Master of Dental Surgery / This work was digitised and made available on open access by the University of Sydney, Faculty of Dentistry and Sydney eScholarship . It may only be used for the purposes of research and study. Where possible, the Faculty will try to notify the author of this work. If you have any inquiries or issues regarding this work being made available please contact the Sydney eScholarship Repository Coordinator - ses@library.usyd.edu.au

Doctor of Dental Science / This work was digitised and made available on open access by the University of Sydney, Faculty of Dentistry and Sydney eScholarship . It may only be used for the purposes of research and study. Where possible, the Faculty will try to notify the author of this work. If you have any inquiries or issues regarding this work being made available please contact the Sydney eScholarship Repository Coordinator - ses@library.usyd.edu.au

Thesis (M.D.S.)--University of Hong Kong, 1998. / Includes bibliographical references (leaves 125-160A) Also available in print.

Thesis (M.D.S.)--University of Hong Kong, 1989. / Includes bibliographical references (p. 66-70). Also available in print.

Thesis (M. D. S.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Thesis (M. D. S.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

No description available.

Thesis (Ph. D.)--University of Hong Kong, 2005. / Title proper from title frame. Also available in printed format.

The purpose of this study was to evaluate a multifactorial caries risk assessment model by comparing the risk factor scores with caries increment. Secondary data analysis included a chart review of 434 dental patients in which basic caries risk scores, total risk score and caries increment were collected. ANOVA and logistic regression were conducted to assess the statistical significance of the difference between caries increments across categories of risk factors. Mean tooth caries increments of the risk groups were 0.20±0.8 (low), 1.13±1.59 (moderate), 2.09±2.63 (high), which were statistically significant (p<0.001). Past and present caries experience, carbohydrates, mucogingival bleeding index, and stimulated salivary flow showed statistically significant associations with caries increment (p<0.05) but the total risk score proved to be the most powerful predictor of future caries activity (p<0.001). The multifactorial etiology of caries necessitates the use of a risk assessment model that includes various factors that contribute to caries development.

The purpose of this study was to determine the impact of insertion angle of orthodontic mini screws on the stability and resistance to movement of the mini screw, and on the peri-implant interface. Three orthodontic mini screws were placed in each tibia of six New Zealand white rabbits bilaterally (N=36), with randomized angulation (65° away, 65° toward, or 90° to the direction of applied force). After two weeks, two orthodontic mini screws within each tibia were loaded with a 200g Nitinol closed-coil spring for up to 14 days. No statistically significant differences were found among the variably angulated loaded and unloaded orthodontic mini screws in the amount of movement or change in angulation demonstrated over the experimental period. Micro CT analysis revealed no clinically significant differences in the amount of cortical bone-to-implant contact. Mini screw placement angulation seems to have minimal impact on stability and migration of orthodontic mini screws over time.