Hardness and degree of conversion of posterior packable composites

• Published in: Operative dentistry Vol. 29; no. 6; p. 642
• Main Authors: Knobloch, Lisa A, Kerby, Ronald E, Clelland, Nancy, Lee, Jeffrey
• Format: Journal Article
• Language: English
• Published: United States 01-11-2004
• Subjects: Acrylic Resins - chemistry; Acrylic Resins - radiation effects; Composite Resins - chemistry; Composite Resins - radiation effects; Hardness; Humans; Light; Materials Testing; Methacrylates - chemistry; Methacrylates - radiation effects; Polymers - chemistry; Polymers - radiation effects; Polyurethanes - chemistry; Polyurethanes - radiation effects; Spectroscopy, Fourier Transform Infrared; Stress, Mechanical; Surface Properties; Time Factors
• ISSN: 0361-7734

Knoop microhardness and the degree of conversion of three packable composites (SureFil, Alert and Solitaire), a microfil composite (Heliomolar), a microhybrid composite (Herculite) and an indirect laboratory-processed composite (Belleglass) were evaluated as a function of distance from the irradiated surface. Cylindrical specimens (5.0 mm [diameter] x 6.0 mm [length]) of each material were visible light cured for 60 seconds in black-backed Teflon molds and sectioned. Knoop microhardness values were then obtained at 0-, 2- and 4-mm using a 50-gram load and 20 second dwell time. Degree of conversion was determined using Fourier Transform Infrared Spectroscopy. ANOVA (p<0.001) and Tukey Multiple Comparison Test (p<0.05) showed the indirect laboratory-processed composite Belleglass exhibited the highest mean values for both hardness and degree of conversion. Alert exhibited significantly greater hardness than SureFil and Solitaire at 0-mm depth. SureFil had significantly greater hardness than Alert at 4-mm depth. The degree of conversion of SureFil packable composite at 4-mm depth was significantly higher than any of the other direct composites tested.