Welcome to My Website - Research Interests
RIZKALLA, Amin S., P.Eng., Ph.D.
Department of Chemical and Biochemical Engineering
Faculty of Engineering,
Graduate Program in Biomedical Engineering,
Chair of the Division of Biomaterials Science
Faculty of Medicine and Dentistry
Telephone: (519) 661-2111 Ext. 82212 / 86086
M. Eng. (
Ph.D. (Dalhousie University.) 1987
Dr. Rizkalla’s main area of research is in wet chemical synthesis and physical and mechanical and biological characterization of glasses, ceramic, nanocomposite and hybrid biomaterials that are used for dental and orthopaedic applications.
Nano-Ceramic Fillers for Composite Biomaterials: Functionalized nano-ceramic particles, fibers and nanotubes are being synthesized by so-gel chemistry, hydrothermal and electrospinning processes. These nanofillers exhibit unique shapes and provide mechanical interlocking with the resin matrix. These modifications result in a significant increase in the elastic moduli and fracture toughness of dental composites. Additional work is being conducted in the synthesis and characterization of nano-composites.
Synthesis of High Strength Machinable Glass-Ceramics for the CEREC System: Wet chemical synthesis provides glass-ceramics of controlled chemistries and improved strength, modulus of elasticity and fracture toughness. A wide range of glass formulations in the system K2O-Na2O-CaO-F-A2O3-SiO2-X are being synthesized by wet chemical methods where X is a network modifier such as TiO2, ZrO2, La2O3, CeO2, and Y2O3. Synthesized powders are processed using novel sol-gel chemistry. From DTA exotherms of resultant glasses, kinetics of crystallization is studied. Optimum heating schedule for each glass will depend upon chemical composition. Effect of structure and composition on mechanical and wear properties of glass-ceramics are studied and compared with Commercial CEREC systems.
Kinetics of Crystallization of Synthesized Glasses: The control of the heating schedule, nucleation and crystallization of glasses is important to optimize the physical chemical and mechanical properties of these materials. The kinetics of crystallization of ion leachable and bioactive and castable glass formulations was determined by differential thermal analysis (DTA). We have demonstrated that DTA is a valuable technique for the optimization of heat treatment that leads to superior properties of biomedical glass-ceramics.
Ion Leachable Glasses: We have developed ion leachable glasses that contain a high percentage fluoride. When these glasses were reacted with poly (acrylic acid), experimental glass-ionomer cements were obtained. These cements exhibited superior mechanical properties & fluoride release that was significantly higher than any commercial material available on the market. The main advantage of high fluoride release is the reduction of secondary caries and stimulation of bone growth.
Bioactive Glass-Ceramics-Polymer Composites:
We have conducted preliminary research dealing with the synthesis and
characterization of bioactive glasses and glass-ceramic-polymer
composites. We found that the ionic release of calcium and phosphorus
from the glass is dictated by the concentration of non-bridging oxygen
within the glass materials. We also found that the silane treatment can
produce a barrier to ionic release. In contrast to conventional
methacrylate bone cement, the range of dynamic elastic moduli values for
the experimental composite systems were significantly higher and within
the typical range of values for cortical bone. This finding has the
potential of reducing stress-shielding effect between the implant and
bone. More research is being developed in the area of thin film coating
of hydroxyapatite and bioactive glasses onto metal substrates and high
strength bioceramics to be used for dental and orthopaedic implants.
Additional work on the synthesis of porous bioceramics, biodegradable
polymers and biocomposites is being conducted for scaffolds used for
dental and orthopaedic applications. Other research interest is in
micro-encapsulation and controlled release of bio-effectors as well as
immobilization of proteins for promotion of mineralization.
KEYWORDS: Biomaterials, synthesis, bioactive glass-ceramic, dental, crystallization, cement, nano-composite, sol-gel, mechanical, physical, chemical, coating, scaffold