PMMA Denture Base Research Articles

Preparation and characterization of fumed silica added PMMA denture base materials

This study was carried out to investigate the chemical, mechanical, and structural properties of increasing amounts of fumed silica added to PMMA denture base material. The effect of adding fumed silica at three different concentrations (0.5%, 1%, and 2% by weight) to PMMA was studied using Fourier transform infrared spectroscopy (FTIR), dynamic mechanical analysis (DMA), density, flexural strength, hardness, atomic force microscopy (AFM), and scanning electron microscopy (SEM). The results showed that the highest flexural strength values (105.64 MPa) and hardness (20.07 microvickers) were obtained with 1% wt. of fumed silica material. According to DMA results, fumed silica samples containing 1% wt. had the highest energy storage (3.24 GPa at 30 °C) and glass transition temperature. As a result, fumed silica in PMMA denture base material reached its maximum saturation limit at 1% wt. A more brittle behavior was observed in samples containing 2% fumed silica, which accumulated on the surface, as confirmed by AFM. The molecular bonds at the resin-fumed silica interface weaken due to the agglomeration of fumed silica. Consequently, the flexural strength and hardness decrease, along with the glass transition temperature and storage modulus. The potential applications of this research are vast, inspiring further exploration and innovation in denture-based materials.

Comparative Evaluation of the Effect of Microwave, 1% Sodium Hypochlorite, and Sodium Perborate Disinfection on the Color Stability of Two Nanoparticle-Reinforced Heat-Polymerized PMMA Denture Base Resins: An In Vitro Study.

Introduction Older adults experience significant improvement in their quality of life by using removable prosthetics to replace missing teeth. Poly(methyl methacrylate) (PMMA) has become the most popular material for denture bases due to its ease of use and affordability. Recently, scientists have started adding nanoparticles like titanium dioxide (TiO2) and zirconium oxide (ZrO2) to PMMA to enhance its physical properties. These resins with nanoparticles need to stay the same color after being disinfected in different ways if they are going to be used for a long time. So, the purpose of this investigation was to assess whether or not there exists any difference between two kinds of thermally cured acrylic resin for artificial tooth bases strengthened with nanoparticles when subjected to various chemical sterilizers alongside microwave irradiation, as well as determine their comparative colorfastness levels. Materials and methods In this lab experiment, we tested how well 5% TiO2 and 7% ZrO2 nanoparticle-reinforced PMMA resins held their color when exposed to microwave irradiation, 1% sodium hypochlorite, or sodium perborate disinfection. We made 120 specimens shaped like discs; half were treated using one method, while the other half were treated using a different method. Color was measured at baseline (T0), after one cycle (T1), after five cycles (T2), and after six months (T3) using a reflectance spectrophotometer, which calculates the color difference (∆E). Results All three methods of disinfection caused significant color changes (p<0.001); however, sodium perborate caused the least amount of change, followed by 1% sodium hypochlorite and microwave irradiation. The mean ∆E values showed that after one day, there was a change in color by 1.1 due to microwave disinfection, which increased to 5.7 after five days; on the other hand, for 1% sodium hypochlorite, the change was recorded as 0.7 after one month and 1.6 after three months and finally reached up to 2.6 after six months, while sodium perborate showed the least amount of change, with ∆E values recorded as 0.2 after one month, 0.5 after three months, and 0.8 after six months. Conclusion Sodium perborate proved to be the most effective disinfectant for maintaining color stability in 5% TiO2 and 7% ZrO2 nanoparticle-reinforced PMMA resins, thus making it ideal for routine disinfection. Therefore, according to this study, sodium perborate should be used as a disinfection method because it results in minimal color change in nanoparticle-reinforced PMMA dentures.

Optimized Performance of PMMA Denture Base Material: Enhanced Mechanical, Biocompatibility, and Antibacterial Properties Modified with Extracted Jackfruit Latex Resin (Artocarpus Heterophyllus)

Optimized Performance of PMMA Denture Base Material: Enhanced Mechanical, Biocompatibility, and Antibacterial Properties Modified with Extracted Jackfruit Latex Resin (Artocarpus Heterophyllus)

Comparative Evaluation to Surface Roughness of Modified Heat Cured Acrylic Resin by Zinc Oxide Nanoparticles and CAD/CAM Denture Base Materials - In Vitro Study

One of the most promising CAD/CAM approaches is milling denture base materials from highly condensed pre-polymerized resin discs. In an effort to overcome the disadvantages of acrylic resin denture base materials, nano-filler materials have been added as well as denture base chemistry adjusted to strengthen the denture base.This eliminates disadvantages associated with polymerization shrinkage compared to conventional heat-cured acrylic resin. Aim of this study: evaluate the surface roughness of PMMA acrylic resin after strengthening the denture- base by addition of zinc oxide nano-filler material to acrylic resin PMMA with concentration (1%) and compare with milled CAD/CAM and non-modified heat-cured PMMA denture base materials. Materials and methods: thirty specimens of acrylic resin PMMA were prepared and divided into three groups 10 specimens for each groups as follows; Control Group (Group1) without ZnO nanoparticles ; Group (2) with (1%) by weight of ZnO nanoparticles ; Group (3) milled CAD/CAM.Each specimen is of dimension ( 10 x 10 x 3 ) in mm and was fabricated using conventional processing method and milling the CAD/CAM blocks .Results: showed the lowest mean value was recorded by milled CAD/CAM (0.230 Ra) Then the non-significant reduction with mean value (0.312 Ra) by PMMA+ ZnO 1% and highest mean value of surface roughness was recorded by pure PMMA without additive (0.327 Ra).Conclusions: There were significant differences between control group PMMA and milled (CAD/CAM) with slight reduction of surface roughness of PMMA with (1%) Zno nanoparticles.

Effect of glass fiber and nylon fiber reinforcement on the mechanical and thermal properties of styrene butadiene rubber mixed PMMA denture base material

ObjectivesThe present investigation is aimed at evaluating the effect of styrene butadiene rubber, glass fibre, nylon fibre and hybrid reinforcement of glass and nylon fibre with 0.5 and 1.0 wt% on the impact, flexural, and compressive properties. MethodsA total of 19 groups were formed, including one control group and 18 study groups. All specimens were fabricated according to the standards and tests were performed. The enhancement of strengths were characterised by using scanning electron micrographs, FTIR results, XRD, and DMA tests. The degradability was studied using TGA/DTA analysis. The results were analysed using one-way ANOVA and Dunnett’s post hoc multiple comparison test at p ≤ 0.05. ResultsThe maximum impact, flexural, and compressive strength were found to be 3.234 ± 0.202 kJ/m2, 70.07 ± 0.7 MPa, and 84.929 ± 0.85 MPa for hybrid reinforcement of 0.5 wt% nylon fiber and 0.5 wt% glass fiber with 1.0 wt% of styrene butadiene rubber (SBR) mixed PMMA denture base material. Statistical analysis shows that the maximum mean impact strength, flexural strength, and compressive strength are about 84%, 58%, and 67% higher than the pure PMMA (control group). The maximum flexural modulus and compressive modulus are 914.4 MPa and 407.847 MPa for denture base material made of 1.0 wt% SBR, 1.0 wt% nylon fiber, 0.5 wt% glass fiber, and 0.5 wt% SBR, 0.5 wt% nylon fiber, respectively. The storage moduli of 1.0 wt% SBR, 1.0 wt% nylon fiber, and 0.5 wt% glass fiber-reinforced denture base material and pure PMMA are 0.096 and 0.422 at 79 °C, respectively, which indicates significant crosslinking of fiber and PMMA. The failure surfaces are characterized by a homogeneous distribution of fiber with increased surface roughness and fiber pullout, strong bonding, and well-dispersed SBR.

Effect of Knitting Pattern of PP Mesh on the Flexural Properties of Heat-cured PMMA Denture Base Resin

Heat-cured polymethyl methacrylate is (PMMA) is the most common denture base material and some mechanical properties such as flexural strength and impact resistance etc. may lead to fail, besides its excellent properties. Polypropylene (PP) hernia mesh is a commercially available medical textile used in surgical repair of different types of hernia. It was aimed to investigate the effect of two different knitting patterns of PP meshes on the flexural properties of the PMMA denture base resin when they are used as reinforcement and compare with glass fiber mesh reinforced and no mesh used resins. Knitting patterns of the PP mesh structures were hexagonal honeycomb pattern and square pattern and these were used as single or double layer as reinforcement. 6 groups were established in the study: control group with no mesh and 5 reinforced groups with meshes (glass fiber mesh, single layer honeycomb patterned PP mesh, double layer honeycomb patterned PP mesh, single layer square patterned PP mesh, double layer square patterned PP mesh). A total of 60 samples with the dimensions of 65x10x3 mm, n=10 in each group were fabricated. The flexural strength, maximum deformation, and flexural modulus were determined by three-point bending test. Fracture surfaces were evaluated by scanning electron microscopy. The obtained data were statistically analyzed by two-way ANOVA test with Bonferroni corrections. The single layer square patterned PP mesh group exhibited the highest (76.67 ± 7.64 MPa), and the control group showed the lowest (63.49 ± 7.18 MPa) flexural strength values. The single layer glass fiber mesh group showed the highest (7.13 ± 0.55 mm) and the control group showed the lowest (4.72 ± 0.81 mm) maximum deformation values. The single layer glass fiber mesh group exhibited the highest (2131.87 ± 205.76 MPa), and the control group exhibited the lowest (1582.26 ± 98.63 MPa) flexural modulus values. Significant increase in flexural strength was observed in all polypropylene mesh-reinforced groups compared to the control group except double layer honeycomb patterned PP mesh group (p &amp;lt; 0.05). Using PP fiber mesh for reinforcement provide a very favorable aesthetic view and PP fiber mesh is concluded to be a promising material for reinforcement of heat-cured PMMA denture base resins.

Color Stability of Conventional PMMA, Modified MMA and Polyamide Denture Base Materials in Different Beverages

Color Stability of Conventional PMMA, Modified MMA and Polyamide Denture Base Materials in Different Beverages

A19-saponin–modified polymethyl methacrylate base denture composites: antimicrobial, mechanical and water absorption potentials

Abstract The increased growth of Candida albicans (C. albicans) with allergy reaction of MMA remains an issue of concern among denture wearers. C. albicans growth inhibition, mechanical and water absorption potentials of extracted A19-saponin–commingled PMMA denture base composites were investigated. Soxhlet extraction technique for defatting of Dialium guineense (D. guineense) stem powder was used with ethanol to extract A19-saponin. Fungicidal inhibition concentration of A19-saponin extract of D. guineense was determined. PMMA denture base was prepared with incorporation of A19-saponin at different concentrations of obtained 23.2 % yield. The mechanical and water absorption properties were determined. The minimum and maximum fungicidal inhibition concentrations and susceptibility of 25 and 100 % for extracted A19-saponin were obtained, respectively. PMMA, MMA and extracted A19-saponin of ratio of 30 g: 5 ml: 5 ml denture was optimally fabricated. A19-saponin increased the impact strength and hardness by 352.94 and 11.54 % with reduced water absorption by 82.85 %. Thus, A19-saponin as an additive improved quality of denture.

Evaluation of Water Sorption and Solubility of 3D-Printed, CAD/CAM Milled, and PMMA Denture Base Materials Subjected to Artificial Aging

Background: This in vitro study aimed to investigate and evaluate the values of water sorption and water solubility of four types of denture base polymers—3D-printed NextDent 3D Denture + (NextDent, 3D Systems, Soesterberg, The Netherlands), CAD/CAM milled Ivotion Base (Ivotion Denture System, Ivoclar Vivadent, Schaan, Liechtenstein), PMMA conventional Vertex BasiQ 20 (Vertex Dental, 3D Systems, Soesterberg, The Netherlands), and conventional heat-cured BMS (BMS Dental Srl, Rome, Italy)—which were subjected to artificial aging. Materials and methods: 200 specimens were created (n = 50), dried, and weighed accurately. They were immersed in artificial saliva (T1 = 7 days, T2 = 14 days, T3 = 1 month) and re-weighed after water absorption. After desiccation at 37 °C for 24 h and then at 23 ± 1 °C for 1 h, samples were weighed again. Next, thermocycling (100 h, 5000 cycles, 5–55 °C) was performed, and the water sorption and solubility were re-measured. IBM SPSS Statistics 0.26 was used for data analysis, revealing a direct correlation between water sorption and material type. Thermocycling at 55 °C increased water sorption for BMS and Vertex BasiQ 20. In conclusion, NextDent’s 3D-printed resin had higher water sorption values throughout the study. Water solubility averages decreased over time, reaching the lowest in the 30-day period for CAD/CAM milled dental resin Ivotion Base. The artificial aging had no effect on Ivotion Base and NextDent’s water sorption. Thermocycling did not affect the solubility of the materials tested. The conducted study acknowledges the great possibilities of dental resins for additive and subtractive manufacturing for the purposes of removable prosthetics in daily dental practice.

Mechanical and spectroscopic investigation of novel f-MWCNTS/g-C3N4/TiO2 ternary nanocomposite reinforced denture base PMMA

In the present work, we report the fabrication, spectroscopic, and mechanical properties of the novel f-MWCNTS/g-C3N4/TiO2 (MGT-NCs) metal-free ternary nanocomposite reinforced denture base PMMA. The functionalised-MWCNTs were introduced into the graphitic carbon nitride (g-C3N4) nanopowders (NPs). The obtained high porous f-MWCNTS/g-C3N4 NPs were mixed with 10 wt% of TiO2 NPs previously hydrothermally synthesized. These prepared powders were characterized by XRD, FE-SEM, HR-TEM, FT-IR, and Raman spectroscopy to study the crystal structure and morphology. Using a mechanical blender 2 wt% of g-C3N4, MWCNT/g-C3N4, and MGT-NCs were sintered into PMMA heat-activated denture base polymer powder and mixed with monomer to fabricate the composites through heat curing. Three different varieties of composite specimens were prepared into flexural, impact, compression, and hardness testing standards. From the comparative assessment of results, it is found that novel MGT-NCs reinforced PMMA exhibited superior mechanical properties. The surface morphology of the fractured and compressed specimens was studied using the SEM analysis and found to have dimples and increased roughness compared to the pristine PMMA and g-C3N4, MWCNT/g-C3N4. Hence, the fabricated novel metal-free MGT-NCs can be used as a reinforcement material in PMMA denture bases to achieve a concurrent enhancement in both physical and mechanical properties.

Tensile Bond Strength between Different Denture Base Materials and Soft Denture Liners.

(1) Background: Various materials are available for CAD-CAM denture base fabrication, for both additive and subtractive manufacturing. However, little has been reported on bond strength to soft denture liners. Therefore, the aim of this study was to investigate tensile bond strength, comparing between different denture base materials and soft denture liners. (2) Methods: Seven different materials were used for denture base fabrication: one heat-polymerized polymethyl methacrylate, three materials for subtractive manufacturing, two materials for additive manufacturing and one polyamide. Two materials were used for soft denture lining: one silicone-based and one acrylate-based. The study was conducted according to the specification ISO No. 10139-2:2016, and the type of failure was determined. The Kruskal-Wallis test with Dunn's post hoc test was used to analyse the values of tensile bond strength, and Fisher's exact test was used to analyse the type of failure. p Values < 0.05 were considered statistically significant. (3) Results: The tensile bond strength values were not statistically significantly different combining all the materials used for denture base fabrication with the acrylate-based soft denture liner (p > 0.05), and the average values ranged between 0.19 and 0.25 Mpa. The tensile bond strength values of the different denture base materials and silicone-based denture liner were statistically significantly different (p < 0.05), and the average values ranged between 1.49 and 3.07 Mpa. The type of failure was predominantly adhesive between polyamide and both additive-manufactured denture base materials in combination with the acrylate-based soft liner (p < 0.05). (4) Conclusions: The use of digital technologies in denture base fabrication can have an influence on different tensile bond strength values for soft denture liners, with different types of failure when compared with heat-cured PMMA. Similar tensile bond strength values were found between the acrylate-based soft denture liner and denture base materials. Significant differences in tensile bond strength values were found between the silicone-based soft denture liner and denture base materials, where the additive-manufactured and polyamide denture base materials showed lower values than heat-cured PMMA and subtractive-manufactured denture base materials.

Effect of Reinforcing PMMA Denture Base Material by Stainless Steel 316L Wires on Flexural Strength

Effect of Reinforcing PMMA Denture Base Material by Stainless Steel 316L Wires on Flexural Strength

The effects of different surface treatments applied to milled PMMA denture base material on repair bond strength.

The high cost of CAD/CAM systems and materials is a severe economic burden. Therefore, repair of CAD/CAM PMMA, selecting appropriate repair materials, and surface modifications are clinically important. This study aims to evaluate the shear bond strength of PMMA repair materials after various surface treatments on CAD/CAM PMMA denture base material. For this purpose, a total of 480 CAD/CAM PMMA denture base test specimens were manufactured. Then all test specimens were divided into 6 groups, and different surface treatments were applied. Group A: sandblasting, Group B: 4% hydro fluoric acid, Group C: tungsten carbide bur, Group D: dichloromethane + methyl methacrylate mixture, Group E: dichloromethane and methyl methacrylate, Group F: no surface treatment. Each group is then divided into 4 different subcategories; repair processes were performed using; heat-cured acrylic resin (n:20), auto-polymerized acrylic resin (n:20), gingiva composite (n:20), and CAD/CAM PMMA tooth material (n:20). After repairs, thermal aging was applied to half of the test specimens in each subcategory. The shear bond strength value was measured with a universal test device. Sandblasting group showed the highest surface roughness value in all test specimens (p < 0.001). Heat-cured acrylic resin with sandblasting exhibited the highest bond strength, while the untreated gingiva composite resin exhibited the lowest value. Thermal aging decreased bond strength in all repair materials (p < 0.001). Among the surface treatment groups, sandblasting with Al2O3 particles exhibited the highest surface roughness value and repair bond strength. The application of organic solvents to the surface increased the surface roughness and repair bond strength. Applying dichloromethane and methyl methacrylate monomer separately is more effective than applying it as a mixture. The ideal bonding among repair materials was obtained with heat-cured acrylic resin.

Evaluation of shear bond strength of high molecular chitosan nanoparticle incorporated heat polymerized polymethyl methacrylate denture base resin with acrylic resin teeth: An in-vitro study

The present study is conducted to evaluate the shear bond strength of acrylic resin denture teeth to high molecular chitosan nanoparticle incorporated heat polymerized polymethylmethacrylate denture base resin. This comparative study is performed at the Department of Prosthodontics and Crown & Bridge, JSSDCH, Mysuru. 45 samples of acrylic resin blocks of size 8 × 10 × 20 mm were fabricated using mold such that the long axis of crosslinked acrylic resin maxillary central incisor teeth is aligned at 45° to the long side of the specimen to which the ridge lap surface is attached. Among these, 15 samples belong to the control group, 15 samples to the 0.5 % chitosan gel incorporated group, and the remaining 15 samples to the 1 % chitosan gel incorporated group. The test specimens were then subjected to a failure load test using the universal testing machine. The readings were tabulated and statistically analyzed using Mean, Standard deviation, Independent t-test, - way and two-way ANOVA, and Scheffes’ Post hoc test. The statistical analysis reveals that the mean bond strength of acrylic denture teeth to conventional heat cure PMMA denture base material increased from 4.6627 ± 0.54198 MPa to 7.5186 ± 0.57461 MPa and 8.9356 ± 0.63675 MPa upon addition of chitosan at 0.5 % and 1 % concentration, respectively. It can be concluded that The mean shear bond strength of acrylic denture teeth to conventional heat cure PMMA denture base material increased with the addition of chitosan at 0.5 and 1 % concentration. The best shear bond strength was observed with the addition of 1 % chitosan as per the evidence.

Evaluation of the effectiveness of bioactive glass fillers against Candida albicans adhesion to PMMA denture base materials: An in vitro study

BackgroundDentures with antimicrobial properties are desirable for preventing Candida albicans adhesion. This study was to assess the effectiveness of bioactive glass (BAG) on C. albicans adhesion, surface roughness, and hardness of denture base materials. MethodsHeat-polymerized (HP) and autopolymerized (AP) acrylic resins were used to fabricate 240 disk specimens (120/material, 60/C. albicans, 60/surface roughness and hardness). Specimens were divided into five groups (n = 10) based on the BAG concentration: 0.5, 1.5, 3, 5, and 7.5 wt% of the acrylic powder, with a control group comprised of unmodified specimens. Direct culture method was used to assess C. albicans adhesion. A profilometer and Vickers hardness test were used to measure surface roughness and hardness respectively. Analysis of variance (ANOVA) and post hoc Tukey’s test were used for data analysis (α = 0.05). ResultsBAG addition significantly decreased the C. albicans count when compared with the control group (P < 0.001) for both HP and AP. Regarding surface roughness, there was no change in the HP acrylic resins (P> 0.05), while the AP acrylic resins exhibited significantly higher surface roughness with BAG addition (P < 0.001). The hardness of the HP and AP acrylic resins were significantly higher with the addition of BAG (P < 0.001). ConclusionsThe addition of BAG to HP and AP acrylic resins effectively decreases C. albicans adhesion. The roughness of AP acrylic resins increases with the addition of BAG, while the hardness of both HP and AP acrylic resins increase with the addition of BAG.

Evaluation of three different long-term addition polymerising silicone denture liners and to compare the changes in their hardness, modulus of elasticity and water sorption after storage in artificial saliva

Aim: To evaluate the properties of three different long-term addition polymerising silicone denture liners in relevant clinical situations. Materials and Methods: Three silicone-based, widely used soft denture liners (autopolymersing chair-side GC RelineTM Soft and Mollosil® and heat cure Molloplast® B) were selected. Forty-two disk-shaped samples were prepared using a heat-polymerised PMMA denture base material using a stainless steel split mould (40mm diameter, 8mm thickness). All three long-term silicone-based soft liners were mixed, and 3mm were poured over the specimens. The samples were stored in artificial saliva for 24 hours at 37 degrees Celsius, and initial measurements were taken for hardness, water sorption and modulus of elasticity. A Shore A durometer measured the hardness, water sorption with precision balance and modulus of elasticity with a universal testing machine. Statistical Analysis: Statistical constants such as mean and standard deviations (SD) were calculated. One-way ANOVA was done using Tukey's multiple comparison test to compare hardness, modulus of elasticity, sorption of three different addition polymerising soft liner after storage in artificial saliva checked at different time intervals.

Investigation on the Potential Use of Polypropylene Mesh for the Reinforcement of Heat-Polymerized PMMA Denture Base Resin.

The aim of this study was to investigate the potential use of polypropylene (PP) hernia mesh as a reinforcement of PMMA denture base resin in comparison with metal and glass fiber meshes, with the expectation of enhancing the mechanical stability of the PMMA dentures in oral conditions. The control group with no mesh, the aluminum metal mesh (Al) group, the PP1 (PP mesh used on top) group, the PP2 (PP mesh used on both the top and bottom) group, the orthopedic casting tape with self-curing resin (DP0) group, and the flushed form (DPA) group were fabricated in a chromium mold. A total of 144 specimens were divided into three equal portions and subjected to: first, no treatment; second, thermal cycling only; and third, thermal cycling and chewing simulation. The flexural strength, maximum deformation, and flexural modulus were determined by a three-point bending test to compare mechanical properties. Fracture surfaces were evaluated by scanning electron microscopy. The obtained data were statistically analyzed by a two-way ANOVA test with Bonferroni corrections. The non-treated Al mesh reinforcement group exhibited the highest (82.66 ± 6.65 MPa) flexural strength, and the PP2 group treated with chewing simulation displayed the lowest (56.64 ± 4.59 MPa) flexural strength. The Al group showed the highest (7.25 ± 1.05 mm) maximum deformation and the PP2 group showed lowest (3.64 ± 0.28 mm) maximum deformation when both groups were not subjected to any treatment. The control group with no treatment exhibited the lowest (1556.98 ± 270.62 MPa) flexural modulus values, and the Al group with no treatment exhibited the highest (3106.07 ± 588.68 MPa) flexural modulus values. All the mesh groups displayed intact fractures. Any type of mesh used for reinforcement exhibited a significant change in all flexural properties (p < 0.001). The PP1 reinforcement group did not exhibit a significant change in mechanical properties when the effect of treatment was compared. Using PP hernia mesh on top enhanced the mechanical properties despite the weakening when it was used on both the top and bottom. The mechanical stability provided by the PP hernia mesh indicated it to be a promising candidate to be used for reinforcement.

Effect of Recycled Denture Base Polymeric Powder Incorporation on the Surface Properties of Heat-cured PMMA Denture Base Acrylic Resin: An In Vitro Study

Effect of Recycled Denture Base Polymeric Powder Incorporation on the Surface Properties of Heat-cured PMMA Denture Base Acrylic Resin: An In Vitro Study

Comparative Effect of Incorporation of ZrO2, TiO2, and SiO2 Nanoparticles on the Strength and Surface Properties of PMMA Denture Base Material: An In Vitro Study.

Objective This study aimed to investigate the effects of nanoparticles (zirconium dioxide (ZrO2), titanium dioxide (TiO2), and silicon dioxide (SiO2)) on the flexural strength, impact strength, hardness, and wear resistance of the acrylic resin denture base material. Materials and Methods Acrylic resin specimens were fabricated in dimensions according to American Dental Association (ADA) specifications per test. Specimens were divided according to nanofiller into four groups; unmodified as control, ZrO2 (Z), TiO2, (T), and SiO2 (S) groups. Each one was subdivided into two subgroups according to nanoparticle concentrations; 3% and 7% (Z3, Z7, T3, T7, S3, and S7). A 3-point bending test, Charpy impact test, and Vickers hardness test were used for flexural strength, impact strength, and hardness measurements, respectively. Wear resistance was measured by the differences in surface roughness of tested specimens before and after the wear test. A scanning electron microscope was used to assess nanoparticle specifications and distributions and for fracture surfaces analysis. ANOVA, Bonferroni's post hoc test, and the Kruskal–Wallis test were applied for data analysis (α = 0.05). Results Regarding the flexural and impact strength, there was a statistically remarkable increase for all tested groups compared with the control group, except for the T7 and S7 groups (P value <0.001, effect size = 0.893) and (P value <0.001, effect size = 0.759), respectively. There was a statistically significant improvement in the hardness of all tested groups compared with the control group (P value <0.001, effect size = 0.67) except T3 and S3. Regarding wear, a statistically significant enhancement was noticed in the wear resistance of all tested groups (P value <0.001, effect size = 0.685), except for the T7 and S7 groups. Conclusion The flexural strength, impact strength, and wear resistance improved with both concentrations of ZrO2 and low TiO2 and SiO2 concentrations. The hardness increased with both concentrations of ZrO2 and high TiO2 and SiO2 concentrations.

Bond Strength between CAD/CAM PMMA Denture Base Resins and Characterisation Composites

Aim: To measure the bond strength between two different CAD/CAM PMMA denture base resins and three different types of gum characterisation composites. Materials and Methods: CAD/CAM single cross-linked (Telio CAD) and double cross-linked (Vivodent CAD) resins were prepared, obtaining a total of 180 bar specimens. Each specimen was prepared according to the manufacturer’s instructions. The specimens were bonded to three different characterisation composites with varying viscosities; Kulzer Pala-creactive (P), Ivoclar SR Nexco (S), Shofu Ceramage (F). All the specimens were then tested using a chevron-notched three-point bond strength test in a universal testing machine to obtain fracture energy release toughness (MPa√m) and bond strength (MPa). The specimens were thermocycled to simulate 6 and 12 months of ageing in vivo. The results were statistically analysed (SPSS). The fractured surfaces of the tested specimens were examined with a scanning electron microscope (SEM) to evaluate the failure modes. Results: Pala-creactive characterisation composites showed the highest overall bond strength (3.49 ± 0.86 MPa) and fracture toughness (1.59 ± 0.34 MPa√m) when bonded to both CAD PMMA denture resins, which were statistically higher than the values obtained when they were bonded to Telio (p &lt; 0.001). The Ceramage composite showed the lowest bond strength (1.05 ± 0.59 MPa) and fracture toughness (0.47 ± 0.4 MPa√m). The dominant mode of failure for all groups was mixed. Conclusion: Single cross-linked PMMA (Telio) showed a higher overall bond strength compared to double cross-linked PMMA when bonded to three different characterisation composites. Telio CAD showed a clear bond strength decrease after 6 and 12 months of artificial ageing, while Vivodent CAD showed a bond strength increase.