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1.
Braz. j. oral sci ; 20: e211670, jan.-dez. 2021. ilus
Artigo em Inglês | LILACS, BBO - Odontologia | ID: biblio-1254259

RESUMO

Aim: To evaluate the effect of different surface treatments and adhesive approaches on the microshear bond strength of resin cement to a polymer-infiltrated ceramic network (PICN). Methods: PICN blocks were randomly assigned into 9 groups (n=10): CTRL: no treatment; HF: 5% hydrofluoric acid etching; HF-S: HF + silane; HF-S-A: HF-S + adhesive (Adper Single Bond 2); HF-UA: HF + universal adhesive (Single Bond Universal); SB: sandblasting with 50 µm Al2O3 particles; SB-S: SB + silane; SB-S-A: SB-S + adhesive; SB-UA: SB + universal adhesive. Resin cement microcylinders (Ø = 0.96 mm; height = 1 mm) (RelyX Ultimate) were built upon the PICN surface after roughness and contact angle measurements. Next, microshear bonding tests (µSBS) were performed (0.5 mm/min) after water storage (37ºC, 90 days) and thermocycling (12,000 cycles; 5ºC-55ºC). Failure modes were observed under stereomicroscope. Bond strength data were analyzed by two-way ANOVA/Tukey's test and t-tests. Kruskal-Wallis/Dunn's tests were conducted for roughness and contact angle data (α = 0.05). Results: A rougher surface and lower contact angles were observed for Sandblasting. HF-S (18.54 ± 2.03 MPa), SB-S (19.00 ± 1.66 MPa) and SB-UA (18.07 ± 2.36 MPa) provided the highest bond strength values, followed by the other treated groups. The CTRL group resulted in lower bond strength (7.18 ± 2.34 MPa). Conclusion: Hydrofluoric acid etching followed by silane application and sandblasting followed by silane or universal adhesive are useful clinical steps to enhance bonding to PICN. Adhesive applications after HF etching have no advantages in bonding to PICN


Assuntos
Propriedades de Superfície , Cerâmica , Adesivos Dentinários , Cimentos de Resina , Abrasão Dental por Ar , Ácido Fluorídrico
2.
J. health sci. (Londrina) ; 23(3): 191-194, 20210920.
Artigo em Inglês | LILACS-Express | LILACS | ID: biblio-1292753

RESUMO

Despite composite resins capacity to mimic dental tissues, they can discolor over time. However, there is no information on the effect of prebrushing mouthwashes on the composite resin staining. This study aimed to evaluate the effect of prebrushing mouthwashes on the color stability of three composite resins. Twenty specimens of each resin were prepared: Filtek Z250 (3M ESPE ­S Paul, MN, USA), Charisma (Heraeus Kulzer GmbH - Hanau - Germany) e EvoluX (Dentsply- Petrópolis - Brazil). Groups were randomly divided accord to the treatment: immersion in prebrushing mouthwash (test group) or immersion in deionized water (control group). Test groups were immersed in 10 ml of prebrushing mouthwash Plax Magic (Colgate-Palmolive, São Bernardo do Campo, SP, Brazil) for 60 s three times a day during 35 days following the manufacturer's instructions. Color measurements were performed after 24 h of specimen's preparation and after 7, 14, 21, and 35 days of immersion time. Results showed that prebrushing mouthwash Plax Magic promoted a color change in all the tested materials and evaluation time. The color change was greater in composite resin Charisma, followed by Z250 and EvoluX. Therefore, prebrushing mouthwash promoted a color change in all the materials used. Composite resin Charisma demonstrated less color stability than Filtek Z250 resin and EvoluX resin, which was the most stable. (AU)


Apesar da capacidade das resinas compostas de mimetizar os tecidos dentais, esses materiais podem ter sua cor alterada com o tempo. No entanto, não há informação na literatura sobre o efeito de evidenciadores de placa na estabilidade de cor desses materiais. Este estudo teve por objetivo avaliar o efeito de um evidenciador de placa na estabilidade de cor e três resinas compostas. Para isso, 20 espécimes de cada resina foram preparados: Filtek Z250 (3M ESPE ­S Paul, MN, EUA), Charisma (Heraeus Kulzer GmbH - Hanau - Alemanha) e EvoluX (Dentsply- Petrópolis - Brasil). Os grupos foram aleatoriamente divididos de acordo com o tratamento a ser submetido: imersão no evidenciador de placa (grupo teste) ou imersão em água deionizada (grupo controle). Os grupos teste foram imersos em 10 ml do evidenciador de placa Plax Magic (Colgate Palmolive, São Bernardo do Campo, SP, Brasil) por 60 s três vezes por dia durante 35 dias, de acordo com a orientações de uso do fabricante. As leituras de cor foram feitas após 24 h da preparação dos espécimes e após 7, 14, 21 e 35 dias de imersão. Os resultados mostraram que o evidenciador de placa Plax Magic promoveu alteração de cor em todos os materiais usados e em todos os tempos de leitura. A alteração de cor foi maior na resina Charisma, seguida da Z250 e EvoluX. Portanto, o evidenciador de placa promove alteração de cor em todos os materiais testados. A resina composta Charisma demonstrou menor estabilidade de cor que as resinas Z250 e EvoluX, que, por sua vez, foi a mais estável. (AU)

3.
J. health sci. (Londrina) ; 23(2): 99-105, 20210621.
Artigo em Inglês | LILACS-Express | LILACS | ID: biblio-1283092

RESUMO

A wide variety of dental ceramics is launched every year. Therefore, clinicians should constantly study and update themselves to correctly indicate these materials. This cross-sectional study aimed to assess the association of dentists' academic aspects with their knowledge and the indication of dental ceramics for metal free restorations. All the dentists from private clinics who affirmed to perform prosthetic treatments on their patients in a Southern Brazilian city were personally invited to this research to avoid dropouts. Participants answered questions related to their knowledge of different dental materials, their information sources and usage frequency of ceramic materials, and related to their academic training/education. Chi-square tests were performed to evaluate the association among the outcomes (knowledge of different materials, information sources considered for material selection and their frequencies of use) and exposure variables (time since graduation and post-graduation degree). Significant associations were also submitted to Chi-square residual analysis. A response rate of 73.3% was reached. The most known and used materials were Y-TZP and porcelain veneered zirconia, respectively, whereas the least known was leucite-based ceramic. The majority of the professionals with at least 25 years since graduation claimed not to know lithium disilicate or leucite-based ceramics, and a significant number of these professionals allow the laboratory prostheses technician to choose the restorative material. In addition, most of dentists with no post-graduation said they did not have knowledge about leucite and lithium disilicate. It was evidenced that continuing education plays an important role in the dentists' attitudes regarding ceramic materials. (AU)


Uma grande variedade de cerâmicas é lançada no mercado a cada ano. Portanto, os clínicos devem se manter em constante estudo e atualização para indicar corretamente o uso desses materiais. Assim, este estudo transversal teve por objetivo avaliar a associação entre aspectos acadêmicos de dentistas com seus conhecimentos e as indicações de cerâmicas dentárias para uso em restaurações livres de metal. Para isso, todos os dentistas de clínicas privadas que afirmaram realizar tratamentos protéticos em seus pacientes em uma cidade do sul do Brasil foram pessoalmente convidados a participar desta pesquisa para evitar desistências. Os participantes responderam a questões relacionadas ao seu conhecimento sobre diferentes materiais dentários, suas fontes de informação, a frequência de uso de materiais cerâmicos, e, também, sobre sua formação acadêmica. Testes qui-quadrado foram realizados para avaliar a associação entre os desfechos (conhecimento de diferentes materiais, fontes de informação consideradas para a seleção do material e sua frequência de uso) e as variáveis de exposição (tempo desde a graduação e grau de pós-graduação). As associações significativas foram submetidas à análise de resíduos do qui-quadrado. A taxa de resposta obtida foi de 73,3%. O material mais conhecido e usado foi a Y-TZP e zircônia recoberta por porcelana, respectivamente, enquanto que o material menos conhecido foi a cerâmica a base de leucita. A maioria dos profissionais com pelo menos 25 desde a graduação afirmaram não conhecer as cerâmicas a base de dissilicato de lítio ou leucita, e um significativo número desses profissionais permitem que o técnico em prótese dentária escolha o material restaurador. Ainda, a maioria dos dentistas sem pós-graduação disseram não conhecer as cerâmicas a base de dissilicato de lítio ou leucita. Concluiu-se que a educação continuada é um fator determinante nas atitudes de dentistas em relação aos materiais cerâmicos. (AU)

4.
Dent Mater ; 37(7): 1096-1106, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33865620

RESUMO

OBJECTIVE: This study evaluated the effect of dwell time (conventional or extended) and cooling protocol (fast or slow) of self-glaze firings on the mechanical (flexural strength and crack propagation) and optical (color and translucency) properties of a porcelain-veneered zirconia system. METHODS: Bilayer disc-shaped samples were prepared (Vita VM9 + In-Ceram YZ) and divided according to the final thermal treatment: glaze firing followed by slow cooling (furnace opening at 200 °C) (G-S) or fast cooling (furnace opening at 600 °C) (G-F, manufacturer-recommended protocol), extended glaze firing (15 min of dwell time) followed by slow cooling (EG-S) or fast cooling (EG-F), or no thermal treatment (CTRL). Porcelain roughness (Ra and Rz) was measured before and after glaze firings. Color (ΔE00) and translucency (TP00) alteration were also evaluated. Flexural strength was measured with the piston-on-three-ball test and crack propagation analysis was performed after Vickers indentations. Complementary analyzes of crystalline phase and scanning electron microscopy were carried out. RESULTS: Significant effect of dwell time was observed, with extended glaze leading to higher flexural strength and shorter crack lengths. Cracks of EG groups were observed to end in clusters of crystals. Color and translucency changed below perceptibility thresholds. All treatments led to a smoother surface and EG groups reached the lowest Rz values. An extra SiO2 peak was revealed in control and EG groups. No effect of cooling protocol was found. SIGNIFICANCE: Extended glaze firing was able to improve the resistance to crack initiation and propagation of porcelain-veneered zirconia without clinically perceptible changes in optical properties.


Assuntos
Porcelana Dentária , Dióxido de Silício , Cerâmica , Análise do Estresse Dentário , Facetas Dentárias , Teste de Materiais , Propriedades de Superfície , Zircônio
5.
J Prosthodont Res ; 2020 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-33028795

RESUMO

PURPOSE: To evaluate the influence of quantity and positioning of veneered zirconia specimens during firing of porcelain on their fatigue performance and colorimetric differences. METHODS: Bilayer discs (Ø=15 mm) were made, following ISO 6872 guidelines, using a Y-TZP core (yttria-stabilized tetragonal zirconia polycrystal ceramic; VITA In-Ceram YZ) and a feldspathic veneering material (VITA VM9), being both layers with 0.7 mm thickness. Y-TZP discs were sintered, the veneering material was applied over it, and the bilayer specimens were fired according to two factors (n=20): 'quantity' (1 or 5 samples per firing cycle; G1 and G5 groups respectively) and 'positioning' of the specimens inside the furnace (center or periphery of the refractory tray; G5C and G5P groups, respectively). The CIEL*a*b* parameters were recorded with a spectrophotometer and the color difference (ΔE 00 ) and translucency (TP 00 ) were calculated using CIEDE2000 equations. The step-stress fatigue test was performed with the veneer facing down (region of tensile stress concentration), 10 Hz frequency, initial tension of 20 MPa for 5,000 cycles, followed by steps of 10,000 cycles using a step size of 10 MPa, up to 100 MPa; data from strength and number of cycles for failure were recorded for statistical analysis. RESULTS: Unacceptable color differences (ΔE 00 >1.8) were observed comparing G5C vs. G1 (quantity) and G5C vs. G5P (positioning), meanwhile translucency parameters were not affected. Besides, only the 'quantity' factor influenced the fatigue performance (G1>G5C). None of the tested specimens survived beyond 90N and/or 75000 cycles. CONCLUSIONS: The quantity and position of the specimens during firing influence the final color of porcelain-veneered zirconia, and firing one specimen per cycle improved the fatigue performance of the bilayer system.

6.
J Mech Behav Biomed Mater ; 107: 103769, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32364945

RESUMO

Considering the long time spent in low frequency cyclic fatigue tests, this study aimed to evaluate the influence of loading frequency (2 Hz and 20 Hz) on the flexural fatigue strength (FFS) and on the time and number of cycles to failure of a leucite-reinforced glass-ceramic. Disc-shaped specimens were produced using leucite-reinforced glass-ceramic CAD/CAM blocks (IPS Empress CAD), according to ISO 6872/2015. Two fatigue tests were performed. The FFS (n = 17) was determined by staircase approach at a lifetime of 500,000 cycles, for 2 Hz (control - chewing frequency estimative) and 20 Hz (accelerated approach). To determine the time and the number of cycles to failure in flexural fatigue, discs (n = 20) were submitted to a cyclic loading ranging from 10 MPa to 99 MPa (60% of the monotonic strength), until a maximum of 500,000 cycles. Means, standard deviation and confidence intervals (CI) at 95% for FFS were calculated, whereas statistical differences were detected based on maximum likelihood estimations and overlapping of 95% CIs. Kaplan Meier (α = 0.05) and log rank post-hoc tests were used to analyze the time (in minutes) and the number of cycles to failure in the lifetime test. FFS did not differ significantly between 2 Hz (mean: 78 MPa; 95% CI: 69-88 MPa) and 20 Hz (mean: 84 MPa; 95% CI: 78-90 MPa). Regarding the lifetime test, there was no difference (p = 0.3) in the time to failure for 2 Hz (mean: 13 min; 95% CI: 6-20 min) and 20 Hz (mean: 69 min; 95% CI: 9-128 min). However, the group tested with 20 Hz survived a significantly (p < 0.01) higher number of cycles (mean: 82,247 cycles; 95% CI: 11,450-153,044) than the group tested with 2 Hz (mean: 1588 cycles; 95% CI: 779-2397). Therefore, in leucite-reinforced glass-ceramic fatigue strength tests, limited to a lifetime of 500,000 cycles, the use of loading frequencies up to 20 Hz did not influence the FFS estimations when compared to 2 Hz (chewing frequency estimative), and may be an alternative to accelerate data collection in this type of mechanical test. However, in lifetime tests, the use of higher loading frequencies, as 20 Hz, did not save time, since a higher number of cycles was necessary to promote the failure, when compared to 2 Hz.


Assuntos
Silicatos de Alumínio , Cerâmica , Desenho Assistido por Computador , Porcelana Dentária , Análise do Estresse Dentário , Teste de Materiais , Propriedades de Superfície
7.
J. health sci. (Londrina) ; 21(5): https://seer.pgsskroton.com/index.php/JHealthSci/article/view/6911, 20/12/2019.
Artigo em Inglês | LILACS-Express | LILACS | ID: biblio-1051612

RESUMO

Little information is available about the optical behavior of glass ceramics and indirect resin composites. This study aimed to evaluate if an indirect resin composite can present similar behavior of color stability and translucency to a glass ceramic after polishing and aging in staining beverage. Specimens of a dental ceramic (IPS e.max Ceram) and an indirect resin composite (SR Adoro) were made. Half the specimens of each material were polished with disc-shaped tips. Groups were divided according to aging media: distilled water or immersion in red wine for 20 min/day during 30 days. CIE L*a*b* coordinates were measured with a spectrophotometer at baseline and after 30 days of aging. Color change was calculated by CIEDE2000 and translucency was calculated by contrast ratio (CR). Statistical analysis were performed with ANOVA and Tukey tests. Aging in red wine caused perceptible color change in both materials. Polishing only increased color change of indirect composite when aged in red wine. Ceramic groups showed greater opacity than the composite in all measurements. The indirect composite remained more translucent and results showed that it is capable of presenting color stability similar to a ceramic. However, polishing seems to increase its color change. (AU)


Pouca informação comparando o comportamento óptico de cerâmicas vítreas e resinas compostas indiretas estão disponíveis na literatura. O objetivo deste estudo foi avaliar se uma resina composta indireta pode apresentar comportamento semelhante a uma cerâmica vítrea em relação à estabilidade de cor e translucidez após polimento e envelhecimento em meio altamente pigmentante. Espécimes de uma cerâmica vítrea (IPS e.max Ceram) e uma resina composta indireta (SR Adoro) foram preparados. Metade dos espécimes de cada material foram polidas com pontas de polimento. Os grupos foram divididos conforme o meio de armazenamento: água destilada ou vinho tinto por 20 min/dia durante 30 dias. As coordenadas CIEL*a*b* foram medidas com espectrofotômetro previamente e após os 30 dias de armazenamento. A alteração de cor foi calculada pela equação CIEDE2000 e a translucidez foi calculada por razão de contraste. A análise estatística foi realizada pelos testes ANOVA e teste de Tukey. O armazenamento em vinho levou a uma alteração de cor perceptível nos dois materiais. O polimento apenas causou alteração de cor na resina composta indireta quando imersa em vinho tinto. A resina composta indireta manteve-se mais translúcida e os resultados mostraram que esse material é capaz de apresentar estabilidade de cor semelhante à cerâmica. No entanto, o polimento parece aumentar sua alteração de cor. (AU)

8.
Dent Mater ; 35(5): 807-817, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30846374

RESUMO

OBJECTIVES: A systematic review of in vitro studies was conducted to assess the effect of thermal treatments on flexural strength or critical load to failure of porcelain-veneered zirconia (PVZ). SOURCES: Literature searches were performed up to June 2018 in PubMed/MEDLINE, Scopus and Web of Science databases, with no publication year or language limits. DATA: From 393 relevant studies, 21 were selected for full-text analysis, from which 7 failed to meet the inclusion criteria. The 14 remaining papers were included in the systematic review: 8 for meta-analysis and 6 restricted to descriptive analyses. Hand searching of reference lists resulted in no additional papers. STUDY SELECTION: In vitro studies using PVZ specimens testing the influence of thermal treatments on the fracture resistance to monotonic or cyclic loading. Papers evaluating cooling rate were divided into those applying fast cooling from above the porcelain glass transition temperature (Tg), or from below it. Meta-analyses were performed separately for flexural strength and critical load to failure, using random effects at a 5% significance level. CONCLUSIONS: Delaying furnace opening at a temperature below the porcelain Tg is advised for PVZ restorations, in order to improve their fracture resistance. Additional information is required to confirm the apparent beneficial effect of self-glaze and repeated veneer firings on the mechanical properties of these restorations. Finally, in order to obtain conclusive and relevant evidence regarding thermal treatments and the fracture resistance of PVZs, future studies should concentrate on anatomically-correct crown specimens.


Assuntos
Porcelana Dentária , Facetas Dentárias , Coroas , Análise do Estresse Dentário , Teste de Materiais , Estresse Mecânico , Propriedades de Superfície , Zircônio
9.
Dent Mater ; 34(9): e225-e235, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29853196

RESUMO

OBJECTIVE: To investigate the effect of intaglio surface adjustment of simplified lithium disilicate ceramic restorations adhesively cemented to a dentin-like material on its fatigue behavior. METHODS: Ceramic discs (IPS e.max CAD) were prepared and an in-Lab simulation of machining roughness was performed by grinding with SiC paper (#60). Ceramic discs were divided into 4 groups according to the internal adjustment of the cementation surface: no adjustments (CTRL); adjustment with a medium (M), fine (F), or extra fine (FF) diamond bur. Dentin-like material discs were also produced. Ceramic disc intaglio surfaces were etched (5% hydrofluoric acid; 20s) and received a silane coating. Dentin-like material discs were etched (10% hydrofluoric acid; 1min) and received a primer coating. Pairs of ceramic/dentin-like material were adhesively cemented (Multilink Automix), and fatigue failure load tests were performed using the Staircase approach (250,000 cycles; 20Hz). Roughness, topographic and fractographic analyses were performed. Statistical analyses were carried out through ANOVA tests. RESULTS: All ground groups (M=521.3 N; F=536.9 N; FF=676.2 N) presented lower fatigue failure load values than the control (1241.6 N). M diamond bur created a rougher surface than F (Ra and Rz parameters). However, FF was similar to F and M for Ra, and similar to F for Rz. SIGNIFICANCE: Bur adjustments on the intaglio surface of simplified lithium disilicate ceramic restorations greatly decreased the fatigue failure load even using an extra-fine diamond bur. Care should be taken when internal adjustments are needed.


Assuntos
Colagem Dentária/métodos , Porcelana Dentária/química , Falha de Restauração Dentária , Condicionamento Ácido do Dente , Cerâmica/química , Instrumentos Odontológicos , Materiais Dentários , Teste de Materiais , Cimentos de Resina/química , Propriedades de Superfície
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