Abstract
This study investigated the effect of intrinsic pigmentation on the transverse strength of a microwave-cured acrylic resin. Forty transverse strength specimens were fabricated according to ADA specification #12 and divided into 5 groups. No fibers were added to group I (GI, control group); acrylic stain (AS) was added to GII and GIII in concentrations of 0.5 and 1.5% w/w, respectively; acrylic fibers (AF) were added to groups GIV and GV in concentrations of 0.5 and 1.5% w/w, respectively. All specimens were irradiated in a microwave oven with a cycle of 3 min at 360 W, followed by 4 min resting, then 3 min at 810 W. Flasks were bench-cooled for 30 min at room temperature, followed by immersion in cold tap water for 30 min. After storage in distilled water at 37 degrees C for 48 h, all specimens were tested for flexural strength in a testing machine (EMIC-DL 500) at a crosshead speed of 0.5 cm/min. Mean and standard deviation (MPa) for the flexural strength test were: GI = 86.0 +/- 7.9; GII = 86.0 +/- 9.8; GIII = 86.6 +/- 7.7; GIV = 84.9 +/- 5.3; GV = 84.9 +/- 5.2. No statistical differences were detected among the groups (ANOVA, p > 0.05). The addition of the acrylic fibers or the acrylic stain did not affect the transverse strength of the microwave-cured acrylic resin.
Highlights
Since the introduction of methyl methacrylate as a denture base material [1], the ultimate goal of prosthodontists has been to improve denture naturalism, involving basically the reproduction of the contour, texture and color of the patient’s gingival tissue in the denture base [2,3]. Several pigments such as carbon black, zinc oxide, titanium dioxide, cadmium red, iron oxide and pure chalk have been associated with acrylic resins in order to match their color to that of the patient’s gingiva, avoiding the stereotyped pink denture base [2,4]
The aim of this study was to investigate the effect of an acrylic stain and acrylic fibers on the transverse strength of a microwave-cured acrylic resin
Analysis of variance demonstrated no statistical differences between groups (p>0.05)
Summary
Since the introduction of methyl methacrylate as a denture base material [1], the ultimate goal of prosthodontists has been to improve denture naturalism, involving basically the reproduction of the contour, texture and color of the patient’s gingival tissue in the denture base [2,3].Several pigments such as carbon black, zinc oxide, titanium dioxide, cadmium red, iron oxide and pure chalk have been associated with acrylic resins in order to match their color to that of the patient’s gingiva, avoiding the stereotyped pink denture base [2,4]. several studies have proposed different methods and materials for denture pigmentation, none of them attempted to investigate their effects on the mechanical properties of the acrylic resin.The use of microwave energy to polymerize acrylic resins was first reported by Nishii [5]. Several studies investigated [6,7,8] the use of microwave energy as a heat source to polymerize PMMA and investigated some properties of denture base resins polymerized by microwave irradiation and conventional heating. They did not find differences for the resin properties between the methods
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