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1.
Braz Oral Res ; 34: e018, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32187304

RESUMO

The objective of this study was to evaluate the influence of hydrofluoric acid (HF) concentration, etching time, and application of phosphoric acid (PA) followed by neutralization with sodium bicarbonate on the bond strength between a feldspar ceramic and resin cement. Thus, 80 blocks (10 x 12 x 2 mm) of glass ceramic (VM - Vita Mark II - Vita Zahnfabrik) were made and randomly assigned to eight groups (n = 10) according to the factors: HF concentration (5 and 10%), etching time (60 and 120 s), and use of phosphoric acid (PA) (with and without). According to the experimental group, 37% PA (Condac, FGM) was applied after HF etching for 60s. Afterwards, samples were immersed in sodium bicarbonate for 1 min then in an ultrasonic bath in distilled water (5 min) for cleaning. After surface bonding treatment, cylinders (Ø = 2 mm; h = 2 mm) of dual resin cement (AllCem / FGM) were made in the center of each block. The samples were then stored in water (37ºC) for 90 days and submitted to the shear bond test (50 KgF, 1 mm/min). Failure analysis was performed by stereomicroscope and scanning electron microscopy. Data (MPa) were analyzed with 3-way ANOVA and Tukey's test. Only the factor "HF concentration" was significant (p = 0.02). Most failures were of cohesive in ceramic (40%) and mixed types (42.5%). The 10% HF resulted in higher shear bond strength value than the 5% HF. Surface cleaning with phosphoric acid followed by sodium bicarbonate and HF time (60 or 120 seconds) did not influence the resin bond strength to feldspar ceramic.


Assuntos
Silicatos de Alumínio/química , Colagem Dentária/métodos , Ácido Fluorídrico/química , Ácidos Fosfóricos/química , Compostos de Potássio/química , Análise de Variância , Porcelana Dentária/química , Teste de Materiais , Metacrilatos/química , Microscopia Eletrônica de Varredura , Valores de Referência , Reprodutibilidade dos Testes , Cimentos de Resina/química , Resistência ao Cisalhamento/efeitos dos fármacos , Silanos/química , Propriedades de Superfície , Fatores de Tempo
2.
Braz Oral Res ; 34: e004, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32022223

RESUMO

The aim of this study was to analyze the structural, morphological and mechanical properties of two different lithium disilicate glass-reinforced ceramics for CAD-CAM systems (IPS e.max CAD and Rosetta SM). Five methodologies were used for both ceramics: microstructure (n = 2) was analyzed using x-ray diffraction (XRD); morphological properties (n = 2) were analyzed by scanning electron microscopy (SEM), with and without hydrofluoric etching; porosity (n = 3) was assessed using 3D micro-computed tomography (micro-CT); flexural strength was measured (n =1 0) using the three-point bending test; and bond strength was determined with self-adhesive resin cement (n = 10), using a microshear bond test. After performing all the tests, the data were analyzed using t-Student test and two-way ANOVA. All the tests used a significance level of α = 0.05. High peak positions corresponding to standard lithium metasilicate and lithium disilicate with similar intensities were observed for both ceramics in the XRD analysis. Morphological analysis showed that the crystalline structure of the two ceramics studied showed no statistical difference after acid etching. Additionally, no significant differences were recorded in the number or size of the pores for the ceramics evaluated. Moreover, no differences in flexural strength were found for the ceramic materials tested, or in the bond strength to ceramic substrates for the resin cements. Based on the study results, no significant differences were found between the two CAD-CAM lithium disilicate glass-reinforced ceramics tested, since they presented similar crystalline structures with comparable intensities, and similar total porosity, flexural strength and bond strength.


Assuntos
Cerâmica/química , Desenho Assistido por Computador , Porcelana Dentária/química , Vidro/química , Análise de Variância , Colagem Dentária/métodos , Resistência à Flexão , Teste de Materiais , Microscopia Eletrônica de Varredura , Porosidade , Valores de Referência , Reprodutibilidade dos Testes , Cimentos de Resina/química , Resistência ao Cisalhamento , Propriedades de Superfície , Difração de Raios X
3.
Braz Oral Res ; 33: e121, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31939500

RESUMO

The objective of the study was to analyze the surface area (SA) of the wear caused by simulated chewing on human enamel and opposing restorative material, namely: composite resin (CR), porcelain fused to metal (PFM), lithium disilicate (LD), or monolithic zirconia (MZr). Forty-eight premolars were selected as enamel specimens and divided randomly into 4 groups (n = 48; n =12) used as antagonists in chewing simulation (250,000 loading cycles) against one of the four selected test materials. Enamel and material specimens were scanned and evaluated under digital microscope, and wear SA (mm2) were recorded. Descriptive statistics, paired t-test, one-way ANOVA, and post-hoc Tukey-HSD tests were used for statistics (p < 0.05). The smallest and largest SA were exhibited by enamel against LD (0.80 mm2) and PFM (1.74 mm2), respectively. PFM (3.48 mm2) showed the largest SA and CR (2.28 mm2) showed the smallest SA. Paired t-test for SA values showed significant difference (p < 0.05) in all wear comparisons between materials and enamel antagonists. The wear of materials were greater than that of their respective enamel antagonists (p < 0.05). One-way ANOVA of the logarithmic means of wear SA revealed significant differences (P<0.05). Post-hoc Tukey test revealed significance for PFM (p < 0.05) with other materials. Wear of all test materials was greater compared to the wear of enamel antagonists. PFM and LD caused the largest and the smallest enamel wear, respectively. CR, LD, and MZr are more resistant than PFM to wear after simulated chewing against enamel.


Assuntos
Resinas Compostas/química , Esmalte Dentário/química , Porcelana Dentária/química , Mastigação , Ligas Metalo-Cerâmicas/química , Desgaste dos Dentes/etiologia , Zircônio/química , Adolescente , Adulto , Análise de Variância , Polimento Dentário/métodos , Humanos , Processamento de Imagem Assistida por Computador , Teste de Materiais , Microscopia/instrumentação , Valores de Referência , Estatísticas não Paramétricas , Propriedades de Superfície , Adulto Jovem
4.
Niger J Clin Pract ; 23(1): 1-6, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31929199

RESUMO

Objective: The aim of this study was to evaluate the marginal adaptation and fracture resistance of feldspathic and Polymer-Infiltrated Ceramic Network (PICN) CAD/CAM endocrowns for maxillary premolars. Materials and Methods: Twenty extracted human permanent maxillary premolars were randomly divided into two groups (n = 10); Group CEREC (GC), which was produced by feldspathic ceramic and the Group Enamic (GE), which was produced by PICN. All teeth were endodontically treated and decoronated horizontally at 2 mm above the cemento-enamel junction. Endocrown preparations were done with 4 mm depth into the pulp chamber. Endocrowns were manufactured using CAD/CAM from ceramic blocks. Following adhesive cementation, all specimens were subjected to thermocycling. Marginal adaptation evaluated under SEM at 200 × magnification. Each specimen was fixed in a universal testing machine and a compressive load was applied at 45° to long axis of the teeth until failure. Failure load was recorded and failure modes were evaluated. Statistical analyses were performed with SPSS 19.0 software and data were compared using Mann-Whitney U test. Results: There were no significant differences in the marginal adaptation between two groups (P > 0.05). GE presented significantly higher fracture resistance when compared to GC (P < 0.05). Failure pattern was similar and characterized by the tooth-ceramic fracture on the force-applied side. Conclusions: CAD/CAM fabricated feldspathic ceramic and PICN endocrowns provide sufficient marginal adaptation, but the PICN endocrowns shows higher fracture resistance than the feldspathic ceramic endocrowns.


Assuntos
Dente Pré-Molar/fisiopatologia , Cerâmica/química , Coroas , Porcelana Dentária/química , Planejamento de Prótese Dentária/métodos , Polímeros , Fraturas dos Dentes/fisiopatologia , Desenho Assistido por Computador , Preparo da Cavidade Dentária/métodos , Porcelana Dentária/uso terapêutico , Planejamento de Prótese Dentária/efeitos adversos , Falha de Restauração Dentária , Análise do Estresse Dentário , Humanos , Teste de Materiais , Cimentos de Resina , Estresse Mecânico , Colo do Dente/lesões
5.
Braz Oral Res ; 33: e041, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31508723

RESUMO

The objective of this study was to evaluate the effect of the hydrofluoridric acid (HF) concentration and time of acid conditioning on bond strength of three glass ceramics to a resin cement. Thus, fifty blocks (10 mm x 5 mm x 2 mm) of each ceramic (LDCAD: IPS e.max CAD; LCAD: IPS Empress CAD and LDHP: IPS e.max Press) were made and embedded in acrylic resin. The surfaces were polished with sandpaper (#600, 800, 1000, and 1200 grits) and blocks were randomly divided into 15 groups (n = 10) according to the following factors: Concentration of HF (10% and 5%), conditioning time (20 s and 60 s) and ceramic (LDCAD, LDHP, and L). After conditioning, silane (Prosil / FGM) was applied and after 2 min, cylinders (Ø = 2 mm; h = 2 mm) of dual resin cement (AllCem / FGM) were made in the center of each block using a Teflon strip as matrix and light cured for 40 s (1,200 mW/cm2). Then, the samples were thermocycled (10,000 cycles, 5/55°C, 30s) and submitted to the shear bond test (50 KgF, 0.5 mm/min). The data (MPa) were analyzed with 3-way ANOVA and Tukey's test (5%). Failure analysis was performed using a stereomicroscope (20x) and a scanning electron microscope (SEM). ANOVA revealed that the "concentration" factor (p = 0.01) and the interaction "acid concentration X ceramic" (p = 0.009) had a significant effect, however, the "ceramic" (p = 0.897) and "conditioning time" (p = 0.260) factors did not influence the results. The LDHP10%60s (10.98 MPa)aA* group presented significantly higher bond strength than LDHP10%20s (6.57 MPa)bA, LCAD5%20s (6,90 ±3,5)aB and LDHP5%60s (5.66 ± 2,9MPa)aA* groups (Tukey). Failure analysis revealed that 100% of specimens had mixed failure. In conclusion, etching with 5% HF for 20 seconds is recommended for lithium disilicate and leucite-reinforced CAD/CAM ceramics. However, for pressed lithium disilicate ceramic, 10% HF for 60 s showed significantly higher bond strength to resin cement.


Assuntos
Condicionamento Ácido do Dente , Cerâmica/química , Colagem Dentária/métodos , Ácido Fluorídrico/administração & dosagem , Porcelana Dentária/química , Análise do Estresse Dentário , Ácido Fluorídrico/química , Teste de Materiais , Microscopia Eletrônica de Varredura , Cimentos de Resina/química , Resistência ao Cisalhamento , Propriedades de Superfície , Fatores de Tempo
6.
Braz Oral Res ; 33: e009, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31508728

RESUMO

This study investigates the color correspondence of resin cements and try-in pastes, and the color stability of bonded lithium disilicate ceramic disks. Resin composite disks were fabricated (n = 36) to serve as the background for lithium disilicate disks prepared in two thicknesses (0.5 and 1.0 mm, n = 18 each). Two brands were used for try-in and cement procedures: Variolink Veneer and AllCem Veneer. For baseline, water was applied between the ceramic disks and their respective backgrounds to achieve the control group. This set was subjected to color measurement using an intraoral measurement device (T0). The try-in was inserted between background and ceramic, and this set was subjected to color measurement (T1). After adhesive procedures, the ceramic disk was placed under cement, and color measurement was performed with uncured cement (T2) and 24 h after light-curing (T3). Each set was immersed in distilled water and thermal-cycled, with color measurement being performed after 10,000 (T4) and 20,000 (T5) cycles. Color differences were calculated by CIELab (rEab) and CIEDE2000 (rE00). Data were analyzed by two-way ANOVA for repeated measurements and Tukey's test (α=5%). There was color correspondence of try-in and resin cement for the Variolink system, regardless of the ceramic thickness (p > 0.05). For the AllCem system, the thickness significantly influenced the color measurement (p < 0.001). The Variolink system also demonstrated color stability after 20,000 thermal cycles with rEab < 3.46 and rE00 < 2.25. It was concluded that the color correspondence between a try-in and its respective cement may vary according to resin cement composition.


Assuntos
Cor , Porcelana Dentária/química , Cimentos de Resina/química , Cerâmica/química , Facetas Dentárias , Técnicas In Vitro , Teste de Materiais , Pomadas/química
7.
Biomed Mater Eng ; 30(4): 365-374, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31476141

RESUMO

BACKGROUND: Ceramic crown that fires the layering porcelain on zirconia corping is starting to be used due to aesthetic requirements. However, many ceramics are used, but wear characteristics are often unknown. OBJECTIVE: This study was performed to investigate the wear of human enamel by porcelains, and to determine the influence of porcelain hardness, surface roughness and crystal of porcelain on the enamel wear. METHODS: Enamel specimens were prepared from extracted human molar teeth. Porcelain specimens were prepared from Deguceram Gold, Vita Omega 900, and Cercon Ceram Kiss. Enamel wear volume was calculated and the porcelain wear depth, surface roughness and Vickers hardness was measured. Moreover, the observation of a crystal by scanning electron microscope and the crystal by X-ray diffraction were identified. RESULTS: Omega 900 showed the smallest enamel wear volume and porcelain wear depth. The Vickers hardnesses of Omega 900 and Cercon Ceram Kiss were almost identical. Leucite was detected from Deguceram Gold and Omega 900, and Silica and Silicon Nitride were detected from Cercon Ceram Kiss. CONCLUSIONS: The enamel wear is influenced not by the hardness of the porcelain but by the surface roughness, the size and shape of the crystal.


Assuntos
Coroas , Esmalte Dentário/anatomia & histologia , Porcelana Dentária/química , Coroas/efeitos adversos , Cristalização , Esmalte Dentário/química , Porcelana Dentária/efeitos adversos , Desgaste de Restauração Dentária/efeitos adversos , Dureza , Humanos , Teste de Materiais , Propriedades de Superfície , Difração de Raios X
8.
BMC Oral Health ; 19(1): 178, 2019 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-31387557

RESUMO

BACKGROUND: The aim of this study was to evaluate the effect of universal adhesives (UA) and silane on the microtensile bond strength (µTBS) of resin cement to a hybrid ceramic Vita Enamic (VE). METHODS: VE specimens were acid etched using hydrofluoric acid (HF) and were assigned to three groups (n = 10) based on the applied bonding technique. In group 1 (S), a silane-based primer was used as a surface treatment prior to the application of a resin cement (Variolink Esthetic DC). In group 2, a silane-containing UA, Clearfil Universal Bond (CUB) was used for the surface treatment, and in group 3, A silane-free UA, Tetric N-Bond Universal (TNU) was used for surface treatment. Resin cement build-ups were prepared. The bonded specimens were sectioned into resin-ceramic beams. Half of the beams of each group were stored for 24 h at 37 °C and the other half were subjected to a thermo-cycling aging. The microtensile bond strength (µTBS) was measured at a crosshead speed of 0.5 mm/min. Failure modes were assessed accordingly. Data were analyzed using a) two-way analysis of variance ANOVA followed by one-way ANOVA and Tukey tests between groups and b) independent t-test to detect differences (α = 0.05) for each group. The surface topographies of the ceramic surface were evaluated using scanning electron microscopy. RESULTS: The results showed that silane-based primer (S) application resulted in significantly higher (p < 0.05) µTBS values after 24 h and after thermocycling compared to both silane-containing UA (CUB) and silane-free UA (TNU). The µTBS values of all groups were significantly reduced after thermocycling. No statistically significant difference was observed between the µTBS of CUB and TNU after 24 h. However, TNU showed significantly higher µTBS after thermocycling. Different failure modes were observed, and adhesive failure was the most common in all groups. Marked surface topographic changes were observed following HF etching. CONCLUSION: It is concluded that, the UAs tested cannot be recommended as substitutes to the silanization of Hybrid ceramic.


Assuntos
Cerâmica/química , Colagem Dentária , Cimentos de Resina/química , Condicionamento Ácido do Dente , Cimentos Dentários , Corrosão Dentária/métodos , Porcelana Dentária/química , Análise do Estresse Dentário , Estética Dentária , Humanos , Teste de Materiais , Microscopia Eletrônica de Varredura , Propriedades de Superfície , Resistência à Tração
9.
J Appl Oral Sci ; 27: e20180351, 2019 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-31365707

RESUMO

OBJECTIVE: Since the transmittance of ceramics can influence the degree of conversion (DC) of resin cements, ceramics composition and shade should be considered in the selection of resin cement. This in vitro study aimed to evaluate the effect of the transmittance of different composition, opacities and shades of ceramics on the degree of conversion of two dual-cured resin cements. METHODOLOGY: Sixty discs were prepared from low translucency (LT) and medium opacity (MO) lithium disilicate ceramic, and zirconia ceramic (Z). Each group was subdivided into 5 subgroups (n=4) in shades A2, A3.5, B2, C2 and D3. The transmittance measurement was performed in a spectrophotometer. The Variolink II and Rely X U200 resin cements were photoactivated by LED (1400 mW/cm2) for 40 s through the ceramic discs and without the discs (control group). The DC was measured with infrared FTIR spectroscopy, immediately after light activation. Data were analyzed with Kruskall-Wallis and one-way ANOVA, following post-hoc comparisons by Tukey test and Pearson's correlation test (P<0.05). RESULTS: LT ceramic exhibited higher transmittance values compared to MO and Z ceramics. LTA2 and LTB2 showed statistically higher transmittance values compared to MOA2, MOA3.5 and ZA3.5. For Variolink II, the ceramic interposition did not influence the DC, since there were no statistical differences between groups with ceramic interposition and the control group. For Rely X U200 cement, the interposition of some ceramics types/shades (LTA3.5, MOA2, MOA3.5 and ZA3.5) significantly decreased the DC values compared to control group. A positive correlation was found between the ceramic transmittance and DC values of both tested cements. Conclusions. The transmittance and DC values of the cements were influenced by composition and shades of the ceramics. The higher the transmittance of ceramics, the higher the DC values for both cements.


Assuntos
Porcelana Dentária/química , Cimentos de Resina/química , Zircônio/química , Análise de Variância , Luzes de Cura Dentária , Cura Luminosa de Adesivos Dentários , Teste de Materiais , Transição de Fase , Polimerização , Valores de Referência , Reprodutibilidade dos Testes , Espectrofotometria/métodos , Estatísticas não Paramétricas
10.
Biomed Res Int ; 2019: 9130806, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31309119

RESUMO

In the article has been presented an analysis of susceptibility of selected dental materials, made in the CAD/CAM technology. The morphology and structural properties of selected dental materials and their composites were determined by using XRPD (X-ray powder diffraction) techniques, as well as the IR (infrared) spectroscopy. Moreover, an adhesion as well as development of biofilm by oral microorganisms has been studied. It has been shown that a degree of the biofilm development on the tested dental materials depended on microorganism genus and species. Streptococcus mutans has demonstrated the best adhesion to the tested materials in comparison with Candida albicans and Lactobacillus rhamnosus. However, the sintered materials such as IPS e.max® and the polished IPS e.max® have showed the best "anti-adhesive properties" in relation to S. mutans and L. rhamnosus that have not formed the biofilm on the polished IPS e.max® sample. Furthermore, S. mutans have not formed the biofilm on both surfaces. On the contrary to S. mutans and L. rhamnosus, C. albicans has demonstrated the adhesive properties in relation to the above-mentioned surfaces. Moreover, in contrast to S. mutans and C. albicans, L. rhamnosus has not formed the biofilm on the polished IPS Empress material.


Assuntos
Biofilmes/crescimento & desenvolvimento , Candida albicans/fisiologia , Desenho Assistido por Computador , Porcelana Dentária/química , Lactobacillus rhamnosus/fisiologia , Teste de Materiais , Streptococcus mutans/fisiologia , Propriedades de Superfície
11.
PLoS One ; 14(7): e0219608, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31295331

RESUMO

To study the relationship between the glazed pottery from southern China and the lead-glazed pottery in northern China in the Han Dynasty (202BC-220AD), 34 samples unearthed from Shangyu(), Zhejiang Province have been studied by LA-ICP-AES, SEM/EDS and XRD. The results showed that these samples included the typical lead-glazed pottery, the proto-porcelain and the glazed pottery using both lead and calcium as glaze fluxing agents. Previously, the lead-glazed pottery type was considered as the main northern products during the Han dynasty while the calcium-glazed pottery type or the proto-porcelain was the representative of the south of China. However, apart from the two typical types above, a new variety of glaze categorized as the calcium-lead glaze was discovered in the samples from Shangyu. This indicates that there were technology exchanges and amalgamation of lead-glaze and calcium-glaze between the south and the north during the Han Dynasty. As a result, a new type of glazed potteries with both features was created, which had a more beautiful appearance than the proto-porcelain but perhaps had some undesirable aspects. The manufacturing process of the new variety might also lay foundations for the invention of celadon.


Assuntos
Cálcio/química , Cerâmica/história , Porcelana Dentária/história , Chumbo/química , Cerâmica/química , China , Porcelana Dentária/química , História Antiga , Humanos , Teste de Materiais , Propriedades de Superfície
12.
Photobiomodul Photomed Laser Surg ; 37(7): 442-450, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31265379

RESUMO

Objective: This study compared the effects of different surface treatments on the surface roughness (Ra), and shear bond strength (SBS) of resin cement to yttria-stabilized tetragonal zirconia (Y-TZP) ceramic and nickel-chromium (Ni-Cr) base metal alloy, respectively. Materials and methods: Thirty disk-shaped specimens (3 mm height and 10 mm diameter) of each material (Y-TZP and Ni-Cr) were prepared. Both zirconia and metal specimens were randomly assigned to three equal groups, according to the surface treatments (n = 10): sandblasting, sandblasting + Er:YAG laser, and sandblasting + Nd:YAG laser. Resin cement cylinders (4 mm diameter and 3 mm thickness) were placed on each specimen. The SBS tests were performed at a 1 mm per minute crosshead speed through a knife-edge rod after 5000 thermal cycles. The Ra (µm) of the specimens was measured using a profilometer and evaluated topographically by atomic force microscopy and scanning electron microscopy. Analysis of variance, followed by Tukey's honestly significant difference, in addition to the Kruskal-Wallis test, followed by the Mann-Whitney U test, were used for statistical analysis (α = 0.05). Results: Combined sandblasting and laser treatment of the metal groups led to statistically higher Ra values than sandblasting alone (p < 0.05). For Y-TZP, there were no significant differences between the Ra values of the subgroups (p > 0.05). The SBS of the sandblasted metal group was significantly higher than the other two laser-irradiated groups, whereas the SBS of sandblasted zirconia was only significantly higher than the Nd:YAG laser-irradiated group (p < 0.05). Conclusions: Combined laser and sandblasting surface treatments resulted in rougher surfaces than sandblasting alone, especially for the metal specimens. Sandblasting, alone, improved the SBS of resin cement in both metal and zirconia, compared with the laser and sandblasting treatments, combined.


Assuntos
Ligas de Cromo/química , Ligas Dentárias/química , Colagem Dentária/métodos , Corrosão Dentária/métodos , Porcelana Dentária/química , Lasers de Estado Sólido , Cimentos de Resina/química , Ítrio/química , Zircônio/química , Teste de Materiais , Microscopia de Força Atômica , Microscopia Eletrônica de Varredura , Resistência ao Cisalhamento/efeitos da radiação , Propriedades de Superfície
13.
Biomed Res Int ; 2019: 7485409, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31355280

RESUMO

Objective of Study: To investigate, using the FEM, the influence of different notching angles on a zirconium dioxide coping with the aim of establishing the optimal connection conditions with veneering ceramic. Materials and Methods: To calculate the stresses in the connection between zirconia coping and veneering ceramic, a model comprising grooves cut perpendicular was adopted. Such a notch profile was used to design the shape and spacing of the grooves on an FEM model simulating a zirconium dioxide coping. For discretization purposes we used twenty-node solid BRICK elements featuring intermediate nodes with three degrees of freedom in each node. The model was divided into 117 745 finished elements and 439 131 nodes. The problem was solved with a GLU type contact. The same load F = 1N divided by the number of nodes on the external surface was applied to each node of the outer surface of the base. In subsequent computing variants the F load changed the orientation by angle α from 0° to 45° every 15°. Results: The highest level of material strain occurs at angle α = 0° σred  max =309 MPa and the lowest at angle α = 45° σred  max =220 MPa. The highest positive stress pressure occurs at angle α = 0° pmax=251 MPa, pmin=-354 MPa and the lowest at angle α = 15°, pmax=171 MPa, pmin=-186 MPa. In the case of tangential stresses on the coping-veneering ceramic connection, the highest values were noted at angle α = 15° τmax=44,4 MPa and the lowest at angle α = 45° τmax=32,7 MPa. Conclusions: To reduce the load on the zirconia-veneering ceramic connection, the notches should be made at an angle of α = 45°.


Assuntos
Cerâmica/química , Porcelana Dentária/química , Zircônio/química , Análise de Elementos Finitos , Teste de Materiais , Estresse Mecânico
14.
J Appl Oral Sci ; 27: e20180297, 2019 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-31166548

RESUMO

INTRODUCTION: Polymer-based composite materials have been proposed as an alternative for single unit restorations, due to their resilient and shock absorbing behavior, in contrast to the brittleness of ceramic materials that could result in failure by fracture. OBJECTIVE: To evaluate the fatigue strength and damage modes of monolithic posterior resin nanoceramic and lithium disilicate glass ceramic crowns. METHODOLOGY: Twenty-six resin nanoceramic (RNC) and lithium disilicate glass ceramic (LD) 2 mm monolithic crowns (n=13) were cemented on composite resin replicas of a prepared tooth and subjected to cyclic load with lithium disilicate indenters for 2 million cycles. Specimens and indenters were inspected every 500,000 cycles and suspended when presenting fractures or debonding. Surviving specimens were embedded in epoxy resin, polished and subsurface damage was analyzed. Specimens presenting fractures or severe subsurface damage were considered as failures. Survival data was subjected to Fisher's exact test; damage modes were subjected to Mann-Whitney test (p<0.05). RESULTS: There were no debonding, cohesive or catastrophic failures. Considering subsurface damage, 53.8% of RNC and 46.2% of LD crowns survived the fatigue test, presenting no statistical difference. Chief damage modes were radial cracks for RNC and inner cone cracks for LD, presenting no statistical difference. CONCLUSIONS: The results suggest that if debonding issues can be resolved, resin nanoceramic figures can be an alternative to posterior crowns. Although distinct, damage modes revealed potential to cause bulk fracture in both glass ceramic and resin nanoceramic crowns.


Assuntos
Cerâmica/química , Coroas , Porcelana Dentária/química , Cimentos de Resina/química , Desenho Assistido por Computador , Planejamento de Prótese Dentária , Falha de Restauração Dentária , Desgaste de Restauração Dentária , Restauração Dentária Permanente/métodos , Análise do Estresse Dentário , Humanos , Teste de Materiais , Reprodutibilidade dos Testes , Estatísticas não Paramétricas , Propriedades de Superfície , Fatores de Tempo
15.
Photobiomodul Photomed Laser Surg ; 37(8): 483-488, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31081712

RESUMO

Objective: The aim of this study was to assess the effect of Er;Cr:YSGG laser parameters (power and frequency) on the bond strength and color stability of lithium disilicate (LD) ceramics. Materials and methods: One hundred ten specimens of LD ceramic were fabricated following heat pressed technique. Fifty disks were randomly distributed into five groups according to types of surface treatment [hydrofluoric (HF) acid, L1S L2S, L1D, and L2D]. For all laser-treated groups, bond preparation settings were used with a gold hand piece using a MZ10 tip (Er;Cr:YSGG, water lase I plus; Biolase). After surface treatment, adhesive bond was applied, and after photopolymerization, a composite buildup was performed. To evaluate shear bond strength, a controlled force was applied until failure using a universal testing machine. Color stability was assessed for six groups (HF, L1S L2S, L1D, L2D, and control) of LD ceramic (shade A1, LT translucency) through the CIE L*a*b* system. Three specimens from each of the six groups were selected randomly for assessment of surface topography using scanning electron microscopy. Means and standard deviations were compared using analysis of variance and Tukey's post hoc test (p < 0.05). Results: The maximum and minimum mean bond strength were shown by the L2D group 19.95 ± 1.014 and L1S group specimens 14.68 ± 0.863, respectively. Highest mean ΔE was found in L2S group 8.17 ± 2.10 and the lowest mean ΔE was found in control group (no treatment) 0.11 ± 0.05. Conclusions: LD specimens lased (Er;Cr:YSGG) with 3.75 W power and 15 Hz frequency for 4 min showed bond strength comparable with HF acid samples, and color changes within acceptable range (ΔE 1.17). Laser treatment (Er;Cr:YSGG) at 3.75 W power and 15 Hz frequency for 4 min of LD ceramics appears to be clinically efficient, showing acceptable bond strength and color stability.


Assuntos
Cerâmica/química , Colagem Dentária/métodos , Corrosão Dentária/métodos , Porcelana Dentária/química , Lasers de Estado Sólido , Cor , Análise do Estresse Dentário , Ácido Fluorídrico , Técnicas In Vitro , Microscopia Eletrônica de Varredura , Resistência ao Cisalhamento , Propriedades de Superfície
16.
Braz Oral Res ; 33: e026, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30970090

RESUMO

The aim of this study is to evaluate the machinability of four CAD/CAM materials (n = 13) assessed by brittleness index, Vickers hardness, and fracture toughness and interaction among such mechanical properties. The materials selected in this in vitro study are Feldspathic ceramic [FC], Lithium-disilicate glass ceramic [LD], leucite-reinforced glass ceramic [LR], and nanofilled resin material [RN]. Slices were made from the blocks following original dimensions 14 × 12 × 3 mm (L × W × H), using a precision slow-speed saw device and then surfaces were regularized through a polishing device. Brittleness index and fracture toughness were calculated by the use of specific equations for each one of the properties. The Vickers hardness was calculated automated software in the microhardness device. One-way Anova and Pearson's correlation were applied to data evaluation. LD obtained the highest values for brittleness index and was not significantly different from FC. LR presented statistically significant difference compared with RN, which had the lowest mean. Vickers hardness showed LD with the highest average, and no statistical difference was found between FC and LR. RN presented the lowest average. Fracture toughness showed FC and LR not statistically different from each other, likewise LD and RN. The brittleness index, considered also as the machinability of a material, showed within this study as positively dependent on Vickers hardness, which leads to conclusion that hardness of ceramics is related to its milling capacity. In addition, fracture toughness of pre-sintered ceramics is compared to polymer-based materials.


Assuntos
Silicatos de Alumínio/química , Cerâmica/química , Desenho Assistido por Computador , Porcelana Dentária/química , Polímeros/química , Cimentos de Resina/química , Análise de Variância , Testes de Dureza , Teste de Materiais , Valores de Referência , Reprodutibilidade dos Testes , Estatísticas não Paramétricas , Propriedades de Superfície
17.
Niger J Clin Pract ; 22(4): 496-502, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30975953

RESUMO

Aim: The aim of this research was to investigate the effect of microwave glazing, conventional oven glazing, and polishing on surface roughness and wettability of porcelains. Materials and Methods: The initial surface roughness values (Ra0) of the prepared specimens for four different porcelains (Vita VM 9, VitaVM 13, Vita VMK 95, IPS e.maxCeram) were determined by profilometry. Then, the specimens were divided randomly into three groups as polishing, conventional oven glazing, and microwave glazing. Final surface roughness values were evaluated by profilometry (Ra1) and scanning electron microscopy. Wettability of glazed specimens were evaluated by contact angle goniometer. Results: Although microwave-glazed specimens had lower Ra1 values compared with the conventional oven-glazed ones for IPS e.maxCeram (P < 0.05), there were not any statistically significant differences between these two procedures in terms of Ra1 values for the other porcelains (P > 0.05). Microwave-glazed specimens had lower wettability values than conventional oven-glazed ones for Vita VM 9. Conclusions: Microwave glazing procedure may be considered as an alternative method because of the advantages of providing volumetric heating, time, and energy saving.


Assuntos
Ligas Dentárias/química , Polimento Dentário/métodos , Porcelana Dentária/química , Teste de Materiais/métodos , Microscopia Eletrônica de Varredura , Micro-Ondas , Molhabilidade , Cerâmica , Temperatura Alta , Humanos , Propriedades de Superfície
18.
Biomed Res Int ; 2019: 5856482, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30949503

RESUMO

The goal of this study was to evaluate the effects of different core and veneer thicknesses on the translucency (T%), average light transmittance (T), translucency parameter (TP), contrast ratio (CR), and spectral reflectance (R) of glass-ceramics using a computer-aided design/computer-aided manufacturing (CAD-CAM) process. In all, 42 specimens (11mm × 11mm) were prepared and divided into six groups (n = 7 for each group). Core materials (IPS e.max CAD; IPS Empress CAD, LT A2 shade) of different thicknesses (0.8, 1.0, and 1.2mm) were fabricated. Each veneer material (thicknesses of 0.7, 0.5, and 0.3mm) was combined with its compatible core ceramic. Each core material was overlapped with its corresponding veneer material to obtain a 1.5-mm thickness by using three different combinations: (0.8+0.7), (1.0+0.5), and (1.2+0.3) mm. A spectrophotometer and color data software were used to measure the T%, T, TP, CR, and R values of each ceramic. The results were statistically analyzed using two-way analysis of variables (ANOVA) and regression analysis (p<0.05). Two-way ANOVA revealed that T%, T, TP, and CR were significantly influenced by the different thicknesses of the core-veneer combinations (p<0.001). At a certain thickness, as the veneer thickness increased and core thickness decreased, T and T% all increased. Regression analysis of the ceramic materials indicated a reduction in T and T% for certain core-veneer combinations. Analysis also revealed that T% and T were all affected by different core-veneer combinations. The T% value was 74.31 for the EM group and 72.81 for the EP group when the thickness of the core was 1.2 mm and the veneer was 0.3 mm. The R value of EM2 was lower than EM1 and EM3. In conclusion, the optical properties were influenced by different core-veneer combinations.


Assuntos
Cerâmica/química , Porcelana Dentária/química , Facetas Dentárias , Humanos
19.
Biomed Res Int ; 2019: 4386709, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30891457

RESUMO

Although the number of complications and failures in bone augmentation procedures is still relatively high, these problems remain poorly documented. Moreover, the literature concerning reconstructive techniques and the treatment of their complications in the anterior areas rarely considers the final esthetic result. The aim of this paper is to propose a new classification of bone augmentation complications in the esthetic area, providing treatment guidelines useful for the management of these cases. Failures of bony regeneration procedures can be mainly divided into partial failures and complete failures. A partial failure can be solved with a corrective surgical intervention: this second surgery can have success or may not be able to provide the desired esthetic result. When the bone reconstructive procedure fails totally, a complete failure occurs and the whole procedure has to be repeated. This new intervention can have success but also this new reconstructive surgery can fail in the same way as the first, causing important damage and a compromise solution that will hardly be acceptable from an esthetic point of view. Bone augmentation techniques are not completely predictable and are not always able to guarantee the expected result, especially in the atrophic anterior maxilla. Complications and failures can often occur and this possibility must always be clearly explained to those patients with high esthetic demands and expectations.


Assuntos
Aumento do Rebordo Alveolar/classificação , Estética Dentária , Maxila/patologia , Maxila/cirurgia , Atrofia , Materiais Biocompatíveis/química , Regeneração Óssea , Reabsorção Óssea/patologia , Coroas , Implantes Dentários , Porcelana Dentária/química , Humanos , Retalhos Cirúrgicos , Resultado do Tratamento
20.
Comput Methods Biomech Biomed Engin ; 22(4): 409-417, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30712384

RESUMO

To evaluate the stress behavior of ceramic fragment restoration, varying the thickness of the cement layer and intraoral temperature variation. A solid model of a upper lateral incisor was obtained and a defect at enamel distal/incisal edge was restored with a ceramic fragment. Based on this initial model, 4 different models (M) were built: M1 - absence of cement layer (CL) (0 µm of thickness); M2 - CL with an uniform thickness of 50 µm; M3 - CL with 50 µm at the margin of ceramics and 100 µm in the inner area far from margins; M4 - CL with 50 µm at the margin of ceramics and 200 µm in the inner area far from margins. The environment temperature changed from 5 °C to 50 °C in 4 increments. The finite element analysis was performed. Increase the cement layer thickness generated higher stress levels on ceramic surface in all temperatures, as well as on cement interface. In general hot temperature was the worst scenario for ceramic fragments integrity, since tensile and compressive stress were more intense. The maximum principal stress on ceramic fragment was found 90 MPa for M4 at 50 °C, followed for M3 (87 Mpa). For CL, the peak of stress was found for M3 at 5 °C (47 MPa). Is it possible to conclude that thick resin cement layer contribute to higher stress concentration on ceramic fragment, and extremely hot temperatures increase the risk of structural failure, since both ceramic and \cl are exposed to higher compressive and tensile stresses.


Assuntos
Porcelana Dentária/química , Análise do Estresse Dentário , Fenômenos Mecânicos , Cimentos de Resina/química , Temperatura , Módulo de Elasticidade , Análise de Elementos Finitos , Humanos , Incisivo/anatomia & histologia , Estresse Mecânico , Propriedades de Superfície
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