Post-cure heat treatments for composites: properties and fractography.
Two commercial and four experimental composites were subjected to post-cure heat treatments of 10 min and 3 h duration immediately after light-curing. Fracture toughness, flexural modulus, microhardness and degree of conversion (FTIR) were evaluated 24 h later. The results showed that post-cure heat treatments at 120 degrees C of short or long duration can be used to produce significant improvements in the degree of cure and the mechanical properties of dental composites used as inlays. A 10 min heat treatment was as effective as a 3 h treatment in enhancing properties and degree of cure. In addition, a 3 h heat treatment carried out 7 days after the initial light-curing was capable of improving properties and cure to almost the same extent as the immediate heat treatments. The improvement in properties, in conjunction with the fractography, indicate a toughening of the filled resin matrix and possibly an improved filler/matrix adhesion in the microfills. The changes appear to be predominantly the result of an increase in degree of cure.
Ferracane
J L
JL
Department of Dental Materials Science, Oregon Health Sciences University, Portland.
Condon
J R
JR
D000180:Acrylic Resins / Q000737:chemistry; D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry*; D004548:Elasticity; D006244:Hardness; D006358:Hot Temperature; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D011140:Polyurethanes / Q000737:chemistry; D019279:Resin Cements; D013499:Surface Properties
D000180:Acrylic Resins; C029012:Composite Dental Resin; D003188:Composite Resins; D011140:Polyurethanes; D019279:Resin Cements; C065770:Herculite XR; C074741:Silux Plus