availability of hydrolytically sensitive groups in the oligomers. As a proof-of concept for the antibacterial feature, antimicrobial function was achieved by covalently incorporating Ciprofloxacin (CF) into the backbone of cross-linking divinyl oligomers (referred to as EDV and HLH-CFPEG). The hydrolytic stability of the oligomers was studied in simulated human salivary esterase and compared to the commercial monomer 2,2-bis[4(2-hydroxy-3-methacryloxypropoxy)-phenyl]propane (BisGMA).Results
Both drug oligomers were found to be significantly more stable than BisGMA. Upon degradation, both drug oligomers released CF differentially in free form. Polymer synthesis from resin formulations containing 15 wt% HLH-CFPEG showed a high degree of vinyl group conversion and gel content, and under hydrolytic conditions showed the release of CF during a 28-day monitoring study period.Significance
HLH-CFPEG can be used in dental resin adhesive systems for local delivery of CF to the marginal interface. Minimizing the growth of Streptococcus mutans at the marginal site can improve longevity by reducing esterase activity derived specifically from S. mutans. 相似文献5.
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6.
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7.
H. Schweikl M. Godula C. Petzel C. Bolay K.A. Hiller W. Buchalla 《Dental materials》2017,33(1):110-118
Objective
Resin monomers such as 2-hydroxyethyl methacrylate (HEMA) induce apoptosis because of the excess formation of reactive oxygen species (ROS). The portion of ROS including superoxide anions, hydrogen peroxide or hydroxyl radicals in monomer-induced apoptosis is unknown. Here, the effectiveness of superoxide anions or hydroxyl radicals was analyzed using tempol or sodium formate as radical scavengers.Methods
RAW264.7 mouse macrophages were exposed to HEMA (0–6–8 mM) in the presence of tempol (0–0.05–0.5–5.0 mM) or sodium formate (0–1–5–10 mM). The formation of ROS using DCFH2-DA or dihydrorhodamine 123 (DHR123) as fluorescent dyes and the induction of apoptosis was determined by flow cytometry after 1 h or 24 h exposure periods. Expression of enzymes related to ROS metabolism was detected by Western blotting.Results
DCF fluorescence significantly increased after short exposure (1 h) while DHR123 fluorescence was enhanced after a long exposure period (24 h) in cells treated with HEMA. Although no influence was detected on the formation of ROS, tempol or sodium formate protected cells from HEMA-induced apoptosis. The number of cells in late apoptosis or necrosis induced with 6 or 8 mM HEMA was reduced in the presence of tempol or low concentrations of sodium formate. HEMA-induced expression of catalase, indicating oxidative stress, decreased in the presence of tempol.Significance
Superoxide anions and hydroxyl radicals contribute to HEMA-induced apoptosis. The current findings support the development of strategies based on the pharmacological inhibition of enzymes producing superoxide anions finally converted to hydroxyl radicals to compensate for potential adverse tissue reactions associated with dental composites. 相似文献8.
Satoshi Yamaguchi Renshirou Kani Kazuma Kawakami Manami Tsuji Sayuri Inoue Chunwoo Lee Wakako Kiba Satoshi Imazato 《Dental materials》2018,34(10):1578-1584
Objective
The aim of this study was to evaluate long-term fatigue behavior using an in vitro step-stress accelerated life test (SSALT), and to determine the crack initiation point using in silico finite element analysis for computer-aided designed and manufactured (CAD/CAM) molar crowns fabricated from three commercial CAD/CAM resin composite blocks: Cerasmart (CS; GC, Tokyo, Japan), Katana Avencia Block (KA; Kuraray Noritake Dental, Niigata, Japan), and Shofu Block HC (HC; Shofu, Kyoto, Japan).Methods
Fifty-one mandibular first molar crowns luted on a resin core die were embedded in acrylic resin and covered with a polyvinyl chloride tube. Single compressive tests were performed for five crowns. SSALT was conducted for 36 crowns using three profiles and reliabilities at 120,000 cycles, and a Weibull analysis was conducted. The maximum principal strain of each CAD/CAM resin composite crown model was analyzed by three-dimensional finite element analysis.Results
Fracture loads of CS and KA (3784 ± 144 N and 3915 ± 313 N) were significantly greater than that of HC (2767 ± 227 N) (p < 0.05). Fracture probabilities at 120,000 cycles were 24.6% (CS), 13.7% (KA), and 14.0% (HC). Maximum principal strain was observed around the mesiolingual cusps of CS and KA and the distobuccal cusp of HC.Significance
CAD/CAM resin composite molar crowns containing nano-fillers with a higher fraction of resin matrix exhibited higher fracture loads and greater longevity, suggesting that these crowns could be used as an alternative to ceramic crowns in terms of fatigue behavior. 相似文献9.
Objectives
Dental materials that can form apatite offer the potential to not only prevent demineralisation but enhance remineralisation of the enamel. The objective of this study was to investigate the ability of a novel BAG-resin adhesive to form apatite in 3 immersion media.Methods
A novel fluoride containing BAG-resin adhesive described previously, with 80% by weight filler load, was used to fabricate 90 disks. Each disk was immersed in 10 ml of either tris buffer (TB), or artificial saliva at pH = 7 (AS7) or pH = 4 (AS4). At ten time points (from 6 h to 6 months), three disks were taken from each of the solutions and investigated by ATR-FTIR, XRD and SEM.Results
The BAG-resin formed apatite on the disk surface, which increased with time, especially in AS4 and AS7. The apatite crystals formed in AS7 were highly oreintated and the oreintation increased with time.Significance
This novel BAG-resin adhesive differs from the currently used adhesives by promting apatite formation, particularly under acidic conditions. Thus, applied in the clinical situation to bond orthodontic brackets, it may discourage the frequent occurrence of white spot lesion formation around the brackets. 相似文献10.
Marc Deviot Isabelle Lachaise Christof Högg Jürgen Durner Franz-Xaver Reichl Jean-Pierre Attal Elisabeth Dursun 《Dental materials》2018,34(2):341-354
Objectives
First, to analyse the in vitro release of BPA and Bis-GMA from an orthodontic resin composite (Transbond XT, 3M Unitek), stored in various conditions, by gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS); then to extrapolate the data to the clinical situation. Secondly, to explore the thermal stability of Bis-GMA.Methods
Cylinders of resin composite were prepared and stored according to 3 different protocols: (1) they were light-cured 20 s, then placed in artificial saliva; (2) they were light-cured 2 s, then placed in acetonitrile; (3) they were light-cured 2 s, then placed in methanol. For each group, BPA and Bis-GMA release were determined with GC/MS and/or LC/MS at least after one week. Besides, 120 brackets (10 of each type) were bonded over metal teeth, then debonded, and the weight and the surface of resin composite residues were measured. BPA and Bis-GMA release of adhesive residues were extrapolated from the data obtained with the cylinders. Besides, BPA release from a heated Bis-GMA solution was measured.Results
With GC/MC, BPA was detected in all samples. With LC/MS, BPA was detected only from samples immersed in MeOH; Bis-GMA was detected, in varying amount according to the extraction media and the light-curing time. BPA was found after heating of the Bis-GMA solution.Significance
Contamination risk and the heat applied in GC/MS may overestimate the BPA release from resin composite. Based on the LC/MS results, the risk of BPA release after orthodontic bonding would be more than 42 000 times lower than the TDI for a 30-kg child. 相似文献11.
Jingou Liang Mingyun Li Biao Ren Tianmu Wu Hockin H.K. Xu Yong Liu Xian Peng Ge Yang Michael D. Weir Shiyong Zhang Lei Cheng Xuedong Zhou 《Dental materials》2018,34(3):400-411
Objectives
A new quaternary ammonium monomer (QAM), triethylaminododecyl acrylate (TEADDA) was synthesized, in which the position of the functional groups was different from that of dimethylaminododecyl methacrylate (DMADDM). The objectives were to: (1) investigate the effect of the changed position of the functional groups on the mechanical properties, anti-biofilm activity and biocompatibility of adhesive resin, and (2) study the anti-bacterial mechanism of QAM to improve the performance of the adhesive system modified by QAM.Methods
TEADDA and DMADDM were added into adhesives. Microtensile bond strength and surface charge density were measured. Multi-species biofilms were incubated on specimens for 16 h, 48 h and 72 h and analyzed via MTT assay, lactic acid measurement and confocal laser scanning microscopy. The ratio of different species of bacteria was measured by real-time polymerase chain reaction. Cytotoxicity and biocompatibility were analyzed by eluents cytotoxicity test and histological images of H&E staining via an animal study in rats.Results
The mass fraction of TEDDA allowed to be added into adhesive was higher than that of DMADDM. However, even 10% TEADDA did not yield a strong anti-biofilm effect on biofilm growth, lactic acid production and bacteria compositions. TEADDA added into adhesives showed better mechanical properties but weaker anti-bacterial effect. There was no significant difference on cytotoxicity and biocompatibility between DMADDM and TEADDA.Significance
The study could be helpful for the investigation of the anti-caries mechanism of QAMs, the design of new QAMs and the improvement of the anti-caries activity of the modified dental materials. 相似文献12.
Marianne Salas Cristina Lucena Luis Javier Herrera Ana Yebra Alvaro Della Bona María M. Pérez 《Dental materials》2018,34(8):1168-1174
Objective
To determine the translucency acceptability and perceptibility thresholds for dental resin composites using CIEDE2000 and CIELAB color difference formulas.Methods
A 30-observer panel performed perceptibility and acceptability judgments on 50 pairs of resin composites discs (diameter: 10 mm; thickness: 1 mm). Disc pair differences for the Translucency Parameter (ΔTP) were calculated using both color difference formulas (ΔTP00 ranged from 0.11 to 7.98, and ΔTPab ranged from 0.01 to 12.79). A Takagi–Sugeno–Kang (TSK) Fuzzy Approximation was used as fitting procedure. From the resultant fitting curves, the 95% confidence intervals were estimated and the 50:50% translucency perceptibility and acceptability thresholds (TPT and TAT) were calculated. Differences between thresholds were statistically analyzed using Student t tests (α = 0.05).Results
CIEDE2000 50:50% TPT was 0.62 and TAT was 2.62. Corresponding CIELAB values were 1.33 and 4.43, respectively. Translucency perceptibility and acceptability thresholds were significantly different using both color difference formulas (p = 0.01 for TPT and p = 0.005 for TAT). CIEDE2000 color difference formula provided a better data fit than CIELAB formula.Significance
The visual translucency difference thresholds determined with CIEDE2000 color difference formula can serve as reference values in the selection of resin composites and evaluation of its clinical performance. 相似文献13.
Ryota Okada Masaki Asakura Akihiro Ando Hirokazu Kumano Seiji Ban Tatsushi Kawai Jun Takebe 《Journal of prosthodontic research》2018,62(3):287-292
Purpose
The purpose of this study was to ascertain whether computer aided design/computer aided manufacturing (CAD/CAM) composite resin crowns have sufficient strength to withstand the bite force of the molar teeth. The null hypothesis was that the fracture strength of CAD/CAM composite resin crowns is lower than the average maximum bite force of the molar tooth.Methods
The crowns, which shape is the right maxillary first molar, were fabricated using four CAD/CAM blanks made of composite resins (Block HC: HC, KZR-CAD HR: HR, KZR-CAD HR2: HR2, Avencia Block: AVE) and one CAD/CAM blank made of lithium disilicate glass-ceramic (IPS e.max CAD: IPS), which was used as a control. Fracture strength of fabricated crowns bonded to metal abutment and biaxial flexural strength of the materials were evaluated.Results
The results of fracture strength test and biaxial flexural strength test showed different tendencies. The fracture strength of CAD/CAM composite resin crowns except HC ranged from 3.3 kN to 3.9 kN, and was similar to that of IPS (3.3 kN). In contrast, biaxial flexural strength of CAD/CAM composite resins ranged from 175 MPa to 247 MPa, and was significantly lower than that of IPS (360 MPa).Conclusions
All CAD/CAM composite resin crowns studied presented about 3–4 times higher fracture strength than the average maximum bite force of the molar tooth (700–900 N), which result leads to the conclusion that CAD/CAM composite resin crowns would have sufficient strength to withstand the bite force of the molar teeth. 相似文献14.
Ornnicha Thanatvarakorn Taweesak Prasansuttiporn Suppason Thittaweerat Richard M. Foxton Shizuko Ichinose Junji Tagami Keiichi Hosaka Masatoshi Nakajima 《Dental materials》2018,34(3):434-441
Objectives
Smear layer deproteinizing was proved to reduce the organic phase of smear layer covered on dentin surface. It was shown to eliminate hybridized smear layer and nanoleakage expression in resin–dentin bonding interface of two-step self-etch adhesive. This study aimed to investigate those effects on various one-step self-etch adhesives.Methods
Four different one-step self-etch adhesives were used in this study; SE One (SE), Scotchbond? Universal (SU), BeautiBond Multi (BB), and Bond Force (BF). Flat human dentin surfaces with standardized smear layer were prepared. Smear layer deproteinizing was carried out by the application of 50 ppm hypochlorous acid (HOCl) on dentin surface for 15 s followed by Accel® (p-toluenesulfinic acid salt) for 5 s prior to adhesive application. No surface pretreatment was used as control. Microtensile bond strength (μTBS) and nanoleakage under TEM observation were investigated. The data were analyzed by two-way ANOVA and Tukey’s post-hoc test and t-test at the significant level of 0.05.Results
Smear layer deproteinizing significantly improved μTBS of SE, SU, and BB (p < 0.001). Hybridized smear layer observed in control groups of SE, BB, and BF, and reticular nanoleakage presented throughout the hybridized complex in control groups of BB and BF were eliminated upon the smear layer deproteinizing.Significance
Smear layer deproteinizing by HOCl and Accel® application could enhance the quality of dentin for bonding to one-step self-etch adhesives, resulting in the improving μTBS, eliminating hybridized smear layer and preventing reticular nanoleakage formation in resin–dentin bonding interface. 相似文献15.
Thiago Henrique Scarabello Stape Leo Tjäderhane Gabriel Abuna Mário Alexandre Coelho Sinhoreti Luís Roberto Marcondes Martins Arzu Tezvergil-Mutluay 《Dental materials》2018,34(7):967-977
Objective
To determine whether bonding effectiveness and hybrid layer integrity on acid-etched dehydrated dentin would be comparable to the conventional wet-bonding technique through new dentin biomodification approaches using dimethyl sulfoxide (DMSO).Methods
Etched dentin surfaces from extracted sound molars were randomly bonded in wet or dry conditions (30 s air drying) with DMSO/ethanol or DMSO/H2O as pretreatments using a simplified (Scotchbond Universal Adhesive, 3M ESPE: SU) and a multi-step (Adper Scotchbond Multi-Purpose, 3M ESPE: SBMP) etch-and-rinse adhesives. Untreated dentin surfaces served as control. Bonded teeth (n = 8) were stored in distilled water for 24 h and sectioned into resin–dentin beams (0.8 mm2) for microtensile bond strength test and quantitative interfacial nanoleakage analysis (n = 8) under SEM. Additional teeth (n = 2) were prepared for micropermeability assessment by CFLSM under simulated pulpar pressure (20 cm H2O) using 5 mM fluorescein as a tracer. Microtensile data was analyzed by 3-way ANOVA followed by Tukey Test and nanoleakage by Kruskal–Wallis and Dunn-Bonferroni multiple comparison test (α = 0.05).Results
While dry-bonding of SBMP produced significantly lower bond strengths than wet-bonding (p < 0.05), DMSO/H2O and DMSO/ethanol produced significantly higher bond strengths for SBMP irrespective of dentin condition (p < 0.05). SU presented significantly higher nanoleakage levels (p < 0.05) and micropermeability than SBMP. Improvement in hybrid layer integrity occurred for SBMP and SU for both pretreatments, albeit most pronouncedly for DMSO/ethanol regardless of dentin moisture.Conclusion
DMSO pretreatments may be used as a new suitable strategy to improve bonding of water-based adhesives to demineralized air-dried dentin beyond conventional wet-bonding. Less porous resin–dentin interfaces with higher bond strengths on air-dried etched dentin were achieved; nonetheless, overall efficiency varied according to DMSO’s co-solvent and adhesive type.Clinical significance
DMSO pretreatments permit etched dentin to be air-dried before hybridization facilitating residual water removal and thus improving bonding effectiveness. This challenges the current paradigm of wet-bonding requirement for the etch-and-rinse approach creating new possibilities to enhance the clinical longevity of resin–dentin interfaces. 相似文献16.
Can pulpal floor debonding be detected from occlusal surface displacement in composite restorations?
João Batista Novaes Elissa Talma Estevam Barbosa Las Casas Wondwosen Aregawi Lauren Wickham Kolstad Sue Mantell Yan Wang Alex Fok 《Dental materials》2018,34(1):161-169
Objectives
Polymerization shrinkage of resin composite restorations can cause debonding at the tooth–restoration interface. Theory based on the mechanics of materials predicts that debonding at the pulpal floor would half the shrinkage displacement at the occlusal surface. The aim of this study is to test this theory and to examine the possibility of detecting subsurface resin composite restoration debonding by measuring the superficial shrinkage displacements.Methods
A commercial dental resin composite with linear shrinkage strain of 0.8% was used to restore 2 groups of 5 model Class-II cavities (8-mm long, 4-mm wide and 4-mm deep) in aluminum blocks (8-mm thick, 10-mm wide and 14-mm tall). Group I had the restorations bonded to all cavity surfaces, while Group II had the restorations not bonded to the cavity floor to simulate debonding. One of the proximal surfaces of each specimen was sprayed with fine carbon powder to allow surface displacement measurement by Digital Image Correlation. Images of the speckled surface were taken before and after cure for displacement calculation. The experiment was simulated using finite element analysis (FEA) for comparison.Results
Group I showed a maximum occlusal displacement of 34.7 ± 6.7 μm and a center of contraction (COC) near the pulpal floor. Group II had a COC coinciding with the geometric center and showed a maximum occlusal displacement of 17.4 ± 3.8 μm. The difference between the two groups was statistically significant (p-value = 0.0007). Similar results were obtained by FEA. The theoretical shrinkage displacement was 44.6 and 22.3 μm for Group I and II, respectively. The lower experimental displacements were probably caused by slumping of the resin composite before cure and deformation of the adhesive layer.Significance
The results confirmed that the occlusal shrinkage displacement of a resin composite restoration was reduced significantly by pulpal floor debonding. Recent in vitro studies seem to indicate that this reduction in shrinkage displacement could be detected by using the most accurate intraoral scanners currently available. Thus, subject to clinical validation, the occlusal displacement of a resin composite restoration may be used to assess its interfacial integrity. 相似文献17.
Tritala K. Vaidyanathan Jayalakshmi Vaidyanathan Pambadikandathil Philipose Lizymol Saraswathy Ariya Kalliyana Venketeswaran Krishnan 《Dental materials》2017,33(1):1-11
Objective
The goal of the study was to characterize the efficiency of polymerization of Type 1 and Type 2 initiators for visible light cure of a BisGMA-TEGDMA monomer mixture.Methods
Raman spectroscopy was used to follow conversion during polymerization of a BisGMA-TEGDMA mixture using a Type I photoinitiator diphenyl(2,4,6 dimethylbenzoyl)phosphine oxide (TPO) and a Type II photoinitiator camphorquinone (CQ) and an amine, both initiators at 0.5 wt.%. Different light exposure times and storage times after light curing were used as variables.Results
There was a significant difference between the relative exposure times of TPO and CQ/amine (5 s for TPO vs. 20 s for CQ/Amine) for attaining maximum % conversion (78% in TPO vs. 65% in CQ/Amine). There was also a significant difference in the effect of storage time (no effect in TPO vs. increased % conversion with CQ/Amine). These effects are attributed to differences in the rate controlling steps of free radical generation in Type 1/Type 2 initiators, and the potential for radiative and non-radiative energy losses in CQ/Amine in its excited state.Conclusions
The results confirm that photo-polymerization of BisGMA is much more efficient with TPO than with CQ/amine. Both exposure and storage times were important variables in CQ/amine, but not in TPO.Significance
TPO photolysis generates significantly more free radicals with potentially very little radiative and non-radiative energy loss in comparison with CQ/amine. The resulting improved monomer conversion is of major importance in resisting chemical and mechanical degradation and preventing toxicological adverse effects. 相似文献18.
Ya-ping Gou Ji-yao Li Mohamed M. Meghil Christopher W. Cutler Hockin H.K. Xu Franklin R. Tay Li-na Niu 《Dental materials》2018,34(12):1814-1827
Objective
Secondary caries and degradation of hybrid layers are two major challenges in achieving durable resin–dentin bonds. The objectives of the present study were to investigate the effects of a 2% quaternary ammonium silane (QAS) cavity cleanser on bacteria impregnated into dentin blocks and the gelatinolytic activity of the hybrid layers.Methods
Microtensile bond strength was first performed to evaluate if the 2% QAS cavity cleanser adversely affected bond strength. For antibacterial testing, Streptococcus mutans and Actinomyces naeslundii were impregnated into dentin blocks, respectively, prior to the application of the cavity cleanser. Live/dead bacterial staining and colony-forming unit (CFU) counts were performed to evaluate their antibacterial effects. Gelatinolytic activity within the hybrid layers was directly examined using in-situ zymography. A double-fluorescence technique was used to examine interfacial permeability immediately after bonding.Results
The cavity cleanser did not adversely affect the bond strength of the adhesives tested (p > 0.05). Antibacterial testing indicated that 2% QAS significantly killed impregnated bacteria within the dentin blocks compared with control group (p < 0.05), which was comparable with the antibacterial activity of 2% chlorhexidine (p > 0.05). Hybrid layers pretreated with 2% QAS showed significant decrease in enzyme activity compared with control group. With the use of 2% QAS, relatively lower interfacial permeability was observed, compared with control group and 2% chlorhexidine (p < 0.05).Significance
The present study developed a 2% QAS cavity cleanser that possesses combined antimicrobial and anti-proteolytic activities to extend the longevity of resin–dentin bonds. 相似文献19.
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20.
Monika Astasov-Frauenhoffer Stephanie Glauser Jens Fischer Fredy Schmidli Tuomas Waltimo Nadja Rohr 《Dental materials》2018,34(11):1702-1709