Browsing by Author "Quezada, Margarida Martins"
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- Comparative analysis of mechanized versus conventional polishing protocols for denture base acrylic resinsPublication . Quezada, Margarida Martins; Fernandes, Carlos; Correia, André; Fonseca, Patrícia; Montero, JavierSurface roughness is primarily determined by the inherent characteristics of a material, the specific polishing protocol and the manual operator’s dexterity. This research intends to conduct a comparative analysis between a conventional and mechanized polishing protocol concerning surface roughness and its impact on surface topography. Thirty samples were included in this in vitro study: six samples for each type of acrylic resin. All specimens underwent a polishing protocol by a conventional method and a mechanized approach with a controlled polishing tool (CPT). Profilometric measures were extracted: arithmetic mean height (Pa), skewness (Psk) and kurtosis (Pku). The Pa values acquired through both the mechanized and conventional polishing techniques are significantly lower compared to the control group. The mechanized polishing notably yielded higher roughness compared to the control group. Relatively consistent skewness and lower-to-moderate values of kurtosis were found across resin types. Differences in the dispersion and pattern for Pa were not detected between the polishing protocols. The CPT protocol reliably maintains consistent skewness and kurtosis values. The conventional protocol remains significant due to the variations observed in the Pa values obtained.
- 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.
- Estudo da rugosidade de superfície de diferentes resinas acrílicasPublication . Quezada, Margarida Martins; Fonseca, Patrícia Alexandra Barroso da; Salgado, Helena Cristina Morais Coelho Teixeira; Fernandes, CarlosINTRODUÇÃO: O polimetilmetacrilato é um material comummente utilizado como material para confeção de bases protéticas. Desvantagens inerentes conduziram ao surgimento de vários tipos de resina para ultrapassar estes problemas, como o sistema CAD/CAM. De entre várias propriedades dos materiais, a rugosidade de superfície tem elevada relevância clínica, pois, uma base protética com maior rugosidade irá promover o desenvolvimento de patologias inflamatórias, como a Candidíase Oral e a Estomatite Protética. O principal objetivo é determinar o efeito do mesmo protocolo de polimento de superfície em diferentes resinas acrílicas utilizadas para a confeção de bases protéticas obtidas por diferentes técnicas de processamento. METODOLOGIA: Foram confecionados 30 provetes de resina acrílica obtidos por diferentes métodos de processamento. Os provetes foram submetidos ao mesmo protocolo de polimento com recurso a duas técnicas distintas, manual e mecanizada. A leitura da rugosidade de superfície foi realizada com recurso a um perfilómetro de contacto. Os dados obtidos foram alvo de análise estatística através do programa SPSS com um nível de significância definido a 0.05. RESULTADOS: Todas as resinas sujeitas a polimento manual apresentaram um valor médio de rugosidade de superfície significativamente inferior às resinas submetidas a um polimento mecanizado, excetuando as resinas termoplásticas (p=0,713). Para as resinas sujeitas a polimento manual, registaram-se diferenças significativas entre os pares de resina fresagem e impressão 3D (p=0,012) e termopolimerizável e fresagem (p=0,024). No caso das resinas sujeitas a polimento mecanizado, verificaram-se apenas diferenças significativas face aos valores de rugosidade entre as resinas autopolimerizável e de impressão 3D (p=0,004) e entre as resinas autopolimerizável e termopolimerizável (p=0,004). CONCLUSÃO: Quando aplicado o mesmo protocolo de polimento, a diferença de valores de rugosidade média entre resinas acrílicas para confeção de bases protéticas pode ser atribuída às características inerentes da resina e às respetivas técnicas de processamento.
- Influence of different processing techniques for prosthetic acrylic resins in the surface roughness parameters: a research articlePublication . Quezada, Margarida Martins; Fernandes, Carlos Miguel da Costa Gomes; Martín, Javier Montero; Correia, André Ricardo Maia; Fonseca, Patrícia Alexandra Barroso daBackground: Different processing techniques are employed to obtain poly (methyl methacrylate) (PMMA) with consistent surface quality in terms of topography and tribological function. The purpose of this research is to evaluate its influence on the surface height distribution. Methods: In this research, samples of conventional and CAD/CAM acrylic resins were prepared. The following surface roughness parameters were extracted from the profilometric readings: arithmetic mean roughness (Pa), skewness (Psk) and kurtosis (Pku). Profilometric profiles were additionally obtained. Results: The average roughness (Pa) with the conventional technique was significantly higher compared to CAD/CAM (t = 4.595; P < 0.001). Heat-cured resins presented the highest mean Pa (F = 6.975; P = 0.06). Heat-cured and milled resins show lower coefficient variation (CV) values, indicating more consistent surface finishing. The surface profiles revealed distinct characteristics in terms of skewness and kurtosis. Conclusions: The surface processing method, chemical composition and resin type significantly influence the surface finishing of the resin. The CAD/CAM resins exhibited superior results in terms of surface arithmetic mean roughness (Pa). However, heat-cured resin revealed to present the better surface consistency.
- 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.