The Effect of Newly Prepared Cleansing Agent on The Surface Roughness and Tensile Strength of Highly Impact Acrylic Denture Base Material

Abstract

Aims:To evaluate the effect of two prepared and commercial solution on surface roughness and tensile strength of highly impact acrylic denture base materialMaterials and Methods:The total number of specimens were one hundred and fifty. They were prepared from highly impact acrylic and subdivided into five groups for each solution (EDTA, Soda+H₂O₂, Lacalut, Corega and distilled water). Two laboratory tests were used for this research. Surface Roughness and tensile strength test. The surface roughness test specimens were constructed with dimensions (10×10×2±0.03mm) (length, width, and thickness respectively). According to ADA specification no.12 the tensile test specimens were constructed with dimensions 90×10×3±0.03mm (length, width, and thickness respectively). The immersion periods in this research are (2day, 7 day and one month). ANOVA and Duncan multiple range test were used. The statistical results were considered significant at p ≤ 0.05. Results:the results showed that (soda+H₂O₂) has no significant change on the surface roughness and tensile strength of highly impact acrylic denture base material in (2day, 7 day, and 1month)conclusion:(soda+H₂O₂) has the lowest effect on the surface roughness and tensile strength of highly impact acrylic denture base material in (2day, 7 day, and 1month)

Key words:denture cleanser, highly impact, lacalut

Introduction

Polymethyl methacrylate (PMMA) has been used in dental pros­thetic devices for almost 70 years. Three fundamental features have contributed for its success: excellent appearance, simple processing technique and easiness of the repair. However, the resistance to impact and fracture of PMMA during function are low fracture^(1-3). The denture base resin is subjected to various stresses during function. During fabrication of a denture, the physical and mechanical properties influence by cure condition and choice of materials. Each cure cycle or fabrication technique is a compromise that attempts to optimize the properties thought important for a given application. Dentist and manufacturers of denture base materials have long been searching for ideal materials and designs for dentures. So far, the results have been noteworthy, although there are still some physical and mechanical problems with these materials⁽⁴⁾.Many attempts have been made to enhance the strength properties of acrylic denture bases including the addition of metal wire. The primary problem of using metal wire reinforcement is poor adhesion between wire and acrylic resin. Although several methods have been used to improve the adhesion between these components, enhancement in mechanical properties, such as transverse strength and fatigue resistance, was not significant.^(5,6)Modifications of chemical structure, by the addition of cross-linking agents such as polyethyleneglycol di-methacrylate or by copolymerization with rubber, have been attempted⁽⁷⁾Various types of fiber including carbon fiber whisker fiber, aramid fiber, polyethylene fiber, and glass fiber have been used as a reinforcement. Reinforcement with fibers enhances the mechanical strength characteristics of denture bases, such as the transverse strength, ultimate tensile strength and impact strength. In addition, fiber reinforcement has advantages compared with other reinforcement methods, including improved esthetics, enhanced bonding to the resin matrix, and ease of repair^{. (8-12)}Cleansers and cleaning methods used may have harmful effect on the plastic or metal component of the denture. Knowledge of constituents of denture cleansers, their efficiency, adverse effect and safety would aid in dispensing appropriate information to the patient , so the dentist must be able to recommend a denture cleanser that is effective, non deleterious to denture material and safe for patient use.^(13,14)

During this resarch of the effect of denture cleanser on the properties of denture base materials, the chemicals disinfectants (Chlorhexidine gluconate, sodium hypochlorite and gluteraldehyde) reduced the tensile strength of denture base material, but this reduction is not significant.⁽¹⁵⁾The aims of this study are to evaluate the effect of two prepared and two commercial solutions on surface roughness and tensile strength of highly impact acrylic denture base material after (2day, 7 day and 1 month).

Materials and Methods

The total number of specimens was one hundred and fifty. Seventy five for each test were prepared from highly impact acrylic and subdivided into five groups for each solution. The immersion periods in this study are (2day, 7 day and one month)

Highly impact acrylic (vertex-dental) used in this research mixed according to the manufacture instruction. The liquid powder ratio is 1 ml liquid and 1.2 mg powder, adding powder to the liquid and then mixing the powder to liquid for 30 min , leave the mixing for 8 min in room temperature 22 °C until reach to the dough stage adding the highly impact acrylic to the flask through in room temperature 22 °C and then press the flask by press , and putting immediately inside hot water approximately 70°C for 90 min and then rising the degree of temperature to the 100 °C for 30 min and the remove the flask and leave it to cool. Two laboratory tests were used for this research. tensile strength and Surface roughness test, According to ADA specification no.12 the tensile test specimens were constructed with dimensions 90×10×3±0.03mm (length, width, and thickness respectively) Then universal testing machine (Gunt, Germany) was used to measure the tensile strength of specimens The force at failure was recorded in Newton (N) and the true tensile strength value was calculated by the following formula: Tensile strength = F(N)/A (mm²)⁽¹⁶⁾. The surface roughness test specimens were constructed with dimensions (10×10×2±0.03mm) (length, width, and thickness respectively) The surface roughness (Ra) values were measured using a profilometer (Stylus 10 UK) which can measure small surface variations by moving a diamond stylus in contact with the surface.⁽¹⁷⁾. The specimens were fabricated by using Type III model dental stone (Zhermack SPA Rovigo, Italy) as a mold. This study deals with five solutions (table 1).two experimental prepared solutions, solution one (Ethylene Diamin Tetra acetic Acid) EDTA and solution two (soda Na₂Co₃and Hydrogen peroxide H₂O₂₎two commercial denture cleanser tablets (Corega, lacalut) for comparison and distilled water as a control solution. Every solution was diluted in 100 ml of distilled water.

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