Polymethyl Methacrylate Denture Base Material Research Articles

Evaluation of the Effect of Impregnation Methods on Flexural Strength of Polypropylene Fibers Reinforced Polymethyl Methacrylate Denture Base Material: An In Vitro Study

Evaluation of the Effect of Impregnation Methods on Flexural Strength of Polypropylene Fibers Reinforced Polymethyl Methacrylate Denture Base Material: An In Vitro Study

COMPARATIVE EVALUATION OF HARDNESS AND SURFACE ROUGHNESS AFTER DIFFERENT COOLING PROCEDURES OF HEAT CURE DENTURE BASE MATERIALS

Aim: To evaluate the influence of different cooling procedures on mechanical properties of DPI & LUCITONE heat cure poly methyl methacrylate denturebase materials before andafter 1year of brushing simulation. Materials And Methods: A total of 100 specimens were prepared using two heat cure denture base materials i.e, DPI and LUCITONE. The specimens in each group were subdivided into five groups (n=10 ) based on the cooling procedure followed: A: Flask remains in water bath till room temperature B: Remove flask from water bath, bench cool for 30min and then cool under running water for 15min C: Remove flask from water bath, bench cool for 10min and then cool under running water for 15min D: Remove flask from water bath and bench cool till room temperature E: Remove the flask from water bath and cool under running water for 15 minutes.After finishing and polishing, samples were placed in a brushing machine to simulate one year of mechanical cleansing. The specimens were tested for surface roughness with profilometer and hardness with Vickers hardness tester before and after brushing. Results were statistically analysed by two and one- way Analysis of variance (ANOVA) plus Tukey post hoc tests. Results: Specimens with type C(Remove flask from water bath, bench cool for 10min and then cool under running water for 15min)cooling procedures have high hardness values, among whichLucitone showed better properties. Surface roughness did not show significant changes among different groups. Brushing did not significantly affect surface roughness and hardness of denture base materials. Conclusion: Two of the treatments tested, Treatment C: bench-cooling for 10 min and cooling under running water for 15min and Treatment A: cooling in water-bath till room temperature provided the highest hardness values.

Fabrication and characterization of PMMA denture base nanocomposite reinforced with hydroxyapatite and multi-walled carbon nanotubes

Polymethyl Methacrylate (PMMA) is still one of the most popular denture base materials in dentistry due to its superior mechanical properties. However, its long-term use can result in defects such as low flexural strength and brittleness, which can be addressed by strengthening its mechanical properties. In this study, the effect of adding non-modified and modified hydroxyapatite nanoparticles (HaP NPs) and multi-walled carbon nanotubes (MWCNTs) on the thermal and mechanical properties of PMMA denture base materials was investigated. First, the modified HaP (MHaP) NPs and modified MWCNTs (MMWCNTs) were prepared by a vinyltriethoxysilane (VTES) agent. Then, two-component PMMA-HaP/MHaP and PMMA-MWCNT/MMWCNT, and three-component PMMA-HaP/MHaP-MWCNT/MMWCNT composite samples were fabricated from commercial dental heat-curing acrylic resin (Acrosun) with different amounts of HaP/MHaP (3, 5, and 10 wt%) and MWCNT/MMWCNT (0.25, 0.5, and 1 wt%). The samples were investigated by Simultaneous Thermal Analysis (STA), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-Ray Spectroscopy (EDS), Dynamic Mechanical Analysis (DMA), and Three-point flexural test. It was observed that surface modification of NPs improved the interaction of NPs and polymer chains in the matrix and resulted in better mechanical properties of nanocomposites. In the sample containing 3 wt% MHaP and 0.25 wt% MMWCNT, the flexural strength and flexural modulus were increased by 45 % and 42 % compared to the control sample, respectively, and the glass transition temperature (Tg) based on the DMA test was 152.7 °C, which was higher than in the other samples. The results of MTT assay studies indicated that adding MHaP and MMWCNT enhanced cell viability. In the PMMA- 3 wt% MHaP- 0.25 wt% MMWCNT composite, the cell viability was increased to 153.75 ± 9.7 % and confirmed its biocompatibility properties.

Comparative Analysis of the Color Stability of Machined Denture Base Materials: An In-Vitro Approach.

Color stability is a crucial aspect in the selection of denture base materials as it directly impacts the esthetic appeal and longevity of dental prostheses. This study aimed to compare the color stability of different denture base materials through an in vitro approach. Three machined denture base materials including polymethyl methacrylate (PMMA), Acetal (AC), and polyether ether ketone (PEEK) were subjected to artificial aging using a xenon-arc lamp. Color measurements were taken before and after aging using a spectrophotometer. Statistical analysis was performed to determine any significant differences among the materials. The color stability of the denture base materials was quantitatively assessed using parameters such as ΔE values. PEEK exhibited the least color change (ΔE = 2.1 ± 0.3), followed by AC (ΔE = 3.5 ± 0.4), while PMMA showed the highest color change (ΔE = 5.9 ± 0.7). In this in vitro study, PEEK demonstrated superior color stability compared to AC and PMMA denture base materials under artificial aging conditions. These findings emphasize the importance of material selection in achieving long-term esthetic outcomes in dental prostheses.

Thermal Conductivity of Polymethyl Methacrylate Denture Base Material Incorporated with Hydroxyapatite Nanoparticles

Thermal Conductivity of Polymethyl Methacrylate Denture Base Material Incorporated with Hydroxyapatite Nanoparticles

In Vitro Cytotoxicity of Linseed Oil as Bio-Based Plasticiser in Polymethylmethacrylate (PMMA) Denture Base Material

Objectives: Polymethyl methacrylate (PMMA) is a polymer that is vastly utilised as denture base material. Previously synthetic plasticiser like Dibutyl phthalate was previously used in the PMMA. However, there are reports of ester leaching causing intraoral toxicity. Thus, bringing the awareness about organic plasticiser usage, like linseed oil. This study aims to evaluate the cytotoxicity of linseed oil to ensure its safety to be used as the natural-based plasticiser in PMMA as denture base material. Materials and Methods: The cytotoxicity of linseed oil was evaluated by culturing Human Gingival Fibroblast cells with 1, 3, 5, 7, and 10% linseed oil for 24, 48, and 72 hours. The WST-1 assay was then used to evaluate cell viability, with cell quantification performed using a spectrophotometer at a wavelength range of 420-480nm. An unpaired t-test was used to analyse all parameters' quantitative cell viability data. Results: The WST-1 Assay demonstrated that linseed oil exhibited greater than 95% cell viability at all doses and incubation durations, indicating biocompatibility. At 72 hours of incubation, there are statistically significant differences between the cells incubated in the Linseed Oil as compared to Dimethyl Sulfoxide (DMSO), which acts as a positive control. Conclusions: The study proves that linseed oil is non-cytotoxic with the Human Gingival Fibroblast cells and safe to use when incorporated later in the PMMA as denture base material.

A biomechanical reinforcement of PMMA denture base material with sericin and fibroin: A preliminary screening study.

Polymethyl methacrylate (PMMA) is a commonly used denture base material, but susceptibility to fracture under functional loading remains a challenge. This preliminary screening study aims to investigate the potential of sericin and fibroin as reinforcing agents in the PMMA denture base material. The flexural and impact strengths of PMMA incorporated with 0.01% sericin, and 0.01% each of sericin and fibroin, were evaluated. The control group consisted of PMMA without any additives. The maximum load and energy required to break the samples were measured. Statistical analysis was performed using one-way ANOVA test and Scheffe Post Hoc tests to compare mean values between subgroups. The results indicated significant improvement in the flexural and impact strengths of PMMA with the addition of sericin and fibroin. The subgroups with 0.01% sericin, and 0.01% each of sericin and fibroin, demonstrated higher mean values in load and energy measurements compared to the control group. The statistical analysis confirmed the significance of these findings. The addition of 0.01% sericin and 0.01% each of sericin and fibroin to PMMA denture-based resin material significantly increases its flexural and impact strengths. These preliminary findings suggest the potential of sericin and fibroin as effective reinforcing agents in PMMA denture base materials, thereby enhancing their biomechanical properties.

Evaluation and Assessment of the Colour Stability of Modified Polymethyl Methacrylate Denture Base Materials and Polyether Ether Ketone in a Cast Partial Denture Framework: An In-Vitro Study.

Background One of the frequent aesthetic issues patients confront is the loss of colour and lifeless appearance of the denturesof the base materials of their dentures after regular use. This leads to a lack of motivation to use the denture regularly. Due to the drawbacks of conventional PMMA, polyether ether ketone (PEEK) and newer polymethyl methacrylate (PMMA)-based materialshave now started being used in cast partial denture frameworks dueto their superior physical and biological properties. The lack of long-lasting colourisone of the main reasons for the repeat of dental prostheses. Hence, the need for the study is to help clinicians decide which would be the most suitable denture base materialto be used based on colour stability. Aim To assess and compare the colour stability of PEEK, polyan, and biodentaplast denture base materials (DBMs) upon staining withdistilled water, tea, coffee, and turmeric solutions after one day, seven days, and 30 days. Methods A total of 20 cuboidal specimens were constructed and immersed in distilled water, tea, coffee, and turmeric (five specimens of each material in each solution, a total of 60 specimens): Group 1: PEEK, Group 2: polyan, Group 3: biodentaplast. All specimens were subjected to colour measurements before exposure to beverage solutions, after 24 hours, on the seventh day and 30th day with a colour reflectance spectrophotometer with computer software. A one-way ANOVA test followed by post hoc Tukey's honestly significant difference (HSD) was performed for comparison of colour stability between the DBMs, revealing a significant difference between PEEK and polyan and PEEK and biodentaplast. Polyan showed the highest delta E values, followed by biodentaplast and PEEK.A two-way ANOVA test, followed by Tukey's HSD post hoc, was done to compare the staining ability of various staining solutions. Turmeric had the highest delta E values, followed by coffee, tea, and distilled water. Data were assessed using Statistical Product and Service Solutions (SPSS, version 23) (IBM SPSS Statistics for Windows, Armonk, NY) software. Results The highest mean delta E value at T1 was seen in biodentaplast immersed in turmeric (12.3900+/-0.442), and the least value at T1 was obtained for PEEK immersed in distilled water (0.4460+/-0.036).The highest mean delta E value at T2was seen in polyan immersed in turmeric (13.0160+/-0.28962), and the least value at T2was obtained for PEEK immersed in distilled water (0.5860+/-0.051). At T3, the highest mean delta E value was seen in polyan immersed in turmeric (16.8600+/-0.49845), and the least value at T3 was obtained for PEEK immersed in distilled water (0.700+/-0.037). Conclusion PEEK had the highest colour stability when compared with polyan and biodentaplast.

Evaluation of Impact Strength and Flexural Strength of Polyether Ether Ketone vs. Computer-Aided Design/Computer-Aided Manufacturing Polymethyl Methacrylate Denture Base Materials: An In-Vitro Study.

The objective is to comparatively assess the impact strength and flexural strength of polyether ether ketone (PEEK) vs. computer-aided design/computer-aided manufacturing (CAD/CAM) polymethyl methacrylate denture base material. A total of 90 samples were fabricated with traditional heat cure PMMA, PEEK, and CAD/CAM PMMA and divided into three groups of 30 samples each.The impact strength of all the samples was measured using an Izod impact tester with a pendulum in the air at 23±2°C. A three-point bending test was used in a Universal Testing Machine to assess the flexural strength of all the samples. The impact strength and flexural strength mean values were computed using a one-way ANOVA test. Impact strength and flexural strength of PEEK (IS=10.22±1.25 kJ/m2 and FS=120±8.0 MPa) is almost identical to CAD/CAM PMMA sample (IS=9.595±3.313 kJ/m2 and FS=118.11±5.00 MPa) whereas for conventional heat cure PMMA (IS=4.00±.011 kJ/m2 and FS=75.4±4.50 MPa) the values are least among the three. PEEK or CAD/CAM PMMA share almost identical and superior mechanical properties, and both can be used as better alternatives for complete denture fabrication rather than using conventional heat cure PMMA.

Comparative Evaluation of Flexural and Impact Strength of Denture Base Acrylic Resin using Different Processing Methods - An in-vitro Study

Background: One of the chief limitations of Polymethylmethacrylate denture base material is its inadequate mechanical property. Different processing methods of Polymethylmethacrylate have varying influences on the mechanical properties of denture base material. Aim: The aim of our in-vitro study was to comparatively evaluate the flexural and impact strength values between CAD-CAM, Compression-molded and Injection- molded Polymethylmethacrylate specimens. Materials and methods: A total of 66 acrylic rectangular specimens of ISO Standardization (64 x10 x3.3mm) were fabricated. This study was conducted between three groups: Group I (n=22)-CAD-CAM Milled specimens (Ruthinium, India), Group II (n=22)- Compression-molded specimens (Dental Products of India, Chennai), Group III (n=22)- Injection-molded specimens (SR- Ivocap High Impact, Ivoclar Vivadent). Flexural strength was evaluated using four-point bend test and Impact strength by IZOD Impact tester. Kruskal Wallis unpaired test was used to compare the mean values between groups and Mann Whitney U test was used to carry out pair wise comparison. Results: Flexural strength of CAD-CAM samples were found to be statistically highest followed by injection molded specimens. Conversely, Impact strength of injection- molded specimens were highest followed by CAD-CAM specimens. Flexural as well as impact strength values were found to be least among compression-molded specimens. Conclusion: CAD-CAM specimens exhibited higher flexural strength whereas Injection-molded specimens had the highest impact strength.

Impact of popular beverages on polyamides versus polymethyl methacrylate denture base materials colour stability: in vitro study

BackgroundChanging of different denture base materials colours could have a detrimental impact on patients' satisfaction and make them seek more frequent adjustments to their prosthesis; hence this study was conducted to investigate the colour stability of the conventional denture base polymer (PMMA) and polyamides.MethodsSpecimens of conventional PMMA and thermoplastic polyamides were constructed according to manufacturer instructions and utilized during the current study. For colour stability test a total of 80 specimens with dimensions of 40 mm (length) X 20 mm (width) X 0.8 mm (thicknesses), the specimens in this test were divided into two equal groups (n = 40) (PMMA specimens and polyamides specimens).ResultsWhen compared to polymethyl methacrylate denture base resin, polyamid denture base resin exhibited the greatest colour change (P 0.001). For 7 and 30 days, both materials had the greatest value in tea solution. One-Way ANOVA test P < 0.00001).ConclusionsWithin limitation of this in vitro study, we found that heat-cure PMMA resin has the significant higher colour stability when compared to the Polyamides after immersion in the tea, cola, coffee and distilled water solutions for 30 days.

Mechanical Properties of Hybrid Composites PMMA Denture Base with Varying Concentrations of Nano-ZrO&lt;sub&gt;2&lt;/sub&gt; and Glass Fiber

Studying the effects of hybrid reinforcement made of nano-zirconium oxide and chopped glass fibers for poly methyl methacrylate (PMMA) denture bases, nano- ZrO2 (n ZrO2) at grain sizes (46.7 nm) which measured using Atomic Force Microscopy (AFM) and different ratios on the mechanical characteristics was the aim of this study .To make the pure sample, a 2:1 powder to liquid ratio of typical acrylic resin was used. Hybrid composites with varying concentrations of nano-ZrO2 (nZrO2) and glass fiber (GFs) (2.5%nZrO2+2.5% GFs), (3.5%nZrO2+1.5%GFs), (1.5%nZrO2+3.5% GFs) were introduced. Mechanical tests as tensile strength, flexural strength, impact strength, shore D hardness are used to learn about the properties of manufactured composites. Antibacterial testing, water absorption, density testing, and thermal conductivity these indicated that composites may be effectively turned into filler material. In addition to X-ray diffraction (XRD), Scanning Electron Microscopy (SEM). The result show increased the mechanical properties of the PMMA denture base material. The tensile strength flexural strength, and impact strength increase for all hybrid ratio and reach maximum value at the concentration (2.5%nZrO2+2.5% GFs) compared to unreinforced PMMA.While hardness increase and reach maximum value at the concentration (3.5%nZrO2+1.5% GFs). In addition, thermal conductivity and density, the maximum value at concentration (1.5%nZrO2+3.5% GFs), as well as water absorption decrease as ratio of nZrO2 increase this shoed in concentration (3.5wt. % nZrO2 +1.5wt. %, GFs).

Evaluating the Effect of Polyetheretherketone Particles Addition on Water Sorption and Solubility of Polymethylmethacrylate Denture Base Material

Aims: To assess water sorption and solubilityof PMMA after incorporating with polyetheretherketone particles (vectrex peek polymer PEEK) material with a different percentage (1%, 2%, and 3%). Materials and Methods:The PEEK particle size of 130μm. Peek with (1%, 2%, 3%by wt.) concentrations were added to the PMMA resin base to compare with the PMMA with no additives (control). The conventional heat-curing method was applied using a water bath to polymerize the specimens and study water sorption and water solubility of prepared samples. Study data was analysed via One-way ANOVA performed at significant P-value of (p≤0.05) and confidence. Fourier transform infrared spectroscopy used to detect any chemical modification occurs.Results: After comparing the results show significant difference in Water sorption of PMMA/PEEK. Water Solubility show no significant difference comparing to other tested groups (p≤0.05). Conclusions: the PEEK particles use it as dental filler at 1%,2% and 3% wt. incorporating PMMA material with3% PEEK material have lowest mean value for water sorption and solubility

The Antifungal and Antibiofilm Activities of Caffeine against Candida albicans on Polymethyl Methacrylate Denture Base Material.

Background: In this study, the effect of pure caffeine was established against Candida albicans (C. albicans) using different microbiological techniques. Methods: Broth microdilution and colony forming units (CFUs) assays were used to detect the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC). The Live/Dead fluorescent dyes were implemented to determine the yeast viability. Polymethyl methacrylate acrylic resin (PMMA) discs were prepared to evaluate caffeine’s effects against adherent C. albicans using microplate reader, CFUs, and scanning electron microscope (SEM). Results: caffeine’s MIC was detected around 30 mg/mL, while the MFC was considered at 60 mg/mL. In an agar-well diffusion test, the inhibition zones were wider in caffeine groups. The Live/Dead viability test verified caffeine’s antifungal effects. The optical density of the adherent C. albicans on PMMA discs were lower at 620 nm or 410 nm in caffeine groups. CFU count was also reduced by caffeine treatments. SEM revealed the lower adherent C. albicans count in caffeine groups. The effect of caffeine was dose-dependent at which the 60 mg/mL dose demonstrated the most prominent effect. Conclusion: The study reinforced caffeine’s antifungal and antibiofilm properties and suggested it as an additive, or even an alternative, disinfectant solution for fungal biofilms on denture surfaces.

Synthesis, characterization, and evaluation of quaternary ammonium-based polymerizable antimicrobial monomers for prosthodontic applications

The present study aims to synthesize and characterize two quaternary ammonium (QAM) based monomers such as - dimethyl-hexadecyl-methacryloxyethyl-ammonium iodide (DHMAI) and 2-dimethyl-2-dodecyl-1-methacryloxyethyl ammonium iodine (DDMAI) and assess their cytotoxicity and antimicrobial properties. The study also aims to incorporate the optimized concentration of these monomers as copolymerizing monomers into conventional Polymethyl methacrylate (PMMA) denture base resin and evaluate their suitability for prosthetic applications. DHMAI and DDMAI monomers were synthesized through a Menschutkin reaction and their chemical structure was characterized using FT-IR and 1H-NMR spectroscopy. Cytotoxicity was determined using Methyl Thiazolyl Tetrazolium (MTT) assay whereas antimicrobial activity was assessed using the agar-disc diffusion method. Subsequently, optimized concentrations of DHMAI or DDMAI, based on the cytotoxicity results, were added to conventional PMMA resin. Antimicrobial activity, cytotoxicity, surface hardness, and water sorption of PMMA denture base rein incorporated with DHMAI or DDMAI were evaluated. FT-IR and 1H-NMR results confirmed the structure of monomers and copolymerization of DHMAI and DDMAI with PMMA resin. DHMAI and DDMAI monomers were found to be cytocompatible with mouse fibroblast cells up to a concentration of 5 μg/mL and 20 μg/mL respectively. In addition, incorporation of DHMAI or DDMAI at 5 μg/mL and 20 μg/mL respectively into PMMA denture base material did not affect their cytocompatibility. PMMA denture base resin incorporated with DHMAI or DDMAI significantly reduced the adhesion of microbes. Further, an increase in the surface hardness and a reduction in the water sorption was observed. Hence DHMAI and DDMAI can be considered as potential candidates for imparting antimicrobial activity to polymeric denture base materials.

Effect of Candida albicans Suspension on the Mechanical Properties of Denture Base Acrylic Resin.

Yeast-like fungi such as Candida albicans (C. albicans) are the primary pathogenic microorganism in the oral cavity of denture wearers. The research available so far, conducted according to a protocol based on the exposure of specimens to a C. albicans suspension and their cutting with water cooling, shows that hard polymethyl methacrylate (PMMA) prosthetic materials are not only surface colonized, but also penetrated by microorganisms in a short time. This justifies the hypothesis that exposure to a suspension of the C. albicans strain causes the changes in mechanical properties due to surface colonization and/or penetration of the samples. In the current study, the chosen mechanical properties (flexural strength, flexural modulus, tensile strength, impact strength, ball indentation hardness, and surface Vickers hardness at 300 g load) of the PMMA denture base material Vertex RS (Vertex-Dental, The Netherlands) exposed for 30, 60, and 90 days to a suspension of C. albicans were investigated. The potential penetration of yeast was examined on the fractured surfaces (interior of specimens) to eliminate the risk of the contamination of samples during cutting. There was no influence on the flexural strength, flexural modulus, tensile strength, impact strength, or ball indentation hardness, but a significant decrease in surface hardness was registered. Microscopic observations did not confirm the penetration of C. albicans. On the surface, blastospores and pseudohyphae were observed in crystallized structures and in traces after grinding, which indicates that in clinical conditions, it is not penetration but the deterioration of surface quality, which may lead to the formation of microareas that are difficult to disinfect, causing rapid recolonization.

Factors Affecting Sorption and Solubility of Denture Base Acrylic Materials: A Review

Heat-cured PMMA is one of the most frequently used materials in the manufacture of removable dentures. Heat-cured material used to fabricate dentures contain soluble elements, allowing the material to absorb and release substances. These factors all directly affect the longevity and performance of protheses fabricated from polymethyl methacrylate denture base material. Various procedures associated with fabrication of removable dentures from heat-cure denture base material are reported to significantly influence the sorption and solubility experienced by the prosthesis. A comprehensive search of peer-reviewed journals located within academic databases was conducted to identify relevant literature pertaining to sorption and solubility of denture base materials. Key aspects of each paper were captured in Microsoft® Excel® to record author/s, location, study design, sample size, methodology, results and conclusions. Mixing ratios and polymerisation cycles have been identified as variables that can negatively influence the rate of sorption and solubility of denture base materials during the fabrication process. Certain surface treatment procedures, as well as storing the denture in artificial saliva solution may reduce the levels of sorption and solubility experienced and optimise its lifespan. In this review we identify these factors and consider the detrimental effects of sorption and solubility on denture base acrylic materials.

Effect of different disinfection protocols on the surface properties of CAD-CAM denture base materials

Statement of problemWhich disinfection protocol provides optimal water contact angle and microhardness for computer-aided design and computer-aided manufacturing (CAD-CAM) polymethyl methacrylate (PMMA) materials is unclear. PurposeThe purpose of this in vitro study was to evaluate the effect of different disinfection protocols (1% sodium hypochlorite, denture cleanser gel, and effervescent tablet) on the water contact angle and microhardness of different CAD-CAM PMMA denture base materials by comparing them with a heat-polymerized PMMA. Material and methodsDisk-shaped specimens (Ø10×2 mm) were fabricated from 3 different CAD-CAM PMMAs—AvaDent (AV), Merz M-PM (M-PM), and Polident (Poli)—and a heat-polymerized PMMA (Vynacron) (CV) (n=21). Three disinfection protocols (1% sodium hypochlorite [HC], denture cleanser gel [GEL], an effervescent tablet [TAB]) were applied to simulate 180 days of cleansing. The water contact angle and microhardness of specimens were measured before and after disinfection and compared by using a 2-way ANOVA (α=.05). ResultsFor water contact angle, material (P=.010) and disinfection protocol (P=.002) had a significant effect. The material (P<.001), disinfection protocol (P=.001), and their interaction (P<.001) significantly affected the microhardness after disinfection. When the condition after disinfection was compared with that before disinfection, the water contact angle increased significantly in all material-disinfection protocol pairs (P≤.025), and microhardness increased significantly in all material-disinfection protocol pairs (P≤.040), except for GEL- (P=.689) or TAB-applied (P=.307) AV, HC-applied M-PM (P=.219), and TAB-applied Poli (P=.159). ConclusionsThe material and disinfection protocol affected the water contact angle of all tested PMMAs after disinfection, resulting in more hydrophobic surfaces for heat-polymerized or CAD-CAM PMMAs. The microhardness of heat-polymerized PMMA was less than that of all CAD-CAM PMMAs after disinfection, regardless of the protocol.

The effect of cooling procedures on monomer elution from heat-cured polymethyl methacrylate denture base materials.

Objective To evaluate the amount of methyl methacrylate (MMA) released in water from heat-cured polymethyl methacrylate (PMMA) denture base materials subjected to different cooling procedures.Methodology Disk-shaped specimens (Ø:17 mm, h:2 mm) were fabricated from Paladon 65 (PA), ProBase Hot (PB), Stellon QC-20 (QC) and Vertex Rapid Simplified (VE) denture materials using five different cooling procedures (n=3/procedure): A) Bench-cooling for 10 min and then under running water for 15 min; B) Cooling in water-bath until room temperature; C) Cooling under running water for 15 min; D) Bench-cooling, and E) Bench-cooling for 30 min and under running water for 15 min. A, B, D, E procedures were proposed by the manufacturers, while the C was selected as the fastest one. Control specimens (n=3/material) were fabricated using a long polymerization cycle and bench-cooling. After deflasking, the specimens were ground, polished and stored in individual containers with 10 ml of distilled water for seven days (37oC). The amount of water-eluted MMA was measured per container using isocratic ultra-fast liquid chromatography (UFLC). Data were analyzed using Student’s and Welch’s t-test (α=0.05).Results MMA values below the lower quantification limit (LoQ=5.9 ppm) were registered in B, C, E (PA); E (PB) and B, D, E (QC) procedures, whereas values below the detection limit (LoD=1.96 ppm) were registered in A, D (PA); A, B, C, D (PB); C, D, E (VE) and in all specimens of the control group. A, B (VE) and A, C (QC) procedures yielded values ranging from 6.4 to 13.2 ppm with insignificant differences in material and procedure factors (p>0.05).Conclusions The cooling procedures may affect the monomer elution from denture base materials. The Ε procedure may be considered a universal cooling procedure compared to the ones proposed by the manufacturers, with the lowest residual monomer elution in water.

How Many Microwave Disinfection Cycles is Safe for the Adaptability of Polymethyl Methacrylate (PMMA) Denture Base Materials?: An In Vitro Study

Introduction: We aimed to determine the maximum microwave disinfection cycles that is safe for the adaptability of polymethyl methacrylate (PMMA) denture bases under power–time setting of 630 W for 3 minutes. Materials and Methods: Thirty PMMA maxillary denture bases were constructed and divided into two groups, control (no disinfection) and test (microwave disinfection at 630W for 3 minutes in water immersion). Coltene Rapid Liner (Coltene/Whaledent AG, Altstatten, Switzerland) silicone was coated onto the internal surface of the samples followed by placement of 8 kgf of axial load. The silicone film was removed, and weighed using analytical balance. One day interval was given between each cycle and samples were stored in 37°C water bath. Tests were carried out until a statistically significant silicone film weight change detected. The data were analyzed on SPSS version 21.0 (IBM Corp, Armonk, NY). Results: Statistically significant change of the denture base was detected after the tenth cycle of microwave irradiation. Conclusion: The maximum microwave disinfection cycles that is safe for the adaptability of PMMA denture bases under power–time setting of 630 W for 3 minutes is only up to 10 cycles.