Acrylic Specimens Research Articles

Shear Bond Strength Comparison Between Heat Cure Acrylic Resin and Other Types of Acrylic Denture Bases

Objective: The study purpose was to examine the shear bonding strength of heat cure acrylic resin to thermoplastic resin and three-dimensional printed resin materials. Methods: A total of 30 acrylic specimens were fabricated in this study. Each specimen had a basal and top parts. The basal part was rectangular in shape. We had three different groups: 10 specimens of a basal part made of heat cured polymethylmethacrylate, 10 specimens of a basal part made of thermoplastic, and 10 specimens of three dimensionally printed resin. The top part of which is attached to the basal one was formed into a cylindrical shape made of heat cure poly methyl methacrylate in all three groups. Results: Significant differences were found between the heat cured polymethylmethacrylate and the other two groups (P<.001). Heat cured polymethylmethacrylate showed the highest bond strength (75 MPa), and thermoplastic resins showed the lowest (37 MPa). No significant difference in the shear bond strength was noticed between three dimensionally printed and thermoplastic acrylic. Conclusion: This study revealed that the shear bond strength of heat cured acrylic denture base to the relining/repairing from the same material was significantly higher than three dimensionally printed and thermoplastic resins with HC relining/repairing material.

Antimicrobial, Optical, and Mechanical Properties of Saliva-Contaminated Silver–Zeolite Nanoparticle-Incorporated Dental Acrylic Resins

Background and Purpose: This study aimed to evaluate the flexural strength, color change and antimicrobial effect of silver–zeolite nanoparticles (NPs) in acrylic resin materials. Methods: Fifty-six disc-shaped acrylic resin samples were divided into four groups (n = 7) according to concentrations of silver–zeolite NPs (0%, 2%, 4%, 5%). Discs were contaminated with C. albicans and S. mutans. The antimicrobial effect was tested by inoculating contaminated discs on Tryptic soy agar (TSA), Sabouraud Dextrose Agar (SDA), Tryptic soy broth (TSB), and Sabouraud dextrose broth (SDB). Forty rectangular 65 × 10 × 2.5 mm acrylic resin specimens were also classified into four groups (n = 10) according to concentrations of silver–zeolite NPs. For the color change, L, a, and b values of rectangular specimens were examined with a spectrophotometer. A three-point bending test was also performed using a Devotrans device to determine the flexural bond strength of rectangular specimens. Scanning electron microscope analysis (SEM/EDX analysis) was also performed. Results: In this study, the antimicrobial effect increased with the concentration of silver–zeolite NPs added to acrylic resin discs. In our study, adding 2% silver–zeolite NPs was more effective against C. albicans. The antimicrobial effect against S. mutans increased with concentration of silver–zeolite NPs (<0.001). The colonization of C. albicans was significantly reduced by silver–zeolite NPs. A significant increase was observed in the color change as the nanoparticle percentage ratio increased (p < 0.001). The flexural strength values of the groups containing 2% and 4% nanoparticles were found to be clinically acceptable. Conclusions: The study showed that bacterial and fungal colonization is significantly reduced by adding silver–zeolite nanoparticles to acrylic resin discs. Based on its antimicrobial, physical, and mechanical properties, we recommend adding 2% silver–zeolite nanoparticles to the acrylic resin material for optimal results.

Reduction of Multispecies Biofilms on an Acrylic Denture Base Model by Antimicrobial Photodynamic Therapy Mediated by Natural Photosensitizers.

The aim of this study is to investigate the antimicrobial efficacy of antimicrobial photodynamic therapy (PDT) using natural photosensitizers (curcumin, riboflavin, and phycocyanin) and light-emitting diode (LED) irradiation against multispecies biofilms in an acrylic denture base model. Forty-five acrylic specimens were fabricated using heat-curing acrylic resin. The specimens were then infected with a mixed culture of bacterial and fungal species (including Streptococcus mutans, Streptococcus sanguinis, Candida albicans, and Candida glabrata) for 4 days. The acrylic discs were divided into nine groups, with each group containing five discs: control, 0.2% chlorhexidine, 5.25% sodium hypochlorite, curcumin, riboflavin, phycocyanin alone or along with LED. After treatment, the number of colony-forming units (CFUs) per milliliter was counted. In addition, the extent of biofilm degradation was assessed using the crystal violet staining method and scanning electron microscopy. All experimental groups exhibited a significant reduction in colony numbers for both bacterial and fungal species compared to the control (p < 0.001). The PDT groups exhibited a statistically significant reduction in colony counts for both bacteria and fungi compared to the photosensitizer-only groups. The results of this in vitro study show that PDT with natural photosensitizers and LED devices can effectively reduce the viability and eradicate the biofilm of microorganisms responsible for causing denture infections.

Comparative study for Enhancing Poly (methyl-methacrylate) (PMMA) Performance with Engineered Nanomaterials

Objectives:The current study was intended to evaluate and compare the effect of addition of Titanium Dioxide Nanoparticles versus Zirconium oxide nanoparticles to denture base materials regarding: impact strength and water sorption Materials and Methods: Thirty heat-polymerized acrylic resin specimens with the dimensions of (60x8x2 mm) were prepared according to the manufacturer’s instructions and divided into three groups each group 10 specimens first group was the control group , the Second group incorporated with 1.5wt% TiO2NPs (Titanium dioxide nanoparticles) to the heat-polymerized acrylic resin powder. And the third group incorporated with 1.5wt% ZrO2NPs (zirconium dioxide nanoparticles) to the heat-polymerized acrylic resin powder : impact strength was examined using Universal Testing Machine. A non-contact optical to compare different groups. water sorption were evaluated for all specimens. Data were statistically analyzed. Results:for heat cured acrylic resin with Zirconium dioxide nanoparticles for flexural stregth ,impact strength and water sorption was the highest value compared to Titanium Dioxide Nanoparticles Conclusions:ZrO2NPs nanoparticles have increased flexural stregth of resins as the concentration increase. For impact strength, water sorption compared to heat cured acrylic resin reinforced with Titanium Dioxide Nanoparticles

Bond Strength of Nanocomposite Hard Liner to CAD-CAM Milled, 3D Printed, and Conventionally Fabricated Denture Base Resins.

To investigate the effect of zirconium dioxide nanoparticles (ZrO2NPs) on the shear bond strength (SBS) of hard denture lines bonded to different denture base resins. Five different denture bases were used in this study: conventional heat-cured resin, IvoCad, AvaDent, NextDent, and FormLabs, in acrylic specimens of 10 × 10 × 2.5 mm3 (N = 150, n = 10). Specimens were centered at the bottom of a silicon mold to create an auto-polymerized holder. Three major groups of reline material were used: no ZrO2NPs (control), 2 wt.%, and 4 wt.% ZrO2NPs. Reline was bonded to the resin surface using a customized jig. After polymerization, specimens were stored in distilled water, and 5000 thermal cycles were performed. Each specimen was fixed to an Instron machine, and SBS was tested using a blade loaded (1 mm/min) at the resin interface until failure. Data was collected and analyzed using two-way ANOVA and post hoc Tukey test (α = 0.05). AvaDent showed the highest SBS when compared with other denture base materials (p < 0.001) except for IvoCad. The addition of ZrO2NPs significantly decreased the SBS of AvaDent (p = 0.003) and IvoCad (p = 0.001), while heat polymerized resin, Formlabs, and NextDent showed no significant change in SBS (p > 0.05). CAD-CAM milled denture base resin showed higher SBS with pure denture reline. The addition of ZrO2NPs decreased the SBS of reline with CAD-CAM milled denture base resins but did not change bond strength with 3D printed and conventional denture base resins.

Comparative analysis of shear bond strength of MTA and Theracal PT with different restorative materials

BackgroundThis study aimed to compare the in vitro shear bond strength (SBS) of mineral trioxide aggregate (MTA) and dual-cured, resin-modified calcium silicate material (Theracal PT) to composite resin, compomer, and bulk-fill composite, and to evaluate the bond failure mode under a stereomicroscope.MethodsNinety acrylic specimens, each with a 4 mm diameter and 2 mm height central hole, were prepared. These specimens were randomly divided into two groups based on the capping materials: MTA and Theracal PT. Each group was further subdivided into three subgroups (n = 15) according to the restorative materials: composite resin, compomer, and bulk-fill composite. The specimens were then subjected to shear testing using a universal testing machine at a crosshead speed of 1 mm/min. Post-test, the fracture locations were examined using a stereomicroscope. Data were analyzed using a two-way analysis of variance (ANOVA) and the Tukey test.ResultsThe SBS values for the Theracal PT group were significantly higher than those for the MTA group (p < 0.001). Within the MTA groups, no significant differences were observed in SBS values across the different restorative materials. However, a significant difference was found between the mean SBS values of the Theracal PT + composite resin group and the Theracal PT + compomer group (p < 0.001).ConclusionsTheracal PT shows promise in dentistry due to its superior bond strength. Given its bond values, Theracal PT appears capable of forming durable and long-lasting restorations by establishing reliable bonds with various restorative materials commonly used in dentistry.

Evaluation of Surface Roughness of Acrylic Denture Bases Polished Using Algishine, a Novel Polishing Material: An In Vitro Study.

Introduction Surface roughness (Ra) significantly impacts the aesthetic and functional qualities of dental prosthetics. Traditional polishing involves pumice, a material routinely used in dental practice. This study introduces Algishine as a potential cost-effective eco-friendly alternative. Materials and methods A 3D design software (Geomagic) created a Standard Tesselation Language (STL) file of 10 mm x 10 mm x 2 mm. 30 STL file outputs were generated. The output was milled in wax. This was then flasked and processed. 30 acrylic resin specimens were fabricated and divided into two groups. Group A was polished using traditional pumice, and Group B was polished using Algishine. The Ra of each sample was measured using surface profilometry, with three readings per sample averaged for each group. Results Kruskal-Wallis test was performed to compare the two groups with the pre-testing samples, which showed p<0.05; indicating that there was a significant difference between the two groups. The average Ra value for unpolished acrylic was 7.105, while the specimens polished with pumice showed an Ra value of 2.218; specimens polished with novel materialAlgishine showed an Ra value of 1.743. This illustrates that Algishine achieves surface smoothness significantly superior to commonly used polishing agent andpumice. Discussion The results of our study demonstrate that Algishine, a novel polishing material derived from recycled alginate, effectively reduces the Ra of acrylic resin. This finding has significant implications, both clinically and environmentally. The primary clinical benefit of a smoother acrylic resin surface is the enhanced aesthetic appearance and increased patient comfort. A polished surface reduces plaque accumulation, thereby decreasing the risk of oral infections and improving the longevity of the dental prosthesis. The results show that Algishine achieves surface smoothness comparable to or better than pumice indicating that it can maintain, if not enhance, these clinical outcomes. Dental professionals can confidently use Algishine, knowing it meets the high standards required for patient care. Conclusion Algishine effectively reduces the Ra of acrylic resin, suggesting it is a viable, eco-friendly alternative to traditional pumice for dental polishing procedures. This indicates potential benefits in maintaining clinical outcomes while promoting environmental sustainability.

Impact of surface treatment and addition of CuO NPs of surface roughness of acrylic denture base bonded to soft liner

Background: The import of the rough surface makes the application of several elements to enhance this feature vital for the adhesion of soft liners. Aim: The study's goal was to to ascertain the impact of copper oxide nanoparticles added in two ratios to heated-cured acrylic resin and fiber laser surface treatment on surface roughness. Materials and methods:60 acrylic specimens in the shape of discs were manufactured and divided into three groups: one received no addition; the other two received the addition of 0.3% CuO NPs; and a third group that received the addition of 0.5% CuO NPs. Each group was divided into two categories: those that were laser treatment and those who did not. The surface roughness test was then examined using a roughness tester called a profilometer. Results: The average roughness values were high for the control groups and low for the CuO NPs 0.5% groups. The mean values in the laser-treated groups had greater roughness than the control groups, according to the laser application.Conclusion:. As the fraction of CuO NPs increased, the surface roughness reduced. The laser treatment also reduced surface roughness.

Influence of different printing orientations and post-polymerization time on the translucency of three-dimensional (3D) printed denture base resins.

To evaluate the effect of different printing orientations and post-polymerization time with thermal cycling on the translucency of 3D-printed denture base resins. Heat-polymerized (HP) acrylic resin specimens were fabricated and 3D-printed denture base materials (NextDent, ASIGA, FormLabs) were printed with different printing orientations (0, 45, 90 degrees) and subjected to different post-polymerization times (15-, 30-, 60-, and 90-min). All specimens were polished and immersed in distilled water for 1day at 37°C. CIEDE2000 was used to measure the translucency parameters (TP00) before and after thermal cycling (5000 cycles) recording the color parameters (L*, a*, b*) against a black and white background using a spectrophotometer. k-factors ANOVA followed by post hoc Tukey's test (α=.05) was performed for statistical analysis. The k-factors ANOVA test showed a significant effect of resin material, post-polymerization time, and printing orientation on translucency (p<0.001). In comparison to HP, all 3D-printed resins showed lower translucency with all post-polymerization times and printing orientation (p<0.001) except FormLabs resin (p>0.05). For all 3D-printed resins, the translucency increased, with increasing the post-polymerization time (p<0.001) and 60- and 90-min showed the highest translucency. For printing orientation, 90 and 45 degrees significantly showed high translucency in comparison to 0 degrees (p<0.001). FormLabs showed significantly higher translucency when compared with NextDent and ASIGA per respective printing orientation and post-polymerization time. The translucency significantly decreased after thermal cycling for all tested resins (p<0.001). The findings of this study demonstrated that the translucency of 3D-printed resins is influenced by the printing orientation, post-polymerization time, and resin type. As a result, choosing a resin type, and printing orientation, with a longer post-polymerization time should be considered since it may improve the esthetic appearance of the 3D-printed resins.

Antimicrobial Properties of Aloe vera Ethanol Extract as a Denture Disinfectant: An In Vitro Study.

Introduction The aim of this study was to evaluate the activity of an ethanolic extract of Aloe vera on Candida albicans and Staphylococcus aureus. Materials and methods A total of 42 heat-cured acrylic resin specimens were made and divided into three groups according to the disinfection method: (1) Corega disinfectant tablets; (2) ethanol extract of Aloe vera; and (3) distilled water (as a control group). Fresh Aloe vera whole leaves were washed with distilled water, chopped into small pieces, air-dried, and ground into powder. The powder was extracted with 95% ethanol. The acrylic specimens were contaminated with C. albicans and S. aureus, and then the specimens were immersed in study solutions for three minutes. The viable colonies were counted using the colony-forming units (CFU) method. Results The results showed a decrease in the number of C. albicans CFU for denture tablets and Aloe vera ethanoic extract groups compared to the negative control group. There were no significant statistical differences between the denture tablet group and the Aloe vera ethanolic extract group (P < 0.05). Aloe vera ethanolic extract groups significantly decreased the number of S. aureus CFU compared to the negative control group and less compared to the denture tablet, where significant statistical differences were found between the tablet group and the Aloe vera ethanolic extract group. Conclusions Within the limitations of this study, it was concluded that Aloe vera extract was effective against C. albicans and S. aureus when acrylic resin specimens were immersed for three minutes.

Anti-Candida activity and biocompatibility of silver nanoparticles associated with denture glaze: a new approach to the management of denture stomatitis.

The association of silver nanoparticles (AgNps) to sealant agent Palaseal® can be a promising alternative for complete denture wearers who may develop denture stomatitis (DS). The study aimed to evaluate the anti-Candida and biocompatible potential of silver nanoparticles synthesized by three routes associated with denture glaze to prevent and/or treat oral candidiasis. Surface acrylic resin specimens were treated with different associations of glaze with AgNps (VER+AgUV, VER+AgTurk and VER+AgGm). As controls, specimens were treated with glaze+nystatin (VER+Nyst), glaze only (VER) or submerged in PBS (PBS). Afterwards, Candida albicans biofilm was developed for 24h, 15 d and 30 d. Subsequently, the biofilm was quantified by CFU/mL, XTT assay and confocal laser scanning microscopy. Fibroblasts were submitted to conditioned medium with the same associations for 24, 48 and 72h and LIVE/DEAD® viability test was carried out. Regardless of the period, there was a significant reduction (p < 0.01) of viable fungal cells load, as well as inhibition of fungal metabolic activity, in specimens treated with glaze+AgNps associations, compared to VER and PBS. The anti-Candida effects of the associations were similar to the VER+Nyst group, with emphasis on VER+AgGm, which showed the highest percentage values of non-viable fungal cells maintained over time. The associations did not prove toxicity to fibroblasts. The AgNps exerted antimicrobial activity against C. albicans biofilms and are biocompatible. The most effective results were achieved with the association of glaze+silver nanoparticles synthesized by the green chemistry method (AgGm), proving to be an innovative alternative in the management of DS.

Influence of Nanodiamond Incorporation on The Impact Strength of Repaired Denture Base acrylic resin: An in Vitro Study

Aim. This research aims to evaluate the effects of integrating Nanodiamond on the impact strength of repaired denture base resin. Methodology. Sixty acrylic resin specimens, sized 50×6×4 mm³ with a v-notch, were created from heat-polymerized acrylic resin. Ten specimens were kept intact while the other 50 specimens were sectioned to half and prepared with 45º beveling and a 2.5mm-repair gap. Nanodiamond particles were added to autopolymerized repair resin and repaired specimens were placed in five categories (n=10) according to Nanodiamond concentrations, unmodified as a control, 0.25%, 0.5%, 0.75%, and 1%ND by weight. Each specimen half was repositioned in a metal jig, and the repair resin was applied to the repair area. Subsequently, all specimens underwent finishing, polishing, and immersion in distilled water before Charpy's impact testing. Data analysis employed Tukey's post hoc test (with significance α=0.05) and one-way ANOVA. Results. Results showed that in comparison with the control group, the impact strength of repaired denture base resin significantly increased with 0.25% and 0.5% Nanodiamond addition to repair resin (significance at P ˂0.001). While it insignificantly decreased with 0.75% and 1% Nanodiamond (P=0.108 and P=0.615) and 1% presented the lowest value of impact strength (3.48 ± 0.43 KJ/m2). Conclusion. Adding a small amount of Nanodiamond to autopolymerized repair resin demonstrated an increase in the impact strength of repaired acrylic denture base resin. The highest impact strength was recorded with 0.25%ND (6.24±0.55 KJ/m2), followed by 0.5%ND (5.93±0.21 KJ/m2), whereas 1%ND exhibited the lowest impact strength value (3.48±0.43 KJ/m2).

Effects of Combinations of Hydrogen Peroxide and Vinegar in Different Ratios on the Surface Roughness of Heat-Cure Denture Base Acrylic Resin

Background: Complete dentures are at high risk of contamination, and their disinfection is imperative to prevent cross-contamination. Also, chemical disinfecting agents can effectively eliminate microorganisms. This study aimed to assess the effect of combinations of hydrogen peroxide (HP) and vinegar in different ratios on the surface roughness of heat-cure denture base acrylic resin. Methods: This in vitro, experimental study evaluated 40 heat-cure acrylic resin specimens that were flasked and heated at 70 ° C for 9 hours for heat polymerization. The acrylic specimens were cut into small cubic pieces measuring 20×20×3 mm using a cutting machine and polished with metallographic abrasive paper. The specimens were randomized into 4 groups of control (artificial saliva) and HP and vinegar in 1:1, 1:3, and 3:1 ratios (three experimental groups). Then, they were immersed in the respective solutions for 8 hours/day for one month. Their surface roughness (Ra) was measured before and after immersion by a profilometer. The data were analyzed using a one-way analysis of variance (α=0.05). Results: The immersion of acrylic specimens in HP+vinegar in 1:1 and 1:3 ratios did not cause a significant change in their surface roughness (P&gt;0.05). However, the surface roughness significantly decreased after immersion in HP+vinegar in a 3:1 ratio (P=0.032). Despite the reduction in the surface roughness of specimens in the 3:1 group, the difference in surface roughness was not significant among the four groups after immersion (P&gt;0.05). Conclusion: Combinations of HP and vinegar in different ratios appear to be suitable for cleaning removable dentures due to their insignificant effects on the surface roughness of acrylic resin.

Effect of Ethanol Addition on some Properties of Self-Polymerized Acrylic Resins

Background: Self-polymerized acrylic resins are widely utilized in dentistry. A higher residual monomer content is seen after polymerization of denture base resins. The literature showed that the ethanol solvent could rise the leaching of residual monomer from the polymer. The purpose of the current research was to investigate the influence of ethanol addition on hardness and roughness of acrylic resins. Materials and Methods: Sixty acrylic resin specimens were prepared and were divided into 2 main sets due to the kind of test used (surface hardness and surface roughness). There were three groups according to the ethanol concentrations. The first group was the control specimens with no ethanol, the second group was loaded with 10 ml of ethanol; and the third group was loaded with 15 ml of ethanol. The acrylic specimens were measured using the Shore A Durometer hardness and the surface roughness tester. Results: showed that the addition of ethanol significantly decrease the surface hardness of acrylic resins. The results indicated that there are significant differences between groups (P&lt; 0.0010). However, no significant differences between 10ml and 15 ml groups (P&gt;0.05). For surface roughness test, no significant differences were found among the studied groups (P&gt;0.05). Conclusions: The addition of ethanol to self-polymerized acrylic resins would significantly decrease the hardness and increases the surface roughness of acrylic resins

Effect of Ethanol Addition on some Properties of Self-Polymerized Acrylic Resins

Background: Self-polymerized acrylic resins are widely utilized in dentistry. A higher residual monomer content is seen after polymerization of denture base resins. The literature showed that the ethanol solvent could rise the leaching of residual monomer from the polymer. The purpose of the current research was to investigate the influence of ethanol addition on hardness and roughness of acrylic resins. Materials and Methods: Sixty acrylic resin specimens were prepared and were divided into 2 main sets due to the kind of test used (surface hardness and surface roughness). There were three groups according to the ethanol concentrations. The first group was the control specimens with no ethanol, the second group was loaded with 10 ml of ethanol; and the third group was loaded with 15 ml of ethanol. The acrylic specimens were measured using the Shore A Durometer hardness and the surface roughness tester. Results: showed that the addition of ethanol significantly decrease the surface hardness of acrylic resins. The results indicated that there are significant differences between groups (P&lt; 0.0010). However, no significant differences between 10ml and 15 ml groups (P&gt;0.05). For surface roughness test, no significant differences were found among the studied groups (P&gt;0.05). Conclusions: The addition of ethanol to self-polymerized acrylic resins would significantly decrease the hardness and increases the surface roughness of acrylic resins

EFFECTS OF ADDITION OF CHITOSAN AND DICARBOXYLIC ACID ON PROPERTIES OF 3D PRINTABLE ACRYLIC RESIN DENTURE BASE

3D-printing has gained popularity in recent years due to the many advantages it offers over the traditional approaches for instance this technology reduces the time a dentist needs to create and fit dentures to just 2–3 sessions. Fumaric, maleic, and adipic acids with the percentage (0.1 wt.%) were added to chitosan solution (2 wt.%) and the final composite was added to the 3D printable acrylic resin. The specimens were examined for several chemical analyses (XRD, SEM, FTIR) and mechanical tests (impact strength and surface hardness tests), where the total number (115) of specimens used in the study was specimens divided into five groups. In chemical analysis, one specimen was constructed for each modified group and one specimen was used as the control group (3d printable resin without addition (non-modified) for each test. For mechanical tests ten specimens were constructed for each modified group and ten specimens were used as the control group (3d printable resin without addition (non-modified) for each test. The results of chemical analysis showed improvement in the properties of modified 3d printable acrylic denture base resin, additionally the mechanical test results showed that the (Fumaric acid and Maliec acid with Chitosan) specimens have the highest properties in comparison with other specimens, while the lowest properties were for specimens of 3D printable acrylic resin with chitosan. The chemical and mechanical properties of the modified 3D-printed denture base are improved when chitosan is modified with dicarboxylic acids. Conversely, if chitosan alone is used to modify the 3D-printed polymers, the mechanical and chemical properties would be decreased.

Impact of Artificial Aging on the Physical and Mechanical Characteristics of Denture Base Materials Fabricated via 3D Printing.

Three-dimensional (3D) printing is becoming more prevalent in the dental sector due to its potential to save time for dental practitioners, streamline fabrication processes, enhance precision and consistency in fabricating prosthetic models, and offer cost-effective solutions. However, the effect of aging in artificial saliva of this type of material has not been explored. To assess the physical and mechanical properties of the two types of 3D-printed materials before and after being subjected to artificial saliva, a total of 219 acrylic resin specimens were produced. These specimens were made with two types of 3D-printed materials, namely, NextDent (ND) and Formlabs (FLs), and a Schottlander heat-cured (HC) resin material that was used as a control. Water sorption and solubility specimens (n = 5) were tested after three months of storage in artificial saliva. Moreover, the Vickers hardness, Martens hardness, flexural strength/modulus, and impact strength were evaluated both under dry conditions and after three months of storage in artificial saliva. The degree of conversion (DC), elemental analysis, and filler content were also investigated. The ANOVA showed that 3D-printed resins had significantly greater sorption than the control group (p < 0.05). However, the flexural strength values of the 3D-printed materials were significantly greater (p < 0.05) than those of the heat-cured material. The DC of the 3D-printed resins was lower than that of the control group, but the difference was not significant (p > 0.05). The 3D-printed materials contained significantly more filler than the control (p < 0.05). Moreover, the artificial saliva had a significant effect on the Vickers hardness for all tested groups and on the Martens hardness for the control group only (p < 0.05). Compared with conventional heat-cured materials, 3D-printed denture base materials demonstrated relatively poorer performance in terms of sorption, solubility, and DC but exhibited either comparable or superior mechanical properties. The aging process also influenced the Vickers and Martens' hardness. The strength of the 3D-printed materials was in compliance with ISO recommendations, and the materials could be used alongside conventional heat-cured materials.

Preparation and performance of acrylic mortar repair material modified suitably by nano-fiber and nano-particle in low-temperature for high-strength gain applications in construction

Nano-particles and nano-fibers have a marked effect on the physico-mechanical properties of polymeric mortar. In this study, to further enhance the mechanical properties of acrylic repair materials used in extreme environments (−25 °C or even lower), we added nano-particles (SiC, Al2O3, B4C, Si3N4, Fe2O3, SiO2), nano-fibers (CFs, MW-CNTs), nano-sheets (GNP, MOS2) and one homemade three-dimensional (3D) nano-fibers SiC–OH@APTES-g-CFs-COOH, respectively, to the polymeric mortar. We investigated how the dimensionality, content and type affect the compressive strength and flexural strength of the acrylic mortar repair materials. Acrylic mortar specimens were prepared by mixing methyl methacrylate binder, aggregates, initiator, accelerator and different nano-particles in a standard cement mixer, which is placed in standard molds of 40mm × 40mm × 160 mm and kept in −25 °C. Compressive and flexural strength of the acrylic mortar repair materials were determined at 1h, 1d and 10d of curing. The carbon fibers were treated with γ-aminopropyltriethoxysilane (APTES), and the 3D nano-fibers SiC–OH@APTES-g-CFs-COOH were prepared. The Scanning electron microscopy (SEM) analysis indicated that a large number of SiC were uniformly and densely distributed on the surface of CFs. The mechanical strength results showed that almost all contents of nano-materials of any dimension used in this article could enhance the mechanical strength of the specimens. Notably, when 0.05 wt% SiC–OH@APTES-g-CFs-COOH was added, the compressive strength and flexural strength values of acrylic mortar specimens at 10d were improved by 41.16 % and 52.28 % than those of control specimens. The incorporation of 3D nano-fibers formed a mechanical engagement with the aggregates, which increased the contact area between the aggregates and 3D nano-fibers and the thickness of the contact layer inside the specimen, thus effectively transferring the stress when the specimen was subjected to the load, and enhance the interfacial properties between the substrate and the nanofillers. Among the explored nano-particles, the addition of Si3N4 could significantly improve the compressive and flexural strength of acrylic mortar. Compared with the control specimen, the compressive strength can be improved by 44.6 % and the flexural strength of acrylic mortar specimens can be improved by 76.2 % when the addition of Si3N4 was 0.3 % by weight. This article demonstrated the availability of nano-powders for improving the mechanical properties of polymeric mortar construction materials.

Impact of effervescent denture cleaning tablets on color and surface characteristics of additively manufactured and hand-cast splint materials.

This study is to evaluate the color stability, surface roughness, and hardness of additively manufactured and hand-cast splint materials after a 6-month commercially available denture cleaning tablet immersion simulation. Disc-shaped additively manufactured and hand-cast auto polymerizing acrylic resin specimens were prepared (N = 40 each). All specimens were exposed to coffee solution totally 2days. Thereafter, all specimens were immersed into three different effervescent solutions that simulated 6months of clinical use. The total color change (ΔE*ab), surface roughness (Ra), and Vickers hardness (Vh) were measured at baseline and after immersion protocols. A two-way ANOVA and Bonferroni's post hoc test were used for color change. The dependent t-test and ANOVA were used for roughness and hardness evaluation. Additively manufactured splint materials were more affected by coffee immersion. It was observed that all denture cleaning tablets induced a noticeable alteration in color of the specimens (p < 0.05). Roughness and hardness measurement changes after solution immersions were statistically significant for both splint groups (p < 0.05). On the other hand, distilled water and denture cleaning tablets created similar roughness and hardness measurements at baseline and after immersion. After 6months use of tested cleaning tables, the color stability, surface roughness, and hardness of both groups were affected. The evaluation of the surface properties of splint materials could be recommended to the dentists in periodic controls during splint treatments. The use effervescent denture cleaning tablets altered the surface characteristics of tested splint materials over time with nonsignificant difference between each other. After 6months, awareness should be raised about surface characteristics of splint materials.

Effect of tea tree oil on candida adherence and surface roughness of heat cure acrylic resin

Background: Denture cleansing was an important step that could prevent the spread of infection and improve a patient's health, the durability of the dentures, and the overall quality of life; therefore, it was necessary to choose a suitable cleanser that, in addition to being effective, did not have an unfavorable effect on the qualities of the denture base resin itself when used for an extended period. For this purpose, this study aimed to evaluate the effect of tea tree oil (TTO) on Candida albicans adhesion and the surface roughness property of poly(methyl methacrylate) denture material after immersion in TTO. Methods: A total of 55 heat-cured acrylic resin specimens were used for C. albicans adherence and surface roughness tests. They were distributed into groups (0.25%, 0.5%, 0.75%, and 1%) of TTO, distilled water (DW), and 2% clorhexidine digluconate, totaling five specimens for each group. The specimens were immersed in accordance with their group for 10 minutes. Surface roughness was determined by a profilometer, and C. albicans adherence was determined by measuring optical density with a spectrophotometer. For comparisons between groups for surface roughness and disinfection tests, one-way ANOVA was performed on SPSS program, considering α = 0.05. Results: TTO had a statistically significant effect on C. albicans adhesion to heat-cured acrylic resin (P &lt; 0.05) compared with negative control. Meanwhile, no statistically significant difference was found between 0.75% and 1% TTO concentrations (P &gt; 0.05), whereas the surface roughness test showed a statistically non-significant difference between TTO concentrations and DW (P &gt; 0.05). Conclusions: Immersion of acrylic resin in TTO was effective in decreasing C. albicans adhesion to it, and the greatest decrease was obtained by 1% TTO. The surface roughness test showed a non-significant difference in acrylic roughness after immersion in TTO.