ABSTRACT
OBJECTIVES: The purpose of this study was to investigate the method of producing pre-polymerized fused-fiber filler modified composite (PP-FFMC) particles and the effectiveness of incorporating these novel filler particles into dental composites. METHODS: Fused-fiber filler (FFF) blocks were impregnated with composite by two different methods. Three-point flexure tests were utilized to determine which was more effective. In order to assess the effect of the addition of PP-FFMC particles, two Bis-GMA/TEGDMA based conventional composite compositions were utilized as baselines, to which the novel particles were added. Mechanical and wear tests were performed to determine the fracture toughness, biaxial flexure strength, and in vitro wear of the materials. RESULTS: Mechanical testing showed that the addition of PP-FFMC particles decreased the strength and toughness of the conventional composites. Wear tests indicated that addition of the same particles improved the wear behavior of the conventional composites. SEM analysis of the fracture surfaces indicated that the PP-FFMC particles were incorporated without creating porosity, and that fracture was transgranular through the reinforcing particles. Microscopic flaws observed in the novel particles are the likely explanation for the observed strength and toughness values. SIGNIFICANCE: The results indicate that PP-FFMC particles have the potential to improve the wear properties of dental composites, however, they adversely affect the fracture behavior. Existing processing techniques for these particles, which introduce imperfections, limit their current usefulness.
Subject(s)
Composite Resins/chemistry , Dental Materials/chemistry , Aluminum Oxide/chemistry , Analysis of Variance , Bisphenol A-Glycidyl Methacrylate/chemistry , Elasticity , Hardness , Humans , Materials Testing , Mechanics , Microscopy, Electron, Scanning , Pliability , Polyethylene Glycols/chemistry , Polymers/chemistry , Polymethacrylic Acids/chemistry , Porosity , Silicon Dioxide/chemistry , Statistics as Topic , Stress, Mechanical , Surface Properties , Tensile StrengthABSTRACT
BACKGROUND: The factors determining a basal cell carcinoma's (BCC's) growth pattern and invasive potential are not known. In other tumors it has been shown recently that the expression of cellular adhesion molecules may determine a tumor's invasive and metastatic potential. Integrins, cell surface molecules important in cell stroma interactions, are present on BCCs and may help regulate the tumor's growth pattern. OBJECTIVE: We compared the expression of cellular adhesion molecules alpha 2 integrin, beta 1 integrin, intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), leukocyte function antigen 1a (LFA-1a), and E-selectin in different histological subtypes of basal cell carcinomas. METHODS: BCCs were obtained from patients undergoing Mohs surgery. The BCCs were classified as nodular, micronodular, mixed, infiltrative, and basosquamous types and stained using an avidin-biotin-immunoperoxidase technique with antibodies against alpha 2 integrin, beta 1 integrin, ICAM, LFA-1a, VCAM-1, and E-selectin. RESULTS: BCCs expressed alpha 2 and beta 1 integrin, but no significant differences in the amount or pattern of expression was seen in the different histologic subtypes. CONCLUSION: The expression of integrins by BCCs by binding to the surrounding stroma may limit BCC's growth; however, their expression does not appear to correlate with their histological pattern.
