جستجوی مقالات مرتبط با کلیدواژه "acrylic resin" در نشریات گروه "پزشکی"

Candida albicans in the oral cavity causes denture-induced stomatitis, but current treatments have side effects and contribute to drug resistance. Selenium nanoparticles (SeNPs) show promise as an antimicrobial agent, but their effectiveness against C. albicans is unknown and warrants further research.

 Acrylic resins containing different concentrations of SeNPs (0.2, 2, and 10 g/mL) were formulated and evaluated against C. albicans isolates. The minimum inhibitory concentration (MIC) of SeNPs was determined, and a fungal biofilm was developed on acrylic samples. The quantity of biofilm was assessed using scanning electron microscopy (SEM) and optical density (OD) at 570 nm after staining with crystal violet. Statistical analysis was performed using STATA software, with Kruskal-Wallis and Mann-Whitney tests to establish significance (P<0.05).

 The MIC of SeNPs was 25%. The OD in the group with 10% SeNPs was 0.477 and 0.547 in the group with 0.2%. Kruskal-Wallis test results showed that at least two groups among those studied had significant differences (P=0.0273). In pairwise comparisons, the differences between all the groups were statistically significant (P=0.049). SEM analysis confirmed the destruction of C. albicans cell walls, leading to reduced colonization, with the 10% group showing the highest efficacy.

The study demonstrated that SeNPs are effective against C. albicans colonization when combined with acrylic resin. Specifically, SeNPs exhibited enhanced antifungal properties at a concentration of 10%. These findings confirm that SeNPs are a promising alternative to traditional antifungal agents for treating oral candidiasis and denture-induced stomatitis.

Vaginal agenesis or atresia in females suffering from MRKH syndrome is more common and management involves both surgical and non-surgical approaches. Use of prefabricated stents to maintain the patency of the canal may not fit appropriately during the initial surgical phase and are not economical. This case report discusses a series of modifications in a custom-made vaginal dilator to improve the retention for expansion after surgical management of MRKH syndrome.

Case report: 

A 28-year-old female diagnosed with MRKH syndrome with characteristic Mullerian agenesis was referred for customised vaginal stent. Customised surgical stent was fabricated with loops for orientation and retention, which was later modified into interim expansion and passive stent.

The customisation of the vaginal stent, provision of a retentive loop that positioned the stent in the proper orientation, and gradual increase in the size of the stent, ensured dilatation in a patient with vaginal agenesis.

This study aimed to find out how exposure to gaseous ozone affected heat-cured acrylic resin’s transverse and impact strengths.

Sixty samples of heat-cured acrylic resin were prepared and divided into three subgroups, control, microwave radiation (positive control), and gaseous ozone. Transverse strength and impact strength were evaluated using testing machines. At a level of significance of 5%, data were assessed using one-way analysis of variance (ANOVA) and Tukey’s post hoc test.

Transverse strength analysis showed a significant difference among groups (P < 0.001). Post hoc test revealed significant differences between all multiple groups (P < 0.001). Impact strength analysis results showed a non-significant difference among groups (P= 0.13).

Within the limits of this research, it is possible to conclude that gaseous ozone exposure improves the transverse strength of heat-cure acrylic resin.

Microbial accumulation is still a significant problem with removable acrylic appliances. This study aimed to assess the antimicrobial properties of a self-cured acrylic resin containing curcumin nanoparticles (CNPs).

This in vitro study used 48 acrylic discs containing 0.5%, 1%, and 2% CNPs. The antimicrobial properties of the discs against Streptococcus mutans, Streptococcus sanguinis, Lactobacillus acidophilus, and Candida albicans were evaluated using disc agar diffusion (DAD), eluted component, and biofilm inhibition tests. The growth inhibition zones were measured, and the colonies were counted after 1, 3, and 7 days.

DAD test showed that none of the curcumin nanoparticle concentrations caused growth inhibition zones for any microorganisms. All the concentrations were effective against all four microorganisms in the biofilm inhibition test except 0.5% for L. acidophilus. In the eluted component test, solutions containing 2% concentration had maximum growth inhibition of all the groups at all time intervals. An increase in curcumin nanoparticle concentration from 0.5% to 1% was effective only against C. albicans.

Generally, CNPs in all concentrations were effective against the biofilms of all four microorganisms assessed in this study. Therefore, incorporating 2% CNPs into acrylic resin seems suitable for clinical use.

The impact of Candida-associated denture stomatitis has been vastly discussed in the literature, starting from simple routine oral hygiene practices to the use of the denture itself as a drug delivery unit. Since candidiasis tends to keep recurring, the use of antifungal drugs in the denture or liner provides the benefit of placing the patient under oral drug intake for a long period of time.  This in-vitro study aimed to assess the release of chlorhexidine from the acrylic resin discs made from two resins, heat cure and light cure. The study also intended to assess the presence of the drug release and its sufficient effectiveness to be reproduced in-vivo in the treatment of oral candidiasis. Standard chlorhexidine solution, Chlorhexidine treated heat cure, and light cure resin disc soaked solutions were subjected to test under high-performance liquid chromatography (HPLC) and scanning electron microscopy for the release of chlorhexidine.  The HPLC analysis of heat cure resin demonstrated that the area and height of chlorhexidine release were comparable to those of the standard chlorhexidine solution. This implies the local release of chlorhexidine in-vitro. In this study, it was found that chlorhexidine release in heat cure discs is less when compared to the standard stock solution; nonetheless, it is good enough to reach the minimum inhibition concentration of chlorhexidine to be effective against candidiasis. Although this study was limited in nature, the results raised hope for further evaluation of dentures as a drug delivery system.

 The disinfection of orthodontic acrylic resins might change the physical and mechanicalproperties of these materials. We aimed to investigate the impact of four different commercially availabledisinfectants on the surface roughness of acrylic resins used for orthodontic appliances.

 Four disinfectant solutions (BirexSE, Opti-Cide3, COEfect MinuteSpray, and CaviCideSpray) were used to disinfect orthodontic acrylic resins using the spraying method. The resins weresubjected to repeated disinfection protocols. Distilled water, also applied via spraying method, was usedas a control. Surface roughness was scrutinized to examine the extent of surface topography changes bystylus profilometry. Data normality was evaluated via the Shapiro–Wilk test, followed by the WilcoxonSigned-Rank test for non-parametric data or paired Student’s t-test for parametric data to compareintra-group differences in roughness before and after the use of the disinfectant solutions.

 Some of the disinfectants (BirexSE and CaviCide) resulted in significant changes in surfaceroughness values before and after the disinfection compared to the controls (P<0.05). The groups thatwere in contact with distilled water, Opti-Cide, and Coeffect did not exhibit significant differences insurface roughness before and after the intervention (P>0.05). However, from a clinical perspective, theresulting variations in surface roughness (<%0.15) induced by these solutions might not reflect clinicallysignificant differences.

The use of disinfectant solutions is unlikely to harm the surface of orthodontic acrylic resins.Oral care providers need to be attentive to the interpretation and implementation of clinically significantchanges in their evidence-based approach regarding potential material damages by disinfection sprays.

Objectives Acrylic resins are one of the most important denture base materials in dentistry due to their favourable mechanical and physical properties. The purpose of present study is to compare 4 available acrylic flexural strength properties before and after thermocycling.
Methods Acrylic resin specimens of Meliodent (Heraeus Kulzer, Hanau, Germany), Vertex (Vertex-dental BV, Zeist, Netherlands), Mead way (Dental Supplies LTD, Surrey, England) and Versacryl (Keystone, Gibbstown, NJ) prepared according to ISO 20745-2 (in dimensions of 25x7x2 mm). Total of 40 blocks obtained: 10 specimens from each type of acrylic resin made one group. Each group divided into two equal subgroups. Flexural strength of specimens in subgroup 1 measured before thermocycling process whereas same measurement carried out for subgroup 2 after thermocycling (5000 cycles) process. Three-point bending test used for the final measurement. Data were analyzed using two-way ANOVA and Bonferroni post-hoc tests with mean difference significant at the 0.05 level (P < 0.05)
Results Mead way acrylic resin showed a higher level of flexural strength (105.98± 4.90 MPa) without thermocycling compared to Meliodent and Vertex resins, however, no significant difference was observed between Mead way and Versacryl resin’s same property. Data analysis revealed that thermocycled Meadway resin had highest flexural strength (90.25±S6.30 MPa) in comparison to other resins (Meliodent, Vertex and Versacryl). Flexural strength appeared significant reduction in all resins after polymerization.
Conclusion Mead way resin presented the highest flexural strength in both thermocycled and non-thermocycled resin groups. Nonetheless, thermocycling process resulted in notably lower measurements of flexural strength in Versacryl, Vertex, Meliodent and Mead way resins

The purpose of this study was to compare dimensional changes of two types of auto polymerizing acrylic resin patterns (APARPs) in three different storing environments.
60 acrylic post and core patterns were made of two types of Duralay acrylic resins (Aria dent, Iran and Reliance, Dental Mfg. Co, USA) using a canine model. Then coronal, apical diameter and coronoapical length of patterns were measured. Afterwards, they were divided into two categories of 30 for each type of Duralay acrylic resin type. Each category was divided into three groups of ten randomly to immerse in three storage environments (Deconex®53plus Borer ChemieAG, Switzerland), Unident ® Impre(USF Healthcare S.A, Sweitzerland) and water. After one hour, three mentioned values were measured again. Data were analyzed by SPSS20 using t-test, paired t-test and ANOVA.
Results showed that there were no statistically difference (p value> 0.05) about all dimensions of auto polymerizing acrylic post and core patterns except apical diameter and coronoapical length of Dental Mfg. Co, USA in Deconex®53 plus.
The best environment to store Duralay APARPs with minimal changes was water and for disinfection, Deconex®53plus and Unident ® Imprecan showed acceptable properties with both of Duralay types.

metalic-Nanoparticles (NPs) is new antifungal materials versus the resistant fungi as Candida albicans (C. albicans) that is the main factor of acrylic-denture candidosis. Whenever Ag NPs as a strong antifungal metalic-NPs exhibit toxic effect on human cells, the aim of this study was evaluation the antifungal effects of ZnO NPs in acrylic resin (polymethyle methacrylate (PMMA)) as a more biocompatible material on C. albicans in comparison to acrylic resin (PMMA) containing Ag NPs.
In this laboratory study, eleven 10-member groups of acrylic resin specimens with ZnO NPs and Ag NPs (totally 110 specimens) were used. The weight percent of NPs 0.5, 2.5, 5, 10, and 20%, that were added to the monomer in each phase and after mixing with powder, flasking carried out in a conventional manner and in a flask with 12 cylindrical cavities with a diameter of 10 mm and thickness of 4 mm in internal space to produce discoid specimens, after deflasking the specimens were finished, polished, cleaned ultrasonically for 5 min in ethanol, rinsed with sterile water and dried in warm air. Afterward they inucleated by 0.1 ml of an inoculating suspension containing 103 concentration of C. albicans (ATCC 10231) and were incubated for 24 hours. Then, the sample was washed with 4.8 ml of 0.9%NaCl solution, and 0.1mL of the washing NaCl solution was taken and cultured on tutrient agar, then incubated for another 24 hours and colony numbers were counted and the data was analyzed by one way ANOVA.
Ag & Zno NPs could significantly decrease population of C. albicans after 24 hour of exposure time, meanwhile Ag NPs exhibited stronger antifungal effect than ZnO NPs (P˂0.001).
Zno NPs can inhibited the C. albicans. To suggest this technique as a reliable method and determination of technical particle, the efficiency of ZnO NPs should be evaluated in clinical trials.

Context: This study aimed to provide an overview of the literature on the radiopacity of dental materials in order to emphasize its importance..
Evidence Acquisition: English-language literature was investigated using manual and electronic searches for the terms “radiopacity,” “dental material,” “cement,” “composite,” “ceramic,” “endodontic root canal sealer,” “bone graft,” and “acrylic resin” in the databases of Medline, google scholar, and Scopus up to April 2016. Seventy-nine selected publications, including review articles, original articles, and books, were evaluated..
The radiopacity of different dental materials may be lower or higher than that of the replaced tissue depending on the restorative material used. The research revealed that highly-radiopaque materials should not be used in dental restorations, except as bone graft and endodontic root canal filling materials. For most of the dental restorative materials, moderate radiopacity within the range of the replaced dental tissue is recommended. However, the lower radiopacity of polymer-based restorative or prosthetic dental materials is still a significant clinical problem..
The author recommends using highly-radiopaque materials whenever possible for treatment of bone defects and root canals. For dental materials that replace clinical crowns, the radiopacity should be within the range of that of the replaced tooth structure (dentin or enamel). The radiopacity of dental cements should be much higher than that of the enamel in order to facilitate detection of the thin cement remnants..

Polymethyl methacrylate (PMMA) is widely used for the fabrication of removable prostheses. Silver nano-particles (AgNps) have been added to PMMA because of their antimicrobial properties, but their effect on the mechanical properties of PMMA is unknown. The aim of this study was to investigate the effects of AgNps on the tensile strength of PMMA. For this study, 12 specimens were prepared and divided into two groups. Group 1 included PMMA without AgNps and group 2 included PMMA mixed with 5 wt% of AgNps. Tensile strength of the specimens was measured by Zwick Z100 apparatus. Statistical analysis was carried out by SPSS using t-test. Statistical significance was defined at P<0.05. This study showed that the mean tensile strength of PMMA in group 2 was significantly lower than that in group 1. Therefore, the tensile strength decreased significantly after incorporation of silver nano-particles. Within the limitations of this study, tensile strength of acrylic resin specimens was influenced by silver nano-particles.

Polymethyl methacrylate, PMMA, is widely used in prosthodontics for fabrication of removable prostheses. This study was undertaken to investigate the effect of adding silver nanoparticles (AgNPs) to PMMA at 2% and 0.2% concentrations on compressive and tensile strengths of PMMA. The silver nanoparticles were mixed with heat-cured acrylic resin in an amalgamator in two groups at 0.2 and 2 wt% of AgNPs. Eighteen 2×20×200-mm samples were prepared for tensile strength test, 12 samples containing silver nanoparticle and 6 samples for the control group. Another 18 cylindrical 25×38-mm samples were prepared for compressive strength test. Scanning electron microscopy was used to verify homogeneous distribution of particles. The powder was manually mixed with a resin monomer and then the mixture was properly blended. Before curing, the paste was packed into steel molds. After curing, the specimens were removed from the molds. One-way ANOVA was used for statistical analysis, followed by multiple comparison test (Scheffé’s test). This study showed that the mean compressive strength of PMMA reinforced with AgNPs was significantly higher than that of the unmodified PMMA (P< 0.05). It was not statistically different between the two groups reinforced with AgNPs. The tensile strength was not significantly different between the 0.2% group and unmodified PMMA and it decreased significantly after incorporation of 2% AgNPs (P< 0.05). Based on the results and the desirable effect of nanoparticles of silver on improvement of compressive strength of PMMA, use of this material with proper concentration in the palatal area of maxillary acrylic resin dentures is recommended.

Acrylic resin denture bases undergo dimensional changes during polymerization. Injection molding techniques are reported to reduce these changes and thereby improve physical properties of denture bases. The aim of this study was to compare dimensional changes of specimens processed by conventional and injection-molding techniques. SR-Ivocap Triplex Hot resin was used for conventional pressure-packed and SR-Ivocap High Impact was used for injection-molding techniques. After processing, all the specimens were stored in distilled water at room temperature until measured. For dimensional accuracy evaluation, measurements were recorded at 24-hour, 48-hour and 12-day intervals using a digital caliper with an accuracy of 0.01 mm. Statistical analysis was carried out by SPSS (SPSS Inc., Chicago, IL, USA) using t-test and repeated-measures ANOVA. Statistical significance was defined at P<0.05. After each water storage period, the acrylic specimens produced by injection exhibited less dimensional changes compared to those produced by the conventional technique. Curing shrinkage was compensated by water sorption with an increase in water storage time decreasing dimensional changes. Within the limitations of this study, dimensional changes of acrylic resin specimens were influenced by the molding technique used and SR-Ivocap injection procedure exhibited higher dimensional accuracy compared to conventional molding.

Debonding of denture teeth from denture bases is the most common failure in removable dentures. The purpose of this study was to evaluate the effect of surface treatments on shear bond strength of denture teeth to heat-polymerized and autopolymerized denture base resins. In this experimental in vitro study, 60 maxillary central incisor acrylic teeth were divided into two groups. Group M was polymerized with heat-polymerized acrylic resin (Meliodent) by compression molding technique and group F was processed by autopolymerized acrylic resin (Futura Gen) by injection molding technique. Within each group, specimens were divided into three subgroups according to the teeth surface treatments (n = 10): (1) ground surface as the control group (M1 and F1), (2) ground surface combined with monomer application (M2 and F2), and (3) airborne particle abrasion by 50 μm Al2O3 (M3 and F3). The shear bond strengths of the specimens were tested by universal testing machine with crosshead speed of 5 mm/min. Data were analyzed by two-way analysis of variance (ANOVA) and Tukey’s honestly signifi cant difference (HSD) tests (P < 0.05). The mean shear bond strengths of the studied groups were 96.40 ± 14.01, 124.70 ± 15.64, and 118 ± 16.38 N for M1, M2, and M3 and 87.90 ± 13.48, 117 ± 13.88, and 109.70 ± 13.78 N for F1, F2, and F3, respectively. The surface treatment of the denture teeth signifi cantly affected their shear bond strengths to the both the denture base resins (P < 0.001). However, there were no signifi cant differences between the groups treated by monomer or airborne particle abrasion (P = 0.29). The highest percentage of failure mode was mixed in Meliodent and adhesive in Futura Gen. Monomer application and airborne particle abrasion of the ridge lap area of the denture teeth improved their shear bond strengths to the denture base resins regardless of the type of polymerization.