Characterization of resin cements

PLEASE NOTE: This work is protected by copyright. Downloading is restricted to the BU community: please click Download and log in with a valid BU account to access. If you are the author of this work and would like to make it publicly available, please contact open-help@bu.edu.Thesis (D.Sc.D)--Boston University, Henry M. Goldman School of Dental Medicine, 2001 (Restorative Sciences/Biomaterials).Includes bibliographic references (leaves 190-210).Objectives: To evaluate the properties of several new resin cements including: film thickness, water sorption and solubility, compressive and diametral tensile strengths, effect of cement thickness on crown retention in vitro, effect of ceramic overlay thickness on the degree of conversion and surface microhardness, and color stability. Materials and Methods: The materails tested were Calibra (Dentsply Caulk), Compolute ESPE America), RelyX ARC (3M dental products), Variolink II (Ivoclar North America), Ketac-Cem (ESPE America), and Zinc phosphate (Mission/Mizzy) cements. The cements were tested according to ADA specifications No.9, 27, & 96. Film thickness: a portion of the standard mix of cement was positioned between two flat glass plates and then a load of 15 kg was applied vertically to the plates. Each resin cement was measured 10 times. Water sorption and solubility: five disks (15 × 0.8mm) were prepared from each resin cement and zinc phosphate cement. Their weights were recorded at baseline and after storage in distilled water for one week at 37 degrees C and sorption and solubility were calculated. Compressive and diametral tensile strengths: cylindrical specimens were made (n=10) for compressive (6 × 12mm) and diametral tensile strength (6 × 3mm) and tested on an Instron testing machine to failure. Effect of cement thickness on crown retention: 300 cylindrical steel cores were cemented (bonded and dual-cured) into corresponding steel retainers. Cores and retainers were divided into groups according to cement type and cement space (50megam, 100megam, 150megam, 200megam, and 400megam). Cores were separated from their retainers in an Instron testing machine. Degree of conversion and surface microhardness: samples for the degree of conversion (n=5), and hardness (n=5) tests were light-cured directly (no overlay ceramic) or through different overlay ceramic thicknesses (0.7mm, 1.5mm, and 2.0mm) for 40s. Degree of conversion was quantitatively analyzed using an FTIR spectrometer. Surface hardness was measured with a Vickers microhardness machine. Color stability resin cement samples (n=10) were either veneered [sandwiched between ceramic veneer (0.7mm, T1) and dentin base (A1 and/or A4)], or non-veneered. Samples were light-cured for 40s and stored in distilled water for one week, then aged for 14 weeks at 60 degrees C. One way ANOVA (GLM) tests were performed for all parameters tested, followed by Student-Newman-Keuls test. Correlation analysis was done between the different variables tested in this study. Results and Conclusion: resin cements film thicknesses ranged from 15.3 to 30.6 megam. RelyX ARC had the lowest film thickness at 15.3 megam (p[less than].05) followed by Calibra at 22.2 megam and Compolute and Variolink II were identical at 30.6 megam. [TRUNCATED