共查询到20条相似文献，搜索用时 31 毫秒
1.
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.
Hiroki Tsuka Koji Morita Kan Kato Hitomi Kimura Hitoshi Abekura Isao Hirata Koichi Kato Kazuhiro Tsuga 《Journal of prosthodontic research》2019,63(1):52-57
Purpose
The mechanical properties of polyetheretherketone (PEEK) are ideally suited for fixed dental prostheses. However, PEEK typically has low adhesion strength to resin-based luting agent. This study assessed the shear bond strength between laser groove treated PEEK and resin-based luting agent.Methods
A total of 230 specimens were randomly divided into five groups (n = 46): no-treatment, air abrasion treatment, 100 μm-deep, 150 μm-deep, and 200 μm-deep laser groove treatments. The surface roughness was measured, scanning electron microscopy was used to observe the specimen surfaces, and X-ray photoelectron spectroscopy (XPS) was used to analyze the surfaces. Each group was divided into four resin-based luting agent subgroups: Panavia V5, RelyX Ultimate Resin Cement, G-CEM Link Force, and Super-Bond C&B. After the resin-based luting agent was bonded to the specimens, the bond strength was measured using shear tests and the failure modes were assessed by stereomicroscopy. The surfaces were also observed by scanning electron microscopy (SEM) after the shear bond strength measurements. The data were statistically analyzed using a two-way analysis of variance and Tukey’s honest significant difference test (α = 0.05).Results
The PEEK surface after laser groove treatment groups exhibited the highest mean Ra values. In the XPS analysis, the laser treated PEEK surface exhibited an effective surface composition for bonding with resin-based luting agent. The shear bond strengths for the laser groove treated samples were significantly higher (p < 0.05) than those of the no-treatment and air abrasion treatment groups.Conclusions
The shear bond strength between PEEK and resin-based luting agent was substantially improved by laser groove treatment. 相似文献4.
Magdalena Kirsten Ragai Edward Matta Renan Belli Ulrich Lohbauer Manfred Wichmann Anselm Petschelt José Zorzin 《Dental materials》2018,34(8):1102-1111
Objective
Low pH neutralization and subsequent remnant hydrophilicity can lead to hygroscopic expansion of self-adhesive resin cements (SARCs) after water storage. The aim of this in vitro study was to investigate the effects of hygroscopic expansion of SARCs, used as luting and partial core build-up material, on integrity and cement gap thickness increase of all-ceramic CAD/CAM crowns.Methods
Human third molars (n = 48) were prepared and anatomical all-ceramic CAD/CAM crowns were manufactured (VITABLOCS Mark II, VITA Zahnfabrik). Crowns internal surfaces were HF etched and silanized. The prepared teeth with their respective crowns were divided into 6 groups (n = 8). In groups 1, 3 and 5 the coronal dentin was removed to simulate a partial core build-up. Groups 1 and 2 were luted with iCEM (Heraeus Kulzer), 3 and 4 with RelyX Unicem 2 Automix (3M), 5 and 6 with Variolink Esthetic DC (Ivoclar Vivadent). All specimens were dual cured and stored in distilled water at 37 °C. Crown integrity was controlled at baseline and in regular intervals until 180 days. Cement gap thickness was measured using an optical 3D scanner (ATOS Triple scan, GOM) at baseline and after 180 days. Crown integrity was statistically analysed using Kaplan–Meier survival analysis and cement gap thickness increase using two-way ANOVA (α = 0.05).Results
After 180 days storage, crack formation was observed in all specimens of group 1 (mean survival time of 85.5 days), in one specimen of group 2 and in two specimens of group 4. Two-way ANOVA analysis revealed a statistically significant interaction between material type and build-up on cement gap size increase for iCEM.Significance
Within the limits of this study, the application of SARCs with low pH neutralization as partial build-up material under CAD/CAM crowns is not recommended for clinical use. 相似文献5.
Shogo Yagawa Futoshi Komine Ryosuke Fushiki Kei Kubochi Fumiaki Kimura Hideo Matsumura 《Journal of prosthodontic research》2018,62(2):204-209
Purpose
The purpose of the present study was to evaluate the effect of priming agents and artificial aging with thermocycling on shear bond strengths of two resin-based luting agents to a translucent zirconia material.Methods
A total of 308 pairs of translucent zirconia disk specimens were divided into seven treatment groups: Alloy Primer (ALP), Clearfil Ceramic Primer Plus (CCP), Meta Fast Bonding Liner (MFB), MR. bond (MRB), Super-Bond PZ Primer Liquid B (PZB), V-Primer (VPR), and an unprimed group (UP). The specimens in each group were bonded with Panavia V5 Universal (UNI) and Opaque shade (OPA). Shear bond strengths (n = 11 each) were tested before and after 5000 thermocycles. The data were analyzed with the Kruskal–Wallis test and the Steel–Dwass test.Results
For both 0 and 5000 thermocycles, the ALP (47.8 and 41.5 MPa, respectively) and CCP (45.8 and 42.3 MPa, respectively) groups showed significantly higher bond strengths than other groups in the UNI luting agent. For the OPA luting agent, CCP group (45.8 MPa) exhibited the highest pre-thermocycling bond strength in all groups. The ALP (32.4 MPa) and CCP (36.5 MPa) groups had significantly higher post-thermocycling shear bond strengths than other groups. In several groups, the shear bond strengths of the UNI luting agent were significantly higher than those of the OPA luting agent before and after thermocycling.Conclusions
Application of priming agents containing hydrophobic phosphate monomer (MDP) yielded the durable bond strengths of resin-based luting agents to a translucent zirconia material. 相似文献6.
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7.
Monika Astasov-Frauenhoffer Stephanie Glauser Jens Fischer Fredy Schmidli Tuomas Waltimo Nadja Rohr 《Dental materials》2018,34(11):1702-1709
Objectives
Monolithic zirconia, polymer-infiltrated ceramic and acrylate polymer cemented with resin composite cement have recently been identified as prosthetic treatment options for zirconia implants. The aim of the present study is to determine in vitro, to what extent bacteria adhere to these materials.Methods
Disks made of zirconia (Vita YZ [YZ]), polymer-infiltrated ceramic (Vita Enamic [VE]), acrylate polymer (Vita CAD-Temp [CT]), self-adhesive cement (RelyX Unicem 2 Automix [RUN]) and of two different adhesive cements (RelyX Ulimate [RUL] and Vita Adiva F-Cem [VAF]) were produced. The biofilm formation of three bacterial species (Streptococcus sanguinis, Fusobacterium nucleatum, Porphyromonas gingivalis) on each material was assessed over 72 h using a flow chamber system. The biofilms were quantified by crystal violet staining (optical density 595 nm) and visualized using SEM. The inorganic composition of the different materials was analyzed and the wettability of the specimens was measured.Results
For the restorative materials lowest biofilm formation was found on CT: OD 0.5 ± 0.1, followed by VE: OD 0.8 ± 0.1 and YZ: OD 1.4 ± 0.3. The biofilm formation on resin composite cements was significantly lower on VAF: OD 0.6 ± 0.1 than for RUL: OD 0.9 ± 0.1 and RUN: OD 1.0 ± 0.1. A high wettability of the specimens with saliva/serum mixture tended to result in a higher biofilm formation. Correlations were obtained between the organic/inorganic composition of the materials and the polar/dispersive part of the surface free energy.Significance
Three-species biofilm formation on restorative and cement materials strongly relies on the materials composition. If the restorative material CT and cement VAF also prevent excessive biofilm formation in a clinical situation should be further investigated. 相似文献8.
Naghmeh Meraji Mohammad H. Nekoofar Kazem Ashofteh Yazdi Mohammad Reza Sharifian Noushin Fakhari Josette Camilleri 《Dental materials》2018,34(9):e236-e245
Objectives
Dentine replacement materials are often placed over caries affected dentine (CAD). The aim of this study was to compare the bonding characteristics and interactions of selected hydraulic calcium silicate-based dentine replacement materials to CAD and sound dentine.Methods
Three hydraulic calcium silicate-based dentine replacement materials were assessed: Retro MTA, Biodentine and Theracal LC. Material characterization was done by scanning electron microscopy and X-ray diffraction analyses. Blocks of sound and CAD were prepared and standardized by Vickers microhardness testing. Half of the affected and sound dentine blocks were pretreated with 5.25% NaOCl prior to material placement. The materials were stored either for 1 week or 24 weeks in 37 °C in fully saturated conditions. Shear bond strength was assessed at both time periods. Radiopacity of the interfacial dentine was also evaluated to assess the remineralization potential of the dentine replacement materials.Results
The reaction of Theracal was slower than that of the water-based materials. The bond strengths of different materials did not differ after 1 week (P > 0.05). The bond strength of Biodentine and Retro MTA increased over time but no change was observed for Theracal. NaOCl pre-treatment deteriorated the bond strength to sound dentine but improvement was observed in affected dentine. Radiopacity changes were observed after 24 weeks.Significance
Biodentine and Retro MTA showed better bonding to CAD. Pretreatment with NaOCl improved the bond strength of dentine replacement materials to CAD. 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.
C.M.F. Hardy S. Bebelman G. Leloup M.A. Hadis W.M. Palin J.G. Leprince 《Dental materials》2018,34(9):1278-1288
Objective
To determine the limitations of using light-curable resin-based luting composites (RBLCs) to bond indirect ceramic/resin-composite restorations by measuring light transmittance through indirect restorative materials and the resulting degree of conversion (DC) of the luting-composites placed underneath.Methods
Various thicknesses (0–4 mm) and shades of LAVA Zirconia and LAVA Ultimate were prepared and used as light curing filters. A commercial, light curable RBLC, RelyX Veneer (control) was compared with four experimental RBLCs of the following composition: TEGDMA/BisGMA (50/50 or 30/70 wt%, respectively); camphorquinone/amine (0.2/0.8 wt%) or Lucirin-TPO (0.42 wt%); microfillers (55 wt%) and nanofillers (10 wt%). RBLCs covered with the LAVA filter were light-cured for 40 s, either with the dual-peak BluephaseG2 or an experimental device emitting either in the blue or violet visible band. The samples were analyzed by Raman spectroscopy to determine DC. Light transmittance through the filters was measured using a common spectroscopy technique.Results
All the factors studied significantly influenced DC (p < 0.05). RBLCs with increased TEGDMA content exhibited higher DC. Only small differences were observed comparing DC without filters and filters ≤1 mm (p > 0.05). For thicknesses ≥2 mm, significant reductions in DC were observed (p < 0.05). Transmittance values revealed higher filter absorption at 400 nm than 470 nm. A minimal threshold of irradiance measured through the filters that maintained optimal DC following 40 s irradiation was identified for each RBLC formulation, and ranged between 250–500 mW/cm2.Significance
This work confirmed that optimal photopolymerization of RBLCs through indirect restorative materials (≤4 mm) and irradiation time of 40 s is possible, but only in some specific conditions. The determination of such conditions is likely to be key to clinical success, and all the factors need to be optimized accordingly. 相似文献11.
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12.
Annalisa Mazzoni Valeria Angeloni Allegra Comba Tatjana Maravic Milena Cadenaro Arzu Tezvergil-Mutluay David H. Pashley Franklin R. Tay Lorenzo Breschi 《Dental materials》2018,34(2):288-295
Objective
The objectives of the study were to evaluate the ability of a 1-ethyl-3 (3-dimethylaminopropyl) carbodiimide (EDC)-containing primer to improve immediate bond strength of either self-etch or etch-and-rinse adhesive systems and to stabilize the adhesive interfaces over time. A further objective was to investigate the effect of EDC on the dentinal MMPs activity using zymographic analysis.Methods
Freshly extracted molars (n = 80, 20 for each group) were selected to conduct microtensile bond strength tests. The following groups were tested, immediately or after 1-year aging in artificial saliva: G1: Clearfil SE (CSE) primer applied on unetched dentin, pretreated with 0.3 M EDC water-solution for 1 min and bonded with CSE Bond; G2: as G1 but without EDC pre-treatment; G3: acid-etched (35% phosphoric-acid for 15s) dentin pretreated with 0.3 M EDC, then bonded with XP Bond (XPB); Group 4 (G4): as G3 without EDC pre-treatment. Further, gelatinase activity in dentin powder treated with CSE and XPB with and without EDC pre-treatment, was analyzed using gelatin zymography.Results
The use of 0.3 M EDC-containing conditioner did not affect the immediate bond strength of XPB or CSE adhesive systems (p > 0.05), while it improved the bond strength after 1 year of aging (p < 0.05). Pre-treatment with EDC followed by the application of CSE resulted in an incomplete MMPs inactivation, while EDC pretreatment followed by the application of XPB resulted in an almost complete inactivation of dentinal gelatinases.Significance
The μTBS and zymography results support the efficacy of EDC over time and reveal that changes within the dentin matrix promoted by EDC are not adhesive-system-dependent. 相似文献13.
Antonio Gloria Saverio Maietta Massimo Martorelli Antonio Lanzotti David C. Watts Pietro Ausiello 《Dental materials》2018,34(7):1063-1071
Objectives
To assess conceptual designs of dental posts consisting of polyetherimide (PEI) reinforced with carbon (C) and glass (G) glass fibers in endodontically treated anterior teeth.Methods
3D tessellated CAD and geometric models of endodontically treated anterior teeth were generated from Micro-CT scan images. Model C-G/PEI composite posts with different Young’s moduli were analyzed by Finite Element (FE) methods post A (57.7 GPa), post B (31.6 GPa), post C (from 57.7 to 9.0 GPa in the coronal–apical direction). A load of 50 N was applied at 45° to the longitudinal axis of the tooth, acting on the palatal surface of the crown. The maximum principal stress distribution was determined along the post and at the interface between the post and the surrounding structure.Results
Post C, with Young’s modulus decreasing from 57.7 to 9.0 GPa in the coronal–apical direction, reduced the maximum principal stress distribution in the restored tooth. Post C gave reduced stress and the most uniform stress distribution with no stress concentration, compared to the other C-G/PEI composite posts.Significance
The FE analysis confirmed the ability of the functionally graded post to dissipate stress from the coronal to the apical end. Hence actual (physical) C-G/PEI posts could permit optimization of stress distributions in endodontically treated anterior teeth. 相似文献14.
Objective
The aim of this study was to improve the mechanical properties, wear resistance and antibacterial properties of conventional glass ionomer cements (GICs) by fluorinated graphene (FG), under the premise of not influencing their solubility and fluoride ion releasing property.Materials and methods
FG with bright white color was prepared using graphene oxide by a hydrothermal reaction. Experimental modified GICs was prepared by adding FG to the traditional GICs powder with four different weight ratios (0.5 wt%, 1 wt%, 2 wt% and 4 wt%) using mechanical blending. Compressive and flexural strength of each experimental and control group materials were investigated using a universal testing machine. The Vickers microhardness of all the specimens was measured by a Vicker microhardness tester. For tribological properties of the composites, specimens of each group were investigated by high-speed reciprocating friction tester. Fluoride ion releasing was measured by fluoride ion selective electrode methods. The antibacterial effect of GICs/FG composites on selected bacteria (Staphylococci aureus and Streptococcus mutans) was tested with pellicle sticking method.Results
The prepared GICs/FG composites with white color were successfully fabricated. Increase of Vickers microhardness and compressive strength and decrease of friction coefficient of the GICs/FG composites were achieved compared to unreinforced materials. The colony count against S. aureus and S. mutans decreased with the increase of the content of FG. And the antibacterial rate of S. mutans can be up to 85.27% when the FG content was 4 wt%. Additionally, fluoride ion releasing property and solubility did not show significant differences between unreinforced and FG reinforced GICs.Significance
Adding FG to traditional GICs could not only improve mechanical and tribological properties of the composites, but also improve their antibacterial properties. In addition, the GICs/FG composites had no negative effect on the color, solubility and fluoride ion releasing properties, which will open up new roads for the application of dental materials. 相似文献15.
Objective
The aims were to evaluate, via multi-year student cohorts: (i) the incidence of pre-test failures and (ii) shear bond strengths of single- and multi-step adhesives to bovine dentin.Methods
The experiments were performed by cohorts of dental students (2008–2016). Each year the bond strengths of three dental adhesives to bovine dentin were tested. Four self-etching adhesives (Optibond-All-in-One, [OBAIO]; Optibond XTR [OBXTR]); Xeno V [XV]; Xeno V+ [XV+]; a three-step etch-and-rinse-system (Optibond FL, [OBFL]), a self-etch universal adhesive (Scotchbond Universal [SBU]) and a self-etch/etch-and-rinse adhesive (Xeno Select, [XS]) were included in the study. Composite-cylinders were bonded perpendicularly to prepared bovine dentin surfaces. Shear-tests were performed with a universal-testing-machine.Results
Both overall, and within years, XV and XV+ showed significantly (p < 0.01) higher percentages of pre-test failures versus other adhesive systems tested in the period 2008–2014 (OAIO, OBFL, OBXTR). Fewest pre-test failures were observed for OBFL, OBXTR and SBU. Trends in mean bond strengths and Weibull distributions were noted, per adhesive, with trends in the incidence of pre-test failures. Pre-test-failures and bond strengths depended on the air-drying technique. The adhesive systems showed variable technique sensitivity.Multistep bonding systems (Optibond FL and Optibond XTR) showed minimal pre-test failures and high bond strength applied by relatively inexperienced operators and irrespective of the applied air-drying technique. However, two single-step adhesives (OAIO and SBU) showed comparable results to the multi-step systems.Significance
The clinical need for rapid application dentine adhesives can result in varied outcomes with relatively inexperienced operators. These outcomes include both the incidence of pre-test failures as well as the distributions of shear bond strengths achieved, although these measures appear to be related. However, both outcomes are dependent upon the adhesive products utilised and especially upon the applied air pressure (flow rate). Some rapid application systems appear to perform comparably with well-established multi-step adhesives. 相似文献16.
Norbert Krämer Ngoc-Han Nana Bui Khac Susanne Lücker Vitus Stachniss Roland Frankenberger 《Dental materials》2018,34(2):331-340
Objectives
Aim of the present study was to evaluate resin composite adhesion to dental hard tissues affected by molar incisor hypomineralisation (MIH).Methods
94 freshly extracted human molars and incisors (53 suffering MIH) were used. 68 teeth (35 with MIH) were used for μ-TBS tests in enamel and dentin, 26 (18 with MIH) for qualitative evaluation. Specimens were bonded with Clearfil SE Bond, Scotchbond Universal, and OptiBond FL. For MIH affected enamel, additional OptiBond FL groups with NaOCl and NaOCl + Icon were investigated. Beside fractographic analysis, also qualitative evaluations were performed using SEM at different magnifications as well as histological sectioning.Results
Highest μ-TBS values were recorded with dentin specimens (ANOVA, mod. LSD, p < 0.05). Results were independent of adhesive and dentin substrate (p > 0.05). Pre-test failures did not occur in dentin specimens. Sound enamel specimens exhibited significantly higher μ-TBS values than MIH enamel (p < 0.05). The two-step self-etch adhesive (Clearfil SE Bond) and the two-step etch-and-rinse adhesive (Scotchbond Universal) showed the lowest values in affected enamel specimens (p < 0.05) with most pre-test failures (p < 0.05). OptiBond FL on affected enamel showed better results than Clearfil SE Bond (p < 0.05). An additional pre-treatment of affected enamel with NaOCl or NaOCl and Icon did not enhance enamel bonding (p > 0.05), however, it caused less pre-test failures (p < 0.05). Micromorphological analyses revealed that conventional phosphoric acid etching produces a much less pronounced etching pattern in affected enamel and a porous structure as weak link for the resin-enamel bond was identified.Significance
Bonding to porous hypomineralized MIH enamel is the limiting factor in adhesion to MIH teeth. MIH-affected dentin may be bonded conventionally. 相似文献17.
Objective
To evaluate the effect of ionizing radiation from high energy X-ray on properties of restorative materials.Methods
Study materials (3M-ESPE) were: Z250—microhybrid resin-based composite (Filtek Z-250); Z350—nanofilled resin-based composite (Filtek Z-350XT); VIT—resin-modified glass ionomer cement (Vitremer); and KME—conventional glass ionomer cement (Ketac Molar Easymix). Sixty bar-shaped and cylinder-shaped specimens were fabricated from each material. Specimens were light activated (980 mW/cm2, Radii, SDI) for 60 s (3 × 20 s for Z250 and Z350) and 120 s (3 × 40 s for VIT) and thirty specimens from each shape were irradiated (IR) with 1.8 Gy/day for 39 days (total IR = 70.2 Gy). IR and non-irradiated (NI) specimens were evaluated for flexural strength (σ, n = 30) followed by fractography (SEM), diametral tensile strength (DTS, n = 30), hardness (H, n = 10), surface roughness (Ra, n = 10) and chemical composition (n = 3). The IR effect on each material property was statistically analyzed using Student’s t test (α = 0.05). Data from σ and DTS were also analyzed using Weibull statistics.Results
IR significantly increased the mean σ values of VIT and KME and the mean DTS value of VIT (p < 0.05). IR increased Ra and H values for VIT and decreased H value for Z-250 (p < 0.05). The remaining materials and properties were not significantly affected by IR (p > 0.05). There was no significant change on materials composition after IR.Significance
The recommended radiotherapy protocol for head and neck cancer altered some material properties, mainly for glass ionomer cements. Such variations on material properties are not related to chemical composition changes. 相似文献18.
Lorenza Capriotti Katia Greco Gaetano Paolone Maria Teresa Sberna Giuseppe Cantatore 《Giornale Italiano di Endodonzia》2018,32(1):47-50
Aim
The purpose of this study was to evaluate temperature changes generated on radicular surface of extracted monoradicular teeth during ultrasonic removal of fiber posts.Methodology
Forty intact monoradicular teeth, with not less than 15 mm root canal length, with mature apex and without root fractures, were selected. After root canal instrumentation and obturation of teeth, dowel space preparation was obtained at 9 mm length. Samples were randomly divided into two groups according to the type of fiber post used: the first group received quartz fiber posts D.T. Light Post n. 0.5; the second group cemented silica fiber post TECHOLE S with central hole. Removal technique was performed with microblades ultrasonic tips, in particular Start-X #3. Operative protocol provided succession of dry use of ultrasonic inserts for a period of 25 s, air cooling for 25 s and water cooling for 25 s, until posts entire removal. Thermographic measurements were recorded taking photography and videos using Thermal Imaging Camera FLIR-One.Results
Results show that dry use leads to rapid increase in root surface temperature beyond critical limit, while both air cooling and water one decreases it to lower value for both of groups. The best results were obtained by water cooling.Conclusions
Air or water cooling seems to be essential during the use of ultrasonic tips to reduce the risk of periodontal tissue and bone damage due to an excessive temperature raise. It's necessary to increase the samples number to conduct statistical analyses. 相似文献19.
U. Daood J.K.H. Tsoi P. Neelakantan J.P. Matinlinna H.A.K. Omar M. Al-Nabulsi A.S. Fawzy 《Dental materials》2018,34(8):1175-1187
Objective
Collagen fibrils aid in anchoring resin composite restorations to the dentine substrate. The aim of the study was to investigate effect of non-enzymatic glycation on bond strength and durability of demineralized dentine specimens in a modified two-step etch-and-rinse dentine adhesive.Methods
Dentine surfaces were etched with 37% phosphoric acid, bonded with respective in vitro ethanol and acetone adhesives modified with (m/m, 0, 1%, 2% and 3% ribose), restored with restorative composite–resin, and sectioned into resin–dentine slabs and beams to be stored for 24 h or 12 months in artificial saliva. Bond-strength testing was performed with bond failure analysis. Pentosidine assay was performed on demineralized ribose modified dentine specimens with HPLC sensitive fluorescent detection. The structural variations of ribose-modified dentine were analysed using TEM and human dental pulpal cells were used for cell viability. Three-point bending test of ribose-modified dentine beams were performed and depth of penetration of adhesives evaluated with micro-Raman spectroscopy. The MMP-2 and cathepsin K activities in ribose-treated dentine powder were also quantified using ELISA. Bond strength data was expressed using two-way ANOVA followed by Tukey’s test. Paired T tests were used to analyse the specimens for pentosidine crosslinks. The modulus of elasticity and dentinal MMP-2 and cathepsin K concentrations was separately analyzed using one-way ANOVA.Results
The incorporation of RB in the experimental two-step etch-and-rinse adhesive at 1% improved the adhesive bond strength without adversely affecting the degree of polymerisation. The newly developed adhesive increases the resistance of dentine collagen to degradation by inhibiting endogenous matrix metalloproteinases and cysteine cathepsins. The application of RB to acid-etched dentine helps maintain the mechanical properties.Significance
The incorporation of 1%RB can be considered as a potential candidate stabilizing resin dentine bond. 相似文献20.
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