Microwave-cured acrylic resins and silicone-gypsum moulding technique.
This study evaluated the residual monomer (RM), Knoop hardness (KHN) and transverse strength (TS) of two microwave-cured acrylic resins (Acron MC(R) (A), GC Dent. Ind. Corp., Tokyo, Japan and Onda Cryl (O), AO Classico Ltda, São Paulo, Brazil) when processed with an all-type III gypsum moulding technique (G) or a silicone-gypsum moulding technique (S). One hundred and forty four specimens were fabricated and equally distributed into four groups (AG, AS, OG and OS). The TS tests were conducted after 48 h of water storage, and KHN values were obtained after 24, 48, 72 h and 30 days. The RM was determined every 24 or 48 h over a period of 288 h. The acrylic resins were prepared and processed according to the manufacturer's directions. Both AS and OS showed the highest means (P < 0.05) for RM (microg cm-2) only after 24 h (AS = 56.84 +/- 27.39/AG = 7.51 +/- 5.75/OS = 3.59 +/- 1.60/OG = 1.02 +/- 0.3), 48 h (AS = 28.99 +/- 9.35/AG = 2.65 +/- 2.17/OS = 2.37 +/- 0.84/OG = 0.68 +/- 0.49) and 72 h (AS = 15.98 +/- 9.01/AG = 1.40 +/- 0.57/OS = 1.87 +/- 0.52/OG = 0.75 +/- 0.44). Both AS and OS showed the highest means (P < 0.02) for KH after 24 h (AS = 18.69 +/- 2.3/AG = 17.79 +/- 0.7/OS = 18.41 +/- 1.0/OG = 16.04 +/- 0.6). After 48 h the mean values for OS and OG differed significantly (P < 0.03) (OS = 18.67 +/- 0.8/OG = 16.75 +/- 0.8). No differences of KHN were found among the groups during the storage periods. The TS values for A and O were not affected by either G or S (P > 0.05). Silicone-gypsum mould technique affected the RM and KHN of the resins in the first 2 and 5 days of analysis, respectively. The type of mould did not affect TS, and the acrylic resins differed from each other for all properties regardless of the type of mould.
Del Bel Cury
A A
AA
University of Campinas, Piracicaba Dental School, Brazil. altcury@fop.unicamp.br
Rached
R N
RN
Ganzarolli
S M
SM
D000180:Acrylic Resins / Q000737:chemistry / Q000528:radiation effects*; D000704:Analysis of Variance; D002133:Calcium Sulfate / Q000737:chemistry*; D016001:Confidence Intervals; D003734:Dental Casting Investment / Q000737:chemistry*; D003735:Dental Casting Technique; D003764:Dental Materials / Q000737:chemistry / Q000528:radiation effects*; D003775:Dental Polishing; D003799:Dental Stress Analysis / Q000295:instrumentation; D006244:Hardness; D006801:Humans; D007101:Immersion; D008422:Materials Testing; D020366:Methylmethacrylate / Q000737:chemistry; D008768:Methylmethacrylates / Q000737:chemistry; D008872:Microwaves; D003765:Models, Dental; D019904:Polymethyl Methacrylate / Q000737:chemistry; D012828:Silicones / Q000737:chemistry*; D013223:Statistics as Topic; D013314:Stress, Mechanical; D013997:Time Factors; D014867:Water / Q000737:chemistry
D000180:Acrylic Resins; D003734:Dental Casting Investment; D003764:Dental Materials; D008768:Methylmethacrylates; D012828:Silicones; D014867:Water; C075051:Acron MC; D020366:Methylmethacrylate; C009931:poly(ethylmethacrylate); D019904:Polymethyl Methacrylate; D002133:Calcium Sulfate