Browsing by Author "Fernandes, Carlos"
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- #109 Avaliação da rugosidade e cor de pastas com carvão vs. outras pastas sobre resina compostaPublication . Almeida, Carlos Ferreira de; Carreiro, Elisa Mariana Ferreira; Fernandes, Carlos; Correia, André; Cardoso, Miguel AgostinhoObjetivos: Avaliar se a escovagem com dentífrico com carvão ativado conduz a mudanças significativas na cor e rugosidade da superfície da resina composta face a outras pastas. Comparar as mudanças ao nível da resina composta com diferentes tipos de pastas com carvão ativado. Materiais e métodos: Foram confecionados 84 discos de resina Amaris O1 (Voco, Alemanha) com 10 mm de diâmetro por 2 mm de altura. À posteriori foram divididos em seis grupos de estudo (n = 14): Grupo 1? Controlo (Saliva Artificial), Grupo 2? Escovagem com pasta dentífrica convencional (Colgate Total), Grupo 3? Escovagem com pasta dentífrica branqueadora (Colgate Max White), Grupo 4? Escovagem com pasta dentífrica com carvão ativado não branqueadora (Colgate Total Charcoal), Grupo 5? Escovagem com pasta dentífrica de carvão ativado regulamentada (Curaprox Black is White) e Grupo 6? Escovagem com pasta dentífrica de carvão ativado não regulamentada (Zebra Teeth Whitening, China). Desta forma, a cor e a rugosidade de cada disco foram avaliadas em quatro momentos utilizando um espectrofotómetro (VITA Easyshade Compact) e um perfilómetro de contacto Hommelwerke um Plint TE 66, respetivamente: inicial; duas semanas e depois de um e três meses. Toda a escovagem foi realizada de acordo com a norma ISO 11609 – 2017, utilizando uma escova elétrica (Oral? B Pro 3000, Braun). A análise dos dados foi realizada com recurso ao programa de análise estatística SPSS® v.25. Para todos os testes usou? se estatisticamente p≤0,05. Resultados: Globalmente, no que diz respeito à rugosidade, a variável Rvk e a que apresenta o maior aumento global também do desvio padrão. A maior variação do valor é registada ao fim de 3 meses, principalmente nas variáveis Rz e Rvk. O grupo que apresenta maior variação de rugosidade corresponde à pasta grupo 5, seguida dos grupos 6 e 4. No que concerne à cor, é passível de se observar uma maior variação global de cor ao nível dos dentífricos com carvão principalmente com especial destaque no grupo 6, que se apresenta estatisticamente diferente de todos os outros. Conclusões: A escovagem diária, independentemente do dentífrico ou não, promove o aumento da rugosidade superficial. No nosso estudo, o dentífrico com carvão ativado não regulamentado apresenta rugosidade e capacidade de alteração de cor agravadas. Estudos futuros devem ser realizados.
- Antimicrobial activity of a 3D-printed polymethylmethacrylate dental resin enhanced with graphenePublication . Salgado, Helena; Gomes, Ana T. P. C.; Duarte, Ana S.; Ferreira, José M. F.; Fernandes, Carlos; Figueiral, Maria Helena; Mesquita, PedroThe present study aimed to test, in vitro, the antimicrobial activity against Candida albicans and Streptococcus mutans and the surface roughness of a 3D-printed polymethylmethacrylate dental resin enhanced with graphene. A 3D-printed polymethylmethacrylate dental resin was reinforced with four different concentrations of graphene: 0.01, 0.1, 0.25 and 0.5 wt%. Neat resin was used as a control. The specimens were printed in a liquid crystal display printer. Disc specimens were used in antimicrobial evaluation, and bar-shaped specimens were used to measure surface roughness. The study of antimicrobial activity included the inhibition of the growth of C. albicans and S. mutans and their adhesion to the resin’s surface. Surface roughness increased with the increase in the graphene concentration. The growth inhibition of C. albicans was observed in the different concentrations of graphene after 24 h, with no recovery after 48 h. The specimens doped with graphene were capable of inactivating S. mutans after 48 h. The surface-adhesion studies showed that the density of microbial biofilms decreases in the case of specimens doped with graphene. Graphene, despite increasing the resin’s surface roughness, was effective in inhibiting the growth and the adhesion to the resin’s surface of the main inducers of prosthetic stomatitis.
- A different approach to analyzing the surface roughness of prosthetic dental acrylic resinsPublication . Quezada, Margarida Martins; Fernandes, Carlos; Montero, Javier; Correia, André; Salgado, Helena; Fonseca, Patrícia(1) Introduction: Apart from the polishing method, conventional or mechanized, the arithmetic mean roughness (Ra) is the most common metric to evaluate the surface roughness of denture base acrylic resins. An overview of the constraints related to this roughness parameter is highlighted in this study. This research introduces new parameters for accessing a functional analysis of surface roughness. (2) Materials and Methods: Five samples of CAD/CAM 3D-printed acrylic resins were prepared. Two polishing techniques, manual and mechanical, were applied. Surface roughness parameters were extracted from a profilometer reading: arithmetic mean height (Ra and Pa), skewness (Rsk and Psk), and kurtosis (Rku and Pku). (3) Results: Significant differences (p < 0.001) were found in the Ra distribution among the study samples, in contrast with the lack of significance in Pa values. Surface roughness parameters revealed an increased coefficient of variance (CV) value due to mechanized polishing across the specimens analyzed. Skewness and kurtosis indicate a more pronounced distribution with the manual polishing technique. (4) Conclusion: This preliminary study exhibits the influence of different polishing protocols on surface roughness parameters. The primary profile, skewness, and kurtosis should be assessed for the surface characterization of acrylic resins.
- Investigation of the effect of the same polishing protocol on the surface roughness of denture base acrylic resinsPublication . Quezada, Margarida Martins; Salgado, Helena; Correia, André; Fernandes, Carlos; Fonseca, PatríciaThis investigation aims to determine the effect of the same polishing protocol on the surface roughness (Ra) of different resins obtained by different processing techniques. Acrylic resins obtained by CAD/CAM technology overcame the disadvantages identified in conventional materials. A total of thirty samples (six of each resin): self-cured, heat-polymerized, injection molded, CAD/CAM 3D-printed and CAD/CAM milled were prepared. JOTA ® Kit 1877 DENTUR POLISH was used to polish the samples by two techniques: manual and mechanized, with a prototype for guided polishing exclusively developed for this investigation. The Ra was measured by a profilometer. The values were analyzed using ANOVA, Games-Howell post-hoc test and One-sample t-test, with p < 0.05. Manual polishing produces lower values of Ra compared to mechanized polishing, except for injected molded resins ( p = 0.713). Manual polishing reveals significant differences between the resin pairs milling/3D-printing ( p = 0.012) and thermopolymerizable/milling ( p = 0.024). In the mechanized technique only, significant differences regarding the R a values were found between the self-cured/3D-printed ( p = 0.004) and self-cured/thermopolymerizable pair resins ( p = 0.004). Differences in surface roughness values can be attributed to the inherent characteristics of the resin and the respective processing techniques.