共查询到20条相似文献，搜索用时 46 毫秒
1.
Mareike Warkentin Cora Freyse Olaf Specht Detlef Behrend Reinhard Maletz Ralf Janda Peter Ottl 《Dental materials》2018,34(7):1036-1040
Objective
To investigate if Vickers microhardness of dentin and enamel correlated with acoustic velocity c(l) or acoustic reflection from the sample’s top (amplitude).Methods
Eight transversal sections of a sound human tooth were investigated with scanning acoustic microscopy (SAM) and Vickers microhardness measurements. Longitudinal acoustic velocity c(l), amplitude and microhardness MHV were evaluated and for each c(l) test point corresponding amplitude and MHV were linearly interpolated and graphically analyzed. Spearman rank order correlation (rS) was calculated (p < 0.05).Results
c(l) was predominantly 6100–7000 ms?1 in enamel and 3800–4600 ms?1 in dentin and correlated significantly with MHV with 27–420 in enamel and 20–90 in dentin (rs = 0,57). Amplitudes significantly correlated with MHV, too, but even better (rs = 0,77).Significance
Acoustic velocity and amplitudes were appropriate to detect microhardness differences of dentin and enamel and certain value ranges of both could be assigned to certain MHV ranges. Further research is needed to differentiate more precisely between the different hard tooth tissues. 相似文献2.
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3.
Jovana Marjanovic Djordje N. Veljovic Jovana N. Stasic Tatjana Savic-Stankovic Branka Trifkovic Vesna Miletic 《Dental materials》2018,34(5):737-745
Objectives
To evaluate optical properties (color and translucency) of ‘sandwich’ restorations of resin-based composites and esthetically unfavorable dentin restoratives.Methods
Cylindrical ‘dentin’ specimens (8 mm in diameter and 2 mm thick, N = 5/group) were prepared using EverX Posterior (GC), Biodentine (Septodont), experimental hydroxyapatite (HAP) or conventional composites (Gradia Direct Posterior, GC; Filtek Z250 and Filtek Z500, 3M ESPE). Capping ‘enamel’ layers were prepared using composites (Gradia Direct Posterior, Filtek Z250 or Z550) of A1 or A3 shade and the following thickness: 0.6, 1 or 2 mm. Color (ΔE) and translucency parameter (TP) were determined using a spectrophotometer (VITA Easyshade Advance 4.0, VITA Zahnfabrik). Data were statistically analyzed using analysis of variance with Tukey’s post-hoc tests (α = 0.05).Results
TP was greatly affected by layer thickness, whilst ΔE depended on shade and layer thickness of the capping composite. HAP and Biodentine showed significantly lower TP and higher ΔE (deviation from ‘ideal white’) than composites (p < 0.05). Greater TP was seen in EverX_composite groups than in corresponding control groups of the same shade and thickness. TP of composites combined with Biodentine or HAP was below 2, lower than the corresponding control groups (p < 0.05). Within-group differences of ΔE were greatest in HAP_composite groups. EverX_Gradia and EverX_FiltekZ250 combinations showed the most comparable ΔE with the control groups.Significance
A 2 mm thick layer of composite covering dentin restoratives with unfavorable esthetics is recommended for a final ‘sandwich’ restoration that is esthetically comparable to a conventional, mono-composite control restoration. 相似文献4.
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5.
C. Parise Gré D. Pedrollo Lise A.P. Ayres J. De Munck A. Tezvergil-Mutluay R. Seseogullari-Dirihan G.C. Lopes K. Van Landuyt Bart Van Meerbeek 《Dental materials》2018,34(11):1679-1689
Objectives
Dentin biomodification using collagen cross-linkers has been proposed as one of the strategies to improve bond durability of adhesives to dentin. However, literature is not very consistent regarding their benefit, in particular when cross-linkers are applied in clinically realistic application times. This study investigated the effect of three cross-linkers on the mini-interfacial fracture toughness (mini-iFT) of four adhesives bonded to dentin following either etch&rinse (E&R) or self-etch (SE) modes.Methods
60 molars were randomly divided in accordance with the three variables: cross-linker, adhesive and bonding mode (n = 5). The cross-linkers glutaraldehyde (5 wt%; GA), proanthocyanidin (6.5 wt%; PA), or UVA-activated riboflavin (0.5 wt%; RB), and distilled water (control) were applied on dentin for 60 s after acid-etching (E&R) or before self-etching (SE). The 3-step E&R adhesive (3E&Ra) OptiBond FL (Kerr), the 2-step SE adhesive (2SEa) Clearfil SE Bond 2 (Kuraray Noritake) and the universal adhesives G-Premio Bond (GC) and Prime&Bond Active (Dentsply), the latter two employed in both E&R and SE modes, were applied following the respective manufacturer’s instructions. Composite buildups (8 × 8 × 8 mm) were made using Filtek Supreme XTE (3M) prior to 1-week storage in artificial saliva. After the teeth were sectioned into mini-specimens (1.5 × 2.0 × 18 mm), a single notch was prepared at the adhesive–dentin interface. Half of the specimens were immediately loaded until failure by 4-point bending to determine the mini-iFT, while the remaining specimen set was tested upon 6-month aging. Data were statistically analyzed with a linear model (p < 0.05).Results
No significant decrease in mini-iFT was noted only for PA (p < 0.05), while the mini-iFT decreased for both other cross-linkers and in quite a similar way as when solely water (Wa) was applied.Significance
The cross-linker proanthocyanidin (PA) applied in clinically relevant conditions was able to maintain a stable mini-iFT after 6-month aging. The incorporation of UVA-activated riboflavin (RB) and glutaraldehyde (GA) in the dentin-bonding protocol appeared not effective to improve the stability of adhesive–dentin interfaces. 相似文献6.
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7.
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8.
Objective
To measure the effect of simulated human salivary esterases (SHSE) and metalloproteinases (MMP) inhibition on the integrity of restoration–tooth interfaces made from traditional or polyacid-modified resin composites bonded to human dentin by either total-etch or self-etch adhesives.Methods
Resin–dentin specimens, made from traditional (Z250) or polyacid-modified (Dyract-eXtra) composites were bonded to human dentin using total-etch (TE-Scotchbond) or self-etch (SE-EasyBond) adhesives. TE was applied with or without the MMP inhibitor galardin. Specimens were incubated in phosphate-buffer or SHSE (37 °C/pH = 7.0) for up to 180 days, then suspended in a continuous flow biofilm fermenter cultivating biofilms of Streptococcus mutans UA159. Interfacial bacterial penetration, biofilm biomass and viability were measured by confocal laser scanning microscopy and biomarker dyes and used as interfacial biodegradation markers.Results
All specimens showed increased biofilm penetration and biomass with time regardless of incubation condition. SHSE increased bacterial penetration in all experimental samples after 180 days (p < 0.05). Galardin reduced interfacial bacterial ingress and bacterial biomass vs. non-MMP-inhibited TE-bonded specimens (p < 0.05). TE interfaces showed lower interfacial bacterial biomass vs. SE after 90-day and 180-day (p < 0.05). Dyract-eXtra specimens showed lower bacterial cell viability within the interface vs. Z250 (p < 0.05).Significance
The biodegradation of resin–tooth interfaces is accelerated by esterases, modulated by MMP inhibition and is dependent on the material’s chemistry and mode of adhesion. The in vitro bacterial growth model used in this study facilitates the elucidation of differences in interfacial integrity and biostability between different materials and techniques and is suitable for assessment of their performance prior to clinical evaluation. 相似文献9.
L. Medvecky R. Stulajterova M. Giretova J. Mincik M. Vojtko J. Balko J. Briancin 《Dental materials》2018,34(3):442-451
Objectives
To investigate the tubule occlusion and remineralization potential of a novel toothpaste with active tetracalcium phosphate/monetite mixtures under de/remineralization cycling.Methods
Dentin de/remineralization cycling protocol consisted of demineralization in 1% citric acid at pH 4.6 with following remineralization with toothpastes and soaking in artificial saliva. Effectiveness of toothpastes to promote remineralization was evaluated by measurement of microhardness recovery, analysis of surface roughness, thickness of coating and scanning electron microscopy.Results
The novel tetracalcium phosphate/monetite dentifrice had comparable remineralization potential as commercial calcium silicate/phosphate (SENSODYNE®) and magnesium aluminum silicate (Colgate®) toothpastes and significantly higher than control saliva (p < 0.02). Surface roughness was significantly lower after treatment with prepared and SENSODYNE® dentifirice (p < 0.05). The coatings on dentin surfaces was significantly thicker after applying toothpastes as compared to negative control (p < 0.001).Conclusions
The new fluoride toothpaste formulation with bioactive tetracalcium phosphate/monetite calcium phosphate mixture effectively occluded dentin tubules and showed good dentin remineralization potential under de/remineralization cycling. It could replace professional powder preparation based on this mixture. It was demonstrated that prepared dentifrice had comparable properties with commercial fluoride calcium silicate/phosphate or magnesium aluminum silicate dentifrices. 相似文献10.
Objective
This study evaluated the capability of profilometry, microhardness, Optical Coherence Tomography (OCT) and Tandem Scanning Confocal Microscopy (TSM) in characterising the early erosive lesion in polished and natural human enamel in vitro.Methods
Polished (n = 60) and natural (n = 60) human enamel surfaces, were immersed and agitated in 0.3% citric acid erosion at 0 s, 10 s, 30 s, 60 s, 120 s, and 300 s (n = 10). Changes in the surface were measured with 3D-step height change (μm), surface roughness (μm), surface microhardness (KHN), and images were assessed qualitatively with OCT and TSM.Results
Mean (SD) 3D-step height change (μm) was measurable for polished enamel at: 60 s (0.24 ± 0.1), 120 s (1.16 ± 0.71), 300 s (2.01 ± 0.47; p < 0.05); a step height change was not detectable on acid challenged natural enamel surfaces. Mean (SD) surface roughness (μm) of polished enamel was detected at 10 s (0.270 ± 0.013; p < 0.05) and all erosion periods; and in natural enamel detected after 120 s (0.830 ± 0.125) and 300 s (0.800 ± 0.140; p < 0.005). Polished enamel Mean (SD) microhardness (KHN) statistically significantly decreased at all time points (p < 0.001); this was unmeasurable for natural enamel. Qualitative image analysis of both surface types indicated erosive change at the surface level, with progression after increasing erosion time.Significance
The early erosive lesion in polished enamel could be characterised quantitatively surface roughness and microhardness and qualitatively using OCT and TSM; whilst in natural enamel only surface roughness could be utilised. Further investigation of early erosion in natural enamel is required to develop new more clinically relevant models. 相似文献11.
Berdan Aydin Ariene A. Leme-Kraus Cristina M.P. Vidal Thaiane R. Aguiar Rasika S. Phansalkar Joo-Won Nam James B. McAlpine Shao-Nong Chen Guido F. Pauli Ana K. Bedran-Russo 《Dental materials》2019,35(2):328-334
Objectives
The interactivity of proanthocyanidins (PACs) with collagen modulates dentin matrix biomechanics and biostability. Herein, PAC extracts selected based on structural diversity were investigated to determine key PAC features driving sustained effects on dentin matrices over a period of 18 months.Methods
The chemical profiles of PAC-rich plant sources, Pinus massoniana (PM), Cinnamomum verum (CV) and Hamamelis virginiana (HV) barks, as well as Vitis vinifera (VV) seeds, were obtained by diol HPLC analysis after partitioning of the extracts between methyl acetate and water. Dentin matrices (n = 15) were prepared from human molars to determine the apparent modulus of elasticity over 18 months of aging. Susceptibility of the dentin matrix to degradation by endogenous and exogenous proteases was determined by presence of solubilized collagen in supernatant, and resistance to degradation by bacterial collagenase, respectively. Data were analyzed using ANOVA and Games–Howell post hoc tests (α = 0.05).Results
After 18 months, dentin matrices modified by PM and CV extracts, containing only non-galloylated PACs, were highly stable mechanically (p < 0.05). Dentin matrices treated with CV exhibited the lowest degradation by bacterial collagenase after 1 h and 18 months of aging (p < 0.05), while dentin matrices treated with PM showed the least mass loss and collagen solubilization by endogenous enzymes over time (p < 0.05).Significance
Resistance against long-term degradation was observed for all experimental groups; however, the most potent and long-lasting dentin biomodification resulted from non-galloylated PACs. 相似文献12.
Objectives
To assess the precision of optical profilometry for characterising the 3D surface roughness of natural and polished human enamel in order to reliably quantify acid mediated surface roughness changes in human enamel.Methods
Forty-two enamel samples were prepared from extracted human molars and either polished flat or left unmodified. To investigate precision, the variability of thirty repeated measurements of five areas of one polished and one natural enamel sample was assessed using 655 nm Confocal Laser Profilometry. Remaining samples were subjected to forty-five minutes orange juice erosion and microstructural changes were analysed using Sa roughness change (μm) and qualitatively using surface/subsurface confocal microscopy.Results
Enamel surface profilometry from the selected areas revealed maximal precision of 5 nm for polished enamel and 23 nm for natural enamel. After erosion, the polished enamel revealed a 48% increase in mean (SD) Sa roughness of 0.10 (0.07) μm (P < 0.05), whereas in contrast the natural enamel revealed a 45% decrease in mean (SD) roughness of ?0.32 (0.42) μm (P < 0.05). These data were supported by qualitative confocal images of the surface/subsurface enamel.Significance
This study demonstrates a method for precise surface texture measurement of natural human enamel. Measurement precision was superior for polished flat enamel in contrast to natural enamel however, natural enamel responds very differently to polished enamel when exposed to erosion challenges. Therefore, thus future studies characterising enamel surface changes following erosion on natural enamel may provide more clinically relevant responses in comparison to polished enamel. 相似文献13.
Kou Fujita Toru Nikaido Akishi Arita Satoshi Hirayama Norihiro Nishiyama 《Dental materials》2018,34(10):1555-1565
Objective
We determined the amounts of calcium salt of 10-methacryloyloxydecyl dihydrogen phosphate (MDP-Ca salt) and dicalcium phosphate dihydride (DCPD) with an amorphous phase developed during the application of commercial MDP-based all-in-one adhesives to enamel and dentin. This is because the demineralization by MDP and following calcium salt formation of MDP may be limited by an ionic bond formation of MDP to hydroxyapaptite in the enamel and dentin and following intermediary layer formation of MDP, since MDP forms a chemically-stable adsorption layer.Methods
Scotchbond Universal Adhesive, Clearfil Tri–S Bond ND, Clearfil Tri–S Bond ND Quick, G–Bond Plus and our designed MDP-based all-in-one adhesive were used. Enamel and dentin reactant residues of each adhesive were prepared by varying the adhesive application periods: 1, 30 and 60 min, and were analyzed using phosphorous-31 nuclear magnetic resonance and X-ray diffraction.Results
Increasing the adhesive application period to enamel and dentin led to the increased amount of MDP-Ca salt in contrast to amorphous DCPD. In the dentin, each adhesive showed a saturated value on the production amount of MDP-Ca salt when the adhesive was applied more than 30 min. In contrast, in the enamel, each adhesive showed an intermediate value on the saturated production amount of MDP-Ca salt that the respective adhesive exhibited. This is due to MDP employed demineralizes the enamel and dentin until MDP was completely consumed yielding MDP-Ca salt.Conclusion
Commercial MDP-based all-in-one adhesives would not form an intermediary layer of MDP on hydroxyapatite throughout their application period to enamel and dentin.Clinical relevance
The rate of MDP-Ca salt produced by the demineralization of enamel and dentin depends on the components that constitute commercial adhesive more strongly than on the concentrations of MDP and water in the respective adhesive. This is because HEMA-containing adhesive shows a slower production rate of MDP-Ca salt than HEMA-free adhesive in the enamel and dentin samples. 相似文献14.
Gianluca Turco Milena Cadenaro Tatjana Maravić Andrea Frassetto Eleonora Marsich Annalisa Mazzoni Roberto Di Lenarda Franklin R. Tay David H. Pashley Lorenzo Breschi 《Dental materials》2018,34(3):452-459
Objective
The present study evaluated the influence of time, mass and surface area of demineralized dentin collagen matrices on telopeptides release. The hypotheses tested were that the rates of ICTP and CTX release by matrix bound endogenous proteases are 1) not time-dependent, 2) unrelated to specimen mass, 3) unrelated to specimen surface area.Methods
Non-carious human molars (N = 24) were collected and randomly assigned to three groups. Dentin slabs with three different thicknesses: 0.37 mm, 0.75 mm, and 1.50 mm were completely demineralized and stored in artificial saliva for one week. Collagen degradation was evaluated by sampling storage media for ICTP and CTX telopeptidases. Activity of MMPs in the aging medium was evaluated using fluorometric activity assay kit.Results
A statistically significant (p < 0.05) decrease in the release of both ICTP and CTX fragments over time was observed irrespective of the specimen thickness. When data were normalized by the specimen mass, no significant differences were observed. Releases of ICTP and CTX were significantly related to the aging time as a function of surface area for the first 12 h. Total MMP activity, mainly related to MMP-2 and -9, decreased with time (p < 0.05).Significance
Because the release of collagen fragments was influenced by specimen storage time and surface area, it is likely that cleaved collagen fragments closer to the specimen surface diffuse into the incubation medium; those further away from the exposed surface are still entrapped within the demineralized dentin matrix. Bound MMPs can only degrade the substrate within the limited zone of their molecular mobility. 相似文献15.
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16.
Tokinori Kato Tamaki Nakano Yuya Fujita Tomoyuki Kobayashi Hirofumi Yatani 《Journal of prosthodontic research》2018,62(4):490-496
Purpose
To prospectively evaluate morphological changes in the horizontal and vertical dimensions of peri-implant tissue at 1-year post-prosthesis implantation.Methods
Thirty-four patients who had received implants with conical connections in the aesthetic region were included in the follow-up study. Patients had received either traditional delayed implant placement or tissue augmentation with or without immediate implant placement. The horizontal and vertical dimensions of the buccal alveolar bone of the implant and its surrounding soft tissues were then evaluated using cone beam computed tomography.Results
Implants placed alongside tissue augmentation, with or without immediate placement, were as successful as those placed into sites with traditional delayed implant placement. Statistically significant negative correlations were observed between initial horizontal bone thickness and changes in vertical bone height (r = 0.585, p < 0.05) and vertical soft tissue height (r = 0.378, p < 0.05), and between initial horizontal soft tissue thickness and the change in vertical soft tissue height (r = 0.627, p < 0.05).Conclusions
Regardless of the bone and soft tissue augmentation approach, implants with conical connections may effectively preserve peri-implant tissues. However, the thickness of the peri-implant soft tissue is essential, because a change in soft tissue margin level tends to be affected by the thickness of the peri-implant soft tissue rather than the bone width. 相似文献17.
Muhanad M. Hatamleh Xiaohong Wu Ahmad Alnazzawi Jason Watson David Watts 《Dental materials》2018,34(4):676-683
Objective
Surface and mechanical properties of titanium alloys are integral for their use in restoring bone defects of skull and face regions. These properties are affected by the method of constructing and surface treatment of the titanium implant. This study aimed to investigate the effects of titanium finishing protocols on the surface morphology, hardness and biocompatibility of TiAl6V4.Methods
Square shaped TiAl6V4 specimens (ASTM F68) (10 × 10 × 0.5 mm) were divided into seven groups of different surface treatments (n = 10). The treatments included mechanical polishing, sandblasting with AL2O3 (50 μm), immersion in different acids, and/or electro-chemical anodization. Weight loss %; 3D micro-roughness; Knoop micro-hardness, and osteoblast cell attachment and proliferation (after 3 days) were determined for each specimen. Data was analysed using one way ANOVA and Dunett T3 post-hoc tests, and t-test (p < 0.05).Results
Weight loss % was in the range of 1.70–5.60 as mechanical polishing produced the highest weight loss, followed by sandblasting, and combined protocol of mechanical polishing and acid treatment (p < 0.05). Micro-roughness values (μm) were in the range of 2.81–16.68. It was the highest for control specimens (p < 0.05), and smoothest surfaces after combined mechanical polishing and acid treatment; or after electro-chemical treatment (p < 0.05). Micro-hardness values (MPa) ranged 170.90–442.15 as sandblasting with/without acid treatment caused statically significantly the highest values (p < 0.05) while control and mechanically polished specimens had the lowest values (p < 0.05). All treatments produced equally biocompatible surfaces (p > 0.05) after 1 h or 3 days. Furthermore, osteoblast cell proliferation statistically significantly increased after 3 days among each surface treatment (p < 0.05).Significance
Different finishing treatments have variable effect on cranioplasty titanium surface loss, micro-roughness and micro-hardness but constant improved biocompatibility effect. Electro-chemical treatment caused less material loss and produced biocompatible smoothest surface of comparable hardness; hence it can be suitable for cranioplasty titanium surface finishing. 相似文献18.
Objective
Synthesize a new BPA-free monomer for use in methacrylate-based materials and evaluate critical properties of resin and composite materials based on the monomer.Methods
Bis-EFMA was synthesized through reaction between 9,9-bis[4-(2-hydroxyethoxy)-phenyl]fluorene and 2-(methacryloyloxy)ethyl isocyanate. Experimental Bis-EFMA-based resin (Bis-EFMA/TEGDMA = 50/50, wt./wt.) and composite were prepared. Critical properties were investigated according to standard or referenced methods Bis-GMA/TEGDMA (50/50, wt./wt.) resin system, Bis-GMA-based composite and 3 M ESPE Filtek? Z250 were used as controls.Results
FT-IR and 1H NMR spectra confirmed the structure of Bis-EFMA monomer. Cured resin materials: Bis-EFMA-based and Bis-GMA-based resins had nearly the same degree of conversion (p > 0.05); Bis-EFMA-based resin had significantly lower shrinkage, water sorption and solubility, and cytotoxicity than Bis-GMA-based resin (p < 0.05); flexural properties of Bis-EFMA-based resin were all higher than those of Bis-GMA-based resin (p < 0.05). Cured composite materials: There was no significant difference in conversion (p > 0.05); Bis-EFMA-based composite had significantly lower shrinkage and solubility (p < 0.05); water sorption of Bis-EFMA-based composite and Z250 were similar (p > 0.05), but lower compared to Bis-GMA-based composite (p < 0.05); Bis-EFMA-based composite had the deepest curing depth (p < 0.05); Before water immersion, there was no significant difference in flexural strength between Bis-EFMA-based composite and each control composite (p > 0.05), while FS became lower than that of Z250 (p < 0.05), but higher than that of Bis-GMA-based composite (p < 0.05) after water immersion; Flexural modulus of Bis-EFMA-based composite and Z250 were nearly the same (p > 0.05), higher than that of Bis-GMA-based composite (p < 0.05); Bis-EFMA-based composite showed less cytotoxicity than Bis-GMA-based composite and Z250 (p < 0.05).Significance
Bis-EFMA has potential as a substitute for Bis-GMA to prepare Bis-GMA-free dental composites. 相似文献19.
Taichi Iwashita Atsushi Mine Mariko Matsumoto Hayaki Nakatani Mami Higashi Asuka Kawaguchi-Uemura Tomoshige Kabetani Yuko Tajiri Dai Imai Ryosuke Hagino Jiro Miura Takuya Minamino Hirofumi Yatani 《Journal of prosthodontic research》2018,62(4):449-455
Purpose
The purpose of this study was to evaluate drying methods for post space dentin bonding in a direct resin composite core build-up method.Methods
Experiment 1: Four root canal plastic models, having diameters of 1.0 or 1.8 mm and parallel or tapered shapes, were prepared. After drying each post space using three drying methods (air drying, paper-point drying, or ethanol drying, which involves filling the space with 99.5 vol% ethanol followed by air drying), the residual liquid in the models was weighed. Experiment 2: Thirty endodontically treated single-root teeth were dried using the above-described drying methods and filled with dual-cure resin composite. The bonded specimens were sectioned into square beams of approximately 1 mm2 for microtensile bond strength (μTBS) testing. Nine teeth were observed through transmission electron microscopy (TEM) and micro computed tomography (μCT). The weight of residual liquid and μTBS were analyzed using Scheffé multiple comparison.Results
Experiment 1: The results of air drying were significantly different from those of paper-point drying (p < 0.001) and ethanol drying (p < 0.001), and no significant difference was observed between paper-point drying and ethanol drying. Experiment 2: The μTBS significantly decreased in the order of ethanol drying, paper-point drying, and air drying (air drying/ethanol drying: p < 0.001, air drying/paper-point drying: p = 0.048, ethanol drying/paper-point drying: p = 0.032). TEM and μCT observation revealed a sufficient dentin/adhesive interface in the ethanol drying group.Conclusions
Ethanol drying was found to be more effective for post space dentin bonding, as compared with air drying and paper-point drying. 相似文献20.
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