1999 Summer Research Faculty-Student Team

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Dr. Gary Halvorson and Chad Shields

Gary Halvorson is an instructor in the Department of Agri-Businees at Sitting Bull College.
Chad Shields is a freshman at Sitting Bull College majoring in Environmental Studies.

Interaction of Bioactive Glass with Collagen
Gary Halvorson and Chad Shields
Sitting Bull College

Lorraine F. Francis
Department of Chemical Engineering and Materials Science, University of Minnesota

Bioactive glasses in the Ca Mg phosphosilicate system were prepared and their bonding to collagen gels and demineralized dentin (largely collagen) was investigated. Bioactive glass beads were prepared by melting glass powder in a platinum crucible and pouring the melt onto an aluminum block. After annealing and polishing, the glass beads were placed adjacent collagen gels in vials containing artificial saliva. Type I collagen derived from calf skin was used to make the gel according to the protocol established by Knapp et al. (1997). The gel/glass combinations were held at 37¡C for at least 3 weeks. During the incubation period, the gel was compressed under the weight of the glass and migrated to cover the entire piece of glass. Upon removal, the pair was firmly bonded together and a white deposit was noted. In a separate experiment, glass beads were placed against pieces of dentin and demineralized dentin according the procedure developed by Efflandt et al. (1998). The pairs were secured with an elastic band and incubated for 3 weeks at 37¡C. Upon removal of the elastic band, the demineralized dentin/glass pair held together weakly while the dentin/glass pair was bonded more strongly. Collagen/glass and dentin/glass samples were then treated with glutaraldehyde to fix the collagen and then carefully dried. SEM and XRD analysis showed that the collagen/glass pair did not form any crystalline phase at the interface while the dentin/glass pairs did. Extensive shrinkage of the collagen and demineralized dentin hindered the analysis. A method to create a sol-gel derived bioactive glass was also established. Using metalorganic precursors, a solution was created with a composition identical to the bioactive glass. The solution gelled when exposed to a humid atmosphere. The gel was dried and then heated to remove the organic constituents. Thermal decomposition of these organics was challenging and more work needs to be done with thermal schedules and atmosphere to eliminate them. Sol-gel derived materials were incubated with collagen gels and bonding was observed.