Composite Filler Characterization by Scanning Electron Microscopy, Image Analysis and Thermogravimetry

The morphological and compositional characterization of the filler particles in selected dental composites has been accomplished by a combination of backscattered elec tron imaging, digital imaging , energy dispersive X-ray analysis and thermogravimetry. Backscattered electron images provide excellent composition contrast between the filler and the matrix in this analysis . Qualitative energy dispersive spectroscopy was used to classify the filler composition in the composites studied. The digital imaging technique of feature analysis was utilized to quantitatively characterize the particle morphological parameters and their distributions. Several parameters were determined of which the particle area, breadth, height and Waddel diameter are emphasized. Particle size distribution histograms were also obtained. The filler contents in commercial composites were also determined by thermogravimetry. Thus a comprehensive method has been developed and applied to characterize filler morphology in particulate dental composites, which include both commercial and experimental systems. The commercial systems show variations in filler composition, filler size and distribution as well as filler loading levels. The experimental systems confirm variations in particle size and size distributions as a function of filler processing time.