Purpose: This study was designed to investigate the in vitro effects of geraniol (GE) and thymoquinone (TQ) on Candida biofilms on denture acrylic and any accompanying changes in acrylic surface roughness or color. Methods: The susceptibility of Candida species to GE and TQ was determined using the broth microdilution method and time-kill assay. A minimum biofilm eradication concentration (MBEC) assay was performed using 7-day Candida biofilms grown on denture acrylic. Results: The minimum inhibitory concentration (MIC) of GE and TQ for Candida spp. was 256 and 32 µg/mL, respectively. The Candida strain complete kill rates for GE and TQ at 5-fold MIC were determined after 1 h of incubation. At 5-fold MIC, GE and TQ inhibited the preformed biofilm activity (MBEC80) of all Candida strains on denture acrylic by more than 80% after treatment for 3 h. At sub-MIC levels, GE and TQ prevented the development of C. albicans and C. tropicalis hyphae. SEM images demonstrated that GE and TQ damaged the fungal cell membrane and induced cell lysis. On the other hand, GE and TQ at 10-fold MIC did not alter the surface roughness or color of the denture acrylic. Conclusion: GE and TQ are interesting natural substances that could be developed as promising disinfectants for removable dentures.
Objectives:The study aimed to compare the residual forceoflocally produced Thai orthodontic elastomeric ligatureswith 2 commercial brands.Materials and Methods: The study compared Thai clear and blue orthodontic elastomeric ligatures with clear and blue commercial brands[Unitek (USA) and W&H (China)]. The dimensional characteristics of the ligatures (i.e., inner diameter, outer diameter and cross-section thickness) were measured. Then initial extension force was measured. After that, the residual force was determined at day 1and repeated on day 2,3,4,5,6,7,14,21, and 28 andthe percentage of residual force wascalculatedaccording to ISO 21606:2007. The data were analyzed with Two-way ANOVA and multiple linear regression (p<0.05). Results: Thai ligatures had significantly greater inner diameter(clear 1.22 mm, blue 1.21 mm) and cross-section thickness (clear 0.78 mm, blue 0.79 mm) in both colors when compared with Unitek and W&H brands. Thai ligatures had no significant difference in cross-section thickness between clear and blue.Thai clear ligatures hadthe highest initial extension force(2.30 N). Thai ligatures showed similar force decay patterns as other brands, rapidly decreasing the first day, gradually decreasing over 7 days and remaining nearly constant until 28 days.However, both clear and blue Thai elastomeric ligatures had significantly less outer diameters (clear 3.12 mm, blue 3.15mm). Thai blue ligatures had the lowest initial extension force (1.96 N).TheThai clear and blue demonstrated less percentage of residual force in the first day (clear 53.00%, blue 50.66%) and28 days (clear, 37.69%, blue, 37.00%) butthey were clinically acceptable. In general, clear ligatures exhibited a greater percentage of residual force than blue ligatureamong the 3 brands. Conclusion:Thai orthodontic elastomeric ligature properties are comparable to commercially available brands and acceptable for clinical application.
The mechanical properties of six 35Ag-30Pd-20Au-15Cu alloys containing different contents (2% and 4%) of Sn, Ga, or In and a 35Ag-30Pd-20Au-15Cu alloy without additives were evaluated.These alloys were subjected to four different heat treatments before a mechanical test. The distribution of the elements and their contents were analyzed. The mechanical properties of 35Ag-30Pd-20Au-15Cu alloy changed in wide-ranging ways with different heat treatments and with different additive contents.The effects of heat treatment on tensile strength and hardness significantly varied with different additives and their contents.These different changes could be attributed to the formation of different phases in these alloys. Based on the high strength and wide-ranging changes in the mechanical properties when subjected to softening and hardening heat treatments, the 2% Sn-added, 2% In-added, and 4% Ga-added alloys can be recommended for different dental restorations such as crown & bridges, inlays, and denture frameworks. The results of previous studied1-4) have shown that some of the prepared experimental alloys seem to have high hardness and low elongation, which indicates that these alloys need to be softened for crown & bridges and inlays. In order to claim the efficacy of 35Ag-30Pd-20Au-15Cu alloys for multiple dental applications, it is necessary not only to determine the effects of different heat treatments on the mechanical properties of these alloys, but also to evaluate if these heat treatments could be effectively utilized in applying these alloys for different dental restorations.In previous studied1-4), either Sn, Ga, or In was added to the 35Ag-30Pd-20Au-15Cu alloy and the effect of additives was investigated.The results showed that these additives were very effective in increasing the strength and hardness of the alloy. As aforementioned, these results were obtained at ascast or ceramic-firing condition, but no information was available about the effects of these additives at different heat-treated conditions. The purpose of this study was to determine the effects of heat treatments as well as those of the additive metals such as Sn, Ga, and In at different heat-treated conditions on the mechanical properties of 35Ag-30Pd-20Au-15Cu alloy, and to evaluate if these alloys could have suitable properties for different dental applications. modulus, and Vickers hardness) were statistically analyzed using two-way ANOVA and Tukey's multiple comparison test. Proof stress could not be measured for 10 test conditions due to early fracture before 0.2% elongation; thus, one-way ANOVA and Tukey's multiple comparison test were used instead. For elongation, Dunnet's T3 test was used to statistically compare the average values since homogeneous variation of data could not be assumed. Table 2 shows the average values and standard deviations for tensile strength, proof stress, elongation, and Vickers hardness, as well as the statistical differences between the average values. Table 3 is the result of two-way ANOVA for the aforementio...
Dental impression is a source of cross infection and transmission of diseases. Conventional disinfection may lead to a change in physical properties. Self-disinfectant irreversible hydrocolloid is an alternative to the disinfection and can prevent microbial cross contamination. The present study evaluates the physical properties of irreversible hydrocolloid impression material incorporated with 0.5%, 1.0% and 1.5% w/w silver nanoparticles (AgZrPO4, Sunshine Factory Co.,Ltd, China). The working time and detail reproduction were tested according to ISO 21563:2013 with some modification. The result showed that AgZrPO4 did not significantly affect the physical properties of the impression material. Based on this in vitro study, AgZrPO4 can be added to the impression material for its antimicrobial benefit without significant changes in the physical properties of the material.
Polymethylmethacrylate (PMMA) resin is one of the most commonly used materials for fabricating the base of removable orthodontic appliances. It is known that PMMA resin can promote the adhesion of microbes due to its surface porosity and from long-term use. Vanillin-incorporated PMMA resin has been reported to have antimicrobial effects against Candida albicans. However, the influence of vanillin incorporation on the water sorption and solubility of self-curing orthodontic PMMA resin has not been studied. Objective: To determine the water sorption and solubility of self-curing orthodontic PMMA resin incorporated with different concentrations of vanillin. Materials and methods: Three groups of self-curing orthodontic PMMA resin incorporated with 0.1% and 0.5% vanillin as well as PMMA without vanillin as a control were prepared with ten specimens per group. Water sorption and solubility tests were performed according to ISO 20795-2:2013 specifications. One-way ANOVA and Tukey’s multiple comparison tests at a p<0.05 significance level were used to analyse the data. Results: All three groups met ISO standard requirements. The means of water sorption values showed insignificant differences among the three groups even though the value of the 0.5% vanillin group tended to decrease. Water solubility of the 0.1% vanillin-incorporated group was not significantly different when compared with the control group whereas that of the 0.5% vanillin-incorporated group exhibited a significant lower value when compared with both control and 0.1% vanillin-incorporated groups. This suggests that increasing concentrations of vanillin would decrease the water solubility of PMMA resin. Conclusion: The incorporation of 0.5% vanillin into self-curing orthodontic PMMA resin could significantly reduce its water solubility and showed a trend of less water sorption property. Even with different vanillin concentrations, the water sorption and water solubility properties of PMMA resin were within the ISO standards. Nevertheless, further studies are recommended to determine the amount of residual monomer present in different concentrations of vanillin-incorporated PMMA resin.
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