Cold-curing Acrylic Resin Research Articles

Comparative evaluation of incorporation of ferrule in premolars endocrown designs to check any alterations in their fracture resistance: A pilot study.

Endocrown preparation of endodontically treated teeth as final restoration has been extensively studied for different teeth. Bindl et al. questioned the application of endocrowns for premolars due to the pulp chamber space's smaller dimensions, which diminish bonding surface area. The addition of ferrule into the endocrown preparations of premolars has not been extensively studied. Comparative evaluation of incorporation of the ferrule in premolars endocrown designs to check any alterations in their fracture resistance. The sample consisted of 40 maxillary first premolars without cracks or caries, extracted for orthodontic or periodontal purposes. The teeth were individually mounted with cold-cure acrylic resin. Group A: Composite endocrown without ferrule and Group B: Composite endocrown with ferrule. An endocrown former was prepared with elastomeric polyvinyl siloxane material (GC Exaclear). Endocrowns were then prepared with dual-cure core build-up composite-Core-x flow (Dentsply Maillefer, Switzerland) using the endocrown former so that morphologically, they all were almost identical. Endocrowns are cemented by dual-cure resin cement following manufacturer instructions. The fracture resistance of endocrowns with and without ferrule was evaluated and compared. The data were tabulated in Microsoft Excel and analyzed with SPSS version 24 software. The variables were presented with mean, standard deviation, and independent t-test. The P ≤ 0.05 is considered statistically significant. Group B (with ferrule) showed higher fracture resistance (622.06 N) than Group A (537.59 N) (without ferrule). Independent t-test showed that the difference was statistically significant (P = 0.008). Comparing the failure load findings, it could be concluded that ferrule-containing endocrown needed greater loads than ordinary endocrown restorations for failure.

Effect of adding chrome-cobalt, titanium, and tungsten alloys to cold-cure acrylic resin oral stent for cancer patients with head and neck radiotherapy

Effect of adding chrome-cobalt, titanium, and tungsten alloys to cold-cure acrylic resin oral stent for cancer patients with head and neck radiotherapy

Effect of herbal antioxidants on the shear bond strength of composite resin to bleached enamel at different time intervals.

Anterior tooth discolorations can be treated conservatively and noninvasively through bleaching to achieve the desired esthetic outcomes. However, bleaching along with composite resin is advisable for certain clinical cases for optimum results. However, shear bond strength (SBS) of composite resin to the bleached tooth gets significantly lowered. Before placing the composite restoration, the bleached enamel needs to be treated with antioxidant agents to increase its SBS. The study aims to evaluate and compare the effect of herbal antioxidants on SBS of composite resin to bleached enamel at different time intervals. Sixty extracted single-rooted maxillary incisors postdecoronation, keeping their labial surfaces up were mounted in cold-cure acrylic resin. The samples were randomly divided into: Group I - unbleached; Group II - 10% pine bark extract for 10 min postbleaching; Group III - 10% pine bark extract for 20 min postbleaching; Group IV - application of 10% rosemary extract for 10 min postbleaching, Group V - application of 10% rosemary extract for 20 min postbleaching; Group VI - no application of antioxidant. 35% hydrogen peroxide was used for bleaching all the samples except those which served as negative control. Later composite cylinder 4 mm in diameter and length were built on prepared enamel. The maximum load at failure was recorded using the universal testing machine. Data were analyzed using the analysis of variance and Tukey's t-test with significance level of P < 0.05. Highest load was exhibited by Group I. Group V showed satisfactory shear strength followed by Groups IV, III, II, and VI. Both 10% rosemary and 10% pine bark extracts showed better results when applied for 20 min as compared to 10 min application. Increased duration of antioxidant application increases the SBS.

Evaluation of the Shear Bond Strength of the Orthodontic Composites Modified with Various Concentrations of TiO2 Nanoparticles: An In vitro Study

Aim: This study aimed to evaluate the effect of various concentrations of TiO2 nanoparticles incorporation on the shear bond strength of the two different orthodontic composites.&#x0D; Materials and Methods: A total of 80 freshly extracted premolars were divided into two groups of 40 teeth each. The extracted teeth in each of these two groups were further divided into four subgroups with ten teeth (n=10) in each, depending on the concentrations of TiO2 NPs (0.0%, 1.0%, 5.0% and 10.0%) in the Transbond XT and Enlight composites. Then the teeth were mounted in cold-cure acrylic resin poured into PVC tubes. The teeth were vertically embedded in acrylic up to the cementoenamel junction (CEJ), and a standard bonding procedure was carried out to bond the brackets using both composites. The shear bond strength was evaluated using a universal testing machine at a crosshead speed of 05mm/minute until the brackets de-bond from the tooth surface. The obtained data were subjected to statistical analysis using Oneway ANOVA and Posthoc tests.&#x0D; Results: The control groups of both the composites showed more shear bond strength compared to the modified groups. One-way ANOVA showed significant differences (p=0.000) among the groups. Posthoc analysis showed significant differences between the control and modified groups and also between the modified groups in both the composites except between the control and 1.0 wt% and 5.0 and 10.0wt% groups of the Enlight composite.&#x0D; Conclusion: A decrease in the shear bond strength was observed with an increase in the concentrations of TiO2 nanoparticles in both the composites.

The Effects of Magnesium Oxide Nanoparticles Addition on Flexural Strength of Cold-cured Acrylic Resin material

Aims: This study investigates the effects of the addition of magnesium oxide Nanoparticles(MgO NPs) with size (50 nm) on the flexural strength of cold˗cured acrylic resin. Materials and methods: Forty acrylic specimens were made, which divided into four groups (10 specimens for each group) which were control group (pure acrylic without addition), group of acrylic specimens containing 1.25% MgO NPs, group of acrylic specimens containing 2.5%MgO NPs, and a group of acrylic specimens containing 5%MgO NPs, the flexural test was performed using the universal testing machine, FTIR test performed using (BRUKER LASER CLASS 1). The statistical analysis was done by using SPSS program including descriptive statistics, ANOVA, and the Duncan΄s test at p ≤ 0.05. Results: The Maximum mean of flexural strength belong to the group with 1.25% of MgO NPs,the minimum mean of flexural strength belongs to a group with 5% MgO NPs. Conclusion: The addition of MgO NPs affected the flexural strength of the cold-cured acrylic resin, it improved the flexural strength at low concentration but decreased it at higher concentratios.

The Effect of Adding Magnesium Oxide Nanoparticles to The Cold Cured Acrylic Resin on Candida albicans Adhesion

Aims: This study aims to assess the impact of the addition of MgO nanoparticles(NPs) with size of 50nm at different concentrations,which are 1.25%,2.5% and 5% on adherence of Candida albicans to cold- cured acrylic resin. Materials and Methods: Twenty-four specimens with the dimensions of (10mm ×10mm×2mm)length, width, and thickness respectively were made and divided into four groups, 6 specimens for each group; controlled (without the addition of MgO NPs) ,group of 1.25% MgO NPs ,group of 2.5% MgO NPs and group of 5% MgO NPs; were subjected to adherence test. The statistical analysis was done by using SPSS program including descriptive statistics, ANOVA, and the Duncan΄s test at p ≤ 0.05. Results: Results showed that, the maximum reduction in Candida albicans adherence obtained at a concentration of 5% followed by 2.5% then 1.25% ; while the control group showed that the highest number of Candida albicans colonies adhered to cold-cured acrylic. Conclusions: The MgO NPs influenced the adherence of Candida albicans to cold-cured acrylic resin, there is a significant reduction in the number of Candida albicans attached to cold-cured acrylic modified with MgO nanoparticles at different concentrations;and this reduction increases with increasing the concentration of MgO nanoparticles.

Effect of Different Resin Cements on Shear Bond Strength between Acrylic Denture Teeth and Resin Composite

Abstract The purpose of this study was to evaluate the effect of different bonding agents and resin cements on shear bond strength (SBS) between acrylic resin teeth and resin composite. Thirty acrylic teeth were cut along the long axis and embedded in cold-cure acrylic resin. The specimens were randomly divided into 3 groups (n = 10) according to the types of luting agents: Group C (OptiBond FL), Group P (Panavia F2.0), and Group S (Superbond C&amp;B). SBS was measured using the Shimadzu EZ-S Universal Testing Machine. The collected data were analyzed using a one-way ANOVA to determine significant differences with P-value &lt; 0.05. Multiple comparisons of SBS were calculated using the Tukey HSD test at a 95% confidence level. The average SBS values in MPa were 5.78 ± 0.97 for Group C, 13.60 ± 1.20 for Group P, and 17.93 ± 1.24 for Group S. The SBS value for Group S was significantly higher compared to the other groups, while the value for Group C was significantly lower. Group C was categorized as an adhesive failure, while Group S was accounted as a cohesive failure and Group P was shown to be a mixed failure. In conclusion, different resin cements significantly affected the SBS between acrylic resin teeth and resin composite. Keywords: Acrylic denture tooth, Bonding agent, Resin cement, Resin composite, Shear bond strength

Impact strength of 3D printed and conventional heat-cured and cold-cured denture base acrylics.

To evaluate and compare the impact strength of 3D-printed resin to conventionally fabricated denture bases of heat-cured and cold-cured acrylic resin. Denture base materials were evenly divided into three groups (n = 25 each; N = 75): (1) 3Dprinted material (Denture Base LP, Formlabs); (2) Heat-cured acrylic resin (Lucitone 199, Dentsply Sirona); and (3) cold-cured acrylic resin (Lucitone HIPA, Dentsply Sirona). The 3Dprinted specimens were designed through computer-aided design (CAD) software (Autodesk Meshmixer) with the dimensions 64 mm long, 12.7 mm wide, and 3.2 mm thick, then printed with a desktop stereolithography printer (Form 2, Formlabs). Heat-cured and cold-cured acrylic resin specimens were fabricated through conventional (compression and pouring) methods. The impact energy was read directly from the impact tester in joules, and the cross-sectional area of each specimen was used to calculate the impact strength in kJ/m2. Analysis of variance, Tukey multiple comparisons test, and a likelihood ratio α = .05 were conducted. The average mean impact strength was 8.9 kJ/m2 for heat-cured acrylic resin, 11.2 kJ/m2 for 3D-printed resin, and 14.9 kJ/m2 for cold-cured acrylic resin. Tukey multiple comparisons test showed that the impact strength for the cold-cured group was significantly greater than the 3D-printed resin and heat-cured acrylic resin groups. Within the limitations of this study, the cold-cured acrylic (Lucitone HIPA) showed the greatest impact strength, followed by 3D-printed resin (Denture Base LP) and conventional heat-cured denture base materials (Lucitone 199), respectively.

Incorporation of Chitosan Nanoparticles into a Cold-Cure Ortho-Dontic Acrylic Resin: Effects on Mechanical Properties.

Improvement of the antibacterial properties of acrylic resins, used in the construction of removable orthodontic appliances, is an important strategy to reduce the incidence of caries and oral diseases in orthodontic treatments. The addition of antimicrobial agents to acrylic resins is one of the effective methods to enhance the antimicrobial properties of these materials. However, one main concern is that modification of acrylic resin has negative effects on its mechanical properties. Recently, chitosan nanoparticles (NPs), as biocompatible and biodegradable polysaccharides with remarkable antimicrobial properties, have been used in different areas of dentistry and medicine. This study aimed to investigate the effects of adding chitosan NPs on the mechanical properties of a cold-cure orthodontic acrylic resin. The chitosan NPs were added to the acrylic resin in various weight percentages: 0% (control), 0.5%, 1%, 2%, and 4%. The flexural strength, compressive strength, Vickers microhardness, and impact strength measurements were performed for all five groups. The results showed that adding up to 1% (w/w) chitosan NPs to an acrylic resin had no significant negative effects on its flexural strength and compressive strength, while it decreased these parameters at weight percentages of 2% and 4% (w/w). The results also revealed that modification of acrylic resin with chitosan NPs up to 4% had no significant negative effects on the microhardness and impact strength of acrylic resin. In conclusion, the addition of chitosan NPs up to 1% (w/w) had no significant negative effects on the mechanical properties of cold-cure acrylic resin.

The Effect of Adhesive Material and Surface Roughness on the Tensile Bond Strength between Some Elastomeric Impression Materials and Cold Cure Acrylic

: The detachment of impression materials from impression tray is considered as an important problem which is difficult to be detected clinically. Several attempts were used to handle this problem, as roughening the surface of the tray, perforating it, or by the use of adhesive solutions which are recommended to be used by manufacturers. Objectives: To determine the tensile bond strength of two elastomeric impression materials; polysulphide and polyether to cold-cure acrylic resin disks with or without tray adhesive application at different drying and surface treatment. Material and Methods: Eighty specimens prepared consisted of two disks with impression material sandwiched between, then divided into two groups; 40 specimens for each type of impression. The “PD” hold adhesive material was applied on the acrylic surfaces which were smooth and rough. The adhesive was allowed to dry for 2, 5, and 10 minutes before the application of impression materials. To determine tensile bond strength at the interface between the adhesive-acrylic, and the adhesive-impression materials, a universal Instron testing machine was used. Results: Polyether impression material showed higher tensile bond strength to cold-cure acrylic than polysulphide impression material, without adhesive application. However, after adhesive application, the bond strength to polyether decreased, while for polysulphide increased significantly. Roughening the acrylic surface significantly increased the bond strength for both impression materials with or without adhesive application. Also, increasing the drying time from 2 up to 10 minutes significantly increased the bond strength for both impression materials, and smooth and rough acrylic surfaces. Conclusions: Polyether impression showed higher bond strength to cold-cure acrylic than polysulphide impression, without adhesive application.

Experimental and theoretical fracture analyses for three biomaterials with dental applications

Dental materials are known as efficient tools to revive the functionality and integrity of decayed/missing tooth structure. Being frequently subjected to different mixtures of tensile and shear loads accompanied by temperature changes and suffering from pre-existing voids and imperfect interfaces at the same time, dental restorations and prostheses are found to be susceptible to crack initiation and growth. In this paper, fracture properties of three dental biomaterials namely polymethylmethacrylate (PMMA), 75Sr and 75Sr10 undergoing mixed tensile-shear loads are investigated. The PMMA used in this study has application as a cold-cured acrylic resin for repairing dental prostheses, while 75Sr and 75Sr10 are dental restorative materials. Fracture growth angle and onset of crack propagation are evaluated experimentally using shortened semi-circular bend specimens made from PMMA. In addition, the generalized maximum tangential strain (GMTSN) criterion is applied to theoretically predict the fracture behavior of the tested PMMA, as well as two other dental bio-composites reported in the literature viz 75Sr and 75Sr10. Good agreement is met between theory and practice when comparing fracture curves extracted from the GMTSN criterion and the experimental data points. Further, it is found that conventional stress- and strain-based fracture models fail to provide suitable estimates of crack growth behavior.

Effect of delmopinol application on Candida albicans adherence on denture-bearing surface of heat-cured and cold-cured acrylic resins – An in vitro study

Purpose: In this in vitro study, we evaluate the effect of delmopinol application on Candida albicans adherence on heat-cured acrylic resin and cold-cured acrylic resin. Materials and Methods: A total of 60 specimens of every sort of acrylic resin were made, 20 specimens of each type were control group, 20 specimens were contaminated before delmopinol application, and 20 specimens were contaminated after delmopinol application. Each specimen in each tube was individually transferred to a spectrophotometer at 530 nm wavelength to measure the turbidity degree through the transmittance. Aliquots of 10 μl of every tube were then collected and inoculated into agar Sabouraud plates containing 500 mmol/l of sucrose, which was incubated for 24 h at 37°C, so as to see the microbial growth. Two-way ANOVA analysis of variance test and post hoc Turkey's test were carried out to ascertain the level of significance (P Conclusion: In case of contamination after delmopinol application, heat-cured acrylic resin showed a greater reduction in the adherence of C. albicans in this study.

Comparative evaluation of shear bond strength of sixth- and seventh-generation bonding agents with varying pH - An in vitro study.

Introduction:To compare and evaluate the shear bond strength of sixth- and seventh-generation bonding agents with varying pH – an in vitro study.Materials and Methods:Eighty extracted human premolar teeth were collected and cleaned and polished with pumice and water. The root portion of teeth was resected, and only the coronal portion was embedded in the cold-cure acrylic resin. The labial surface of mounted teeth was prepared with a high-speed handpiece using #245 carbide bur. The samples prepared were divided into four groups, with 20 specimens in each group: Group A: Sixth-generation bonding agent, Adper Prompt L-Pop (APLP) (3M ESPE)Group B: Sixth-generation bonding agent, Xeno III (X III) (Dentsply)Group C: Seventh-generation bonding agent, Adper Easy One (AEO) (3M ESPE)Group D: Seventh-generation bonding agent, Xeno IV (X IV) (Dentsply). Tooth surface were rinsed and dried, and bonding agents were applied on tooth surface. Composite resin (Z-350 XT, 3M ESPE) was placed in a two-layer increment on tooth and was light cured. Specimens were subjected to the universal testing machine in a compression mode force at a crosshead speed of 1 mm/min keeping blade parallel to the adhesive–dentin interface. Shear force required to debond the specimen was recorded in megapascal. The data obtained were analyzed statistically using ANOVA and post hoc test.Results:AEO (pH = 2.3, Group C seventh generation) showed higher bond strength, and pH values did not influence the shear bond strength significantly in the tested adhesive systems.Conclusion:The pH values did not influence the shear bond strength significantly in the tested adhesive systems. ADPER EASY ONE (pH= 2.3, GROUP C Seventh Generation) showed higher bond strength followed by XENO IV(pH = 2.1, GROUP D), XENO III (pH = 1.5, GROUP B) on dentinal surface ,where as ADPER PROMPT L POP (pH =0.7 to 1 Sixth Generation, GROUP A) showed lower bond strength.

Mechanical Properties Evaluation of Cold-Curing Acrylic Resin Reinforced by Banana Peels’ Fibers.

Although low mechanical properties of Acrylic resin, it is the most popular used substance as based denture materials. This drawback could be treated through adding reinforcing phase. In this work washing and non-washing banana peels as kind of natural fibers with different weight fractions, (5, 10, 15 and 20) % wt. and standared Acrylic, for compartion purpose, are used to prepare composite specimens by modeling method on order to study possibility of reinforcing cold-curing acrylic resin by banana peels. Peels had been dried, crashed, and washed by distillation water before using in the work. Unwashed peels also used for comparing purpose. Hardness, impact, and tendsile tests were performed to evaluate the development in mechanical properties of the prepared composite. Generally the results show that washed banana peels have more effective than that of un-washed peels, adding banana peels could improve hardness of composite and hardness increase with increasing weight fraction of peels till specific value, (10) % wt. where highest hardness recorded, using high weight fraction of reinforcing phase could negatively effect into mechanical properties of composite, Also the results show that using banana fibers as reinforce phase, didin’t improve impact strength, fracture toughness, and modules of elasticity properties of acrylic.

A New Technique For Splinting Traumatized Anterior Dental or Dento Alveolar Segment . A Clinical Study

A New Technique For Splinting Traumatized Anterior Dental Or Dento alveolar Segment. A Clinical Study Running Title: Splinting Traumatized Anterior Teeth Abstract Back ground: Many different splinting techniques have been described in dental trauma articles. Wire-composite splint, Orthodontic splint, TTS splint, Resin splint, Kevlar/fiberglass splint (fiberglass), Self-etching and bonding material, Suture splint. We describe here a new technique for splinting traumatized teeth and alveolar bone. To evaluate the simplicity and reliability of cold-cured acrylic resin immediate splinting in the management of traumatized anterior teeth. Results: A total number of (46) patients with traumatized dental or dento-alveolar segment due to accident or operation were managed with immediate cold-cured acrylic resin splint without the need for anesthesia for fixation, the study carried out from January (2008–2014). Forty four dento-alveolar trauma patients, 2 patients following upper dento-alveolar osteotomy, 2 splints dropped down (2) days post-splinting, the splints removed (14-21) days. Conclusion: this new technique in the management of dento-alveolar trauma is a reliable, simple, easy, less technical, painless and less time consuming procedure.

Effect of Addition Retention Bead and Repair Material on Transverse Strength of Repaired Acrylic Denture Resin

Objective: One of the most important practical deficiencies of present denture base materials is fracture, therefore manyattempts have been made to reinforce of the repaired denture base resin. A desirable objective for this service is to obtainoptimum strength for repairs, which can be achieved by making available a good bond between original and repairedmaterials.Methodology: The present study was carried out to evaluate and compare the transverse strength of acrylic specimensrepaired by two different materials (hot-cure and cold-cure acrylic resin). A total of 50 specimens were prepared by hot(40) repair: (10) by hot with retention bead, (10) by cold with retention bead and (10) repair by hot only, (10) repair by coldonly, and (10) un repair control made from hot cure acrylic resin. Transverse strength was measured for each specimenusing three points bending on a brinell transverse testing machine.Results: The result showed that the repair with heat-cure acrylic resin with retention bead has a significant higher than therepair with cold-cure acrylic resin with retention bead and higher than control specimen (unrepaired).Recommendations: It can be concluded that the hot acrylic resin with retention bead are an important parameter in thereinforcement of repaired acrylic denture base resin.

EFFECT OF INCORPORATION OF SILVER NANO-PARTICLES ON THE REPAIRABILITY OF CONVENTIONAL AND MICROWAVE DENTURE BASES

Background: Repeated fracture of denture base is a common problem in prosthodontics, it represents an annoyance for the clinician. Therefore, the possibility of increasing repairability using new reinforcement materials is of great interest to prosthodontists. Aim of the study: This study aimed to evaluate the effects of incorporation of silver nano-particles on the flexural strength of repaired polymethylmethacrylate (PMMA) and microwave denture bases. Materials and methods: thirty-six specimens of conventional and microwave denture base materials were fabricated (18 for each) and divided into three subgroups according to surface design (Dovetail, 45° bevels and butt joints). Silver nano-particles was added to repair cold cure-acrylic resin powder. A three - point bending test was used to measure flexural strength. The results were analyzed with a P-value of <0.05 being significant. Results: totally it was found that repaired Microwave group recorded statistically non-significant (p>0.05) higher flexure strength mean value. Silver nano-particles modified cold cure repaired subgroup recorded statistically significant (p 0.05). Conclusion: Incorporation of silver nano-particles into the repair resin improved the flexural strength of repaired denture base

Evaluation of the effect of different surface treatment on the transverse strength of the repaired acrylic denture base resin cured by two different techniques

One of the most important practical deficiencies of present denture base materialsis fracture, therefore many attempts have been made to reinforce of the repaireddenture base resin, a desirable objective for this service is to obtain optimum strengthfor repair, which can be achieved by making available a good bound between originaland repair materials.The present study was carried out to evaluate and compare the effect of differentsurface treatments (monomer, acetone, combination monomer + acetone) on thetransverse strength of acrylic denture base.Seventy (70) specimens were prepared from pink heat-cure acrylic resin of which(10) specimens were considered a control group. The remaining specimens weredivided into two main groups (30specimens repaired by Ivomat and 30 specimensrepaired by air method).The joint treated before cold-cured acrylic resin was applied to the joint space.Specimens were repaired by cold-curing resin (major). Then they were stored indistilled water at (37 Co) for (48) hours. These were subjected to three-point loadingtesting machine to determine the transverse strength.The results showed that air cured acrylic resin has significant lower transversestrength than Ivomat cured acrylic resin also show that the specimen treated with(Acetone + monomer) have a higher transverse strength.Finally, it can be concluded that curing methods and surface treatment willimprove transverse strength of the repaired acrylic denture base re

Viscosity effects of polyvinyl siloxane impression materials on the accuracy of the stone die produced

The purpose of the present study was to investigate the effect of different viscosities of polyvinyl siloxane (PVS) impression materials on the accuracy of the stone die produced. A three-unit bridge master model was fabricated using cold-cure acrylic resin. Four combinations of different viscosities of PVS impression materials - regular body (monophase) alone, light body with regular body, light body with heavy body, and light body with putty - were used to make an impression of the master model. Ten impressions from each group were taken and Type IV gypsum stone was used to generate the dies. The dies were measured at the inter-abutment distance, occlusogingival length, and shoulder width with a measuring microscope and were compared with the master model using one-way analysis of variance and Tukey (honest significant difference) test. Differences were found for inter-abutment distance between the master model and the light body with regular body and light body with putty dies (both P < 0.02). A difference was found for shoulder width between the master model and the regular body alone die (P = 0.01). No differences were found for occlusogingival distance (all P > 0.08). Results suggested inter-abutment distance was most accurate when using a PVS light body combination. Occlusogingival length was accurate using any of the studied PVS combinations, and shoulder width was more accurate when using the regular body PVS. These results should be considered when choosing the viscosity of the PVS to use for producing impressions of high accuracy and fabricating a well-fitting fixed prosthesis.

Evaluation the tensile strength of cold-cured acrylic resin denture base material by adding silver nanoparticles

Evaluation the tensile strength of cold-cured acrylic resin denture base material by adding silver nanoparticles