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Title: Fluoride release and uptake from resin-modified glass ionomer cements used for orthodontic purposes : an in vivo investigation
Author: Chung, Chor Kwan
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1996
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Aims: The cariostatic ability of two resin-modified glass ionomer cements (Vitremer and Dyract) was compared to that of a conventional adhesive resin (Right-On) in a half-mouth orthodontic bonding trial. The local and systemic uptake of fluoride from the two resin-modified glass ionomer cements were also compared to those from the conventional adhesive resin. Materials and methods: One of the resin-modified cements was allocated to each of 26 patients (mean age 13.4 years) at random in a half-mouth orthodontic bonding trial. Only non-carious premolar teeth scheduled for orthodontic extraction were included in the study. Each patient used a non-fluoride toothpaste for four weeks prior to bracket bonding and for the four week trial period. To assess decalcification, colour transparencies of each extracted tooth (96 in total) were coded and randomly arranged and projected onto a screen in a darkened room. Each transparency was scored by two examiners independently under identical conditions, two weeks apart, using a modified caries index (0='no white spot'; l='frank white spot'; 2='cavitation'). Salivary and urinary fluoride concentrations were measured pre-bonding and 4 weeks post-bonding. Plaque samples around bonded brackets on premolars were analysed also for fluoride concentration on the two occasions. Results: 2% of premolars bonded with the fluoride-releasing materials in contrast to 19% of premolars bonded with the non-fluoride-releasing material developed early carious lesions or cavitation after 4 weeks in vivo. In relation to the degree of decalcification observed, a significant difference was found between Vitremer and Right-On (p=0.033), but the difference between Dyract and Right-On was not significant (p=0.179). Neither Vitremer nor Dyract altered salivary fluoride concentration significantly 4 weeks post-bonding (0.012ppm and 0.009ppm respectively; p > 0.05 t-test). The difference in urinary fluoride concentration was not statistically significant for both test materials (0.051ppm Vitremer; 0.048ppm Dyract; p > 0.05 t-test). Plaque fluoride concentration increased significantly around premolars bonded with Vitremer (upper arch p=0.032; lower arch p=0.012; t-test). A slight but insignificant increase in plaque fluoride concentration was observed around premolars bonded with Dyract. Conclusions: 1. The cariostatic ability of the resin-modified glass ionomer cement, Vitremer, was superior to that of the non-fluoride-releasing cement Right-On, but there was no significant difference between the cariostatic ability of Dyract versus Right-On. 2. Fluoride release from the resin-modified glass ionomers (Vitremer and Dyract) is likely to exert a local and not a systemic effect.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (D.Sc.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available