Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Biochemistry

Supervisor

Siqueira, Walter L.

Abstract

Titanium implants are used in dental practice to replace damaged or lost teeth. The implant needs to integrate with the surrounding gingiva to protect it against bacterial invasion that leads to implant loss. The biointegration is dependent on the implant surface that interacts with proteins from biological fluids to modulate tissues response. Tailoring the surface with specific proteins from the enamel matrix derivative (EMD) would be beneficial to improve the implant-gingiva interface since EMD can affect various cells including gingival fibroblasts. A surface-affinity approach using three different titanium surfaces and saliva was utilized as a model in combination with tandem mass spectrometry (MS/MS) to investigate protein binding specificity and the possibility of creating a surface-specific coating with identified bioactive proteins in EMD. Using this approach, we showed a low specificity for protein binding despite differences in surface characteristics. Due to the lack of specificity, EMD composition was investigated through the MudPIT methodology, which resulted in the analysis of 32 fraction. The proteome characterization through MS/MS identified 2000 proteins including novel proteins that are associated with biomineralization, wound healing, and biological adhesion. The further exposure of HGF to EMD fractions revealed two fractions (F23 and F24) that promoted significantly higher HGF adhesion than native EMD and other fractions. Overall, our results provide an in-depth insight into EMD composition showing its high complexity in protein content, including novel proteins that are related to EMD biological activity such as on adhesion of HGF.

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