Polymethyl Methacrylate Denture Base Resin Research Articles

Effects of SiO2 Incorporation on the Flexural Properties of a Denture Base Resin: An In Vitro Study.

Objective The aim of this study was to evaluate the effects of the addition of low-silicon dioxide nanoparticles (nano-SiO 2 ) on the flexural strength and elastic modulus of polymethyl methacrylate (PMMA) denture base material. Materials and Methods A total of 50 rectangular acrylic specimens (65 × 10 × 2.5 mm 3 ) were fabricated from heat-polymerized acrylic resin. In accordance with the amount of nano-SiO 2 , specimens were divided into the following five groups ( n = 10 per group): a control group with no added SiO 2 , and four test groups modified with 0.05, 0.25, 0.5, and 1.0 wt% nano-SiO 2 of acrylic powder. Flexural strength and elastic modulus were measured by using a 3-point bending test with a universal testing machine. A scanning electron microscope was used for fracture surface analyses. Data analyses were conducted through analysis of variance and Tukey’s post hoc test (α = 0.05). Results Compared with the control group, flexural strength and modulus of elasticity tended to significantly increase ( p ˂ 0.001) with the incorporation of nano-SiO 2 . In between the reinforced groups, the flexural strength significantly decreased ( p ˂ 0.001) as the concentrations increased from 0.25 to 1.0%, with the 1.0% group showing the lowest value. Furthermore, the elastic modulus significantly increased ( p ˂ 0.001) at 0.05% followed by 1.0%, 0.25%, 0.5%, and least in control group. Conclusion A low nano-SiO 2 addition increased the flexural strength and elastic modulus of a PMMA denture base resin.

Influence of Dental Glass Fibers and Orthopedic Mesh on the Failure Loads of Polymethyl Methacrylate Denture Base Resin.

The aim of the present study was to evaluate the fracture loads of polymethyl methacrylate (PMMA) complete denture bases reinforced with glass-fiber mesh and orthopedic casting tape (OCT) in comparison to conventional PMMA dentures under artificial aging. Dental fiberglass framework (Group 1) and OCT (Group 2 and 3) reinforced PMMA acrylic dentures were fabricated on the edentulous ridge. Ten PMMA dentures without reinforcement (Group 4) were included as controls. All specimens were placed in a chewing simulator chamber, and fatigue load was applied. To assess the fracture loads, static loads with a universal testing machine were applied. Fractured specimens in each group were evaluated under a scanning electron microscope. The data were statistically analyzed employing analysis of variance and Tukey post-hoc test. The association of denture weight and thickness on fracture load was assessed using Pearson and Spearman correlations. Dental fiberglass (Group 1) displayed the highest fracture load (692.33 ± 751.41 N), and Group 4 (control) exhibited the lowest fracture loads (281.41 ± 302.51 N). Dentures reinforced with fiberglass mesh framework exhibited intact fractures. In contrast, Group 2 and 3 specimens using OCT demonstrated ditching fractures. It was observed that the thickness and weight of all the reinforced specimens influenced the load required to fracture the dentures (p < 0.001). Denture specimens strengthened with OCT (Groups 2 and 3) exhibited failure loads lower than dental fiberglass (Group 1) specimens but higher than unreinforced controls.

Color Stability and Surface Properties of PMMA/ZrO2 Nanocomposite Denture Base Material after Using Denture Cleanser

Objectives This study aimed to evaluate denture cleanser effects on color stability, surface roughness, and hardness of PMMA denture base resin reinforced with nano-ZrO2. Materials and Methods A total of 420 specimens were fabricated of unreinforced and nano-ZrO2 reinforced acrylic resin at 2.5% and 5%, resulting in 3 main groups. These groups were further subdivided (n = 10) according to immersion solution (distilled water, Corega, sodium hypochlorite, and Renew) and immersion duration. Surface roughness, hardness, and color were measured at baseline (2 days-T0) in distilled water and then after 180 and 365 days of immersion (T1 & T2) in water or denture cleansing solutions. Data was collected and analyzed using two-way ANOVA followed by Bonferroni post hoc test (α = 0.05). Results Surface roughness increased significantly after denture cleanser immersion of unmodified and nano-ZrO2-modified PMMA materials while hardness decreased (P < 0.001). The denture cleansers significantly affected the color of both PMMA denture bases (P < 0.001). The immersion time in denture cleansers significantly affected all tested properties (P < 0.001). Within denture cleansers, NaOCl showed the highest adverse effects (P < 0.05) while Renew showed the least adverse effects. Conclusion Denture cleansers can significantly result in color change and alter the surface roughness and hardness of denture base resin even with ZrO2 nanoparticles addition. Therefore, they should be carefully used.

Effects of Different Forms of Denture Adhesives on Biofilm Formation, Adhesive Strength and Hygiene of Complete Dentures.

To evaluate the effect of different forms of denture adhesives on the formation of biofilm and on adhesive strength, as well as the effectiveness of hygiene protocols for their removal. Samples of the heat-cured polymethyl methacrylate denture base resin were made and divided into four groups: control (no adhesive), ultra Corega cream, Corega strip adhesive, and ultra Corega powder (GlaxoSmithKline). Biofilm formation was evaluated by counting colony-forming units and fluorescence microscopy. To evaluate the effectiveness of the hygiene protocols, the samples were divided into five subgroups: brushing with distilled water; brushing with Protex soap; brushing with Colgate toothpaste; immersion in Corega Tabs; and immersion in Corega Tabs followed by brushing with the solution itself. The remaining adhesive was quantified with ImageJ software. The adhesive strength was tested at different time intervals after application. After verifying the data distribution using Shapiro-Wilk test, parametric or nonparametric analysis was applied (α = .05). Candida albicans formed more biofilm in strip (P = .007) and powder (P = .001), Pseudomonas aeruginosa in cream (P < .001) and powder (P < .001), and Staphylococcus aureus in strip (P < .001). All forms of the adhesives promoted higher biofilm formation when compared to control (P = .003). Brushing with Colgate and Protex was most effective for removing the adhesives (P < .05). Independently, Powder had the highest adhesive strength (P < .05). Only Strip showed a change in adhesive strength, with higher values after 3 hours of application (P = .004). Daily treatments with mechanical cleaning of the prosthesis are important for removing the adhesives, since the presence of this material can favor biofilm accumulation. The adhesive strength may vary depending on the commercial type, but all forms can be effective in retaining prostheses for a satisfactory period of time.

Effects of boron on the mechanical properties of polymethylmethacrylate denture base material.

The objective of this study was to determine whether the addition of different types of boron (Borax, Boric Acid and Colemanite) to polymethyl methacrylate denture base resin would improve flexural and impact strengths, and surface hardness of polymethyl methacrylate. Borax, Boric acid, Colemanite were added to heat polymerized polymethyl methacrylate specimens were prepared for flexural strength (65x10x2.5 mm), impact strength (50x6x4 mm), and hardness (20x6x4 mm) tests according to the manufacturers' instructions (n=10). To determine flexural strength of the specimens, they were loaded until failure on a universal testing machine using a three point bending test. Specimens were subjected to the Charpy impact test machine. Hardness of the specimens was measured with an analog shoremeter Shore D. The data were analyzed with Kruskal-Wallis and Mann-Whitney U tests (α=0.05). The highest mean flexural strength value was seen in 3% Borax group and followed by 1% Colemanite group. In addition, the highest mean impact strength value was recorded in 1% Colemanite group, and differences between 1% Colemanite group and control group were found to be statistically significant (p=0,001). Furthermore, there was significant difference in hardness between control group and all other groups (p<0.001). The addition of 1% Colemanite to polymethyl methacrylate improved the mechanical properties of PMMA.

Physicomechanical, optical, and antifungal properties of polymethyl methacrylate modified with metal methacrylate monomers

Statement of problemThe high recurrence rates of denture stomatitis may be associated with the resistance of biofilms to therapeutics. Therefore, methods that provide biomaterials with antifungal properties are an attractive solution to improving microbial control. PurposeThe purpose of this in vitro study was to modify conventional polymethyl methacrylate (PMMA) through the incorporation of metal methacrylate monomers and to evaluate the physicomechanical and optical properties and antifungal activity of the modified materials. Material and methodsExperimental denture base acrylic resins were fabricated through the addition of zirconium methacrylate (ZM), tin methacrylate (TM), and di-n-butyldimethacrylate-tin (DNBMT) to the liquid of a commercially available denture base PMMA resin. Unmodified PMMA resin was used as the control. The degree of conversion of the materials was tested through Fourier transform infrared spectroscopy (n=3). A digital spectrophotometer was used to assess the color change of the modified materials (n=8). Differences in Knoop hardness and roughness between experimental groups were also evaluated (n=8). A biofilm accumulation test with Candida albicans (ATCC 62342) (n=4) was performed for 5 days in Sabouraud broth culture supplemented with 10% sucrose. Data were subjected to analysis of variance and the post hoc Tukey honestly significant difference test (α=.05). ResultsThe degree of conversion and color-change values of the experimental materials were statistically similar to those of the control (P=.593). The incorporation of DNBMT significantly increased the hardness of the modified material (P=.014). The ZM, TM, and DNBMT groups had higher antifungal activity against C. albicans (P=.001) and lower roughness than the control group (control 0.65 ±0.05 μm; ZM 0.34 ±0.09 μm, TM 0.34 ±0.11 μm, and DNBMT 0.41 ±0.08 μm). ConclusionsThe metal-containing methacrylate monomers provided antifungal action to the modified materials without affecting the physicomechanical or optical properties of the denture base resin. ZM, TM, and DNBMT are potential reactive agents for the fabrication of PMMA denture base resins with antifungal properties.

Flexural strength and anti-fungal activity of copper nano-particles on poly-methyl methacrylate denture base resins

Poly-methyl methacrylate is the most common dental material used for removable dental prosthesis. With copper nano-particles known for their inherent anti-microbial nature, influence of copper nano-particles on flexural strength and the anti-fungal properties on Poly-methyl methacrylate (PMMA) based denture base resins was evaluated. Copper nano-particles were prepared from cupric nitrate and samples were prepared as parts per million of copper to the control, 12.5 ppm (D12.5), 25 ppm (D25) and 50 ppm (D50). Three-point bending test was evaluated using a universal testing machine and anti-fungal property was evaluated using crystal violet staining. The results reveal flexural strength of PMMA was affected by the incorporation of copper nanoparticles. Addition of 25 ppm of copper nano-particles (D25) to denture base resins showed highest flexural strength and has an inhibitory effect on Candida albicans biofilm formation.

A comparative evaluation of shear bond strength between self-cured resilient liner and denture base resin with different surface treatments

Statement of problem: Soft denture liners are widespread materials used in prosthetic dentistry. Their mechanical properties have to meet several key requirements such as adequate bond to denture base resins in order to provide right function of masticatory system and oral hygiene. Purpose: To evaluate and compare the shear bond strength between a commercially available self-cured silicon-based liner and polymethyl methacrylate (PMMA) denture base resin with different surface treatments. Materials and Methods: A soft denture liner Ufi-Gel P (silicone-based liner) and polymethyl methacrylate denture base resin (Rodex) were chosen for this study. A total of 50 samples were made, the samples were divided into five groups, containing 10 samples each. Group I: Consisted of an untreated surface of polymethyl methacrylate which acted as the control. Group II: The polymethyl methacrylate surface was treated with Acetone. Group III: The surface of polymethyl methacrylate surface was treated with laser Er:YAG with three different pulses duration. The shear bond strength was examined by Instron Universal Testing Machine at crosshead speed of 40mm/min. T-student test was used to analyze the data (α=0.05). Results: There was a statistically significantly difference in shear bond strength between laser-treated and untreated specimens (P

Effect of zinc oxide nanoparticles on the flexural strength of polymethylmethacrylate denture base resin.

This study evaluated the flexural strength of polymethyl methacrylate (PMMA) reinforced with various concentrations of zinc oxide (Zn O) nanoparticles. Nano ZnO was added in 0, 0.4, 0.6, 0.8, 1.2 and 1.4 percentage to PMMA denture base material. 60 specimens of heat cure polymerizing acrylic resin of dimensions 10mm x 4mm x 80mm were fabricated in accordance to ISO 20795-1-2013. The specimens were divided into 6 groups. Acrylic specimens were processed according to manufacturer's instruction. Three-point bending test was performed to evaluate the flexural strength. Surface analysis was performed with scanning electron microscopy (SEM) to observe the fracture surfaces of specimens. ANOVA and Tukey tests were used for the statistical analysis (p < 0.05). Statistical analysis revealed significant differences in strength between groups. The flexural strength improved with the addition ZnO nanoparticles. Highest mean value was observed in Group nZn -14 (91.31 MPa) and lowest in control Group nZn-0 (61.36 MPa). ANOVA and Tukey's honestly significance test found statistical significant differences among the groups ( p<0.001). The addition of ZnO nanoparticles in all concentrations increased the flexural strength of acrylic resin when compared to the control group.

The Impact of Polymerization Technique and Glass-Fiber Reinforcement on the Flexural Properties of Denture Base Resin Material.

Objective Different polymerization and reinforcement techniques have been tested to enhance the mechanical characteristics of denture base acrylic resins. The goal of the present study was to evaluate the influence of autoclave polymerization techniques with glass fiber reinforcement on the flexural strength and elastic modulus of polymethyl methacrylate denture base resins. Materials and Methods Ninety specimens were fabricated from heat-polymerized acrylic resin and randomly distributed depending on the polymerization technique into three groups ( n = 30): water bath polymerization, short-cycle autoclave polymerization, and long-cycle autoclave polymerization. Each group was further divided into three subgroups ( n = 10) based on the concentration of glass fiber 0, 2.5, and 5wt%. The flexural strength and elastic modulus were investigated using a universal testing machine. One-way ANOVA and Tukey’s post hoc test were performed to analyze the results ( α = 0.05). Results The flexural strength and elastic modulus values were significantly higher in 5wt% glass fiber reinforced long-cycle autoclave group in comparison with the other test groups ( p < 0.05). Conclusions The long-cycle autoclave polymerization technique with the glass fiber reinforcement significantly increased the flexural strength and elastic modulus of the denture base resin material.

Impact of Surface Treatment with Different Repair Acrylic Resin on the Flexural Strength of Denture Base Resin: An In Vitro Study

The aim and objective of the present study was to assess the flexural strength of denture base resin based on surface treatment with different acrylic resin repair materials. Totally, 120 heat-polymerized polymethyl methacrylate denture base resin materials which are rectangular shaped with the size of 65 mm × 10 mm × 2.5 mm were fabricated. 150 μm-sized alumina used for surface treatment. All the 120 heat-cured, surface-treated acrylic denture base resin samples were randomly divided into three groups. Group I: glass-fiber-reinforced auto-polymerizing acrylic resin, group II: auto-polymerizing acrylic resin, and group III: light-cured acrylic resin. A universal testing machine was used to test the flexural strength of the repaired specimens. A highest mean flexural strength (88.96 ± 0.31) was demonstrated by group I, followed by group II (72.18 ± 1.86) and group III (66.30 ± 1.02). ANOVA demonstrated a statistically significant inter-group difference. On multiple comparisons, using Tukey's post hoc test a statistically significant difference between groups I and II and between groups I and III was found. After considering the limitations, the present study concluded that the highest flexural strength is shown by glass-fiber-reinforced auto-polymerizing acrylic resin than by auto-polymerizing acrylic resin and light-cured acrylic resin. Denture repair comprises of joining two fractured parts of a denture with a denture repair material. The success of denture repair depends on the adhesion phenomenon. The treatment of the surface can be accomplished using a suitable material which changes chemically and morphologically and thus promotes better adhesion.

Effect of titanium oxide and zirconium oxide nanoparticle incorporation on the flexural strength of heat-activated polymethyl methacrylate denture base resins – An in vitro experimental study

Introduction: Flexural strength is one of the most important properties which determine the clinical success of dentures. Even though titanium oxide nanoparticles (nano-TiO2) and zirconium oxide nanoparticles (nano-ZrO2) are extensively used to modify the properties of polymethyl methacrylate (PMMA) resin, there is negligible documentation in the literature comparing these two.Aim: The aim of the study is to find out and compare the effect of incorporation of 1 weight % nano-TiO2 and nano-ZrO2 on the flexural strength of heat-activated PMMA resin.Materials and Methods: 1 weight % of TiO2 and ZrO2 nanoparticles were weighed using a digital weighing balance and mixed with PMMA resin powder using the geometric dilution method. Sixty “35 mm × 10 mm × 3 mm” rectangular-shaped specimens fabricated were divided into three different groups, each containing twenty samples each. The specimens were loaded to failure at a crosshead speed of 1 mm/min and with 500 N load cell in a Universal Instron Testing Machine, Model 3345. Flexural strength was registered by the machine with 0.001 MPa precision.Results: PMMA with nano-TiO2 group had the maximum flexural strength, load at maximum flexure, and load at break followed by unreinforced PMMA and PMMA with nano-ZrO2. Statistically significant difference was noted between the three groups (P < 0.001). Post hoc analysis using Tukey's post hoc test showed a statistically significant difference for all three pair-wise comparison.Conclusions: Within the limitations of this study, it can be concluded that nano-TiO2 greatly enhanced the flexural strength, load at maximum flexure load, and load at break of PMMA resin, whereas nano-ZrO2 significantly reduced these properties of PMMA.

Comparison of Flexural Strength of Kevlar, Glass, and Nylon Fibers Reinforced Denture Base Resins With Heat Polymerized Denture Base Resins.

ABSTRACTIntroduction:Polymethyl methacrylate (PMMA) has been widely accepted and used in dentistry owing to its working characteristics, aesthetics and stability in the oral environment, ease in manipulation, and inexpensive processing methods and equipment.Aim and Objectives:The aim of this study was to evaluate the flexural strength of a high-impact PMMA denture base resin material and flexural strength of a commonly available heat cure PMMA denture base material with Kevlar, glass, and nylon fibers.Materials and Methods:The test samples were studied under two groups. The Group I (control group) comprised pre-reinforced PMMA (Lucitone 199; Dentsply Sirona Prosthetics, York, Pennsylvania, USA) consisting of 12 samples and second group comprised regular PMMA (DPI, Mumbai, India) reinforced with different fibers. The second test group was further divided into three subgroups as Group 2, Group 3, and Group 4 comprising 12 samples each designated by the letters a–l. All the samples were marked on both ends. A total of 48 samples were tested. Results were analyzed and any P value ≤0.05 was considered as statistically significant (t test).Results:All the 48 specimens were subjected to a 3-point bending test on a universal testing machine (MultiTest 10-i, Sterling, VA, USA) at a cross-head rate of 2 mm/min. A load was applied on each specimen by a centrally located rod until fracture occurred; span length taken was 50 mm. Flexural strength was then calculated.Conclusion:Reinforcement of conventional denture base resin with nylon and glass fibers showed statistical significance in the flexural strength values when compared to unreinforced high impact of denture base resin.

Comparison on the Transverse Strength of Heat Cure Polymethylmethacrylate Denture Base Resin Repaired with Different Surface Treatments and Surface Design Modifications

Comparison on the Transverse Strength of Heat Cure Polymethylmethacrylate Denture Base Resin Repaired with Different Surface Treatments and Surface Design Modifications

The Influence of Graphene in Improvement of Physico-Mechanical Properties in PMMA Denture Base Resins.

The clinical performances of dental materials depend on their mechanical profiles, determining their long-term deformation and wear resistance. This paper describes a study on the mechanical properties, water absorption and morphological properties of a polymethyl methacrylate (PMMA) resin enriched with graphene-silver nanoparticles (Gr-Ag). Two different concentrations—1 and 2 wt.%—of Gr-Ag were loaded into the PMMA material. For the mechanical characterization, the compression behavior, flexural strength and tensile strength were evaluated. Optical microscopy in polarized light and scanning electron microscopy were used for filler analysis. The filler addition led to an improvement in all mechanical properties, with slight changes being derived from the filler content variation. Gr-Ag use led to an increase in the applied maximum loads. Moreover, 1 wt.% Gr-Ag determined an increase of 174% in the modulus of rupture, which indicates high flexibility.

Grapefruit seed extract effectively inhibits the Candida albicans biofilms development on polymethyl methacrylate denture-base resin.

This study aimed to investigate the cleansing effects of grapefruit seed extract (GSE) on biofilms of Candida albicans (C. albicans) formed on denture-base resin and the influence of GSE on the mechanical and surface characteristics of the resin. GSE solution diluted with distilled water to 0.1% (0.1% GSE) and 1% (1% GSE) and solutions with Polident® denture cleansing tablet dissolved in distilled water (Polident) or in 0.1% GSE solution (0.1% G+P) were prepared as cleansing solutions. Discs of acrylic resin were prepared, and the biofilm of C. albicans was formed on the discs. The discs with the biofilm were treated with each solution for 5 min at 25°C. After the treatment, the biofilm on the discs was analyzed using a colony forming unit (CFU) assay, fluorescence microscopy, and scanning electron microscopy (SEM). In order to assess the persistent cleansing effect, the discs treated with each solution for 5 min were aerobically incubated in Yeast Nitrogen Base medium for another 24 h. After incubation, the persistent effect was assessed by CFU assay. Some specimens of acrylic resin were immersed in each solution for 7 days, and changes in surface roughness (Ra), Vickers hardness (VH), flexural strength (FS), and flexural modulus (FM) were evaluated. As a result, the treatment with 1% GSE for 5 min almost completely eliminated the biofilm formed on the resin; whereas, the treatment with 0.1% GSE, Polident, and 0.1% G+P for 5 min showed a statistically significant inhibitory effect on biofilms. In addition, 0.1% GSE and 0.1% G+P exerted a persistent inhibitory effect on biofilms. Fluorescence microscopy indicated that Polident mainly induced the death of yeast, while the cleansing solutions containing at least 0.1% GSE induced the death of hyphae as well as yeast. SEM also revealed that Polident caused wrinkles, shrinkage, and some deep craters predominantly on the cell surfaces of yeast, while the solutions containing at least 0.1% GSE induced wrinkles, shrinkage, and some damage on cell surfaces of not only yeasts but also hyphae. No significant changes in Ra, VH, FS, or FM were observed after immersion in any of the solutions. Taken together, GSE solution is capable of cleansing C. albicans biofilms on denture-base resin and has a persistent inhibitory effect on biofilm development, without any deteriorations of resin surface.

Biofilm Formation of Respiratory Pathogens on Vanillin-Incorporated Denture Base Resin

The adherence of microorganisms to denture base materials and the consequent formation of biofilms on these surfaces are contributing factors to biofilm-related oral and systemic diseases. Aspiration pneumonia is a potentially life-threatening respiratory infection associated with the entry of foreign materials into the bronchi. Vanillin-incorporated polymethyl methacrylate (PMMA) resin has been developed for the use in dentistry and demonstrated to have antimicrobial activity. Objective: To evaluate antimicrobial property of vanillin-incorporated PMMA denture base resin on biofilm formation of respiratory pathogens. Materials and methods: The heat polymerized PMMA denture base resin samples (Siam Cement Group, Thailand) were prepared according to the percentage of vanillin incorporation (0%, 0.1% and 0.5% vanillin). Another group of commercial resin samples without vanillin (Triplex®, Ivoclar Vivadent, USA) was prepared in the same manner. All samples were coated with sterile unstimulated saliva collected from three healthy adult volunteers at 37 °C for 60 min. The respiratory pathogenic bacteria used in this study were Staphylococcus aureus ATCC 5638, Streptococcus pneumoniae ATCC 49619, and Pseudomonas aeruginosa ATCC 27853. They were prepared to a concentration of approximately 107 colony forming unit (CFU)/mL. The bacterial biofilm formation was done in 96-well plate and incubated at 37°C for 24-48 h. The amount of biofilm was quantified by Cell Counting Kit WST-8 (Dojindo Molecular Technologies, USA) at 420 nm. All tests were performed in triplicate on three separate occasions. One-way ANOVA and Turkey’s test were used for the statistical analysis. Results: The vanillin-incorporated resin groups (0.1% and 0.5% vanillin) had a significant reduction of S. aureus and P. aeruginosa biofilm mass compared with resins without vanillin (0% vanillin and commercial resin groups). No significant difference was observed in the S. pneumonia biofilm formation. Up to 80% and 33% reductions of biofilm mass were demonstrated on P. aeruginosa and S. aureus, respectively. Conclusion: The incorporation of vanillin to denture base PMMA resin could significantly inhibit biofilm formation of respiratory pathogens. Using this PMMA resin, denture base materials with antimicrobial property can be applied to reduce a risk of respiratory infection in denture wearing patients.

Flexural Strength, Antimicrobial Activity and Color Stability of Ginger (&lt;i&gt;zingiber&lt;/i&gt;&lt;i&gt; &lt;/i&gt;&lt;i&gt;officinale&lt;/i&gt;) Modified Heat Cured Denture Base Material

Objective: This study evaluated ginger modified heat cured poly methyl methacrylate (PMMA) denture base material regarding; surface roughness, flexural strength, antimicrobial activity, and color stability. Materials and methods: Ginger was used in powder and oil forms to modify the polymer and monomer. Seven experimental groups were formulated; Group (I) control; Group (II) 3 wt% ginger-powder modified polymer; Group (III) 5 wt% ginger-powder modified polymer; Group (IV) 3 v/v% ginger-oil modified monomer; Group (V) 5 v/v% ginger-oil modified monomer; Group (VI) 3 wt% ginger-powder modified polymer mixed with 5 v/v% ginger-oil modified monomer; Group (VII) 5 wt% ginger-powder modified polymer mixed with 3 v/v% ginger-oil modified monomer. Specimens were tested for surface topography, surface roughness, flexural strength, antimicrobial activity, and color stability. The data were statistically analyzed by one-way ANOVA and post-hoc LSD analysis with a significance factor of α = 0.05. Results: The PMMA polymer modified with 3 v/v% ginger-oil (Group IV) exhibited a significant reduction in surface roughness, a significant increase in flexural strength with clinically acceptable color change. No antimicrobial activity was detected for any of the evaluated groups. Conclusions: 3 v/v% ginger-oil was able to improve the mechanical properties of heat cured PMMA denture base resin with a tolerable color change.

Effectiveness of 405-nm blue LED light for degradation of Candida biofilms formed on PMMA denture base resin.

This study investigated (i) the degradation effect of 405-nm blue light-emitting diode (LED) light irradiation on Candida albicans and C. glabrata biofilms formed on denture base resin and (ii) the effects of 405-nm blue LED light irradiation on the mechanical and surface characteristics of the resin. Polymethyl methacrylate denture base resin discs were prepared, and C. albicans or C. glabrata biofilms formed on the denture base resin discs. Each biofilm was irradiated with 405-nm blue LED light under a constant output power (280mW/cm2) for different times in a moisture chamber with 100% relative humidity. Postirradiation, each biofilm was analyzed using a colony-forming unit assay, fluorescence microscopy, and scanning electron microscopy (SEM). Parallelepiped specimens of acrylic resin were prepared, and changes in their flexural strength (FS), flexural modulus (FM), and surface roughness (Ra) preirradiation and postirradiation with 405-nm blue LED light were evaluated. Irradiation for 30min completely inhibited colony formation in both Candida species. Fluorescence microscopy showed that almost all Candida cells were killed because of irradiation. SEM images showed various cell damage patterns, such as wrinkles, shrinkage, and cell surface damage. An increase in FS was noted postirradiation, but no significant changes were observed in FM and Ra preirradiation and postirradiation. In conclusion, irradiation with 405-nm blue LED light induces degradation of C. albicans and C. glabrata biofilms on denture base resin, even in the absence of photosensitizers, without resin surface deterioration.

Comparative Evaluation of Water Sorption of Heat-Polymerized Polymethyl Methacrylate Denture Base Resin Reinforced with Different Concentrations of Silanized Titanium Dioxide Nanoparticles: An In vitro Study.

Statement of Problem:Polymethyl methacrylate (PMMA) is the most regularly used material in denture fabrication. Water sorption of denture base PMMA denture base resin has negative effects on physical properties, may lead to harmful tissue reactions in patients, and also has detrimental effects on color stability of the denture base.Purpose:The purpose of this study was to evaluate the effect on water sorption of heat-cured PMMA denture base material after incorporation of 1%, 3%, and 5% by weight of silanized titanium dioxide (TiO2) nanoparticles.Materials and Methods:For preparation of test samples, TiO2 nanoparticles (PCode: 700339, Sigma-Aldrich, USA) were coated with a layer of trimethoxysilylpropylmethacrylate (PCode: 440159, Sigma-Aldrich, USA) before sonicated in monomer (MMA) (DPI Heat Cure) with the percentages 1%, 3%, and 5% by weight; after sonication, it was mixed with PMMA powder using conventional denture fabrication procedure. Then, we prepared total 40 samples for study; 10 samples for each four groups, i.e. that is one control group and three experimental groups. The first group was prepared from PMMA without addition of TiO2 nanoparticles (control group), the second group with the addition of 1 wt% TiO2 nanoparticles, the third group with 3 wt% TiO2 nanoparticles, and the fourth one with 5 wt% TiO2 nanoparticles (experimental groups). Water sorption test was then conducted on each sample.Results:Each group was evaluated for water sorption test, and it was found that increasing the wt% of nanoparticles, there was a significant decrease in water sorption of denture base resin from 1.74 to 1.46 mean wt%. P value suggested that the difference of mean percent increase across all groups was statistically significant with P = 0.034.Conclusion:The maximum decrease in water sorption was observed in denture base resin incorporated with 5 wt% TiO2 nanoparticles.