Impact Strength Of Acrylic Resin Research Articles

Evaluation of the Effect of Nano and Micro Hydroxyapatite Particles on the Impact Strength of Acrylic Resin: In Vitro Study

Poly (methylmethacrylate) is considered the basis material for a denture base. However, such substance has some drawbacks such as poor impact resistance, which is thought to be the primary cause of fracture of denture base resins. The purpose of the study was to determine how Nano and Micro hydroxyapatite particles affected the impact strength of acrylic resin. Thirty specimens were constructed of heat-cured acrylic resin and were divided into three groups: Ten specimens for the control, 10 for 1%nano hydroxyapatite, and 10 for micro hydroxyapatite. Acrylic samples were subjected to an impact strength test via a Charpy-type. Data were then analysed using SPSS v20. The ANOVA test was used for comparison among the groups. Highly statistically significant differences among all studied groups (P-value <0.0001). Both 5% Micro hydroxyapatite and 1% Nano hydroxyapatite had a higher mean value than the control. Incorporating Nano and Micro hydroxyapatite into PMMA improved the impact strength of acrylic resins.

The Effect Of Heating Acrylic Resin Of Various Types With Different Temperatures On Impact Strength

Resin polymerization which is affected by unstable temperature causes the resin to break easily. The strength of the base material is affected by the forces acting in the mouth, such as transverse forces, other resistance or fatigue, and flexibility. Fracture of denture caused by masticatory loads and is affected by forces acting in the mouth, including transverse, resistance or fatigue, and flexural forces. Experimental Laboratory total of 72 samples consisting of 18 samples of type A, B and C cured at normal temperature, 100oC, 200oC, and 300oC. Types A, B and C have the effect of heating with the addition of temperature on the impact strength of acrylic resin, because the value of sig = 0.001 < 0.05, so H0 is rejected. An effect with the addition of temperature on the impact strength of the resin types A, B and C, because sig = 0.001 < 0.05, so H0 is rejected, which means that the average results are significantly different due to differences in temperature.

EVALUATION OF IMPACT STRENGTH OF HEAT CURE ACRYLIC RESIN REINFORCED WITH NYLON FIBER MESH WITH AND WITHOUT PRESTRESSING (IN VITRO STUDY)

INTRODUCTION: Acrylic resin prostheses are liable to high levels of forces due to their frequent removal by patients and accidental slippage. Hence, the impact strength of acrylic denture base material is of major significance in providing long-term functional prostheses.OBJECTIVES: The aim of this study was to evaluate the reinforcing effect of prestressed nylon fiber meshwork and the specimen thickness increase on the impact strength of heat cure acrylic resin.MATERIALS AND METHODS: 72 specimens were divided into 3 groups (I, II and III) which were heat cure acrylic resin (control), Nylon mesh reinforced acrylic resin and prestressed-nylon mesh reinforced acrylic resin. Each group was formed of 24 specimens, which were further subdivided into 3 subgroups (A, B and C) of different dimensions; 75 mm × 10 mm × 3 mm and 75 × 10 × 4 mm and 75 x 10 x 5 mm. Thus, the specimens were divided into 9 experimental subgroups (n=8 per subgroup). A Charpy’s impact tester was used to measure the impact strength of acrylic resin. The data were analyzed using Anova-test (p≤0.05).RESULTS: The mean impact strength of groups II and III was higher than the control group I impact strength. The difference between the reinforced groups and control group was statistically significant for all specimen thicknesses.CONCLUSIONS: The impact strength of heat cure acrylic resin was increased by the incorporation of nylon fiber mesh whether prestressed or not.

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.

Effect of Oil Paint Addition on Impact Strength of the Scleral Part of the Acrylic Ocular Prosthesis

Background: For many dental and facial restorations, acrylic resins are the materials of choice because of their appropriate physical and mechanical properties. When making the ocular prosthesis from such materials, it is essential to add the perfect shade in order to match the colour of normal eye. This, however, might have a significant effect on the mechanical properties of acrylic resins. Objective: The purpose of this study was to assess the effect of adding the white oil paint (titanium dioxide) to clear acrylic resins on their impact strength. Methods: 20 samples were constructed from heat cured acrylic resins, and divided into two groups (control and experimental) and each group had 10 samples. The first group was made from clear acrylic resin without the addition of white oil paints, and the second group (experimental) comprised the addition of 1 ml of the white oil paints to acrylic samples. Such samples were prepared with dimensions of (80 mm X10 mm X4 mm) length, width, and thickness, respectively. All the samples were tested by the Charpy's impact strength test. They were exposed to the load till the fracture occurred. All the values were analyzed using SPSS version 20, and the independent T-test was used for comparison between the 2 groups. Results: A statistically significant decrease (P-value < 0.001) was found in the impact strength of acrylic resins after the addition of titanium dioxide oil paints (experimental group: 5.97 + 1.11, control group: 9.42+1.32 KJ/M2). Conclusion: This study concluded that the addition of titanium dioxide oil paint significantly reduces the impact of strength of the acrylic resin. It is suggested to use different stains which will have no negative effect on impact strength of the acrylic resin.

Effect of Polymerization Cycles on Gloss, Roughness, Hardness and Impact Strength of Acrylic Resins.

The aim of this study was to evaluate the conventional and boiled polymerization cycles on gloss, roughness, hardness and impact strength of acrylic resins. Samples were made for each Classico and QC-20 materials (n=10) in dental stone molds obtained from rectangular metallic matrices embedded in metallic flasks. The powder-liquid ratio and manipulation of the acrylic resins' were accomplished according to manufacturers' instructions and the resins were conventionally packed in metallic flasks. After polymerization by (1) conventional: 74 °C for 9 h (Classico) and (2) boiled: 20 min (QC-20) cycles, the samples were deflasked after cooling at room temperature and conventionally finished and polished. The properties were evaluated after storage in water at 37 °C for 24 h. Gloss was verified with Multi Gloss 268 meter (Konica Minolta), surface roughness was measured with Surfcorder SE 1700 rugosimeter (Kosaka), Knoop hardness number was obtained with HMV-200 microdurometer, and impact strength was measured in an Otto Wolpert-Werke device by Charpy system (40 kpcm). Data were subjected to Student's t-test (at α=0.05). The results were: Gloss: 67.7 and 62.2 for Classico and QC-20 resins, respectively; Surface roughness: 0.874 and 1.469 Ra-µm for Classico and QC-20, respectively; Knoop hardness: 27.4 and 26.9 for Classico and QC-20, respectively; and Impact strength: 37.6 and 33.6 kgf/cm2 for Classico and QC-20, respectively. No statistically significant difference (p>0.05)were found between the resins for the evaluated properties. In conclusion, conventional and boiled polymerization cycles had similar effects on gloss, roughness, hardness and impact strength of both Classico and QC-20 resins.

Impact strength of denture base and reline acrylic resins subjected to long-term water immersion

Water may influence the mechanical properties of the acrylic resins. Thus, the effect of water storage on the impact strength (IS) of one denture base (Lucitone 550 - L) and four reline resins (Tokuyama Rebase II - T; UfiGel Hard - U; Kooliner - K; New Truliner - NT) was evaluated. Bars of L were made (60 x 6 x 2 mm) and relined (2 mm) with T, U, K, NT and L. Intact specimens of each material (60 x 6 x 4 mm) were also fabricated for comparative purposes. Specimens were submitted to Charpy impact tests without water storage (control) and after immersion in water for 7, 90 and 180 days. Data (kJ/m(2)) analyzed by two-way ANOVA and Tukey's test (p=0.05) revealed that after 90 days, U exhibited an increase in the IS (0.93) compared to 7 days (0.58). K (1.48) and L/K (7.21) exhibited a decrease at the 7-day period (1.01 and 3.23, respectively). NT (0.60) showed an increase in the IS after 180 days (1.52), whereas L/NT (7.70) showed a decrease (3.17). Water immersion improved the IS of U and NT, and decreased the IS of K, L/K, and L/NT. Water may affect differently the IS of acrylic resins and, consequently, the resistance to fracture of relined denture bases.

Fractographic analysis, accuracy of fit and impact strength of acrylic resin

This study evaluated accuracy of fit, impact strength, types and morphology of fractures of a microwave acrylic resin polymerized with a cycle alternative to that recommended by the manufacturer. Onda Cryl was polymerized according to the manufacturer's instructions (MC), 3 min at 360 W, 4-min pause, and 3 min at 810 W; and with an alternative cycle (AC) of 6 min at 630 W. Accuracy of fit was measured at 3 points at the right (A) and left (B) ridge crests and at the midline (C) on the posterior palatal seal for each denture base (n = 10/group). The measurements were taken immediately after finishing and after 30-day storage in water. The impact strength test (Charpy method) was performed with a 40 kJ/cm load (n = 20/group). Fractographic analysis was accomplished for all fragments and the fracture types were characterized by means of their morphology, crack propagation angles and microstructure. Accuracy of fit data were analyzed by ANOVA, impact strength and radius values were compared by the t test, and the fractographic analysis data, by the Wilcoxon Mann-Whitney test. The significance level was fixed at p < 0.05. No statistical differences were found between the two cycles of polymerization used. However, after the 30-day storage period in water, the denture bases showed better fit (P < .05). Most of the fractures were classified as brittle (MD: 70%, AC: 80%). Based on the results of this study, it could be concluded that both polymerization cycles are adequate to polymerize the denture resin studied.

The effect of including ultra-high-modulus polyethylene fibre on the impact strength of acrylic resin.

The effect of including ultra-high-modulus polyethylene fibre on the impact strength of acrylic resin