Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 113
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
Dent J (Basel) ; 9(7)2021 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-34356194

RESUMO

BACKGROUND: Durable bonding between resin composite luting agents (CLA) and zirconia is still a matter of controversy. The purpose of this study was to evaluate the effect of water storage on hardness and interfacial strength of three CLA, a non-adhesive (Multilink Automix/ML), an adhesive (Panavia F 2.0/PF) and a self-adhesive (PermaCem 2.0/PC), bonded to polished (CL) and grit-blasted (AL: 50 µm alumina, SJ: Sil-Jet + Monobond Plus silane) monolithic zirconia surfaces. METHODS: CLA specimens (n = 5/cement, condition) were prepared, stored under dry conditions or immersed in water, and Vickers hardness (VH) measurements were obtained at 1 h, 24 h, 1 week and 3 weeks intervals. Optical profilometry was used to determine the roughness parameters (Sa, Sz, Sdr, Sci) of zirconia surfaces (n = 5/treatment). A shear strength test (SBS, n = 10 × 2/cement) was performed to assess the strength and fractography of the cements bonded to zirconia after isothermal water storage and thermal-cycling (TC). RESULTS: PF demonstrated significantly lower VHN after water storage at all time intervals, PC at 1 w, 3 w and ML at 3 w. SJ and AL showed significantly higher values from CL in all roughness parameters. Weibull analysis revealed the following significance in σο ranking within the same material: AL, SJ, ALTC > SJTC, CL > CLTC (PF); SJ, SJTC, AL, ALTC > CL, CLTC (PC) and SJ, SJTC > AL > ALTC > CL, CLTC (ML). Within the same surface treatment subgroups, the significance in σo ranking was PC, ML > PF (before/after TC) for SJ; PC > PF > ML (before TC), PC, PF > ML (after TC) for AL, and PC > PF > ML (before/after TC) for CL. For the m ranking, the only significant difference within each material group was found in PC (AL > ALTC) and for the same surface treatment in AL (PC > ML). CONCLUSION: There are significant differences in the water plasticization susceptibility of the CLA tested; the materials with adhesive monomers were the most affected. Tribo-chemical silica coating combined with a silane coupling agent was the most efficient bonding treatment for the non-adhesive and the self-adhesive materials. The adhesive CLA performed better on alumina-blasted than on tribo-chemically coated surfaces.

2.
J Mech Behav Biomed Mater ; 122: 104655, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34246080

RESUMO

The aim of the present laboratory study was to mechanically characterize the interface between two dental resin-based composite (RBC) increments, and to investigate if elevated temperatures have an influence on the quality of the interface mimicking clinical filling procedure. Four RBCs (CLEARFIL MAJESTY™ Posterior, Kuraray (CMP)/Filtek™ Supreme XTE, 3M (FSX)/Grandio®SO, VOCO (GSO)/VisCalor® bulk, VOCO (VCB)) were tested with a fracture toughness test using Chevron notched beams (KI,CNB) at 23, 37 and 54 °C. KI,CNB specimens (3 × 4x25mm) with a V-shaped notch at the incremental interface were loaded until failure in a 4-point bending set-up. Failure modes were characterized using light microscopy, microstructural interface was analyzed using SEM. Statistical analysis was performed using Kolmogorov-Smirnoff test, two-way ANOVA and Tukey Post-Hoc test (p = 0.05). Mean KI,CNB ranged between 0.73 ±0.14 MPam0.5 (VCB, 23 °C) and 1.11 ± 0.11 MPam0.5 (FSX, 23 °C). The tested conventional highly filled RBCs presented fracture toughness at the incremental interface comparable to the cohesive strength of the bulk materials. VCB showed reduced interfacial fracture toughness at 23 and 37 °C, but performed well at elevated temperature of 54 °C.


Assuntos
Resinas Compostas , Análise do Estresse Dentário , Humanos , Teste de Materiais , Propriedades de Superfície , Temperatura
3.
Dent Mater ; 37(8): 1316-1324, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34144794

RESUMO

OBJECTIVES: The purpose of the study was to evaluate the integrity of dentine type I collagen after self-etching (SE) treatments with strong and mild universal adhesives. METHODS: Coronal dentine specimens (n=10/product) were imaged by optical microscopy and analyzed by ATR-FTIR spectroscopy before and after treatment with 32% phosphoric acid gel (PA-negative control), 17% neutral EDTA (ED-positive control) conditioners and Adhese Universal (AD), Clearfil Universal Bond Quick (CQ), G-Premio Bond (GP), Prelude One (PR) and Scotchbond Universal (SB) adhesives. From the spectroscopic analysis the following parameters were determined: a) Extent of dentine demineralization (DM%) and b) percentage area of the Amide I curve-fitted components of ß-turns, 310-helix/ß-turns, α-helix, random coils, ß-sheets and collagen maturation (R) index. Statistical analysis was performed by one-way ANOVA (DM%), paired t-test/Wilcoxon test (Amide I components) and Spearman correlation coefficient (DM% vs Amide I components) at an a=0.05 level. RESULTS: PA, ED and GP removed the smear-layer and opened tubule orifices, whereas all other treatments removed only the intratubular smear-layer fraction. The ranking of the statistically significant differences in DM% was PA>GP>ED>AD, SB, CQ, PR, with AD being significantly different from PR. Regarding the Amide I components, PA demonstrated a significant reduction in ß-turns, α-helices and an increase in ß-sheets, GP a reduction in ß-turns, AD an increase in ß-turns and random coils, and CQ an increase in ß-turns. PR, SB and ED showed insignificant differences in all the Amide I components. Significant correlations were found between DM%-random coils and DM%-R. SIGNIFICANCE: The universal adhesives used in the SE mode induced none to minimal changes in dentine collagen structure, without evidence of the destabilization pattern observed after conventional phosphoric acid treatments.


Assuntos
Colagem Dentária , Adesivos Dentinários , Condicionamento Ácido do Dente , Colágeno , Cimentos Dentários , Dentina , Teste de Materiais , Cimentos de Resina , Propriedades de Superfície , Resistência à Tração
4.
Eur J Orthod ; 2021 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-33950232

RESUMO

OBJECTIVE: To investigate alterations in the mechanical properties of in-house three-dimensional (3D) printed orthodontic aligners after intraoral ageing. MATERIALS AND METHODS: Sixteen 3D-printed aligners (TC-85DAC resin, Graphy, Seoul, Korea) were used for the purpose of the study, which were divided into 10 control (not used) aligners and 6 materials retrieved from 4 patients after 1-week service (retrieved group). Samples from the control group were analysed by attenuated total reflectance-Fourier-transform infrared (ATR-FTIR) spectroscopy. Samples from control/retrieved groups were embedded resin and subjected to instrumented indentation testing (IIT) to record force-indentation depth curves, calculating the following (as per ISO 14577-1, 2002 standard): Martens hardness (HM), indentation modulus (EIT), and elastic index (ηIT), and the indentation relaxation index (RIT). Differences between control and retrieved 3D-printed aligners were checked with Mann-Whitney/t-tests at an alpha = 5%. RESULTS: ATR-FTIR analysis showed that aligners were made of a vinyl ester-urethane material. The results of the IIT testing were: HM (control: median 91.5 N/mm2, interquartile range [IQR] 88.0-93.0/as-retrieved: median 90.5 N/mm2, IQR 89.0-93.0); EIT (control, mean 2616.3 MPa, standard deviation [SD] 107.0 MPa/retrieved, mean 2673.2 MPa, SD 149.4 MPa); ηIT (control: median 28.6%, IQR 28.2-30.9%/as-retrieved: median 29.0%, IQR 28.7-29.2%); and RIT (control: median 45.5%, IQR 43.0-47.0%/as-retrieved: median 45.1%, IQR 45.0-45.3%). No differences between as-retrieved and control aligners were found for any of the mechanical properties tested (P > 0.05 in all instances). CONCLUSION: The mechanical properties of the in-house 3D-printed aligners tested were not affected after 1 week in service period.

5.
Dent Mater ; 37(3): 413-422, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33353736

RESUMO

OBJECTIVE: To investigate the influence of pre-heating different classes of dental resin composites on viscosity and stickiness at five different temperatures. METHODS: Six flowable, five conventional packable, and one thermo-viscous bulk-fill resin composites were heated up to 54°C in a plate-plate rheometer to determine their complex viscosity. Normal force measurements were carried out for the six packable materials to determine the unplugging force and unplugging work (stickiness) over the same temperature range. Data were analyzed using Kolmogorov-Smirnoff test, one-way ANOVA and Tukey Post Hoc test with α=0.05 as level of significance. RESULTS: At 23°C packable composites showed viscosity between 6.75 and 19.14kPas, while flowable composites presented significantly lower viscosities between 1.31 and 2.20kPas. Pre-heating led to a drop of 30-82% in the viscosity of packable materials. The thermo-viscous material dropped to the level of flowables at 45 and 54°C thus behaving as a packable composite at room temperature with flowable-like viscosity at higher temperatures. No statistically significant differences for viscosity were observed among flowable composites at any temperature. The unplugging force decreased for packable composites, while their unplugging work generally increased at elevated temperature. At 23°C unplugging force was measured between 7.50 and 19.18N, while pre-heating up to 54°C led to values between 2.9 and 6.2N. Regarding unplugging work at 23°C the calculated values were between 3.0 and 8.9×10-3J and at 54°C between 8.8 and 13.0×10-3J. SIGNIFICANCE: Pre-heating significantly reduced viscosity of highly viscous resin composites, while no influence was shown for flowable composites. In general stickiness, measured as unplugging work, increased at elevated temperatures. The thermo-viscous material showed low viscosity comparable to flowable composites at 45 and 54°C, yet its stickiness did not increase significantly compared to the values at 23°C.


Assuntos
Resinas Compostas , Fenômenos Mecânicos , Teste de Materiais , Temperatura , Viscosidade
6.
Int J Prosthodont ; 33(6): 656-662, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33284908

RESUMO

PURPOSE: To investigate the effect of aging on the morphology of the interface between monolithic implant crowns and standardized titanium base abutments. MATERIALS AND METHODS: Four groups of hybrid abutment crowns differing in restorative material (lithium disilicate [LD] or polymer-infiltrated ceramic network [PICN]) and in fabrication procedure of the interfacial zone for luting to a titanium abutment (milled during CAD/ CAM procedure [M] or prefabricated [P]) were formed: LDS-M, LDS-P, PICN-M, and PICN-P (n = 10 each). The morphology of the crown-abutment interface was examined before and after artificial aging using scanning electron microscopy. The total gap length per specimen was measured at both time points, and intergroup (Kruskal-Wallis [KW]) plus pairwise (Wilcoxon Mann-Whitney [WMW]) comparisons were performed (α = .05). RESULTS: Before aging, statistically significant differences in gap length were identified among groups (KW: P = .0369) for PICN-P > LDS-P (WMW: P = .0496) and LDS-M > LDS-P (WMW: P = .0060). The effect of aging among the groups, expressed as an increment of total gap length, was 50% in LDS-M, 30% in LDS-P, 20% in PICN-M, and 30% in PICN-P. After aging, the statistically significant differences in gap length identified among groups (KW: P = .0048) were for PICN-P > LDS-P (WMW: P = .0134); LDS-M > PICN-M (WMW: P = .0204); PICN-P > PICN-M (WMW: P = .0486); and LDS-M > LDS-P (P = .0022). However, comparison of the difference in gap length from before to after aging among the groups was not statistically significant (KW: P = .3549). CONCLUSION: The cementation interfaces of CAD/CAM crowns on standardized titanium base abutments demonstrated a high percentage of gaps before and after thermomechanical loading. The composition of the restorative material and the nature of the interface influenced the interfacial gap dimension.


Assuntos
Cimentação , Titânio , Cerâmica , Desenho Assistido por Computador , Coroas
7.
J Orthod ; 47(3): 223-231, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32615846

RESUMO

OBJECTIVE: The characterisation of surface roughness and energy of contemporary thermoplastic materials used in manufacturing of orthodontic aligners. DESIGN: In vitro, laboratory study. MATERIALS AND METHODS: Four commercially available thermoplastic materials were selected (CA-medium/CAM, Essix-copopyester/COP, Duran/DUR and Erkodur/ERK). Five disks from each, as received, material were tested and subjected to: (1) reflected light microscopy; (2) optical profilometry for the estimation of Sa, Sz, Sq, Sdr, Sc, Sv surface roughness parameters (n = 5); and (3) contact angle measurements with a Zisman series of liquids for the estimation of critical surface tension (γC), total work of adhesion (WA), as well as the work of adhesion due to polar (WP) and dispersion (WD) components employing the Zisman method (n = 5/liquid). Thermoformed disks were prepared against a dental stone model and the roughness parameters were calculated again Statistical analysis was performed by one-way ANOVA/ Tukey multiple comparison test and t-test (a = 0.05). RESULTS: Microscopic and profilometric analyses revealed a smooth surface texture in the as-received materials, but a very rough texture after thermoforming, with insignificant differences within each state. Significant differences in the as-received state were found in the surface energy parameters; CAM showed the lowest γC and the highest WA, WP, WD, whereas ERK with the highest γC demonstrated lower WA. COP and DUR were ranked in an intermediate group regarding γC, with a statistically significant difference in WA between them, mainly attributed to the lower WP of the former. CONCLUSION: Given the differences in surface energy parameters and the lack of roughness differences within the as received or thermoformed groups, it may be concluded that variations in the plaque retaining capacity are anticipated, determined by γC, WA and the WP, WD components.


Assuntos
Subunidade gama Comum de Receptores de Interleucina , Teste de Materiais , Propriedades de Superfície , Molhabilidade
8.
Materials (Basel) ; 13(11)2020 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-32486443

RESUMO

Composite dust generation is most likely a continuous and daily procedure in dental practice settings. The aim of this systematic review was to identify, compile and evaluate existing evidence on interventions and composite material properties related to the production of aerosolized dust during routine dental procedures. Seven electronic databases were searched, with no limits, supplemented by a manual search, on 27 April 2020 for published and unpublished research. Eligibility criteria comprised of studies of any design, describing composite dust production related to the implementation of any procedure in dental practice. Study selection, data extraction and risk of bias (RoB) assessment was undertaken independently either in duplicate, or confirmed by a second reviewer. Random effects meta-analyses of standardized mean differences (SMD) with associated 95% confidence intervals (CIs) were employed where applicable. A total of 375 articles were initially identified, resulting in 13 articles being included in the qualitative synthesis, of which 5 contributed to meta-analyses overall. Risk of bias recordings ranged between low and high, pertaining to unclear/raising some concerns, in most cases. All types of composites, irrespective of the filler particles, released significant amounts of nano-sized particles after being ground, with potentially disruptive respiratory effects. Evidence supported increased % distribution of particles < 100 nm for nanocomposite Filtek Supreme XTE compared to both conventional hybrid Z100MP (SMD: 1.96, 95% CI: 0.85, 3.07; p-value; 0.001) and nano- hybrid Tetric EvoCeram (SMD: 1.62, 95% CI: 0.56, 2.68; p-value: 0.003). For cytotoxicity considerations of generated aerosolized particles, both nanocomposites Filtek Supreme XTE and nanohybrid GradiO revealed negative effects on bronchial epithelial cell viability, as represented by % formazan reduction at 330-400 µg/ml for 24 hours, with no recorded differences between them (SMD: 0.19; 95% CI: -0.17, 0.55; p-value: 0.30). Effective and more rigorous management of dental procedures potentially liable to the generation of considerable amounts of aerosolized composite dust should be prioritized in contemporary dental practice. In essence, protective measures for the clinician and the practices' personnel should also be systematically promoted and additional interventions may be considered in view of the existing evidence.

9.
Materials (Basel) ; 13(11)2020 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-32503174

RESUMO

The purpose of this study was to investigate the surface characteristics and color stability of gingiva-colored composite restorative materials (Anaxgum-ANG, Ceramage-CMG and Gradia Gum-GRG). The microstructure, composition, degree of conversion (DC %) and 3D roughness (Sa, Sz, Sdr, Sc) were examined by LV-SEM/EDS, ATR-FTIR and optical profilometry, respectively. For the color stability (CIE L*, a*, b* system) and hardness (HV), measurements were performed at baseline and after 30 days storage in distilled water, coffee and red wine. The ANG and GRG contain prepolymerized particles in aromatic and aliphatic resin matrices, respectively, whereas CMG contains inorganic zirconia silicate/silica particles, in an aromatic resin matrix, with a smaller particle size and a higher surface area fraction. Urethane monomers were mainly identified in CMG and GRG. The DC% showed statistically insignificant differences between the materials. The same applied for the roughness parameters, except for the greatest Sdr in CMG. ANG showed a color difference (ΔE) of > 3.3 after immersion in all media, CMG in coffee and wine and GRG only in coffee. Sc was the only roughness parameter demonstrating correlations with the ΔL*, Δb* and ΔE*. The HV values showed insignificant differences between the storage conditions per material. There are important differences in the color stability of the materials tested, which were mostly affected by the roughness parameters due to variations in their microstructure.

10.
Materials (Basel) ; 13(8)2020 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-32316154

RESUMO

The aim of this study was to estimate possible differences in the chemical composition and relaxation of orthodontic aligner materials. Four commercially available thermoplastic materials CAM (Scheu-Dental, Iserlohn, Germany), COP (Essix, Dentsply Raintree Essix Sarasota,FL, USA), DUR (Great Lakes Dental Technologies, Tonawanda, NY) and ERK (Erkodent Erich Kopp, Pfalzgrafenweiler Germany) were included in this study. Rectangular strips from each material were prepared according to the manufacturer's instructions and subjected to attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy and stress relaxation characterization. The reduction in applied stress (RAS) after one week was estimated and statistically analyzed by one-way ANOVA at the 0.05 level of significance. All specimens were subjected to optical microscopy before and after stress relaxation testing under transmittance polarized illumination. ATR-FTIR microscopy revealed that all materials are made of polyethylene terephthalate glycol (PETG) while no significant differences were identified in RAS values among materials tested, which ranged from 6%-10% (p ≥ 0.05). All samples illustrated the developments of shear bands during relaxation testing according to optical microscopy findings. The tested materials illustrated similar chemical composition and relaxation behavior and thus no differences in their clinical efficacy are anticipated.

11.
Materials (Basel) ; 13(3)2020 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-32023979

RESUMO

The aim of the study was to evaluate the stability, reactivity, and bond strength with a lithium disilicate ceramic of a self-etch silane primer (Monobond Etch and Prime/MEP). The stability was evaluated by 1H-,31P-NMR spectroscopy (before/after aging), and the reactivity by micro MIR-FTIR spectroscopy on Ge surfaces (0, 1, 24 h) using a prehydrolyzed silane primer (Calibra Silane Coupling Agent/CLB), as a control. The effect of MEP vs. 5% HF-etching on ceramic roughness was assessed by optical profilometry. The shear bond strength (SBS) of a resin composite bonded to polished ceramic surfaces treated with MEP, HF without silane (HF+NS), HF+CLB, and HF+MEP (n = 20) was evaluated after storage in water (A: 37 °C/1 week, B: 5000×/5-55 °C and C: 100 °C/24 h). Aging did not affect the silanol groups of MEP, but only the phosphate co-monomer. Silanols were reactive forming siloxanes, but exhibited lower consumption rate than CLB. HF-etching induced significantly higher values than MEP, in all the roughness parameters tested (Sa, Sz, Sdr, Sc, Sv), with the greatest differences found in Sdr and Sv. For SBS, MEP was inferior to all treatments/storage conditions, except of HF+NS in A, where the values were similar. However, on a HF-etched substrate, MEP provided highest strength and reliability.

12.
Materials (Basel) ; 12(24)2019 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-31847233

RESUMO

The aim of the present study was to quantitatively assess changes in enamel roughness parameters before and after lingual bracket debonding. The lingual surface of 25 sound premolars extracted for orthodontic reasons was studied by 3D optical interferometric profilometry before and after debonding of lingual brackets following enamel finishing (with fine diamond) and polishing (with 12- and 20-fluted carbide burs). The roughness parameters tested were the amplitude parameters Sa and Sz, the hybrid parameter Sdr, and the functional parameters Sc and Sv. The parameter differences (after debonding-reference) were calculated, and statistical analysis was performed via a Wilcoxon signed-rank test. Statistically significantly higher values were observed in all the surface roughness parameters of enamel surfaces after finishing and polishing, with the mostly affected parameter being the Sdr. Under the conditions of the present study, the finishing and polishing instruments used after debonding of lingual noncustomized brackets created a surface texture rougher than the control in all the tested roughness parameters.

13.
Dent J (Basel) ; 7(4)2019 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-31694197

RESUMO

The purpose of this study was to investigate the bonding capacity of composite core build-up materials with prefabricated glass fiber-reinforced posts possessing different coronal morphologies. Five post types (Archimede Line (ARL), Fibrekleer (FBK), Glassix (GLX), Matrix Plus (MTP), and ParaPost White (PRW) and three core build-up materials (ClearfilPhoto Core (CPC), ClearfilDC Core (CDC), ClearfilNew Bond (CNB) of different curing modes (light-, self-, dual-cured respectively) were selected. The coronal part was embedded in the core build-up materials and the specimens were loaded under tensile force up to failure. The reliability (ß) and characteristic life (σο, in Ν) of the debonding force were evaluated by Weibull statistics and the debonded specimens were subjected to failure mode analysis. The results showed that ARL, MPT posts were the most and GLX the least retentive, despite the core build-up material used. CPC provided the highest retention with four posts (FBK, GLX, MTP, and PRW), without statistically significant differences from CDC in two (FBK and MTP) and CNB in one (PRW). CPC and CDC were the most reliable core materials for two posts (ARL and PRW), with no statistically significant difference from CNB in three (FBK, GLX, and MTP). GLX and PRW demonstrated the highest (93%) incidence of post detachment from core, whereas FBK demonstrated the highest percentage of core material fracture, with most fractures occurring in CDC (57%). Post fractures were most prominent in MTP when combined with CNB. The presence of specific coronal retentive features did not essentially ensure increased strength with the core material, due to their delamination.

14.
Materials (Basel) ; 12(21)2019 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-31683544

RESUMO

Tooth wear may be described as a side-effect of occlusal forces that may be further induced by the common use of contemporary prosthetic materials in practice. The purpose of this systematic review was to appraise existing evidence on enamel wear from both in vitro and clinical research and explore whether evidence from these study designs lies on the same direction. Five databases of published and unpublished research were searched without limitations in August 2019 and study selection criteria included in vitro and clinical research on enamel tooth wear. Study selection, data extraction, and risk of bias assessment were done independently and in duplicate. Random effects meta-analyses of standardized mean differences (SMDs) or weighted mean differences (WMDs) with 95% confidence intervals (CIs) were conducted while a Monte Carlo permutation test for meta-regression on the exploration of the effect of the study design on the reported outcomes was planned. A total of 27 studies (23 in vitro and 4 clinical) were eligible while 12 contributed to meta-analyses. Overall, some concerns were raised for the quality of the existing evidence and the potential for risk of bias. Enamel wear (mm) of antagonist teeth was more pronounced when opposed to conventional porcelain compared to machinable ceramics (SMD = 2.18; 95%CIs: 1.34, 3.02; p < 0.001). Polished zirconia resulted in decreased volumetric enamel wear (mm3) of opposing teeth compared to pure natural enamel (SMD = -1.06; 95%CIs: -1.73, -0.39; p = 0.002). Monolithic zirconia showed evidence of enhanced potential for antagonist wear (µm) compared to natural teeth (WMD = 107.38; 95%CIs: 30.46, 184.30; p = 0.01). Study design did not reveal an effect on the tooth wear outcome for the latter comparison when both clinical and in vitro studies were considered (three studies; Monte Carlo test, p = 0.66). In conclusion, there is an overriding need for additional evidence from clinical research to substantiate the findings from the already existing laboratory simulation studies.

15.
Dent J (Basel) ; 7(3)2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31374865

RESUMO

The aim of this study was to evaluate (a) the reactivity of six universal dental adhesives with polished cobalt-chrome (Co-Cr) alloy and zirconia (3Y-TZP) surfaces; and (b) to assess the shear bond strength (SBS) of a resin composite with polished and alumina-blasted surfaces as mediated by these adhesives. The products tested were Adhese Universal (AD), All-Bond Universal (AB), Clearfill Universal Bond (CB), G-Premio Bond (GP), Prelude One (PO) and Scotchbond Universal (SB). The reactivity on polished substrates was evaluated by reflection infrared microscopy (RFTIRM). The roughness parameters of polished and 50 µm alumina grit-blasted surfaces were assessed by optical profilometry. The SBS of the composite bonded to the substrates treated with each adhesive (n = 10/product) was evaluated after 1 week of storage (H2O/37 °C) by Weibull statistics. Evidence of phosphate interaction with polished substrates was obtained by FTIRM, with higher peaks on the alloy. Alumina-blasting increased all roughness parameters with higher values on the alloy. AD, CB were the strongest (σ0) treatments on alloy surfaces and AD, CB, AB, SB on zirconia. GP was the weakest on both substrates and the least reliable (ß) on alloy. On polished alloy GP, PO performed better (σ0), whereas on zirconia there were no significant differences. All adhesives showed more prominent reaction with the Co-Cr alloy than with 3Y-TZP.

16.
Dent Mater ; 35(8): 1082-1094, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31171365

RESUMO

OBJECTIVE: To evaluate the silane status in commercially available products and their bonding capacity with polished glass-ceramic surfaces before and after hydrofluoric (HF) acid-etching. METHODS: The products tested were Calibra Silane Coupling Agent/CS, G-Multi Primer/GM, Kerr Silane Primer/KS, Monobond Plus/MB and Scotchbond Universal Adhesive/SB. The silane status was studied by 13C nuclear magnetic resonance spectroscopy (13C-NMR). The roughness parameters of polished (group A) and HF acid-etched (group B) lithium disilicate glass-ceramic surfaces were measured by optical profilometry (n = 5/group). The interaction of the products with group A and B ceramic surfaces was examined by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). The shear strength (SBS) of a flowable composite bonded to the ceramic surfaces (groups A, B) was assessed before (NS) and after silane treatment (n = 20/group, product). RESULTS: The NMR analysis showed the presence of silanol monomers only in CS. Methoxylated-siloxane adducts were found in GM, silanol-siloxane adducts in MB, SB, and siloxane polymers in KS. Acid-etching greatly increased Sa, Sz, Sdr, Sc and Sv parameters (p < 0.001) and ATR-FTIR analysis demonstrated evidence of bonding with the substrate in CS. Weibull analysis of SBS revealed the following rankings in characteristic life (p < 0.05): CS > SB,KS,MB > GM > NS (group A) and CS > GM > SB,KS,MB,NS (group B). The most reliable treatment in both groups was CS. For the same silane treatment, the SBS of group B were significantly higher from group A. Failures were mainly of adhesive type, except of several partial resin cohesive failures found in group B. SIGNIFICANCE: The chemical bonding capacity of the silanes was highest in products with silanol monomers. Acid-etching increased bond strength to a level that neutralized the silane contribution in products with silanol-siloxane adducts and siloxane polymers, providing thus bond strength values similar to silane-free treatments.


Assuntos
Colagem Dentária , Silanos , Cerâmica , Porcelana Dentária , Ácido Fluorídrico , Teste de Materiais , Cimentos de Resina , Resistência ao Cisalhamento , Propriedades de Superfície
17.
Materials (Basel) ; 12(10)2019 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-31137848

RESUMO

The aim of the study was to evaluate the performance of six commercially available universal dental adhesives: Adhese Universal (ADU), All-Bond Universal (ABU), Clearfil Universal Bond Quick (CBQ), G-Premio Bond (GPB), Prelude One (PRO) and Scotchbond Universal (SBU). The properties tested were: (a) degree of C=C conversion (DC%); (b) Vickers micro-hardness (VHN); (c) extent of oxygen inhibition (OI/µm), all related with the adhesive film properties; (d) extent of dentin demineralisation (DM%), insoluble salt formation (AS%); and (e) shear bond strength (SBS, self-etch mode) related to the adhesive-dentin interactions. Statistical analysis (α = 0.05) was performed by one-way ANOVA and Tukey's test (DC%, VHN, OI, DM% AS%) and Weibull analysis (SBS, σ0-ß). The DC ranged from 67.2-82.5% (all >GPB), OI from 5.6-18.6 µm (SBU > ADU, GPB, ABU > CBQ > PRO), microhardness from 1.1-6.6 VHN (SBU > ADU > ABU > CBQ > PRO > GPB: not measurable), DM from 69.3% (GPB) to 16-12.5% (CBQ, SBU, ADU) and 13.2-10.6% (ABU, ADU, PRO), in homogeneous groups and AS from 26-15.9% (ABU, CBQ > GPB, PRO, ADU, SBU). For SBS the σ0 (characteristic life) ranged from 29.3-16.6 MPa (CBQ, ADU, ABU, SBU > PRO > GPB), the ß (reliability) from 5.1-9.7 (p > 0.05). All failure modes were of mixed type (adhesive and composite cohesive). Although all these adhesives were based on the 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) adhesive monomer, the different co-monomers, solvents and catalysts led to variations in their film properties, reactivity and bonding capacity with dentin.

18.
J Orthod ; 45(4): 269-274, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30392447

RESUMO

OBJECTIVE: The purpose of this study was to assess enamel gloss changes induced by orthodontic bracket bonding with a light-cured composite or a light-cured resin-reinforced glass ionomer cement. SETTING: The Department of Biomaterials, School of Dentistry, National and Kapodistrian University of Athens, Greece. DESIGN: Laboratory study. METHODS: A total of twenty extracted upper human first premolars were included in this study and each tooth served as a control for itself. Their buccal surfaces were subjected to 60o-angle gloss measurement (G%60) with a standardized and secure repeated analysis of the same site. After baseline evaluation, a bracket was bonded on the buccal surface of each tooth. Half of the specimens were bonded with acid-etching and a light-cured composite whereas the other half with a light-cured resin-reinforced glass ionomer cement without prior enamel conditioning. Gloss measurements were repeated after bracket debonding and removal of the composite/glass ionomer cement with an 18-fluted carbide bur. Gloss differences between the two measurement conditions (baseline and post-debonding) were analyzed through linear regression with standard errors derived using the bootstrap method. Level of significance was set at a < 0.05. RESULTS: A statistically significant difference was detected between the tested groups for the outcome of interest. Teeth bonded with light-cured composite exhibited larger enamel gloss changes as compared to resin-reinforced glass ionomer cement (ß = 0.74; 95% CIs: 0.10, 1.38; p = 0.02). CONCLUSIONS: Bracket bonding with two common bonding protocols (acid-etching with a light-cured composite vs. no etching with resin reinforced glass-ionomer cement) and subsequently debonding and adhesive removal with an 18-fluted carbide bur induced enamel gloss changes.


Assuntos
Colagem Dentária , Braquetes Ortodônticos , Resinas Acrílicas , Resinas Compostas , Esmalte Dentário , Cimentos de Ionômeros de Vidro , Humanos , Teste de Materiais , Cimentos de Resina , Propriedades de Superfície
19.
Biomed Res Int ; 2018: 9054301, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30186870

RESUMO

The aim of the study was to comparatively evaluate the fracture strength and mode of root canal treated teeth restored with resin composites with and without posts. The lingual cusps of root canal treated first upper premolars (n = 10/group) were removed down to cervical enamel and restored with the following: group A: glass-fiber post (Glassix) followed by a particulate-filled composite resin (PFC, G-aenial posterior, 3 × 2 mm layers); group B: glass-fiber reinforced composite bulk fill liner (EverX posterior, 4 mm layer) with the PFC (2 mm layer). Specimens were immersed in H2O (1 w/37°C), then subjected to load cycling (50 N/0.2 Hz/200k cycles), and fractured under compressive loading. Failure mode was characterized by stereomicroscopy. Statistical analysis was performed by Mann-Whitney (load) and Chi-square (mode) at a = 0.05. No statistically significant differences (p = 0.273) were found in fracture load between median values of groups A (860 N) and B (1059 N). In group A, 60% of the specimens demonstrated catastrophic root fractures and 40% mixed crown fractures (tooth cusp and restoration), whereas in group B, no root fractures were found, and the failure modes were equally distributed between mixed fractures as above and fracture of the buccal cusp. These differences were statistically significant (p = 0.004). The combination of the glass-FRC bulk fill liner with the PFC diminished the catastrophic root fractures induced by FRC posts, at a similar or higher fracture load.


Assuntos
Resinas Compostas , Forramento da Cavidade Dentária , Fraturas dos Dentes , Análise do Estresse Dentário , Vidro , Humanos , Teste de Materiais , Dente não Vital
20.
Prog Orthod ; 19(1): 12, 2018 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-29732491

RESUMO

BACKGROUND: The purpose of the study is to investigate the effect of the bonding procedure on the mechanical properties of human enamel. METHODS: A total of 20 extracted human premolars were included in this study, with the half of each tooth acting as its own internal control. Embedded and horizontally cut specimens were prepared, and two bucco-orally zones were separated. The first enamel zone of each tooth remained untreated. The opposing zone was subjected to simulated bonding and debonding, including etching with 37% phosphoric acid, bonding with primer and flowable composite resin, and subsequent removal of the composite with an adhesive removal bur. The properties tested were (a) elemental composition by energy-dispersive X-ray analysis, (b) mechanical properties of specimens by instrumented indentation testing (Martens hardness, elastic modulus, and elastic index), (c) enamel morphology by low-vacuum scanning electron microscopy, and (d) molecular composition by Raman microspectroscopy. Statistical analysis was performed by one-way mixed-effects analysis of variance at a = 0.05. RESULTS: No significant differences could be found in the mechanical properties (Martens hardness, elastic modulus, and elastic index) and elemental composition of intact and treated enamel, with the possible exception of Si traces, which were found only in the latter. Raman analysis revealed no differences between the two surface states while shallow grooves and parallel lines were found on the surface of treated enamel by SEM analysis. CONCLUSIONS: Under the limitations of the conditions of the study, there were no mechanical properties' alterations on enamel subjected to orthodontic bonding.


Assuntos
Colagem Dentária/métodos , Descolagem Dentária/métodos , Esmalte Dentário , Condicionamento Ácido do Dente , Dente Pré-Molar , Fenômenos Biomecânicos , Resinas Compostas , Módulo de Elasticidade , Dureza , Humanos , Técnicas In Vitro , Teste de Materiais , Microscopia Eletrônica de Varredura , Espectrometria por Raios X , Análise Espectral Raman , Propriedades de Superfície
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...