共查询到20条相似文献，搜索用时 31 毫秒
1.
Hilton Riquieri Jaiane Bandoli Monteiro Diogo Cabecinha Viegas Tiago Moreira Bastos Campos Renata Marques de Melo Guilherme de Siqueira Ferreira Anzaloni Saavedra 《Dental materials》2018,34(10):1483-1491
Objectives
The aim of this study was to characterize the microstructure of two zirconia-reinforced lithium silicate (ZLS) glass-ceramics and evaluate their mechanical properties before and after the crystallization firing process (CFP).Methods
Field emission-scanning electron microscope (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses were performed for microstructural characterization. To evaluate the pattern of crystallization and the molecular composition of ZLS glass-ceramics, was used X-ray diffraction (XRD). Vickers hardness, fracture toughness by the indentation method, and biaxial flexural strength were also measured. One hundred and forty ceramic discs were produced (diameter = 12 mm; thickness = 1.2 mm) and allocated among four groups (n = 30): Sfir, Sunf-ZLS Vita Suprinity; and Cfir and Cunf-ZLS Celtra Duo; fired and unfired, respectively. Statistical analysis was performed and Weibull failure probabilities were calculated.Results
Cfir showed the highest characteristic strength (251.25 MPa) and hardness (693.333 ± 10.85 GPa). Conversely, Sunf presented the lowest characteristic strength (106.95 MPa) and significantly lowest hardness (597.533 ± 33.97 GPa). According to Weibull analysis, Sunf had the highest structural reliability (m = 7.07), while Sfir presented the lowest (m = 5.38). The CFP was necessary to crystallize zirconia in the partially crystallized ZLS glass-ceramics. Sfir had a lower percentage of crystallized zirconia than did Cfir. Fractographic analyses showed that all failures initiated from an inherent critical defect in Sunf and from processing defects in the remaining groups.Significance
The CFP had a direct influence on the flexural strength and microstructural characteristics of both ZLS materials. 相似文献2.
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3.
Luiza Helena S. Almeida Rafael R. Moraes Renata D. Morgental Sérgio S. Cava Wellington Luiz O. Rosa Patrícia Rodrigues Anderson S. Ribeiro Marcus Só Fernanda G. Pappen 《Dental materials》2018,34(8):e214-e223
Objective
To synthetize calcium aluminate (C3A) and silver-containing C3A particles (C3A + Ag) testing their effects on the properties of a MTA-based endodontic sealer in comparison to an epoxy resin- and a calcium silicate-based sealer.Methods
Pure C3A and C3A + Ag particles were synthesized by a chemical method and characterized using XRD to identify crystalline phases. SEM/EDS analysis investigated morphology, particle size, and elemental composition of particles. Setting time, flow, radiopacity, water sorption and solubility of commercial and modified sealers were evaluated according to ISO 6876/2012. The pH and ions release were measured using a pHmeter and a microwave induced plasma optical emission spectrometer. The inhibition of biofilm growth was evaluated by confocal laser scanning microscopy (CLSM). Data were rank transformed and analyzed by ANOVA and Tukey test (P < 0.05).Results
The C3A particles showed an irregular grain agglomerated structure with voids and pores. In C3A + Ag particles, Ag modified the material morphology, confirming the deposition of Ag. The physicochemical properties of the modified MTA-based sealer were similar to the commercial material, except for the significant increase in Ca+2 release. However, there was no Ag release. Setting time, flow, radiopacity, water sorption and solubility were adequate for all materials. All the materials showed alkaline pH. Antibiofilm effect was improved in the presence of C3A particles, while the biofilm inhibition was lower in the presence of Ag.Significance
The modified sealer presented improved antibiofilm properties and calcium release, without dramatic effects on the other characteristics. It is expected a positive effect in its antimicrobial behavior. 相似文献4.
Objective
To evaluate the effect of different pH media on zirconia-reinforced lithium silicate glass ceramic and how they interact with opposing dentition after being aged in different pH cycling and high temperature conditions.Methods
Twenty-five rectangular shaped specimens were prepared from lithium silicate reinforced with zirconia blanks (Suprinity, Vita Zahnfabrick) and stored in different pH media (3 & 7.2) for different periods (24 h & 7 days) at temperature (55 °C). After their surface roughness (Ra) evaluation, aged ceramic specimens were subjected to cyclic abrasive wear with opposing natural teeth enamel for 150,000 cycles using a chewing simulator. Weight loss and Scanning Electron Microscope (SEM) images were used to evaluate the cyclic wear results.Results
After different pH storage, ceramic group stored at 3 pH for 1-W (1 week) gave significantly higher mean Ra value (0.618 μm ± 0.117) than control lowest mean value (0.357 μm ± 0.054) before cyclic wear. On the other hand, it caused the least significant weight loss value (0.004 gm ± 0.001) to opposing tooth enamel. There was significant tooth enamel weight loss (0.043 gm ± 0.004) when opposed with ceramic group stored in 3 pH media for 24 h (24-H). Their SEM images showed a prominent wear scar on enamel cusp tip. There was a significant increase in surface roughness Ra of ceramic material after abrasive cyclic wear.Significance
Great attention should be paid to Ra of this type of glass ceramic even if it is considered as minimal values. It can induce a significant amount of enamel tooth wear after a period equivalent to one year of intra-oral function rather than the significantly higher surface Ra of such ceramic type can do. 相似文献5.
Jaiane Bandoli Monteiro Hilton Riquieri Catina Prochnow Luís Felipe Guilardi Gabriel Kalil Rocha Pereira Alexandre Luiz Souto Borges Renata Marques de Melo Luiz Felipe Valandro 《Dental materials》2018,34(6):891-900
Objectives
To evaluate the effect of ceramic thickness on the fatigue failure load of two zirconia-reinforced lithium silicate (ZLS) glass-ceramics, adhesively cemented to a dentin analogue material.Methods
Disc-shaped specimens were allocated into 8 groups (n = 25) considering two study factors: ZLS ceramic type (Vita Suprinity — VS; and Celtra Duo — CD), and ceramic thickness (1.0; 1.5; 2.0; and 2.5 mm). A trilayer assembly (? = 10 mm; thickness = 3.5 mm) was designed to mimic a bonded monolithic restoration. The ceramic discs were etched, silanized and luted (Variolink N) into a dentin analogue material. Fatigue failure load was determined using the Staircase method (100,000 cycles at 20 Hz; initial fatigue load ～60% of the mean monotonic load-to-failure; step size ～5% of the initial fatigue load). A stainless-steel piston (? = 40 mm) applied the load into the center of the specimens submerged in water. Fractographic analysis and Finite Element Analysis (FEA) were also performed.Results
The ceramic thickness influenced the fatigue failure load for both ZLS materials: Suprinity (716 N up to 1119 N); Celtra (404 N up to 1126 N). FEA showed that decreasing ceramic thickness led to higher stress concentration on the cementing interface.Significance
Different ZLS glass-ceramic thicknesses influenced the fatigue failure load of the bonded system (i.e. the thicker the glass ceramic is, the higher the fatigue failure load will be). Different microstructures of the ZLS glass-ceramics might affect the fatigue behavior. FEA showed that the thicker the glass ceramic is, the lower the stress concentration at the tensile surface will be. 相似文献6.
Marina Popal Joachim Volk Gabriele Leyhausen Werner Geurtsen 《Dental materials》2018,34(12):1783-1796
Objectives
Phenylbis(acyl) phosphine oxide (BAPO) and diphenyl(acyl) phosphine oxide (TPO) are alternative photoinitiators to camphorquinone (CQ) in dental resinous materials. Aim of this study was to investigate their cytotoxic/genotoxic potential in human oral keratinocytes (OKF6/Tert2) and Chinese hamster lung fibroblasts (V79) in comparison to CQ.Methods
Cells were exposed to different concentrations of BAPO and TPO (1–50 μM). Cytotoxicity was evaluated using H33342 and MTT assay, cell proliferation by BrdU proliferation assay and microscopy. Effects on cellular redox homeostasis were assessed by detecting intracellular levels of reactive oxygen/nitrogen species (ROS/RNS) using the DCFH2 assay and by quantification of mRNA expression of oxidatively regulated, cyto-protective enzymes. Genotoxic potential was determined by use of micronucleus (MN) assay.Results
BAPO and TPO induced a concentration-dependent decrease of cell number. BAPO and TPO showed 50- to 250-fold higher cytotoxicity than CQ. In contrast to CQ, both photoinitiators revealed no increase of intracellular ROS/RNS. However, BAPO (10 μM) at least significantly induced mRNA-expression of redox-regulated proteins after 24 h similar to 2.5 mM CQ. Additionally, BAPO significantly raised the number of micronuclei, but only in V79 cells (10 μM: 12 ± 1, 2.5 mM CQ: 15 ± 1, medium control: 6 ± 3). However, it also significantly decreased proliferation of these cells (10 μM BAPO: 19.8% ± 7.3% compared to controls).Significance
BAPO and TPO revealed concentration-dependent cytotoxic effects in human oral keratinocytes and V79 cells. However, in contrast to CQ, no generation of intracellular ROS/RNS was found. Only BAPO induced genotoxicity in V79 cells. 相似文献7.
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8.
Paula Fernanda Damasceno Silva Lais Rani Sales Oliveira Stella Sueli Lourenço Braga Cácia Signori Steve R. Armstrong Carlos José Soares Maximiliano Sérgio Cenci André Luis Faria-e-Silva 《Dental materials》2018,34(9):1289-1298
Objectives
This study aimed to develop a method to induce carious lesions in the pulpal floor dentin of a class II cavity preparation, and to determine the effects of this carious lesion on the biomechanical behavior of the dental composite restoration.Methods
The pulpal floor dentin of class I cavities in sound third molars were demineralised with acetic acid for 35 days followed by a 7-day exposure to pooled human saliva biofilm and demineralization was verified by micro-CT. Subsequently, the proximal walls were removed forming a class II cavity and the caries lesion was left intact or was completely removed prior to restoration with a bulk-fill dental composite (n = 10). Cuspal deflection was assessed by strain-gauge and micro-CT imaging. The presence of enamel cracks was assessed by transillumination before and after restoration, and again after 1,200,000 cycles of mechanical fatigue in a chewing simulator. Finally, resistance to fracture by axial compressive loading and failure mode was determined. Data were analyzed by 2-way repeated measures ANOVA, Fisher’s exact test, and t-test (α = 0.05).Results
The presence of carious lesions had no significant effect upon cuspal deflection, formation of enamel cracks, and fracture strength of the dental composite restorations. The restorative procedure increased the number of enamel cracks, which was not affected by mechanical cycling.Significance
Maintaining carious lesions does not affect the biomechanical behavior of class II restorations performed with bulk-fill dental composite. 相似文献9.
Keita Taguchi Keiichi Hosaka Masaomi Ikeda Ryuzo Kishikawa Richard Foxton Masatoshi Nakajima Junji Tagami 《Journal of prosthodontic research》2018,62(3):330-336
Purpose
The use of warm air-blowing to evaporate solvents of one-step self-etch adhesive systems (1-SEAs) has been reported to be a useful method. The purpose of this study was to evaluate the effect of warm air-blowing on root canal dentin.Methods
Four 1-SEAs (Clearfil Bond SE ONE, Unifil Core EM self-etch bond, Estelink, BeautiDualbond EX) were used. Each 1-SEA was applied to root canal dentin according to the manufacturers’ instructions. After the adhesives were applied, solvent was evaporated using either normal air (23 ± 1 °C) or warm air (80 ± 1 °C) for 20 s, and resin composite was placed in the post spaces. The air from the dryer, which could be used in normal- or hot-air-mode, was applied at a distance of 5 cm above the root canal cavity in the direction of tooth axis. The temperature of the stream of air from the dryer in the hot-air-mode was 80 ± 1 °C, and in the normal mode, 23 ± 1 °C. After water storage of the specimens for 24 h, the μTBS were evaluated at the coronal and apical regions. The μTBSs were statistically analyzed using three-way ANOVA and Student’s t-test with Bonferroni correction (α = 0.05).Results
The warm air-blowing significantly increased the μTBS of all 1-SEAs at the apical regions, and also significantly increased the μTBS of two adhesives (Estelink and BeautiDualBond EX) at coronal regions.Conclusions
The μTBS of 1-SEAs to root canal dentin was improved by using warm air-blowing. 相似文献10.
Friederike Bötel Tycho Zimmermann Mona Sütel Wolf-Dieter Müller Andreas Dominik Schwitalla 《Dental materials》2018,34(9):e246-e254
Objective
The aim of this study was to evaluate the impact of oxygen and argon/oxygen low-pressure plasma on the shear bond strength (SBS) between dental PEEK compounds and veneering composites as a function of plasma process time.Methods
Of an unfilled PEEK (“Juvora”) and two pigment powder filled PEEK compounds (“DC4420”, “DC4450”), 273 rectangular plates were prepared and polished up to 1200 grit. Afterwards the samples were sandblasted and randomly assigned to five different surface pre-treatment groups (1. No plasma (control); 2. O2 plasma for 3 min; 3. O2 plasma for 35 min; 4. Ar/O2 plasma for 3 min; 5. Ar/O2 plasma for 35 min). Surface roughness and water contact angles were recorded using three samples of each PEEK compound for each of the plasma treatment groups. An adhesive (visio.link, Bredent GmbH & Co KG, Senden, Germany) was applied onto the specimen surfaces and light cured. A mold was used to shape three different veneering composites (a) Vita VM LC, “Vita” (Vita Zahnfabrik, Bad Säckingen, Germany); (b) GC GRADIA, “Gradia” (GC Europe, Leuven, Belgium); (c) GC GRADIA DIRECT Flo, “Gradia Flo” (GC Europe, Leuven, Belgium)) into a cylindrical form on the sample surface before light curing. SBS was measured using a universal testing machine after 24 h of incubation in distilled water at 37 °C.Results
The two pigment filled PEEK compounds treated with O2 plasma and veneered with Gradia Flo showed the highest SBS values (34.92 ± 6.55 MPa and 34.2 ± 1.87 MPa) followed by the combination of the unfilled PEEK material with Gradia Flo (29.57 ± 3.71 MPa). The SBS values of the samples veneered with Gradia were lower, but not significantly so. The SBS values of the specimens with Vita were for the most part associated with significantly lower results.Significance
A low-pressure plasma process using oxygen plasma for a duration of 35 min, preceded by sandblasting, seems to be the most effective in increasing shear bond strength between veneering composites and PEEK materials. 相似文献11.
Andressa B. Venturini Catina Prochnow Gabriel K.R. Pereira Arie Werner Cornelis J. Kleverlaan Luiz Felipe Valandro 《Dental materials》2018,34(4):667-675
Objective
This study investigated the influence of hydrofluoric acid (HF) etching at different concentrations on the fatigue failure load of adhesively cemented feldspathic ceramic discs (Vita Mark II). Besides, their effect on the micromorphology of ceramic surface was investigated.Methods
Eighty ceramic discs (? = 10?mm; thickness = 1.5?mm) were cemented to epoxy supporting discs (? = 10?mm; thickness = 2.0 mm) using different surface conditioning methods (n = 20): nonetched control (CTRL), or etched for 60 s with different HF concentrations: 1% (HF1), 5% (HF5), or 10% (HF10). All the ceramic discs received a silane application (Monobond Plus). The epoxy discs were etched with 10% HF for 60 s and received a primer coating (Multilink Primer A + B). Adhesively cementation was performed (Multilink Automix), and the assemblies (ceramic discs/epoxy discs) were subjected to cyclic loads in water by a staircase approach (500,000 cycles; 20 Hz; initial load = 290 N; step size = 30 N). Fatigue failure load data were analyzed using 1-way ANOVA and post-hoc Tukey’s tests (α = .05).Results
Mean failure load of the HF5 group (255.0 ± 23.0 N) was significantly lower; HF1 group (301.7 ± 71.0 N) presented intermediate values, and the highest values were achieved in CTRL (351.7 ± 13.4 N) and HF10 (341.7 ± 20.6 N) groups. All the failures were radial cracks starting from the bonding surface.Significance
In terms of fatigue failure load, etching with 1% and 5% HF had a deleterious effect on the fatigue behavior of an adhesively cemented feldspathic ceramic, while 10% HF had no negative influence. 相似文献12.
Akiko Tsujisaka Shingo Haraki Shigeru Nonoue Akira Mikami Hiroyoshi Adachi Takahiro Mizumori Hirofumi Yatani Atsushi Yoshida Takafumi Kato 《Journal of prosthodontic research》2018,62(3):317-323
Purpose
Concomitant occurrence of respiratory events can be often overlooked in the clinical practice of SB. This study assessed physiological characteristics of rhythmic masticatory muscle activity (RMMA) and concomitant respiratory events in young sleep bruxism (SB) subjects asymptomatic to obstructive sleep apnea (OSA).Methods
Twenty-two subjects (age: 24.1 ± 1.9 years; F 8: M 14; BMI: 20.2 ± 1.9 kg/m2) were polysomnographically diagnosed as moderate-severe SB. Sleep architecture, oromotor (RMMA and non-specific masseter activity [NSMA]) and apnea/hypopnea events were scored.Results
All subjects showed normal sleep architecture whereas 6 exhibited respiratory events at a mild level of OSA. In all subjects, RMMA predominantly occurred in Stage N1 + N2 while NSMA occurred in Stage N1 + N2 (approximately 60 %) and in Stage R (up to 30 %). Up to 50 % of respiratory events were scored in Stage R. RMMA occurred more frequently in close association (e.g., within 10 s) with respiratory events in 6 subjects with OSA than those without. The percentage of RMMA occurring closely to respiratory events was positively correlated with apnea–hypopnea index (AHI) in Stage N1 + N2 only while that of NSMA was positively correlated with AHI in Stage N1 + N2 and Stage R. A sub-analysis in 6 subjects with OSA, RMMA after respiratory events was followed to arousals while those before respiratory events were mostly associated with central apnea.Conclusions
A subpopulation of young SB subjects can show concomitant respiratory events. Further large sample studies are needed to demonstrate that the occurrence of subclinical respiratory events represents a clinical subtype of SB. 相似文献13.
Abdulrahman Elmougy Alvaro Muñoz Schiemann Duncan Wood Sarah Pollington Nicolas Martin 《Dental materials》2018,34(10):1509-1517
Objectives
To characterise the mechanical properties of the machinable polymers Pekkton® (Cendres-Meteaux, Biel/Bienne, Switzerland), Lava Ultimate® (3MESPE, Seefeld, Germany), Vita Enamic® (Ivoclar Vivadent, Schaan, Liechtenstein) and the ceramic IPS e.Max Press® (Ivoclar Vivadent, Schaan, Liechtenstein). To determine the structural integrity of full coverage crowns fabricated from these materials.Methods
The following tests were conducted: Biaxial flexural strength (BFS) using the piston on 3 balls jig (n = 10); Vickers Hardness (VH) 10 indentations per sample with 10 kg load & 20 s dwell time (n = 5); Hygroscopic Expansion Change (HEC) in artificial saliva over 68 days (n = 5). Structural Strength (SS) of teeth analogues (n = 20) restored with monolithic crowns from the four materials. Mean values and standard deviations for BFS, VH, HEC and SS tests were calculated and compared using one-way ANOVA with post-hoc Tukey’s test at a level of 5% significance.Results
BFS: IPS e.Max Press® (317 MPa ± 37 MPa), Pekkton® (227 MPa ± 18 MPa), Lava Ultimate® (145 MPa ± 18 MPa) and Vita Enamic® (137 MPa ± 7 MPa) with a significance between groups of p < 0.0001. VH: IPS e.Max Press® (5064 MPa ± 131 MPa), Vita Enamic® (1976 MPa ± 12 MPa), Lava Ultimate® (924 MPa ± 27 MPa) and Pekkton® (445MPa ± 21 MPa) with a significance between groups of p < 0.0001. HEC (%vol change): Pekkton® (0.14% ± 0.14%), Vita Enamic® (0.38% ± 0.16%) and Lava Ultimate® (1.06% ± 0.17%). SS for full-coverage crowns: Pekkton® (2037 N ± 49 N no fracture), IPS e.Max Press® (1497 N ± 165 N), Lava Ultimate® (1476 N ± 142 N) and Vita Enamic® (1127 N ± 108 N).Significance
The properties investigated suggest that full coverage monolithic PEKK crowns possess adequate mechanical and physical properties for use in the posterior region of the mouth. These results must be considered alongside other data including clinical studies. 相似文献14.
Xin Li Mariano Simón Pedano Bernardo Camargo Esther Hauben Stéphanie De Vleeschauwer Zhi Chen Jan De Munck Katleen Vandamme Kirsten Van Landuyt Bart Van Meerbeek 《Dental materials》2018,34(9):1410-1423
Objectives
To overcome shortcomings of hydraulic calcium-silicate cements (hCSCs), an experimental tricalcium silicate (TCS) cement, named ‘TCS 50’, was developed. In vitro research showed that TCS 50 played no negative effect on the viability and proliferation of human dental pulp cells, and it induced cell odontogenic differentiation. The objective was to evaluate the pulpal repair potential of TCS 50 applied onto exposed minipig pulps.Methods
Twenty permanent teeth from three minipigs were mechanically exposed and capped using TCS 50; half of the teeth were scheduled for 7-day and the other half for 70-day examination (n = 10). Commercial hCSCs ProRoot MTA and TheraCal LC were tested as references (n = 8). Tooth discoloration was examined visually. After animal sacrifice, the teeth were scanned using micro-computed tomography; inflammatory response at day 7 and day 70, mineralized tissue formation at day 70 were assessed histologically.Results
Up to 70 days, TCS 50 induced no discoloration, ProRoot MTA generated gray/black discoloration in all teeth. For TCS 50, 40.0% pulps exhibited a mild/moderate inflammation at day 7. No inflammation was detected and complete reparative dentin with tubular structures was formed in all pulps after 70 days. ProRoot MTA induced a similar response, TheraCal LC generated a less favorable response in terms of initial inflammation and reparative dentin formation; however, these differences were not significant (Chi-square test of independence: p > 0.05).Significance
TCS 50 induced reparative dentinogenesis in minipig pulps. It can be considered as a promising pulp-capping agent, also for aesthetic areas. 相似文献15.
Izabela Cristina Maurício Moris Yung-Chung Chen Adriana Cláudia Lapria Faria Ricardo Faria Ribeiro Alex Sui-Lun Fok Renata Cristina Silveira Rodrigues 《Dental materials》2018,34(8):e197-e204
Objective
This study aimed to evaluate the fracture load and pattern of customized and non-customized zirconia abutments with Morse-taper connection.Methods
18 implants were divided into 3 groups according to the abutments used: Zr — with non-customized zirconia abutments; Zrc — with customized zirconia abutments; and Ti — with titanium abutments. To test their load capacity, a universal test machine with a 500-kgf load cell and a 0.5-mm/min speed were used. After, one implant-abutment assembly from each group was analyzed by Scanning Electron Microscopy (SEM). For fractographic analysis, the specimens were transversely sectioned above the threads of the abutment screw in order to examine their fracture surfaces using SEM.Results
A significant difference was noted between the groups (Zr = 573.7 ± 11.66 N, Zrc = 768.0 ± 8.72 N and Ti = 659.1 ± 7.70 N). Also, the zirconia abutments fractured while the titanium abutments deformed plastically. Zrc presented fracture loads significantly higher than Zr (p = 0.009). All the zirconia abutments fractured below the implant platform, starting from the area of contact between the abutment and implant and propagating to the internal surface of the abutment. All the zirconia abutments presented complete cleavage in the mechanical test. Fractography detected differences in the position and pattern of fracture between the two groups with zirconia abutments, probably because of the different diameters in the transmucosal region.Significance
Customization of zirconia abutments did not affect their fracture loads, which were comparable to that of titanium and much higher than the maximum physiological limit for the anterior region of the maxilla. 相似文献16.
Michel Lehmensiek Haitham Askar Fredrik Brouwer Uwe Blunck Sebastian Paris Falk Schwendicke 《Dental materials》2018,34(12):e317-e323
Objective
Secondary caries lesions next to direct restorations are associated with the restoration material and the integrity of the tooth-restoration-interface (presence of interfacial gaps) as well as the application of masticatory forces. It remains unclear if this is true for indirect restorations. We aimed to evaluate secondary lesions next to conventionally-cemented partial gold (PG) and adhesively-cemented partial ceramic (PC) restorations, placed with or without interfacial gaps.Methods
In human molars, standardized two-surfaced cavities were prepared. Four groups (restoration material + cementation strategy) were compared: (1) gold + glass ionomer cement (Degudent/Ketac Cem), (2) lithium disilicate ceramic + self-adhesive resin cement (IPS e.max Press/RelyX Unicem 2), (3) lithium disilicate ceramic + self-etch adhesive + resin cement (IPS e.max Press/Adhese Universal/Variolink Esthetic DC), (4) lithium disilicate ceramic + etch-and-rinse adhesive + resin cement (IPS e.max Press/Syntac/Variolink Esthetic DC). Half of the restorations received a simulated interfacial gap (mean gap height was 237 μm), while the other half did not (n = 12/group). Specimens were submitted to a Lactobacillus rhamnosus-monospecies-biofilm-model with concomitant cyclic loading for 10 days. Mineral loss (ΔZ) of enamel-surface-lesions (ESL) and dentin-wall-lesions (DWL) was analyzed using transversal microradiography.Results
For ESL, neither the presence of an interfacial gap nor the restoration material nor the cementation strategy had a significant influence on ΔZ (p > 0.05/Generalized Linear Modelling). For DWL, ΔZ was significantly higher beneath restorations with interfacial gaps (p = 0.003/GLM); the restoration material and cementation strategy did not have a significant influence (p > 0.05).Significance
The presence of interfacial gaps, but not the restoration material or cementation strategy determined secondary caries lesions next to indirect restorations in vitro. 相似文献17.
Objective
To provide insight of the setting reactions of Biodentine?, a hydraulic calcium silicate cement, based upon observations using Fourier Transform Infra-Red (FTIR) spectroscopy.Methods
FTIR spectra of components before and during the setting reaction were taken using the attenuated total reflectance (ATR) technique. Measurements over wavelengths 600–4000 cm?1 were taken at regular intervals for two days.Results
FTIR spectrum of Biodentine? powder revealed a number of peaks from 650 to 1100 cm?1 and a plateau from 1400 to 1500 cm?1, indicative of SiO and CO3-bonding, while the mixing fluid exhibited water peaks. Results following mixing displayed three distinct regimes; (i) incubation phase, during the first 35 min, when minimal change occurred, (ii) rapid transitory stage, between 35 and 90 min, when major changes occurred, and (iii) slow sustained reaction stage for remaining 45 h. Incubation appears to be associated with the presence of CO3-peaks. The transition region indicates formation of CaOH and Jennite OH-peaks, anticipated intermediate reaction phases. At 90 min, the end of second stage, CaOH and Jennite are replaced by a dominant Portlandite (Ca(OH)2)-peak and minor presence of Tobermorite, another anticipated intermediate phase, and water reduction. During the following 45 h Portlandite and Tobermorite decline while the water peak increases.Significance
FTIR can be used to follow the chemical reactions in dental cements and provides insight into the relatively slow setting reactions of hydraulic calcium silicate cements. 相似文献18.
Jin Feng Lei Cheng Xuedong Zhou Hockin H.K. Xu Michael D. Weir Qian Li Matthias Hannig Stefan Rupf 《Dental materials》2019,35(3):434-443
Objectives
The aims of this study were to investigate the effects of water aging for up to 6 months on the mechanical and anti-biofilm properties of a novel antibacterial glass ionomer cement (GIC) containing dimethylaminododecyl methacrylate (DMADDM).Methods
GIC specimens (n = 180) which contained DMADDM (0 wt.%, 1.1 wt.% or 2.2 wt.%) were prepared. The mechanical properties surface roughness, microhardness and the surface charge density of ammonium groups were measured before and after water aging for 3 and 6 months at 37 °C. Further six months aged specimens (n = 216) were worn by 6 volunteers in their oral cavities for 24 h and 72 h. Biofilm formation was analyzed and rated by fluorescence microscopy (FM) and by scanning electron microscopy (SEM). Biofilm viability was analyzed by FM.Results
Water aging did not show any adverse effects on the surface roughness and hardness of the material. The surface charge density of the GIC samples containing DMADDM decreased due to the aging procedure, however, was still higher than that of the GIC without DMADDM. In situ biofilm formation was significantly reduced after 24 h on DMADDM containing GIC (p < 0.05). FM results showed a higher ratio of red/green fluorescence on GIC-DMADDM samples.Significance
Incorporating DMADDM into GIC affected the material properties in a tolerable manner even after 6 months of storage in water. The new GIC is a promising material to affect the biofilm formation on the surface of restorations. 相似文献19.
Katharina Debye Taskin Tuna Shaza Bishti Stefan Wolfart 《Journal of prosthodontic research》2018,62(4):416-421
Purpose
In implant dentistry, temporary restorations (TR) might often be required for up to one year. The aim of this in vitro study was to evaluate the long-time performance of four-unit TRs in the posterior region based on different materials and reinforcement methods.Methods
One hundred and forty four TRs were manufactured on 16 models simulating an oral situation of two missing posterior teeth. With a computer-aided-design/computer-aided-manufacturing (CAD/CAM) workflow, a TR was fabricated (CAD; Telio CAD), which served as a template for other subgroups. With a vacuum-formed template, unreinforced and reinforced TRs [glass fibres (g; EverStick); polyethylenefibres (p; Ribbond original) and TRs with increased connector area (c; 27.5–35 mm2)] were manufactured. Two different composite materials were used (C1: Luxatemp, C2: Protemp). Altogether, 16 subgroups with 8 specimens each were tested. After temporary luting (Temp Bond NE) and artificial-aging [1600 thermo-cycles (5–55 °C), 240,000 chewing-cycles (50 N)], all specimens were tested until fracture in a universal testing machine.Results
After artificial aging, mean fracture loads (N) were: (C1)201.2 ± 109.7, (C1c)1033.0 ± 173.1, (C1p)90.0 ± 40.0, (C1g)75.9 ± 25.9, (C2)108.6 ± 58.6, (C2c)1363.3 ± 148.6, (C2p)104.7 ± 54.7, (C2g)50.0 ± 0.0 and (CAD)232.5 ± 19.1. The one-factor ANOVA analysis showed significant differences for the factors temporary material (p < 0.047), reinforcement (p < 0.0001) and artificial-aging (p < 0.0001).Conclusions
The study indicated that both CAD/CAM TRs and TRs with increased connector areas are suitable for long-term use of one year. No enhancement of fracture load was observed for fibre-reinforced TRs except for the fact that fractured TRs were not totally separated. 相似文献20.
Tim Joda Benjamin Voumard Philippe K. Zysset Urs Brägger Marco Ferrari 《Journal of prosthodontic research》2018,62(2):258-263