Polymethyl Methacrylate Resin Research Articles

Effect of titanium dioxide and zirconium dioxide nanoparticle incorporation on the thermal conductivity of heat-activated polymethylmethacrylate denture base resins: An in vitro experimental study

Aim: The aim is to determine thermal conduction by heat-activated polymethylmethacrylate (PMMA) infiltrated with 1 weight% Titanium Dioxide (TiO2) and 1 weight% Zirconium Dioxide (ZrO2) nanoparticles and to compare with that of conventional PMMA. Study Setting and Design: In vitro experimental study. Materials and Methods: Eighteen disc shaped specimens with a thickness of 5 mm and diameter of 50 mm, were fabricated and grouped according to the material used: Group B1 (resin infiltrated with 1 weight% TiO2), Group B2 (resin infiltrated with 1 weight% ZrO2), and Control Group B3 (heat-activated conventional PMMA resin). Disc-shaped specimens were analyzed for thermal conductivity using “modified guarded hot plate apparatus” in the thermal lab of the Indian Space Research Organisation. Statistical Analysis Used: One-way ANOVA followed by Tukey’s post hoc test was used to compare the arithmetic means of all three groups. Results: A statistically significant difference was noted among all three groups. Group B2 had the maximum thermal conductivity, followed by Group B1. Thermal conductivity was the least for Group B3. A post hoc comparison revealed that the difference was significant between Group B2 and Group B3. Conclusion: Nano ZrO2 addition in PMMA increased its thermal conductivity. There is evidence that it improves its mechanical properties as well. Hence, Nano ZrO2 addition in PMMA is highly recommended. Nano TiO2 addition in PMMA did not provide any significant advantage in terms of thermal conductivity, but its addition in PMMA is justified because of its mechanical and antimicrobial properties.

Comparative Evaluation of the Flexural Strength of Heat-Activated Polymethyl Methacrylate Denture Base Resin With and Without 0.2% by the Weight of Silver Nanoparticles Cured by Conventional and Autoclave Methods: An In Vitro Study.

Heat-activated polymethyl methacrylate (PMMA) is the most common and widely accepted denture base material. Two important drawbacks are the development of denture stomatitis and the high incidence of fracture of denture bases. The present study investigated the effect of adding 0.2% by weight of silver nanoparticles (AgNps) and using the autoclave method of terminal boiling on the flexural strength of heat-activated PMMA denture base resin. A total of 40 samples of heat-activated PMMA blocks were divided into four groups, with 10 samples (n = 10) in each group. Group 1 consisted of unmodified heat-activated PMMA resin (PMMA-1) polymerized by the conventional method of terminal boiling (conventional curing); Group 2 consisted of 0.2% by weight AgNPs added to heat-activated PMMA resin (PMMA-2) polymerized by conventional curing; Group 3 consisted of PMMA-1 polymerized by the autoclave method of terminal boiling (autoclave curing); and Group 4 consisted of PMMA-2 polymerized by autoclave curing. The flexural strength was tested using a universal testing machine. Descriptive statistics were expressed as mean ± SD and median flexural strength. Kruskal-Wallis ANOVA with Mann-Whitney U post hoc test was applied to test for statistical significance between the groups. The level of significance was set at p<0.05. The results showed a statistically significant reduction in flexural strength in Group 2 compared to Group 1. The samples from Group 4 showed a statistically significant increase in flexural strength compared to Group 2. The Group 4 denture base had the highest flexural strength (115.72 ± 7.27 MPa) among the four groups, followed by Group 3 (104.16 ± 4.85 MPa). The Group 1 samples gave a flexural strength of 101.45 ± 3.13 MPa, and Group 2 gave the lowest flexural strength (85.98 ± 3.49 MPa) among the four groups tested. The reduction in flexural strength of the heat-activated PMMA denture base after adding 0.2% by weight of AgNP as an antifungal agent was a major concern among manufacturers of commercially available denture base materials. It was proved in the present study that employing the autoclave curing method of terminal boiling for the polymerization of 0.2% by weight of AgNp-added heat-activated PMMA denture base resulted in a significantly higher flexural strength compared to the conventional curing method of terminal boiling for polymerization. Unmodified heat-activated PMMA gave higher flexural strength values when polymerized by autoclave curing compared to the conventional curing method of terminal boiling.

A plate containing a central rectangular hole made of PMMA resin and reinforced with graphene particles: low-velocity impact analysis

Purpose Due to the important and extensive use of graphene in the engineering structures, the purpose of this paper is to investigate the low-velocity impact (LVI) response of a graphene-reinforced plate with a rectangular central hole. Design/methodology/approach In this paper, Halpin-Tsai theory is used to model the mechanical properties of the plate made of polymethyl methacrylate (PMMA) resin and graphene particles. First, the plate displacement field is presented, and then the strains and stresses are obtained. The motion equations are extracted using energy equations, Ritz method and generalized Lagrange equations. The verification of theoretical formulation shall be carried out using the ABAQUS finite element software suite. Findings The effects of graphene volume fraction, approaching the impact point to the corner of the rectangular plate, and different boundary conditions of the plate are studied for LVI of impactor with spherical tip on the rectangular central hole reinforced by graphene. Important responses of the impact, such as the contact force between the impactor and the plate as well as the displacement of the plate at the impact place, are investigated and analyzed in this research. Originality/value Considering the wide application of graphene in the engineering structures, the simulation of the LVI on the graphene-reinforced plate made of PMMA resin with a rectangular central hole is carried out in this paper using numerical and theoretical modeling.

Effect of milling procedures in CAD-CAM systems on the color changes of CAD-CAM polymethyl methacrylate resin material as interim material

PurposeThis study aimed to investigate the effects of new and used burs on CAD-CAM PMMA resin color changes following thermocycling.Materials and methodsTwenty disk-shaped specimens (10 × 2 mm) were made using a single brand of CAD-CAM polymethyl methacrylate resin (Polident) for the color test. Group N consisted of half of the specimens that were machined using the new tungsten carbide bur set, and Group U consisted of the specimens that were milled using the used bur set (500 machining time). A color test was performed on the specimens both before and after thermocycling. For the statistical analysis, the Kruskal-Wallis and Dunn Pairwise Comparison tests were employed.ResultsThe ∆E* value of specimens (2.057) milled with the used bur was higher than those of specimens milled with the new bur (0.340), but this value is within clinically acceptable limits. After thermocycling, specimens milled with the utilized burs had the greatest L* (93.850) and b* (5.000) values. After thermocycling, statistically significant differences were discovered between Group N and Group U as well as between specimens milled with the utilized bur before and after thermocycling.ConclusionThermocycling process have an effect on the mean ∆E values of specimens milled with the used carbide bur, but these ∆E* values were not statistically significant.Clinical significanceThe color and clinical performance of CAD-CAM restorations may be affected by variations in CAD-CAM milling bur properties, particularly those related to their frequent use.

Assessing the suitability of fused deposition modeling to produce acrylic removable denture bases.

To study the feasibility of using poly methyl methacrylate(PMMA) filament and fused deposition modeling (FDM) to manufacture denture bases via the development of a study that considers both conventional and additive-based manufacturing techniques. Five sample groups were compared: heat and cold cured acrylic resins, CAD/CAM milled PMMA, 3D-printed PMMA (via FDM), and 3D-printed methacrylate resin (via stereolithography, SLA). All groups were subjected to mechanical testing (flexural strength, impact strength, and hardness), water sorption and solubility tests, a tooth bonding test, microbiological assessment, and accuracy of fit measurements. The performance of sample groups wasreferred to ISO 20795-1 and ISO/TS 19736. The data was analyzed using one-way ANOVA. Samples manufactured using FDM performed within ISO specifications for mechanical testing, water sorption, and solubility tests. However, the FDM group failed to achieve the ISO requirements for the tooth bonding test. FDM samples presented a rough surface finish which could ultimately encourage an undesirable high level of microbial adhesion. For accuracy of fit, FDM samples showed a lower degree of accuracy than existing materials. Although FDM samples were a cost-effective option and were able to be quickly manufactured in a reproducible manner, the results demonstrated that current recommended testing regimes for conventionally manufactured denture-based polymers are not directly applicable to additive-manufactured denture base polymers. Therefore, new standards should be developed to ensure the correct implementation of additive manufacturing techniques within denture-based fabrication workflow.

Mechanical properties and wear performance of denture base polymethyl methacrylate reinforced with nano Al2O3

Polymethyl methacrylate (PMMA) has been widely used as a material in dentistry. The deterioration of pure PMMA denture teeth is a significant issue that can alter the vertical dimensions of dentures. This study investigates the effect of aluminum oxide (Al2O3) nano-ceramic addition as reinforcements into the heat-cure acrylic resin denture teeth. The PMMA was reinforced with Al2O3 concentrations of 1, 3, 5, and 10 wt.%. The PMMA without ceramic addition is produced for comparison purposes. The color change, densification, microhardness, and compressive properties of the produced PMMA resin and its composites were investigated to detect the effect of Al2O3 nano ceramic addition on the physical and mechanical properties. Furthermore, the microstructure was also performed using scanning electron microscopy (SEM) analysis. A chewing simulator was utilized to conduct two-body wear testing, employing a human enamel antagonist. The wear behavior of the PMMA and their composites were assessed by measuring the weight loss after submitting them to 37,500 cycles. The SEM microstructure analysis revealed sound specimens of PMMA reinforced with 0, 1, 3, and 5 wt.% Al2O3 without any porosity and micro defects using the applied production procedures. In contrast, the aggregated sites and propagation of cracks were detected for the PMMA/10 wt.% Al2O3 specimen. The densification and hardness properties of the produced PMMA composites improved with increasing the Al2O3 additions. The microhardness of PMMA/10 wt.% Al2O3 improved by around 233% compared to the PMMA matrix. The higher compressive properties were detected for the PMMA/5 wt.% Al2O3 composite specimen with ultimate compressive strength (UCS) of 54.75 MPa and yield strength (YS) of 45.6 MPa and improved than the PMMA matrix by around 98 % and 117 %, respectively. In addition, incorporating Al2O3 nano-ceramic particles into a PMMA matrix revealed a significant improvement in the wear resistance of the produced composites compared to the PMMA matrix.

Effect of thermal cycling on the flexural strength of 3-D printed, CAD/CAM milled and heat-polymerized denture base materials

BackgroundThis study compared the impact of thermal cycling on the flexural strength of denture-base materials produced through conventional and digital methods, using both subtractive and additive approaches.MethodsIn total, 60 rectangular specimens were fabricated with specific dimensions for flexural strength tests. The dimensions were set according to the International Organization for Standardization (ISO) guideline 20795-1:2013 as 64 × 10 × 3.3 ± 0.2 mm. Specimens from each material group were divided into two subgroups (thermal cycled or nonthermal cycled, n = 10/group). We used distinct methods to produce three different denture-base materials: Ivobase (IB), which is a computer-aided-design/computer-aided-manufacturing-type milled pre-polymerized polymethyl methacrylate resin disc; Formlabs (FL), a 3D-printed denture-base resin; and Meliodent (MD), a conventional heat-polymerized acrylic. Flexural strength tests were performed on half of the samples without a thermal-cycle procedure, and the other half were tested after a thermal cycle. The data were analyzed using a two-way analysis of variance and a post hoc Tukey test (α = 0.05).ResultsBased on the results of flexural-strength testing, the ranking was as follows: FL > IB > MD. The effect of thermal aging was statistically significant for the FL and IB bases, but not for the MD base.ConclusionsDigitally produced denture bases exhibited superior flexural strength compared with conventionally manufactured bases. Although thermal cycling reduced flexural strength in all groups, the decrease was not statistically significant in the heat-polymerized acrylic group.

Comparative Evaluation of Flexural Strength and Microhardness of Two Different Ceramic Reinforced 3-D Printed Resins with Cad-cam Milled and Conventional Tooth Coloured Heat Cured Polymethylmethacrylate Resins as Long-term Provisional Restorative Materials” – An in Vitro Study

Background: Long-term provisional restorations play a crucial role in complex clinical scenarios, Implant-supported prostheses, full-mouth rehabilitation cases &amp; Maxillofacial Prosthodontics. Understanding the mechan-ical properties such as flexural strength and microhardness of newer commercially available provision-al restorative materials is necessary to select an optimum material for long-term provisional fixed den-tal prosthesis. This Research study was conducted to evaluate and compare the Flexural Strength and Microhardness of Two Different Ceramic-reinforced 3-D Printed Resins with CAD-CAM Milled and Conventional Tooth Coloured Heat Cured Polymethylmethacrylate Resins as Long-Term Provisional Restorative Materials. Methods: Twenty-one specimens of dimensions 25 mm × 2 mm × 2 mm (ADA-ANSI specification #27) were fabricated each using: Group A (Control group)-Conventional tooth colored heat cured polymethyl-methacrylate resin (DPI Heat cure tooth moulding powder), Group B-CAD-CAM milled resin, Group C- Ceramic reinforced polymer 3-D printed resin (Temporary CB resin) and Group D- Ceramic rein-forced polymer 3-D printed resin (Permanent CB resin). Flexural strength and microhardness were measured and the values obtained were evaluated. Results: The measured mean flexural strength values (Mega Pascals) were 39.41 (Group A), 153 (Group B), 124.91 (Group C), and 136.50 (Group D). The measured mean microhardness values (Knoop hardness number) were 37.9 (Group A), 40.5 (Group B), 34.67 (Group C), and 43.88 (Group D). The difference in flexural strength and microhardness values of the three groups was statistically significant according to the analysis of variance (ANOVA) as well as the intergroup comparison done using Tukey’s honest significant difference (HSD) Post Hoc test (P &lt; 0.05). Conclusions: Flexural strength with higher values in Group B were noted and the Microhardness test showed higher values in Group D.

The Effect of Aging on Artificial Saliva at Different pH Values on the Color Stability of New Generation Denture Base Materials.

New-generation denture base materials are used successfully in denture fabrication; however, the effect of saliva pH change on the color stability of materials is unknown. The purpose of this in vitro study is to evaluate the color stability of new-generation denture base materials after immersion in artificial saliva with different pH values (3,7,14). Disc-shaped samples (Ø 10 mm x 2 mm) were prepared from three different denture base materials (1 pre-polymerized polymethylmethacrylate [PMMA], 1 graphene-reinforced PMMA, and heat-cure polymethyl methacrylate resin) (n=10). After polishing, color coordinates were measured using a PCE-CSM 5 colorimeter programmed in the CIE system (L* a* b*). The samples were kept in artificial saliva at different pH values and 37°C for 21 days. At the end of 21 days, color coordinates were measured again. The suitability of the measurements for a normal distribution was examined with the Kolmogro-Smirnov test. Whether color measurements obtained at different pH levels differed according to groups was examined with the Kruskal-Wallis test. The correlation between the CIEDE2000 and CIELab color difference formulas was examined by correlation analysis. The highest color difference occurred in heat-cure samples at pH 3 (p<0.001). The color difference at different pH values was least observed in pre-polymerized PMMA samples. Significant color differences occurred in the graphene-reinforced pre-polymerized PMMA group at pH 7 (p<0.001). It was observed that color differences occurred in all groups. Dentures made of new-generation CAD/CAM PMMA, which are less exposed to color differences, can be recommended for elderly patients with systemic diseases who are frequently exposed to pH changes in the oral cavity. Color differences on denture surfaces over time negatively affect aesthetics. Since pH changes cause changes on the prosthesis surface, it may be recommended for these patients to fabricate dentures from new-generation CAD/CAM PMMA resins, which are less deformable.

Assessment of Marginal and Internal Adaptation in Provisional Crowns Utilizing Three Distinct Materials.

This study aimed to assess the marginal and internal adaptation of provisional crowns fabricated from polymethyl methacrylate (PMMA) blocks by the computer-aided design/computer-aided manufacturing (CAD/CAM) system, autopolymerizing PMMA, and acrylic base composite resin. In this in vitro experimental study, a brass die was obtained, and provisional crowns were fabricated in three groups using Teliocad PMMA blocks by the CAD/CAM system, Tempron GC auto-polymerizing PMMA, and Bisico acrylic base composite resin (n = 7 in each group). The provisional crowns were coded and randomly placed on the die. Their marginal adaptation was evaluated under a stereomicroscope at 40× magnification, while their internal adaptation was assessed by the replica technique. Data were analyzed by one-way analysis of variance (ANOVA) (α = 0.05). The mean marginal gap was the highest in autopolymerizing PMMA and the lowest in the CAD/CAM PMMA group (p < 0.05). The mean marginal gap in the autopolymerizing PMMA group was significantly higher than that in the resin material (p = 0.014) and CAD/CAM PMMA (p = 0.000) groups. The difference between the resin material and CAD/CAM PMMA groups was not significant (p = 0.13). The mean internal gap was the highest in autopolymerizing PMMA group and the lowest in CAD/CAM PMMA group (p < 0.05). The mean internal gap in autopolymerizing PMMA group was significantly higher than that in composite resin (p = 0.002) and CAD/CAM PMMA (p = 0.00) groups. The difference between the resin material and CAD/CAM PMMA groups was not significant (p = 0.322). Computer-aided design/Computer-aided manufacturing PMMA provisional crowns showed the highest marginal and internal adaptation followed by acrylic base resin material crowns. Computer-aided design/computer-aided manufacturing PMMA crowns demonstrate superior marginal and internal adaptation compared with autopolymerizing PMMA and acrylic base composite resin crowns, suggesting CAD/CAM technology's potential for enhancing clinical outcomes. How to cite this article: Jalalian E, Younesi F, Golalipour S, et al. Assessment of Marginal and Internal Adaptation in Provisional Crowns Utilizing Three Distinct Materials. J Contemp Dent Pract 2023;24(11):853-858.

Mechanical and fatigue resistance of restorations supported by welded-framework and realized using computer-aided designed prosthetic shells: In vitro pilot study.

Resin coating in implants rehabilitation cannot always be aesthetic, durable and comfortable for the patient mainly due to the limited dimensions of the final structure. Intraoral welding technique and computer-aided designed prosthetic shells may be a solution. This in vitro study evaluates the capacity of load and the weakest point of implant-supported provisional prosthesis using welded titanium framework. Twelve samples were produced to simulate an implant supported fixed prosthetic bridge. Two implants (Ankylos; Dentsply Sirona Implants; Germany) were inserted inside blocks of nanoceramic material produced with a stereolithographic 3D printer. A polymethylmethacrylate (PMMA) resin shell was performed with CAD/CAM and relined on welded framework. Six samples were produced with the same procedure reducing resin thickness. The samples were subjected to fatigue test (6,500,000 cycles) using ElectroForce 3310 fatigue machine (t1); subsequently a mechanical compression test using a universal Shimadzu AGS-X 10 machine (t2). The samples were analyzed with a photographic and radiographic documentation at t0, t1 and t2. The samples survived mechanical fatigue test without evidence of failure. The radiographic and photographic evaluation revealed the fracture of resin coating after the mechanical compression test. The samples with minimal resin thickness fractured first. Adequate assessment of the resin thickness is mandatory to improve the longevity of these rehabilitations. CAD-CAM digital prosthetic design allows us to optimize the thicknesses and the prosthetic shapes, allowing us to obtain good degrees of resistance even in the presence of reduced prosthetic spaces.

Comparative Assessment of Flexural Strength in Heat-cured Polymethyl Methacrylate Resin Reinforced with Silver Nanoparticles, Siwak, and Fluconazole: An In-vitro Study

Introduction: For crafting complete dentures, Polymethylmethacrylate (PMMA) has long been the material of choice. Various reinforcements are being used to enhance the properties of PMMA and minimise denture fracture. Aim: The present in-vitro study compared the flexural strength of PMMA resin samples reinforced with Silver Nanoparticles (Ag NP), siwak, and fluconazole. Materials and Methods: The present in-vitro experiment was conducted from July to August 2017 at the Prosthodontics Department of a Dental College with technical support from the Centre for Scientific Research and Development (CSRD), affiliated with People’s University in Bhopal, Madhya Pradesh, India. Flexural testing was conducted at the Central Institute of Plastic Engineering and Technology (CIPET), Bhopal. A total of 120 acrylic resin samples, each measuring 65 mm in length, 10 mm in width, and 2.5 mm in thickness, were fabricated in accordance with American Dental Association (ADA) Specification No. 12. These specimens were categorised into four distinct groups. The first group consisted of only PMMA resin (Group A), while the remaining three groups comprised PMMA resin enhanced with AgNP (Group B), Siwak (Group C), and Fluconazole (Group D), respectively, with each group containing 30 samples. Subsequently, these specimens underwent a flexural strength assessment through a 3-point flexural test. The statistical analysis to assess and compare the mean flexural strength of the samples was conducted. The present analysis was performed first by applying an Analysis of Variance (ANOVA) test, followed by pairwise comparisons with Tukey’s Post-hoc test. A p-value less than 0.05 was used to determine statistical significance. Results: The mean flexural strength (±Standard Deviation) in N/mm2 for PMMA; PMMA+AgNP; PMMA+Siwak and PMMA+ Fluconazole was 82.33±5.18; 80.55±5.67; 71.50±10.15; and 74.03±10.84, respectively. The mean flexural strengths of the PMMA and PMMA+AgNP groups were similar (p=0.842). However, the flexural strength of the Siwak+PMMA and Fluconazole+PMMA groups was significantly less than that of the other two groups. Conclusion: The flexural strength of PMMA is unaffected by the inclusion of AgNP at a concentration of 1%, and its incorporation would allow the benefit from its antibacterial qualities. It is not advised to add fluconazole or siwak because doing so reduces the flexural strength.

Comparison of fracture strength, surface hardness, and color stain of conventionally fabricated, 3D printed, and CAD-CAM milled interim prosthodontic materials after thermocycling.

The purpose of this in vitro study was to investigate the fracture resistance, surface hardness, and color stain of 3D printed, CAD-CAM milled, and conventional interim materials. A total of 80 specimens were fabricated from auto polymerizing polymethyl methacrylate (PMMA), bis-acryl composite resin, CAD-CAM polymethyl methacrylate resin (milled), and 3D printed composite resin (printed) (n = 20). Forty of them were crown-shaped, on which fracture strength test was performed (n = 10). The others were disc-shaped specimens (10 mm × 2 mm) and divided into two groups for surface hardness and color stainability tests before and after thermal cycling in coffee solution (n = 10). Color parameters were measured with a spectrophotometer before and after each storage period, and color differences (CIEDE2000 [DE00]) were calculated. The distribution of variables was measured with the Kolmogorov Smirnov test, and one-way analysis of variance (ANOVA), Tukey HSD, Kruskal-Wallis, Mann-Whitney U tests were used in the analysis of quantitative independent data. Paired sample t-test was used in the analysis of dependent quantitative data (P < .05). The highest crown fracture resistance values were determined for the 3D printed composite resin (P < .05), and the lowest were observed in the bis-acryl composite resin (P < .05). Before and after thermal cycling, increase in mean hardness values were observed only in 3D printed composite resin (P < .05) and the highest ΔE00 value were observed in PMMA resin for all materials (P < .05). 3D printing and CAD-CAM milled interim materials showed better fracture strength. After the coffee thermal cycle, the highest surface hardness value was again found in 3D printing and CAD-CAM milled interim samples and the color change of the bis-acryl resin-based samples and the additive production technique was higher than the PMMA resin and CAD-CAM milled resin samples.

Konvansiyonel, Eksiltmeli ve Eklemeli İmalat Tekniklerinde Kullanılan Geçici Kron Materyallerinin Yüzey Pürüzlülüğüne Diş Fırçalama ve Yüzey İşlemlerinin Etkisi: İn Vitro Çalışma

Background: This study aimed to compare the effect of the surface treatment and toothbrushing abrasion on the surface roughness of interim crown material specimens manufactured using conventional, subtractive, and additive processing techniques.&#x0D; Material and methods: 80 disk-shaped specimens were prepared from 4 different interim crown materials; one auto-polymerized polymethyl methacrylate resin (PMMA);(IM) and one bis-acryl composite resin;(AC) for conventional technique, one computer-aided design/computer-aided manufacturing (CAD-CAM) PMMA block;(TC) for subtractive process, one 3-dimensionally (3D) printed resin;(CB) for additive process. Specimens of each interim crown material were divided into two subgroups according to applied surface treatments; conventional polishing or surface sealant agent coupling (n=10). The surface roughness values of specimens before (Ra0) and after 10,000 cycles of toothbrushing (Ra1) were measured with a profilometer. Data were statistically analyzed.&#x0D; Results: The polished groups of all interim crown materials showed significantly higher Ra0 values compared to the sealant groups before toothbrushing (p˂0.05). While the polished IM groups exhibited the highest Ra0 value (0.44±0.08), the sealed TC groups exhibited the lowest Ra0 value (0.23±0.06). The Ra values of all material groups increased after simulated 1-year toothbrushing. While the polished IM group exhibited the highest Ra1 value (0.45±0.14), the sealed CB group had the lowest Ra1 value (0.31±0.09).&#x0D; Conclusion: It was observed that toothbrushing caused an increase in the surface roughness of all interim materials. The application of a surface sealant agent to these materials is more effective than polishing to reduce surface roughness. Sealed 3D printed resin for additive process exhibited the lowest mean roughness value after toothbrushing.&#x0D; Keywords: Additive Manufactured, Interim Crown Material, Roughness, Subtractive Manufactured, Toothbrushing Abrasion

Evaluation of antimicrobial properties of conventional poly methyl methacrylate denture base resin materials containing silver doped titanium dioxide nanoparticles against cariogenic bacteria and candida albicans

The main aim of the study was to find the antimicrobial properties of a poly methyl methacrylate resin (PMMA) which is modified with silver-doped titanium dioxide nanoparticles. This research study was done to prove that the incorporation of silver-doped TiO2 nanoparticles improves the antimicrobial and antifungal properties.The poly methyl methacrylate resin (PMMA) powder was modified using 0 wt%(control) 1wt% and 3wt% silver doped TiO2 nanoparticles Test specimens were prepared of dimensions 5 mm × 5 mm × 2 mm. The antimicrobial properties of the specimens were evaluated by calculating CFU/ml. The obtained values were analyzed by one-way analysis of variance (ANOVA), Kruskal Wallis test, and post-hoc Tukey’s test at a significance level of 5%. The incorporation of silver-doped titanium dioxide nanoparticles into denture base resin improved antimicrobial activity. Compared to 1% and 3% nanoparticle doped, 3% has given better antimicrobial activity calculated using CFU/ml. It is reduced to one-fourth the microbial growth compared to the control group. The addition of silver-doped titanium dioxide nanoparticles to denture base resin is an effective method for antimicrobial and antifungal action.

Comparative Evaluation of Antifungal Property of Acrylic Resin Reinforced with Magnesium Oxide and Silver Nanoparticles and their Effect on Cytotoxic Levels: An In vitro Study

Abstract Background: About 65% of people who wear dentures suffer from denture stomatitis, a prevalent pathologic illness that is commonly linked to Candida albicans. The necessity for the creation of polymethyl methacrylate (PMMA) materials with intrinsic activity is brought on by increasing resistance of microbes. The study’s objectives were to examine and compare the antifungal properties of acrylic resin by adding silver nanoparticles (AgNPs) and magnesium oxide nanoparticles (MgONPs), as well as to determine its cellular toxicity at various nanoparticle concentrations on mouse fibroblasts. Materials and Methods: A total of 84 samples were created, including 12 control samples, 36 samples of PMMA resin reinforced with AgNPs, and 36 samples of PMMA resin reinforced with MgONPs. Disk diffusion technique was used to assess the antifungal effectiveness of the samples. By using the MTT test, the cytotoxicity of various nanoparticle concentrations was evaluated. Analysis of variance test and unpaired t-test were used to analyze the data, and then Tukey’s post hoc test was performed. Results: The mean values for AgNPs and MgONPs at 2%, 4%, and 6% after 24 h were 13.71 ± 2.07, 18.58 ± 1.62, and 27.96 ± 1.76 and 11.63 ± 1.35, 14.38 ± 1.63, and 18.25 ± 1.39, respectively. In contrast to the MgONPs group, samples with AgNPs showed greater antifungal efficacy against C. albicans. On mouse fibroblasts, MgONP concentrations showed more cytotoxicity, but AgNP concentrations showed less cytotoxicity. Conclusion: By adding AgNPs and MgONPs to acrylic resins, which are highly efficient against C. albicans, denture stomatitis can be treated.

Evaluation of polymethyl-methacrylate and acetal denture base resins processed by two different techniques before and after nano-chlorohexidine surface treatment

BackgroundFlexible denture base polymers have gained popularity in modern dentistry however, their biofilm formation tendency, adversely affecting the oral tissue heath, remains a concern. Consequently, this study aimed to evaluate surface roughness and biofilm formation tendency of two types of denture base resins manufactured with two techniques before and after surface coating with chlorohexidine (CHX) NPs.Materials and methodsAcetal (AC) and Polymethyl-methacrylate (PMMA) resins manufactured by conventional and CAD/CAM methods were shaped into disk (10 X 10 X 1 mm). They were dipped for 8 h and 24 h in colloidal suspension prepared by mixing aqueous solution of CHX digluconate and hexa-metaphosphate (0.01 M). Surface roughness, optical density (OD) of microbial growth media and biofilm formation tendency were evaluated directly after coating. Elutes concentrations of released CHX were evaluated for 19 days using spectrophotometer. Three-way ANOVA and Tukey’s post-hoc statistical analysis were used to assess the outcomes.ResultsAC CAD/CAM groups showed statistically significant higher roughness before and after coating (54.703 ± 4.32 and 77.58 ± 6.07 nm, respectively). All groups showed significant reduction in OD and biofilm formation tendency after surface coating even after 19 days of CHX NPs release.ConclusionsBiofilm formation tendency was highly relevant to surface roughness of tested resins before coating. After CHX NPs coating all tested groups showed significant impact on microbial growth and reduction in biofilm formation tendency with no relation to surface roughness. Significant antimicrobial effect remained even after 19 days of NPs release and specimens storage.

Flexural strength of a polymethylmethacrylate resin produced by computer‐aided design and computer‐aided manufacturing system after repeated usage of tungsten carbide burs and thermocycling

AbstractThe purpose of this study was to examine how new and used burs affected the flexural strength of a polymethylmethacrylate resin produced by computer‐aided design and computer‐aided manufacturing system following thermocycling. A total of 40 rectangular‐shaped specimens (14 mm×4 mm×1.2 mm) for flexural strength test were fabricated from one brand of a polymethylmethacrylate resin produced by computer‐aided design and computer‐aided manufacturing system. Half of the specimens (Group N) were milled using the new tungsten carbide bur set, while the other half (Group U) was milled using the used (250 machining time) tungsten carbide bur set. The specimens were subjected to flexural strength test before and after thermocycling. The One way Analysis of Variance and Duncan tests were used for statistical analysis. Group N had the highest mean flexural strength values, while Group NT (specimens milled with the new bur/before thermal cycling) had the lowest mean flexural strength values. New and used burs have an effect on the flexural strength of a polymethylmethacrylate resin specimens produced by computer‐aided design and computer‐aided manufacturing system. Thermocycling process have an effect on the flexural strength values of specimens milled with the new tungsten carbide bur.

Comparative Analysis of the Structural Weights of Fixed Prostheses of Zirconium Dioxide, Metal Ceramic, PMMA and 3DPP Printing Resin-Mechanical Implications.

Four groups were studied with eight samples for each material (n: 32). Each structure was weighed, subjected to compressive tests and analyzed using 3D FEA. PMMA presented the lowest structural weight (1.33 g), followed by 3DPP (1.98 g), ZR O2 (6.34 g) and PFM (6.44 g). In fracture tests, PMMA presented a compressive strength of 2104.73 N and a tension of 351.752 MPa; followed by PFM, with a strength of 1361.48 N and a tension of 227.521 MPa; ZR O2, with a strength of 1107.63 N and a tension of 185.098 MPa; and 3DPP, with a strength of 1000.88 N and a tension of 143.916 MPa. According to 3D FEA, 3DPP presented the lowest degree of deformation (0.001 mm), followed by PFM (0.011 mm), ZR O2 (0.168 mm) and PMMA (1.035 mm). The weights of the materials did not have a direct influence on the mean values obtained for strength, stress or strain. Since the performance was related to the tension and forces supported by the structures in critical zones, the importance of considering design factors is clear. In vitro and 3D FEA assays allowed us to simulate different scenarios for the mechanical properties of certain materials before evaluating them clinically. Thus, they can generate predictions that would allow for the design of a better research methodology in future clinical trials.

Evaluation The Effects of Ethylmethacrylate and Isobutylmethacrylate on Transverse Strength Of Heat-Polymerized Acrylic Resins

Background in order to regain esthetic, patients are given an ocular prosthesis. The majority of them are made of poly methyl methacrylate resin (PMMA), which is a popular material for maxillofacial prostheses including ocular prostheses, Fracture of poly methyl methacrylate occurs due to several reasons involving careless handling and falling of ocular prosthesis on hard surfaces, it is essential to strength the acrylic to improve the transverse strength of the resin. Materials &amp;methods :50 samples were constructed from heat cured acrylic resins and divided into three groups (1control and 2 experimental group) Each group had ten specimens. The two experimental groups comprised the IBMA, EMA monomer at 1% and 2% concentrations, respectively. Such samples were prepared with dimensions of 65 mm x 10 mm x 2.5mm ± 0.1 length, width and thickness respectively according to (ADA specification, No.12, 1999). All the samples were tested for transverse strength. All data were analyzed using SPSS version 20. Tukey test was used for comparison between the groups.Results: There were highly significant differences (P&lt;0.001) on the transverse strength between the control group and EMA, IBMA copolymers. Conclusion: The scleral acrylic resin incorporation with 1% and 2% wt % EMA, IBMA copolymers showed insignificant increase in transverse strength