Heat-polymerized Acrylic Resin Research Articles

SURVEY OF A FUNCTIONAL STATE OF MASSETER MUSCLES IN EDENTELOUS PATIENTS BASED ON THE DATA OF SURFACE ELECTROMYOGYOPHY STUDIES

The difficulty of prosthetics and rehabilitation of patients with complete loss of teeth is associated with a burdened psychological and anatomical status. The main reasons for teeth extractions are periodontal tissue diseases, diseases of hard tooth tissues of carious and non-carious origin and traumas. Complete loss of teeth leads to a large number of local and general complications. The masticatory apparatus undergoes a number of functional and morphological changes. It becomes necessary to manufacture complete removable dentures to prevent the occurrence of pathologies in such situations. The effectiveness at this type of dentures depends on compliance with the protocols of their fabrication and the quality of the basic dental materials. Currently, prosthodontists use thermoplastic plastics in the fabrication of complete removable prostheses, more commonly the main group of materials for this constructions are heat-polymerized acrylic resins. Evaluation of the quality of the fabricated complete removable dentures and of the functional state of the masticatory system after prosthetics is determined by their fixation and stabilization, restoration of the patient's appearance and degree of masticatory effectiveness. It can be determined by using of a surface electromyography an objective method for evaluation of the functional state of muscles by recording of their electrical biopotentials.
 The aim of our study was to study the functional state of the masseter muscles using surface electromyography in edentulous patients, who got dentures made from a thermoplastic base material «Vertex ThermoSense» in the prosthodontics clinic.
 Material and methods. We used polyamide (nylon) «Vertex ThermoSense», (Netherlands) in this work, for the fabrication of complete removable dentures. We made dentures for 19 elderly and senile patients (60 years and older) with a complete absence of teeth, who retired to the prosthodontics clinic with a goal of manufacturing new complete removable dentures for the upper and lower jaws. Over the past 3-5 years, they have been using complete removable dentures that were made from acrylic resins.
 Results. Assessing the results of the electromyographic study after 1 year of using of the dentures, it can be concluded that the amplitudes during compression approach the norm and almost four times higher than before prosthetics. A similar pattern as observed with the arbitrary chewing: the amplitudes approach the norm in comparison with the results before prosthetics. As for the coefficient «K», its value decreased in comparison with the results before prosthetics almost twice, which is largely close to the norm.
 Conclusion. Based on our study of the functional state of the masticatory muscles using surface electromyography in edentelous patients, who got dentures made polyamide thermoplastic material from a «Vertex ThermoSens», we can conclude that of electromyographic studies before prosthetic treatment are significantly different from normal, and after a year of using of dentures are as close as possible to them, which indicates a quiche adaptation to dentures.

Effect of layering gingiva-shade composite resin on the strength of denture base polymers

Statement of problemAcrylic resin denture base materials, fabricated with either a traditional technique or computer-aided design and computer-aided manufacturing (CAD-CAM) technique, layered with different thicknesses of gingiva-shade composite resin may affect the strength of the definitive prostheses and have not been investigated. PurposeThe purpose of this in vitro study was to assess the flexural strength of acrylic resin denture base materials modified by layering different thicknesses of gingiva-shade composite resin. Material and methodsTwo denture acrylic resins, heat-polymerized type (Lucitone 199) and CAD-CAM prepolymerized type (AvaDent) polymethyl methacrylate (PMMA) resin, were used as the base materials. Three-millimeter–thick specimens were fabricated and prepared according to the ISO 1567 and ISO 20795-1:2013 and were used as the controls. A proprietary gingiva-shade composite resin (GRADIA gum shades) was used to replace different thicknesses (0.5 mm, 1.0 mm, and 1.5 mm) of the denture base materials, giving 4 groups for each tested material (n=16). A 3-point loading test was conducted by using a universal testing machine and a custom fixture with a crosshead speed of 5 mm/min. The maximum fracture loads were recorded, and ultimate flexural strength values were calculated. The collected data were statistically analyzed with ANOVA and the Tukey honestly significant difference (HSD) tests (α=.05). Representative fractured specimens were examined under a stereomicroscope at ×20 magnification and a scanning electron microscope to determine the interface and fracture patterns. ResultsThe mean ±standard deviation of ultimate flexural strengths for the heat-polymerized acrylic resin specimens ranged from 94.79 ±9.89 MPa to 40.34 ±12.79 MPa, and that of the CAD-CAM prepolymerized acrylic resin ranged from 125.98 ±7.96 MPa to 64.16 ±20.77 MPa. Acrylic resin denture base materials after layering with gingiva-shade composite resin had a significantly lower mean fracture load than the controls (P<.05). The Tukey HSD test revealed that the control groups had significantly higher flexural strength values compared with the other tested specimens within each denture acrylic resin group layered with gingiva-shade composite resin (P<.05). The SEM images displayed brittle fracture exhibiting well-defined, flat, compact, and organized surface fractures. ConclusionsThe flexural strengths of CAD-CAM prepolymerized acrylic resins were higher than those of the heat-polymerized denture acrylic resins. The flexural strengths of all 3 thicknesses of the CAD-CAM prepolymerized acrylic resins were greater than 65 MPa.

Effect of Zirconium Oxide Nano-Fillers Addition on Transverse Strength And Impact Strength of Heat-Polymerized Acrylic Resin, An in Vitro Study

Aim: The purpose of this study was to evaluate the effect of Zirconium oxide (ZrO2) nanofillers powder with different concentration (1.5%, 3%, 5% and 7%) on the transverse strength and impact strength of heat-polymerized acrylic resin. Materials and Methods: Zirconium oxide powders with different concentrations (1.5%, 3%, 5% and 7%) were incorporated into heat-cure acrylic resin (PMMA) and processed with optimal condition (2.5:1 Powder/monomer ratio, conventional packing method and water bath curing for 2 hours at 95˚C) to fabricate test specimens of PMMA of dimensions (65 x 10 x 2.5mm) for the transverse strength and (60 x 7 x 4mm) for impact strength. PMMA without additives was prepared as a test control. Two types of mechanical tests; transverse strength and impact strength were carried out on the samples. The recorded values transverse strength in (MPa) and impact strength in (J) were collected, tabulated and statistically analyzed. One way analysis of variance (ANOVA) and Tukey’s tests were used for testing the significance between the means of tested groups which are statistically significant when the P value ≤ 0.05. Results: Addition of Zirconium oxide nanofillers to PMMA significantly increased the transverse strength and impact strength Conclusion: Zirconium oxide nanofillers added to PMMA has a potential as a reliable denture base material with increased transverse strength and impact strength. According to the results of the present study, the best mechanical properties were achieved by adding 7%wt ZrO2 concentration.

Effect of Denture Cleansers on Surface Roughness and Flexural Strength of Heat Polymerised Acrylic Resin – Invitro Study

The surface roughness of denture base fabricated with Acrylic resin is crucial in the maintenance of denture hygiene. Rough surfaces are found to accumulate microorganisms which can colonise the microirregularities leading to foul smell and also compromise the health of the oral tissues. This Study was aimed to measure the surface roughness and flexural strength of heat polymerised resin of 180 day use after its immersion in denture cleanser. Two types of heat polymerised acrylic resins Acryln – H and DPI were selected. 40 specimens were prepared out of each resins. Amoung 40 specimens 20 specimens are taken as a control from each of the resins. Then the specimens were immersed in distilled water and in denture cleansing tablet sodium perborate monohydrate. Surface roughness (RA) and flexural strength (S) was measured before and after immersion in denture cleanser solution.The surface roughness were increased in both Acryln-H and DPI heat cure acylic resin materials after immersion in denture cleansers. The flexural strength were much reduced in Acryln-H material on comparing with DPI after immersion in denture cleanser.

Effect of Repair Gap Width on the Strength of Denture Repair: An In Vitro Comparative Study.

To evaluate the effect of repair gap width on the flexural strength and impact strength of a repaired acrylic denture with and without thermal cycling. A total of 240 heat-polymerized acrylic resin specimens were fabricated in dimensions of 65 × 10 × 2.5 ± 0.2 mm and 55 × 10 × 10 ± 0.2 mm for flexural strength and impact strength testing, respectively. All specimens were sectioned into halves then divided into 6 groups according to repair gap width (n = 10). The repair gap of the control group was 2.5 mm at the base, while the repair gaps of the test groups were prepared as 2.0, 1.5, 1.0, 0.5, and 0 mm at the base. All specimens were prepared with a 45° bevel joint. Each specimen was placed into the mold that retained the original length of the specimen and modified only the repair gap, which was packed with repair resin. After polymerization, specimens were finished and polished, and half of the specimens were thermal cycled for 5000 cycles. Three-point bending test and Charpy impact test were used to determine the flexural strength and impact strength, respectively. ANOVA and Tukey's HSD test were used for statistical analysis, where α was set at 0.05. Decreasing repair gap significantly increased the flexural strength in comparison to control group (p < 0.05); 0.5-mm repair gap showed the highest flexural strength values. Changing the repair gap significantly increased the impact strength of groups 2.0- and 1.5-mm (p < 0.05). Thermal cycling significantly decreased the flexural strength of all tested groups as well as impact strength for groups with wide repair gaps (2.5-, 2.0-, and 1.5-mm) (p < 0.05), while other tested groups had nonsignificant effect on impact strength (p > 0.05). Decreasing repair gap increased the flexural and impact strengths of repaired acrylic resin. A repair gap of 0-, 0.5-, or 1.0-mm with beveled repair surface is recommended to improve repair strength and overcome the drawbacks of increased amounts of autopolymerized repair resin.

Can Nonthermal Plasma Improve the Adhesion between Acrylic Resin for Ocular Prostheses and Silicone-Based Relining Material?

To investigate the influence of nonthermal plasma (NTP) treatment on the tensile bond strength between heat-polymerized acrylic resin for ocular prostheses and silicone reliner, with and without the use of an adhesive primer. One-hundred and sixty-four acrylic resin specimens were fabricated and randomly distributed into four groups according to the type of surface treatment: Sofreliner Primer, NTP, Sofreliner Primer + NTP, and NTP + Sofreliner Primer. Two specimens interposed with relining material (Sofreliner) formed one test sample to perform the tensile bond strength tests, before (initial) and after storage (final) in saline solution (37°C, 90 days, n = 10). Surface characterization was performed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The failure type was classified as cohesive, adhesive, or mixed. The data were analyzed statistically using the two-way ANOVA and Tukey test, as well as the chi-squared test (α = 0.05), Bonferroni correction (α = 0.005), and Spearman correlation coefficient (α = 0.05). The SEM and EDS analyses showed the presence of a thin, homogenous organic film in the groups treated with NTP. The NTP + Sofreliner Primer group presented the largest bond strength mean values in the initial period (p < 0.05). Sofreliner Primer and NTP + Sofreliner Primer groups presented the first and second largest tensile bond strength mean values in the final period (p < 0.05), respectively. NTP + Sofreliner Primer group also had the largest number of cohesive (70%, initial) and mixed (90%, final) failures. The NTP treatment performed before the primer application enhanced the bond between the acrylic resin ocular prosthesis and the Sofreliner silicone-based reliner, even after 90 days of immersion in saline solution.

Comparative Evaluation of the Flexural Strength of Heat Polymerized Acrylic Resin with the Addition of 8% and 13% Aluminum Oxide Powder: An In-vitro Study

Introduction: Acrylic resins have been used successfully as denture bases. However, acrylic resin denture base materials are brittle and have poor strength and thermal conductivity. Therefore, it is essential to improve the flexural strength of heat polymerized acrylic resin. The present study aimed to evaluate and compare the flexural strength of heated polymerized acrylic resin with the addition of 8% and 13% aluminum oxide powder. Methods: In total, 90 acrylic specimens were fabricated and divided into three groups of A1 (unmodified heat-cured denture base resin), A2 and A3 (heat-cured denture base resin polymer modified with 8% and 13% by weight of aluminum oxide powder, respectively). The specimens were stored in distilled water for one week, and flexural strength was assessed using a universal testing machine. Data analysis was performed using one-way analysis of variance (ANOVA). Results: Comparison of groups A1 and A2 (8%) showed the highest flexural strength (85.94 MPa) in group A2. A significant increase was observed in the values of flexural strength with 13% alumina addition. Comparison of groups A1 and A3 (13%) showed the highest flexural strength (86.41 MPa) in group A3, and the difference in the mean values of flexural strength was considered significant. Moreover, comparison of groups A2 and A3 indicated the highest flexural strength in group A3. Conclusion: Addition of alumina to conventional heat-cured acrylic resin shows increase in flexural strength. Increasing the flexural strength of acrylic resin base materials could results in higher clinical success rate.

HPLC characterization of two resins used in removable prosthodontics: ProBase® hot and ProBase® cold

Introduction: Denture base acrylic resins release residual monomers as a result of an incomplete polymerization [1]. Due to its toxic effects on cells and constant contact with the oral mucosa, it is important to analyze the composition of these resins [2]. Organic solvents can mimic the erosive and acidic action of food and beverages and to penetrate resins’ polymeric matrix [3]. According to ISO 10993-5 (1999), to ensure the release of monomers, specimens must remain for at least 24 hours in contact with the solvent. High Performance Liquid Chromatography (HPLC) is the most efficient method to identify these components [3]. The aim of this study is to identify the monomers released by two denture base acrylic resins. Materials and methods: Specimens of self-cured resin ProBase® Cold and heat-polymerized resin ProBase® Hot were prepared according to the manufacturer’s instructions and placed in contact with an organic solvent by the sink-in method. The elution of Hydroxyethyl Methacrylate (HEMA), Methyl Methacrylate (MMA), Triethylene Glycol Dimethacrylate (TEGDMA) and Urethane Dimethacrylate (UDMA) monomers was evaluated by HPLC 0 hours (t0) and 24 hours (t24) after placing the samples in an oven at 37 °C. Results: The four studied monomers were found in both resins’ structures. Self-cured resin ProBase®Cold released higher concentrations of residual monomers compared to heat-polymerized resin ProBase® Hot (ρ = 0.021). TEGDMA and UDMA monomers were not released by acrylic resin ProBase® Hot at t0. Discussion and conclusions: t0 was evaluated in order to study the monomer release once the acrylic denture is placed into the patient’s mouth, at the dentist appointment. The results agree with Bayraktar et al. who stated that self-curing resins release higher ammounts of residual monomers when compared with heat polymerized acrylic resins [4]. Given the toxic effects of each monomer, we may assume that using acrylic resin ProBase® Hot on acrylic dentures is more beneficial to the patient when compared to ProBase® Cold.

Reinforcement of PMMA Denture Base Material with a Mixture of ZrO2 Nanoparticles and Glass Fibers.

This study is aimed at evaluating the hybrid reinforcement effects of zirconium oxide nanoparticles (nano-ZrO2) and glass fibers (GFs) at different ratios on the flexural and impact strengths of a polymethylmethacrylate (PMMA) denture base. A total of 160 specimens were fabricated from heat-polymerized acrylic resins using the water bath technique. For the control group, the specimens did not receive any additions; for the test group, different concentrations of nano-ZrO2/GFs at 5% of the PMMA polymer were added. The concentrations of nano-ZrO2/GFs were as follows: 5%–0%, 4%–1%, 3%–2%, 2.5%–2.5%, 2%–3%, 1%–4%, and 0%–5%. The flexural strength was measured using the three-point bending test. The impact strength was measured using the Charpy impact test. Results were tabulated and analyzed using one-way analysis of variance (ANOVA) and the Tukey–Kramer multiple comparison test (p ≤ 0.05). The flexural and impact strengths of PMMA-nano-ZrO2 + GF composites were significantly improved when compared with those of pure PMMA (p < 0.05). The maximum flexural strength (94.05 ± 6.95 MPa) and impact strength (3.89 ± 0.46 kJ/m2) were obtained with PMMA (2.5%)/nano-ZrO2 + 2.5% GF mixtures and could be used for removable prosthesis fabrication.

Color change of airborne particle–abraded acrylic resin surfaces: A palatography method

Statement of problemA palatogram aids prosthodontists and speech pathologists in evaluating the precise prosthetic treatment needed and the effectiveness of such treatment to improve speech intelligibility. Powder is commonly used to visualize tongue-palate contact, where wetted areas of powder in the oral cavity reveal such contact during palatography. However, discomfort and the risk of aspiration are among the shortcomings of this method, and an improved method is needed. PurposeThe purpose of this in vitro study was to examine the feasibility of a new method of palatography that uses airborne-particle–abraded acrylic resin so that wet areas can be easily distinguished from dry areas. Material and methodsSeventy-two specimens of heat-polymerized acrylic resin were prepared in 6 different resin colors. After the specimens had been airborne-particle abraded, CIELab color values for each specimen were measured using a colorimeter under dry and wet conditions and recorded. Color difference (ΔE) was then computed, and a paired Student t test, 1-way analysis of variance, and multiple comparison using the Tukey post hoc analysis were applied (α=.05). ResultsA significant color difference was found between the 2 conditions in all acrylic resin specimens examined. Mean ΔE ranged from 5.58 to 6.76. ConclusionsThe results indicated that an airborne-particle–abraded acrylic resin surface can show color differences made by wetting on palatograms.

Evaluation of Wettability of Three Saliva Substitutes on Heat-polymerized Acrylic Resin—An In vitro Study

The aim of the present study was to evaluate the wettability of three saliva substitutes on heat-polymerized acrylic resin. Heat-cured acrylic resins 150 were made and divided into three groups containing 50 samples each, i.e., group 1 Aqwet, group 2 Biotene, and group 3 Mouthkote. The prepared wax pattern was cut using 30 × 30-mm two square glass plates along the sides using a sharp carver. The uniformity of the wax samples was checked using the wax gauge. The wax samples were invested using dental plaster in varsity flasks. The samples were prepared using conventional heat-cure denture base acrylic resin. A goniometer was used to calculate receding and advancing contact angles for dynamic contact angle analysis. The least mean value of advancing and receding contact angles was seen in group 1 Aqwet (68.12 ± 1.30 and 58.56 ± 0.10) followed by group 2 Biotene (81.64 ± 0.88 and 74.89 ± 0.45), and group 3 Mouthkote (85.76 ± 1.02 and 80.63 ± 0.66). A significant difference was found between the groups statistically with a p value of 0.001. A significant difference was found on multiple comparisons between group 1 vs group 3 and group 1 vs group 2 with different receding and advancing contact angles of saliva substitutes analyzed with Turkey's post hoc test. The lowest advancing and receding contact angle values were significantly seen in the Aqwet saliva substitute followed by Biotene and Mouthkote on heat-polymerized acrylic resin. The clinical significance of the saliva substitute's good wetting property on acrylic denture base. The quality of life of the patients with xerostomia can be improved using a suitable saliva substitute.

Effect of Incorporation of Nanoclay on the Properties of Heat Cure Denture Base Material: An In vitro Study.

Purpose:The aim of the study was to evaluate the effect of incorporation of organically modified nanoclay in 1%, 3%, and 5% by weight on the flexural strength, surface hardness, and linear polymerization shrinkage of heat cure denture base material.Materials and Methods:One hundred and twenty specimens of heat-polymerized acrylic resin were fabricated. The specimens were divided into four groups (n = 10) coded I to IV. Group I was the control group (unmodified acrylic resin specimens). The specimens of the remaining three groups were reinforced with nanoclay (organically modified montmorillonite) nanoparticles to achieve loadings of 1%, 3%, and 5% by weight. The resulting nanocomposites were subjected to mechanical testing and were characterized using X-ray diffraction, scanning electron microscope, and transmission electron microscope.Results:The statistical analysis showed that there was no significant increase in flexural strength within and between the groups. The most significant increase in surface hardness was observed between Group I (control) and Group II (1% nanoclay). Linear polymerization shrinkage of the specimens showed a significant decrease in the control and all the experimental groups.Conclusion:Addition of 1 wt% nanoclay to polymethyl methacrylate heat cure denture base material could enhance the surface hardness and reduce the linear polymerization shrinkage of the resin. However, there was no significant increase in flexural strength of the resulting nanocomposite.

A comparative evaluation of flexural strengths of two different chairside repair materials with and without modification of implant attachment housings: An in vitro study

Statement of Problem: Implant overdentures become thinner and weaker after direct transfer of implant attachment housings. The introduction of a metal housing changes the character of the repair as denture has to be relieved to provide space for the housings; therefore, a strong method of repair is desirable to avoid prosthesis fracture. Purpose: The purpose of this study was to compare flexural strength of two different chairside repair materials with and without modification of implant attachment housings. Materials and Methods: Eighty 13 mm × 10 mm × 41 mm heat-polymerized acrylic resin blocks were processed, assessed for porosities, and polished. An 8.5-mm diameter hole was created to a depth of 5 mm in the center of each block. Two different attachment housings sandblasted and nonsandblasted were placed into the blocks with two different repair materials: autopolymerized acrylic resin (APAR) and light-polymerized acrylic resin. Later blocks were immersed in water for 7 days in an incubator. A three-point bend test was done in a universal testing machine, and load to fracture was recorded (MPa). Results were compared with one-way analysis of variance (α = 0.05). Results: The mean maximum strength of APAR groups was significantly higher than light-polymerized acrylic resin groups. Groups with sandblasted attachment housings showed significantly higher strength compared to nonsandblasted groups. Conclusions: The flexural strength of self-cured acrylic resin with and without sandblasting of attachment was significantly higher than light-cured acrylic resin with and without sandblasting of attachment housings. Sandblasting produced higher flexural strength in denture blocks repaired with self-cured acrylic.

Effect of Incorporation of an Antimicrobial Monomer 2-tert-Butylaminoethyl Methacrylate on the Flexural Strength and Impact Strength of a Heat-polymerized Acrylic Resin: An In Vitro Study

Effect of Incorporation of an Antimicrobial Monomer 2-tert-Butylaminoethyl Methacrylate on the Flexural Strength and Impact Strength of a Heat-polymerized Acrylic Resin: An In Vitro Study

Influence of Concentrations of Methacrylate and Acrylate Monomers on the Properties of Fiber Reinforced Polymethyl Methacrylate Denture Base Materials

Abstract The study aimed to evaluate the effects of adding different concentrations of 2 hydroxyethyl methacrylate (HEMA), 2-hydroxyethyl acrylate (HEA), ethyl methacrylate (EA) and isobutyl methacrylate (IBMA) monomers on the structural, thermal and mechanical properties of a fiber reinforced heat-polymerized acrylic resin. For each test, 126 acrylic resin specimens were fabricated and divided into 6 groups with 7 specimens each. One group was the control group, the other one is a fiber reinforced group and others were the test groups, which were formed according to the different concentrations of monomers. 6 mm length, and the weight ratio of 3% short glass fibers are added to acrylic powder polymerized by heating. The 2%, 5%, 10%, at 20 % ratios of different comonomers added to a monomer of MMA are composed of copolymer structures. Flexural strength was assessed with a three-point bending test using a universal testing machine. Impact strength testing was conducted using an impact test machine by the Charpy method. The analysis of the connection between acrylic resin and fiber by SEM and structural changes in the acrylic resin was investigated by FTIR spectroscopy. Data analyses using analysis of Kruskal-Wallis and Mann-Whitney U tests (α=0.05) significant difference tests showed that adding 2%, 5% HEMA and IBMA monomers significantly increased the flexural and impact strength compared to the control, only fiber and others group (P&lt; 0.05). It is observed that the process of adding low concentration of HEMA and IBMA monomers improved certain mechanical properties of fiber reinforced with polymethylmethacrylate.

Wettability of 3 different artificial saliva substitutes on heat-polymerized acrylic resin

Statement of problemThe prosthodontic problems faced by a patient with xerostomia are of great concern. To aid in retention, artificial saliva substitutes should exhibit good wettability on the denture base. PurposeThe purpose of this in vitro study was to evaluate the wettability of 3 different artificial saliva substitutes on heat-polymerized acrylic resin and to compare these properties with natural saliva and distilled water. Material and methodsA total of 150 heat-polymerized acrylic resin specimens were prepared with 25×15×2 mm dimensions. The specimens were divided into 5 groups (n=30): human saliva, distilled water, Aqwet, Mouth Kote, and Stoppers 4. The advancing and receding contact angle values were measured by using a goniometer, and the contact angle hysteresis and equilibrium angle were calculated. One-way ANOVA and the Bonferroni multiple comparisons test were performed to determine the difference between contact angle values among the groups (α=.05). ResultsThe means of the 5 groups differed significantly (P<.05). The comparison between human saliva and Aqwet showed no significant difference for advancing contact angle, receding contact angle, contact angle hysteresis, or equilibrium contact angle, while comparison between the remaining groups indicated statistically significant (P<.05) results. All 3 saliva substitutes used in this study (Aqwet, Mouth Kote, and Stoppers 4) had significantly better wetting properties than distilled water. ConclusionsHuman saliva had the lowest advancing, receding, and equilibrium contact angle values and the highest angle of hysteresis on heat-polymerized acrylic resin. Aqwet had better wetting ability than the other artificial salivary substitutes tested and was comparable to the human saliva on heat-polymerized acrylic resin. All saliva substitutes have better wetting properties than distilled water.

Effect of Nanodiamond Addition on Flexural Strength, Impact Strength, and Surface Roughness of PMMA Denture Base.

To assess the effect of addition of different concentrations of nanodiamonds (NDs) on flexural strength, impact strength, and surface roughness of heat-polymerized acrylic resin. 120 specimens were fabricated from heat-polymerized acrylic resin. They were divided into a control group of pure polymethylmethacrylate (PMMA; Major.Base.20) and three tested groups (PMMA-ND) with 0.5%wt, 1%wt, and 1.5%wt of added ND to PMMA. Flexural strength was determined using the three-point bending test. Impact strength was recorded by using a Charpy type impact test. Surface roughness test was performed using a Contour GT machine. One-way ANOVA and Tukey's post-hoc analysis (p ≤ 0.05) were used for statistical analysis. Acrylic resin reinforced with 0.5% ND displayed significantly higher flexural strength than the unreinforced heat-polymerized specimens, acrylic resin reinforced with 1% ND and the 1.5% ND (p < 0.0001). The impact strength of unreinforced heat-polymerized specimens was significantly higher than all nano-composite materials (p < 0.0001) with no significant difference between 1% ND and the 1.5% ND (p > 0.05). The addition of 0.5% ND and 1% ND significantly decreased the surface roughness in comparison to both control and the 1.5% ND groups (p < 0.0001) while no significant differences between 0.5% ND and 1% ND (p > 0.05) were reported. Nano-composite material (0.5% ND) showed significantly lower surface roughness when compared to other specimens. The addition of NDs to acrylic denture base improved the flexural strength and surface roughness at low concentrations (0.5%), while the impact strength was decreased with ND addition.

PERBEDAAN KEKASARAN PERMUKAAN BASIS RESIN AKRILIK POLIMERISASI PANAS MENGGUNAKAN BAHAN PUMIS, CANGKANG TELUR DAN PASTA GIGI SEBAGAI BAHAN POLES

Denture base widely were made from heat polymerized acrylic resin. Either one of physical properties on this material must be concern is surface roughness, rough surface could interfere patient’s comfort, and microbial colonization. Therefore polishing procedure were needed, polishing material that mostly used on acrylic resin was pumice, there is another alternative material i.e eggshell and toothpaste because had abrasive ability. The aim of this research is to determine the difference surface roughness of heat polymerized acrylic denture base resin used pumice, eggshell and toothpaste as polishing materials. The design research in this study is laboratory experimental with rectangle sample with size 50 x 20 x 3 ±1 mm. There are 30 samples for 3 groups. The result of this research shows a significant difference between pumice group and eggshell group with p value = 0,0001 (p &lt; 0,05), pumice and toothpaste with p value = 0,0001 (p &lt; 0,05), egghsell and toothpaste with p value = 0,032 (p &lt; 0,05). Polishing that used an alternative material from eggshell and toothpaste produce lower surface roughness score rather than pumice.

PENGARUH PENAMBAHAN ZIRKONIUM OKSIDA DAN SERAT POLIPROPILEN TERHADAP KEKUATAN IMPAK DAN TRANSVERSAL BAHAN BASIS GIGI TIRUAN RESIN AKRILIK POLIMERISASI PANAS

Heat polymerized acrylic resin is the most common material used for making denture base because of it’s advantages. However, this material still hasn’t fulfill all the ideal requirements as a denture base. Some disadvantages that need to be fixed are low impact and transverse strength causing an easy base of fracture. Several attempts were made to improve the mechanical properties of heat polymerized acrylic resin materials by adding reinforcing materials. Zirconium oxide is one of chemical group that can be used as a reinforcing material and polypropylene fiber which is including in fiber reinforcing groups. This study aims to determine whether there is a difference in the effect of the addition of 5% ZrO2 nanoparticles and 2% chopped polypropylene fibers 6 mm in length on the impact and transverse strength of heat polymerized acrylic resin denture base material. The design of this study is a laboratory experimental and the number of samples in this study are 60 samples. The result of this study shows the mean value of the impact and transverse strength of heat polymerized acrylic resin with ZrO2 nanoparticles reinforced is greater than the control group and heat polymerized acrylic resin group with polypropylene fiber reinforced with significant difference, and the mean value of impact and transverse strength of heat polymerized acrylic resin with polypropylene fibers reinforced is greater than the control group with significant difference.

Titanium Dioxide Addition to Heat Polymerized Acrylic Resin Denture Base Effect on Staphylococcus aureus and Candida albicans

&#x0D; Introduction: Heat-polymerized acrylic resin is used to manufacture almost all denture bases. One of the disadvantages of acrylic resin is its porosity and surface roughness; food scraps attach easily. If the dentures are not cleaned, they become a place for microbial species development and cause denture stomatitis, with Staphylococcus aureus and Candida albicans as the major etiologic agents. Adding nanoparticles of titanium dioxide to heat-polymerized acrylic resin may provide antimicrobial activity to the acrylic resin base.&#x0D; &#x0D; Objectives: This study aimed to determine whether adding TiO2 nanoparticles to heat-polymerized acrylic resin denture base materials affected the amounts of Staphylococcus aureus and Candida albicans.&#x0D; &#x0D; Methods: The samples in this study used heat-polymerized acrylic resin without the addition of TiO2 nanoparticles and with the addition of 2%, 3%, and 4% TiO2 nanoparticles on test bar sizes of 10 mm × 10 mm × 1 mm. There were 48 total test samples: 24 of Staphylococcus aureus and 24 of Candida albicans. The obtained data were analyzed by a one-way ANOVA test.&#x0D; &#x0D; Results: The results showed that adding TiO2 nanoparticles influenced the amount of Staphylococcus aureus (p&lt;0.05) and Candida albicans (p&lt;0.05). A least significant difference test showed differences of effect in the amounts of Staphylococcus aureus when TiO2 concentrations of 2%, 3%, and 4% were added to heat-polymerized acrylic resin denture base and there were differences in effect to amounts of Candida albicans when TiO2 concentrations of 2%, 3%, and 4% were added to heat-polymerized acrylic resin denture base.&#x0D; &#x0D; Conclusion: Adding TiO2 nanoparticles to heat-polymerized acrylic resin denture base material affects the amounts of Staphylococcus aureus and Candida albicans.