The hypothesis of this proposal is that mode I fracture testing of dental composite is insufficient to represent what occurs under clinical conditions and requires the mixed mode approach to fracture analysis. The second portion of the hypothesis is that leached/degraded components from the aging of the composite in water require additional analysis as to qualification and quantification, their rate of removal, and their influence on the fracture properties. The significance of the continuation of the initial project is to extend the understanding and knowledge gained in the first phase on the aging, strength(sf), toughness (KIc), elasticity( E), and crack growth studies. The proposed Continuation consists of three interrelated objectives: 1. Fatigue, fracture, and failure under combIned complex loading condItions and various environments. Failure of dental composites. when used as restorations can occur from cracks or flaws which may be arbitrarily oriented with respect to the applied load. Therefore, complex loading conditions (simultaneous fracture modes I and II) will be investigated since the simulate better a fracture process in a dental restoration. This mixed mode approach will provide a envelope of the fracture threshold from which the ability to predict more realistically lifetime survival under complex loads is possible. 2. Investigations of the effects of the water-matrix-filler interactions on the overall mechanical and environmental stability of dental composites. it is well recognized in the mechanics of composite research that bulk or macro properties (Sf, E, and KIc) are dependent on the micro structure. Thus, the effects of water on the matrix material and reinforcing particles will be thoroughly examined through chemical analyses (atomic absorption and gas chromatography mass spectrometry) as well as materials' morphology characterization (microprobe analysis). Emphasis will be placed on the effect of water in the first one to three months of aging on strength and fracture properties since our investigations showed negligible changes in the fracture properties from six to twelve months. 3. Studies on the effects of specimen size and notch tip geometry on strength, toughness, and fatigue characteristics. Dental composites are inherently brittle materials. Thus essential fracture properties are dependent upon the local notch tip geometry and specimen size. Our preliminary studies have shown that different notch tip geometry yield fracture toughness values which differ up to 60%. In the proposed continuation, the effects of notch tip radius and depth will be tested in various environments.
| Patki, Amol S; Vural, Murat; Gosz, Mike (2011) Confined compression of dental composites for Class I restorations. J Compos Mater 45:1863-1872 |
| Lin, Lihong; Drummond, James L (2010) Cyclic loading of notched dental composite specimens. Dent Mater 26:207-14 |
| Akhmetov, Artem; Moore, Jerry F; Gasper, Gerald L et al. (2010) Laser desorption postionization for imaging MS of biological material. J Mass Spectrom 45:137-45 |
| Aydin Sevinc, Berdan; Hanley, Luke (2010) Antibacterial activity of dental composites containing zinc oxide nanoparticles. J Biomed Mater Res B Appl Biomater 94:22-31 |
| Drummond, James L; Lin, Lihong; Al-Turki, Lulwa A et al. (2009) Fatigue behaviour of dental composite materials. J Dent 37:321-30 |
| Kotche, Miiri; Drummond, James L; Sun, Kang et al. (2009) Multiaxial analysis of dental composite materials. J Biomed Mater Res B Appl Biomater 88:412-8 |
| Drummond, J L (2008) Degradation, fatigue, and failure of resin dental composite materials. J Dent Res 87:710-9 |
| Koin, P J; Kilislioglu, A; Zhou, M et al. (2008) Analysis of the degradation of a model dental composite. J Dent Res 87:661-5 |
| Zhou, Manshui; Wu, Chunping; Akhmetov, Artem et al. (2007) 7.87 eV laser desorption postionization mass spectrometry of adsorbed and covalently bound bisphenol A diglycidyl methacrylate. J Am Soc Mass Spectrom 18:1097-108 |
| Al-Turki, Lulwa I; Drummond, James L; Agojci, Majlinda et al. (2007) Contact versus flexure fatigue of a fiber-filled composite. Dent Mater 23:648-53 |
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