Influence of Light-Curing Glaze and Chlorhexidine Gluconate in the Acrylic Resin Properties: An in situ Study

This in-situ study aimed to evaluate the chromatic stability, microhardness, and surfacefree energy of chemically activated acrylic resin (CAAR) samples. Eighty CAAR samples were made and each volunteer (n = 20) received two palatal plates with two sides of groups (without and with glaze application). The samples were exposed to two conditions: the control condition (sucrose 30%) and the test condition (sucrose 30% and 0.12% chlorhexidine). The volunteers used the first palatal device (control condition) for seven days and the second palatal device (test condition) for another seven days, with a seven-day break between them. Then, the ΔΕ00, microhardness, and surface-free energy tests were performed. Analysis of Variance and the Tukey test were used (α = 0.05). The control group with glaze showed higher ΔΕ00 compared to the group without the glaze. The test group with glaze had less ΔΕ00 than their respective controls. In both periods, when the glaze was applied, higher microhardness values were found for all groups. Groups with glaze showed lower roughness and higher surface-free energy than groups without the glaze. The values obtained in this study were satisfactory, showing the clinical efficacy of glaze and the use of 0.12% CH for maintaining the physical and mechanical properties of CAAR.

Effect of glaze and chlorhexidine on physical and mechanical properties of bis-acryl resin: An in situ study

BACKGROUND

Temporary prosthesis protects the oral tissues, in addition to providing aesthetic look and masticatory function until a definitive prosthesis is manufactured.

OBJECTIVES

To evaluate the effect of glaze and 0.12% chlorhexidine (CHX) on the physical and mechanical properties of bis-acryl, and to evaluate the antimicrobial efficacy of CHX.

MATERIAL AND METHODS

Eighty specimens of bis-acryl resin were made. Over 40 of them the glaze was applied. One specimen with and 1 specimen without glaze were placed in niches of an appliance manufactured for each patient. Each of the 20 volunteers received 2 devices. Initially, the volunteers used one device and treated it with sucrose for 7 days (control), and later they used the other device and treated it with sucrose and CHX for 7 days (test). Color, microhardness, roughness, surface energy, and insoluble extracellular polysaccharides (EPS) tests were performed. All results were submitted to the Tukey's test, with the exception of the EPS results, which were submitted to the Student's t test.

RESULTS

The ΔE00 of the unglazed control group was significantly higher than that of the unglazed test group. In all groups, a significant decrease in microhardness occurred over time. At both times, the glaze significantly increased the microhardness of the specimens (in all the glazed groups). At the final time, the test glaze group showed significantly higher microhardness compared with the control glaze group. Roughness in the groups without glaze increased significantly with CHX treatment over time. At both times, the glaze generated a significant reduction in roughness in the control and test groups. There was a significant reduction in surface energy over time in all groups. In most comparisons, the glazed groups showed significantly higher surface energy values compared with the unglazed control group. At the final time point, the unglazed test group showed a significantly higher surface energy value than the unglazed control group; and the glazed test group showed a significantly higher surface energy value compared with the glazed control group. The resins that received CHX had a significantly lower amount of biofilm.

CONCLUSIONS

Color values were clinically acceptable in all tested groups. At both time points, the roughness values were clinically acceptable only in the glazed groups. Glaze increased the microhardness of the specimens. Microhardness and surface energy were reduced over time in all groups. Chlorhexidine can help prevent microhardness degradation. Glaze and CHX can increase surface energy. Chlorhexidine reduced the amount of bacterial biofilm.

Análise Físico-Química e Resistência ao Cisalhamento de Zircônia em Cimentos Resinosos Após Tratamento com Plasma Não-Térmico e/ou Primer

O objetivo deste estudo foi caracterizar a superfície de Y-TZP tratadas com NTP, primer para ligas metálicas ou a associação entre esses dois métodos, e avaliar o efeito desses tratamentos na resistência de união entre Y-TZP e dois cimentos resinosos. Discos de Y-TZP foram distribuídos em cinco grupos: Co (sem tratamento), Pr (primer), NTP (plasma de metano), Pr + NTP e NTP + Pr. Os discos foram cimentados em substratos de resina composta utilizando Panavia F2.0 ou RelyX U200. As análises de resistência ao cisalhamento (n 10) foram realizadas antes e após termociclagem. Os dados foram submetidos à ANOVA um e três fatores e teste de Bonferroni (a0,05). NTP reduziu a energia de superfície e a rugosidade dos discos de Y-TZP. As análises de morfologia e químicas mostraram a presença da película fina orgânica, o que melhorou significativamente os resultados de resistência de ligação quando foi utilizado Rely X U200, enquanto que o tratamento com primer foi mais eficaz com Panavia F2.0. A termociclagem reduziu significativamente os resultados de resistência de união dos grupos NTP e Pr + NTP cimentados com Rely X U200 e os grupos Pr e NTP + Pr cimentados com Panavia F2.0. O plasma não térmico melhorou a união entre Rely X U200 e Y-TZP e também parece ser resistente à degradação hidrolítrica, enquanto que o Panavia F2.0 apresentou os maiores valores de união quando associado ao primer.Palavras-chave: Resistência ao Cisalhamento. Cimentos Resinosos. Plasma de Pressão Atmosférica Não-Térmica.

Comparison of stress distribution between complete denture and implant-retained overdenture-2D FEA

The aim of this study was to compare the stress distribution induced by posterior functional loads on conventional complete dentures and implant-retained overdentures with different attachment systems using a two-dimentional Finite Element Analysis (FEA-2D). Three models representative of edentulous mandible were constructed on AutoCAD software; Group A (control), a model of edentulous mandible supporting a complete denture; Group B, a model of edentulous mandible supporting an overdenture over two splinted implants connected with the bar-clip system; Group C, a model of edentulous mandible supporting an overdenture over two unsplinted implants with the O-ring system. Evaluation was conducted on Ansys software, with a vertical force of 100 N applied on the mandibular left first molar. When the stress was evaluated in supporting tissues, groups B (51.0 MPa) and C (52.6 MPa) demonstrated higher stress values than group A (10.1 MPa). Within the limits of this study, it may be concluded that the use of an attachment system increased stress values; furthermore, the use of splinted implants associated with the bar-clip attachment system favoured a lower stress distribution over the supporting tissue than the unsplinted implants with an O-ring abutment to retain the mandibular overdenture.