Post-cure heat treatments for composites: properties and fractography

• Published in: Dental materials 1992-09, Vol.8 (5), p.290-295
• Main Authors: Ferracane, J.L., Condon, J.R.
• Format: Article
• Language: English
• Subjects: Acrylic Resins - chemistry; Analysis of Variance; Composite Resins - chemistry; Dentistry; Elasticity; Hardness; Hot Temperature; Materials Testing; Microscopy, Electron, Scanning; Particle Size; Polyurethanes - chemistry; Resin Cements; Surface Properties
• ISSN: 0109-5641; 1879-0097
• DOI: 10.1016/0109-5641(92)90102-I

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°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.