Effect of Environmental pH on Fluoride Release from UEDMA-TEGDMA Composite

*1317 Effect of Environmental pH on Fluoride Release from UEDMA-TEGDMA Composite*
N.-Z. ZHANG, C. SHEN, and K.J. ANUSAVICE, University of Florida, Gainesville, USA Objective: To test the hypothesis that a decrease in environmental pH significantly increases fluoride ion release from a urethane dimethacrylate (UEDMA)-triethyleneglycol dimethacrylate (TEGDMA) resin matrix containing ZnF₂. Methods: Thirty discs containing 54 wt% UEDMA (Esschem, Inc), 23 wt% TEGDMA, and 23 wt% ZnF₂ particles were prepared. Ten ZnF₂-containing discs each were exposed to pH 4.0, 5.0 and 6.0 buffer solutions (sodium acetate/acetic acid). Each disc was placed in a vial containing 5 mL buffer solution and stored in 37°C water. The solution was replaced periodically up to 503 h. Solution samples were analyzed with a fluoride-specific ion electrode and a digital pH/mv meter for the fluorine ion content. Results: The mean fluoride release rate and standard deviation (SD) within the first hour were 105.4 (15.6), 67.0 (13.3), and 28.3 (3.6) (µg/h∙cm²) for pH 4.0, 5.0 and 6.0, respectively. After 503 h, the mean release rates decreased to 5.2 (1.3), 2.2 (0.2), and 1.1 (0.2) for pH values of 4.0, 5.0 and 6.0, respectively. Two-way ANOVA revealed that differences in both storage time and pH were statistically significant and there were statistically significant interactions (p<0.0001) between these two variables. Further analysis revealed that although the release rates exhibited a steady decrease over time, the differences in mean values were not statistically significant (p>0.05) after 35 h of storage in any of the three solutions. The pH 4.0 group consistently yielded the highest release rate. The difference in mean values at a pH of 5.0 to 6.0 was not statistically significant (p>0.05) after 35 h of storage. Conclusion: The fluoride release rate from a ZnF₂-containing resin matrix is strongly influenced by the pH of the environment. The effectiveness decreased for pH ³ 5.0. This study was supported by NIH-NIDR Grants DE06672 and DE13412.
Seq #165 - Polymer Materials: Mechanical and Physical Properties; Fluoride Release 3:45 PM-5:00 PM, Friday, 14 March 2003 Henry B. Gonzalez Convention Center Exhibit Hall C
Back to the Dental Materials: VI - Polymer Materials-Mechanical Properties and Degradation Program Back to the 32nd Annual Meeting and Exhibition of the AADR (March 12-15, 2003)
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