| The purpose of this project is to help guide the development of nonshrinking adhesive dental composite systems. Spiro Ortho Carbonates (SOCs) are known to expand upon polymerization due to a double ring opening mechanism. The copolymerization of such expanding monomers with epoxides may result in a desired zero shrinkage effect. The aim of this study is to develop Quantitative Structure Activity Relationship (QSAR) models (in the form of mathematical equations) for such expanding dental monomers. Important physical and biological properties can be predicted and modified for expanding monomers using the generated models. Four properties being studied in this dissertation are lipophilicity, refractive index (RI) of monomers, polymer RI and mutagenicity.; A training set of molecules is collected for each model. Each molecule is optimized to locate the lowest energy conformation using semiempirical methods. The Austin Model 1 (AMI) method is used to optimize C, H, O, N containing compounds, and the semi-ab inito Model 1 (SAM1) method is used to optimize Si containing compounds. Around five hundred descriptors are calculated based on the optimized geometry for each molecule. A heuristic method is used to perform the multilinear regression and select the qualified models. Finally, internal and external validations are performed through rigorous statistical methods to determine the final model.; The QSAR model generated in this study has two capabilities: interpretation and prediction. Descriptors in the model interpret structural and electronic properties that are responsible for the observed experimental data. Thus, the QSAR model provides direction to modify dental candidate molecules to obtain desired property values. Then, the modified molecule can be predicted using the same QSAR model. |
