Polymerization time for a microwave-cured acrylic resin with multiple flasks

Abstract

This study aimed at establishing the polymerization time of a microwave-cured acrylic resin (AcronTM MC), simultaneously processing 2, 4, and 6 flasks. Required time was measured according to the parameters: monomer release in water, Knoop hardness, and porosity. Samples were made with AcronTM MC in different shapes: rectangular (32 x 10 x 2.5 mm) for monomer release and porosity; and half-disc (30 mm in diameter x 4 mm in height) for Knoop hardness. There were four experimental groups (n = 24 per group): G1) one flask (control); G2) two flasks; G3) four flasks, and G4) six flasks. At first, polymerization protocol was similar for all groups (3 min/450 W). Time was then adjusted for G2, G3, and G4, based on monomer release evaluation in the control group, obtained by spectrophotometer Beckman DU-70, with emitting wave of 206 nm. Knoop hardness test was performed using a Shimadzu HMV 2000 hardness tester, and 10 indentations were performed on each specimen's surface. Porosity was assessed after specimens were immersed in black ink and the pores counted in a microscope. Results showed that the complete polymerization of the resin occurred in 4.5 min for two flasks (G2); 8.5 min for four flasks (G3); and 13 min for six flasks (G4), all with 450 W. Statistical analysis revealed that the number of flasks does not interfere with polymerization, Knoop hardness, and porosity of the resin. Results showed that polymerization of microwave-curing resin with more than one flask is a viable procedure, as long as polymerization time is adjusted.

Comparative study of the transverse strength of three denture base materials

“…[13][14][15][16][17] Advances in polymer science have developed new molding and activation techniques, such as injection-molding and microwave activation. 8,12,14,18,19 Recently, a new methyl methacrylate-free denture base material (Eclipse) was introduced by Dentsply Trubyte, York, PA. In this system, the baseplate resin is used to fabricate the record base, which later becomes the definitive denture base.…”

Various curing methods on transverse strength of acrylic resin

“…Thus, all of those curing methods evaluated in this study were aimed to find an easier technique, to reduce denture manufacturing time, and to achieve better acrylic resin character in the terms of hardness, porosities, and monomer discharge. 5,10 Due to the development of technology, curing method with water-bath and pressure is still used until now even though the use of microwave energy usually used in food industry has more advantages in dentistry since it can be used for acrylic resin curing process for denture base. The study on the activation system of acrylic resin with microwave energy was conducted not only for laboratorial needs, but also for clinical needs.…”

“…4,5 Many studies even showed that those curing techniques had the similar result as conventional curing method in evaluating transverse strength. Nevertheless, choosing the right curing method of acrylic resin that is still important in order to obtain acrylic resin suitable with physical and biocompatible characters of mouth cavity tissue.…”

Avaliação da liberação de monômero residual, absorção de água e porosidade superficial em resinas acrílicas para prótese ocular

“…A constante procura por processos mais rápidos de confecção de prótese ocular que satisfizessem os requisitos de biocompatibilidade motivou os trabalhos de Rezende (1978) e Dias (1986) ALKUMRU, 1994;AZZARI;CORTIZO;ALESSANDRINI, 2003;OLIVEIRA et al, 2003;BOTEGA et al, 2004). Os Grupos 2 e 3 deste trabalho foram polimerizados em microondas utilizando o ciclo sugerido pelo fabricante da resina Onda Cryl®, seguindo o mesmo princípio de polimerização empregado no ciclo térmico convencional sugerido por Phoenix (2005).…”

“…Como descrito na metodologia, a polimerização dos corpos de prova foi realizada colocando-se uma mufla de cada vez no aparelho de microondas, evitando-se assim a necessidade de adequar a potência e o tempo de polimerização devido a presença de mais de uma mufla por vez no aparelho de microondas, como evidenciado por Botega et al (2004).…”