B. Josephson, Jr. [and] M. W. P. Strandberg. / "January 1, 1962." " ... based on a Ph.D. thesis by B. Josephson, Jr., submitted to the Department of Physics, M.I.T., May 19, 1958." Reprinted from J. Phys. Chem. Solids ... 1962, vol.23, pp. 67-73." / Bibliography: p. 73. / Army Signal Corps Contract DA 36-039-sc-78108 Department of the Army Task 3-99-20-001 and Project 3-99-00-000. Army Signal Corps Contract DA 36-039-sc-87376.

Introduction: Early childhood caries (ECC) is common among Hong Kong preschool children. It is a disease caused by dental plaque bacteria and may be controlled by good toothbrushing habits. However, preschool children are often too young to perform effective tothbrushing, and therefore parental toothbrushing is recommended for them. The oral hygiene status of Hong Kong preschool children is usually not good and parental toothbrushing is not common. Fluoride varnish is effective in preventing dental caries in school children and adolescents but its effectiveness in preventing dental caries in preschool children is still inconclusive. Objective: To investigate the effectiveness of hands-on training in parental toothbrushing, with or without semi-annual applications of a 5% sodium fluoride varnish in preventing ECC. Methods: Children aged 8-23 months were recruited and randomly allocated to one of three groups: Group 1 - positive control, a brief oral health education to parents; Group 2 - oral health education to parents, hands-on training in parental toothbrushing, and home visits every six months to reinforce parental toothbrushing; Group 3 - application of a 5% sodium fluoride varnish onto the child’s teeth during home visits in addition to the intervention provided to Group 2. Clinical examination of the children and a questionnaire survey of the parents were conducted at baseline. Interventions for the children and parents were delivered according to their group assignment. Evaluation of the main outcome, development of new dental caries, was conducted after 24 months through clinical examination. Information on children’s oral health-related behaviors and parents’ knowledge of and attitude towards their child’s oral health was collected using a questionnaire at the 24-month follow-up. Results: Out of the 450 children recruited at baseline, 415 (92%) children were examined after 24 months and all examined children’s parents completed the questionnaire. Including both noncavitated and cavitated carious lesions, the incidences of ECC in Gp1 to Gp3 were 11.9%, 11.8%, and 17.5%, respectively (p > 0.05) and; the mean dmfs scores in Gp1 to Gp3 were 0.3, 0.2, and 0.4, respectively (p > 0.05). Proportions of parents who practiced parental toothbrushing twice a day were 62.7%, 60.4%, and 65.7% in Gp1, Gp2, and Gp3, respectively (p > 0.05). Results from a logistic regression analysis showed that children who were older, who had poorer oral hygiene, who had high frequency of sugary snack intake, who had visited a dentist during the study, and whose parents had lower education level would have a higher chance to develop new dental caries during the 24-month study period. Conclusion: Hands-on training in parental toothbrushing, reinforced by face-to-face interview every 6 months, with or without a semi-annual application of 5% sodium fluoride varnish, may not have any additional effect on preventing development of dental caries in young children compared to the standard oral health education provided to parents in Hong Kong. The child’s socio-demographic background, oral hygiene status, and frequency of sugary snack intake are related to ECC. / published_or_final_version / Dentistry / Doctoral / Doctor of Philosophy

In order to test the hypotheses: (1) that the digestive absorption of fluoride (F) is affected by the presence of aluminum (Al), and (2) that the distribution of F absorbed among organs/tissues is affected by Al, 36 American kestrels (Falco sparverius) were randomly divided into 6 groups of 6, and given oral doses daily for 30 days according to the following scheme: (1) deionized water only, (2) 30 mg/kg F$ sp-$, (3) 24 mg/kg F$ sp-$, (4) 24 mg/kg Al$ sp{3+}$, (5) 30 mg/kg F$ sp-$ + 24 mg/kg Al$ sp{3+},$ (6) 24 mg/kg F$ sp-$ + 24 mg/kg Al$ sp{3+}$. Excreta was collected every 24 hours between dosing. Femurae, kidneys, hearts, alimentary canals, skeletal muscle, and livers were obtained from all birds at the end of experiment. All samples were analyzed for F, Al, total phosphate (P) and calcium (Ca). F excretion was significantly higher in birds given 30 mg/kg F$ sp-$ + 24 mg/kg Al$ sp{3+}$ than in their counterparts which received the same amount of either F or Al alone (p $<$ 0.05). Excretion of Al was also elevated in all groups (except those only given water) from the level of excretion before the experiment commenced (p $<$ 0.05), despite the fact that 2 groups out of those 5 received F only. P and Ca contents of excreta were not affected by the oral dose. F contents in femurae from groups receiving both F and Al were significantly lower compared to those levels in those birds which were given F only (p $<$ 0.05). Significantly more Al was found in kidneys from the group receiving 30 mg/kg F$ sp-$ + 24 mg/kg Al$ sp{3+}$ than in those groups given only 1 of the 2 ions (p $<$ 0.05).

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Thesis (Ph.D.)--McMaster University, 2005. / Supervisor: G. J. Schrobilgen. Includes bibliographical references (leaves 305-318).

Thesis (Ph.D.)--McMaster University, 2005. / Supervisor: G. J. Schrobilgen. Includes bibliographical references (leaves 305-318).

Thesis (M.Sc.Dent.) -- University of Adelaide, Dental School, 2002. / Includes bibliographical references (leaves 232-247).

Thesis (D.P.H.)--University of Michigan, 1996.

Thesis (M. D. S.)--University of Hong Kong, 2006. / Also available in print.