Fluoride release from orthodontic composites: in vitro study Liberação de flúor de compósitos ortodônticos: estudo in vitro

ABSTRACT Objective To evaluate the behavior of orthodontic composites, given their fluoride release and uptake ability. Methods The materials were divided into 3 groups: 2 orthodontic composites and 1 resin-reinforced glass ionomer cement used for bonding orthodontic brackets, as follows: Group Q (Quick Cure, Reliance), Group A (Aqualite, OrthoSource) and Group OGLC (Ortho Glass LC, DFL) and a control group. The fluoride release was measured for 28 days (after 1 hour and then 1, 3, 7, 14, 21 and 28 days) via an ion-selective electrode connected to an ion analyzer. To evaluate the recharge of fluoride, the specimens were exposed to sodium fluoride solution (1,000 ppm fluoride) for 28, 30, 31 and 32 days. The variance analysis (ANOVA) and Tukey’s tests were used to evaluate between groups (p< 0.05). Results The results showed that the materials reached the peak of fluoride release 24 hours after polymerization. There was a statistical difference between groups Q and A at the time intervals of 1 hour and at at 1, 3, 7, 14 days and after recharge with fluoride (p˂ 0.05). The Q and A groups showed a statistical difference with the Group OGLC in all periods p< 0.05). Conclusion The Quick Cure composite showed a higher initial ability for fluoride uptake and release compared to the Aqualite composite. Both composites showed similar performance after 21 days. Indexing terms : Composite resins. Fluorine. Sodium fluoride. RESUMO Objetivo Avaliar o comportamento de compositos ortodonticos, quanto a capacidade de liberacao e captacao de fluor. Metodos Os materiais foram divididos em 3 grupos: 2 compositos ortodonticos e 1 cimento de ionomero de vidro reforcado com resina utilizados para colagem de braquetes ortodonticos, sendo: Grupo Q (Quick Cure, Reliance), Grupo A (Aqualite, OrthoSource) e Grupo OGLC (Ortho Glass LC, DFL), como controle. A liberacao de fluor foi medida durante 28 dias (1h e 1, 3, 7, 14, 21 e 28 dias), atraves de um eletrodo ion seletivo conectado a um analisador de ions. Para avaliacao da recarga de fluor, os especimes foram expostos a solucao de fluoreto de sodio (1000 ppm de fluor) nos dias 28, 30, 31 e 32. A analise de variância (ANOVA) e teste de Tukey foram utilizados para avaliacao entre grupos (p< 0.05). Resultados Os resultados evidenciaram que os materiais atingiram o pico maximo de liberacao de fluor com 24 horas apos a polimerizacao. Houve diferenca estatistica entre os grupos Q e A nos tempos de 1 hora , 1, 3, 7, 14 dias e apos recarga com fluor (p<0.05). Os grupos Q e A apresentaram diferenca estatistica com o grupo OGLC em todos os periodos (p<0.05). Conclusao O composito Quick Cure apresentou maior capacidade de liberacao e captacao de fluor inicial comparado ao composito Aqualite. Ambos os compositos apresentaram desempenho semelhante apos 21 dias. Termos de indexacao : Resina composta. Fluor. Fluoreto de sodio.