Evaluation the Effect of Fibers Addition on Mechanical Properties of Flexible Acrylic Resin

Abstract

Background: In chemistry the development of polymer has produced another material to poly methyl methacrylate such as epoxy resins, polyamides (nylon), acetyl resins -----etc. All these resins are suited for thermoplastic processing. Polyamide materials are more flexible than the commonly used polymethylmethacrylate. The flexibility of polyamide allows partial dentures to be pressed in one piece including clasps. Glass fibers are the most widely used reinforcing materials forming about 90 % of the reinforcement in resins. The addition of fibers to provisional restorative resin increases tensile strength, fracture toughness and surface hardness. Objective of the study: An evaluation of the surface roughness, modulus of elasticity and tensile strength improvement of flexible denture bases after adding of glass fibers and altering in powder – monomer ratio. Material and Methods: Eighty samples of flexible acrylic were made and divided into two main groups according to the type of test to be used. Forty samples for surface roughness and forty samples for tensile strength and (modulus of elasticity). Each group is divided into four subgroups according to fibers addition and to the alteration in powder-liquid ratio as follows: group (A) consists of (10 specimens) without the addition of glass fibers and with (3:1) powder- monomer ratio. Group (B) consists of (10 specimens) with addition of glass fibers and with (3:1) powder- monomer ratio, group (C) consists of (10 specimens) without addition of glass fibers and with (2.5:1) powder- monomer ratio and group (D) consists of (10 specimens) with glass fibers and with (2.5:1) powder- monomer ratio. The tensile strength and modulus of elasticity were determined by Instron testing machine at cross speed of 0.5mm/min. The T.R 200 device was used to indicate the values of surface roughness specimens before and after finishing and polishing. Results: In the present study, ANOVA test showed a significant difference at (P<0.05) between all the groups of tensile strength test.Least significant difference( LSD) test showed a non-significant difference at (P>0.05) between most of the tested groups except the groups of 3:1 powder–monomer ratio with and without fibers addition and groups of 3:1 ratio without fibers addition in comparison with the groups of 2.5:1 ratio with fibers addition which showed highly significant . The modulus of elasticity revealed a non-significant difference between all the tested groups at (P>0.05). While there were highly significant difference at (p<0.01) between groups of surface roughness test before and after polishing, except the group of 2.5:1 ratio with and without fibers addition which showed a non-significant difference at (P>0.05.). Conclusion: Conclusion was derived that fibers addition significantly affects tensile strength. The modulus of elasticity was not significantly affected by fibers addition or by powder-monomer ratio. Regarding surface roughness, it was improved after fibers addition and alteration in powder-liquid ratio.

The Influencing Effect of Silver Nitrate Fillers on the hardness of Flexible Resin

“…Exerted the force was gradually to ensure that the dough stage acrylic flowed evenly across the mold region. After that forces are released, then the flask is ready for curing [19].…”

“…After curing, the flask permits it to cool at room temperature. When de flasking process is completed, in this time flexible resin designs are removed [19].…”

“…By Carbide and stone burs and sand, paper sheets were used to finish all of the flexible acrylic resin specimens, while bristle brush and pumice were used to polish them with a dental lathe-polishing machine at a low speed (1500rpm). On the dental lathe, a final glossy finish was achieved using a wool brush and polishing soap [19]. On all samples, the abrasive paper was employed with light manual pressure.…”

Evaluation of the fracture resistance of three different implant supported overdenture base materials

“…(A Mahmoud et al, 2018) It has been shown that acrylic resin and thermoplastic denture base resins can be strengthened through the addition of a structural component of different size distributed in the acrylic matrix, thus forming a more composite structure. (Panyayong et al, 2002) (Abdul-Majeed & Hummudi, 2019 ZrO2 is a hard white amorphous powder that is obtained from zirconium which is found naturally and produced by a thermal process. ZrO2 is a material that is very resistance to crack propagation and has premium mechanical properties with high strength, fracture toughness and high thermal expansion.…”

Evaluation of the effect of adding zirconium or titanium oxide powder to heat cured acrylic resin on the fracture resistance of denture base of the mandibular implant supported overdenture. An invitro study

“…Its worthy mention that Polymethyl methacrylate (PMMA) is the most popular denture base material due to its good esthetics, accurate fit, biocompatibility with the oral tissues, easily repaired if fractured and finally its coast is affordable. Although it has all these advantages but it has also a major drawback which is low fracture resistance that render it weak and easily fractured either when falling down or due to fatigue from long time use (5,6) Many authors suggested that strengthening of polymethyl methacrylate is possible through the addition of a structural component of different size distributed in the acrylic matrix, thus forming a strong composite structure (7,8) .…”