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.
Acrylic Resins , Candida , Acrylic Resins/pharmacology , Acyclic Monoterpenes , Antifungal Agents/pharmacology , Benzoquinones , Biofilms , Dentures/microbiology
The purpose of this study was to investigate the effects of three additives, Sn, Ga, and In, as well as the main constituents, Pd and Cu, of Ag-Pd-Au-Cu alloys on the initial bond strength of 4-META adhesive cement to these alloys. The Ag-Pd-Au-Cu alloys consisted of 20%, 30% or 40% Pd, and 10%, 15% or 20% Cu, 20% Au, and Ag as balance. Besides, additive metals (Sn, Ga, and In) of 2% and 4% were added to these compositions. The addition of three additives, in general, increased the initial bond strength of the cement in comparison to the mother compositions (0% additives), although the degrees of effectiveness of the three additives were different and varied with their contents. Among these additives, a remarkable increase in bond strength was observed with the addition of In. The increase in Cu content, in many cases, resulted in an increase in bond strength at high Pd contents (30% and 40%), but a decrease at low Pd content (20%) in some cases. The positive effects of the three additives and Cu could be due to the formation of a suitable oxide layer for strong bonding with 4-META.
Acrylic Resins/chemistry , Copper/chemistry , Dental Alloys/chemistry , Dental Bonding , Gallium/chemistry , Gold Alloys/chemistry , Indium/chemistry , Palladium/chemistry , Resin Cements/chemistry , Silver/chemistry , Tin/chemistry , Acrylic Resins/analysis , Boron Compounds/analysis , Boron Compounds/chemistry , Copper/analysis , Dental Alloys/analysis , Dental Stress Analysis/instrumentation , Gallium/analysis , Gold Alloys/analysis , Humans , Indium/analysis , Materials Testing , Methacrylates/analysis , Methacrylates/chemistry , Methylmethacrylates/analysis , Methylmethacrylates/chemistry , Palladium/analysis , Resin Cements/analysis , Silver/analysis , Stress, Mechanical , Surface Properties , Temperature , Tensile Strength , Time Factors , Tin/analysis , Water/chemistry
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.
Dental Alloys/chemistry , Analysis of Variance , Calorimetry , Dental Restoration, Permanent , Dental Stress Analysis , Elasticity , Electron Probe Microanalysis , Gallium/analysis , Gallium/chemistry , Hardness , Hot Temperature , Indium/analysis , Indium/chemistry , Materials Testing , Mechanics , Phase Transition , Statistics, Nonparametric , Tensile Strength , Tin/analysis , Tin/chemistry
Ten 35Ag-30Pd-20Au-15Cu alloys containing 0.00, 0.25, 0.50, 0.75, 1.00, 1.25, 1.50, 2.00, 4.00, or 6.00% Ga were experimentally prepared to investigate the effect of Ga on their mechanical properties in addition to their use for denture frameworks, connectors and clasps. The effect of Ga addition on the mechanical properties was marked with a significant increase in the tensile strength, 0.2% off-set proof stress (proof stress) and Vickers hardness observed at low Ga contents (0.25-2.00%). On the other hand, the elongation significantly decreased with the addition of Ga at all contents used in this study. The tensile strength, proof stress and Vickers hardness of the 35Ag-30Pd-20Au-15Cu alloys containing 0.25-2.00% Ga were in the range of 809-957 MPa, 669-857 MPa and 260-301 MPa, respectively. These values are similar to those of Co-Cr alloys, suggesting that 0.25-2.00% Ga alloys can be used for denture frameworks, clasps and connectors.
Dental Alloys/chemistry , Gallium/chemistry , Analysis of Variance , Chemical Phenomena , Chemistry, Physical , Chromium Alloys/chemistry , Copper/chemistry , Dental Clasps , Dental Stress Analysis/instrumentation , Denture Bases , Elasticity , Gold Alloys/chemistry , Hardness , Humans , Materials Testing , Palladium/chemistry , Silver/chemistry , Statistics as Topic , Stress, Mechanical , Tensile Strength
