Enamel demineralization adjacent to orthodontic brackets bonded with hybrid glass ionomer cements: An in vitro study

Enamel demineralization is recognized as a possible side effect of bonding orthodontic brackets with composite resins. Fluoride-releasing restorative materials have been shown to inhibit tooth demineralization. The purpose of this study was to evaluate two fluoride-releasing hybrid glass ionomer bon ding agents for inhibition of enamel demineralization surrounding orthodont ic brackets under two experimental conditions. This in vitro study used 72 extracted human premolars. Twenty-four teeth were bonded with Advance resio nomer, 24 were bonded with Fuji Ortho LC hybrid glass ionomer and 24 were b onded with Transbond XT composite resin as the control. The teeth were cycl ed in an artificial caries challenge three times daily for 30 days. Half of the teeth in each group were brushed twice daily with a fluoridated dentif rice, and the other half were not brushed. Demineralization of enamel surro unding orthodontic brackets was evaluated with polarized light microscopy. Enamel lesions were photographed under maximum illumination. Images were pr ojected, and demineralized areas were traced. Both average depth and area w ere measured with a sonic digitizer. Analysis of variance (P < .0001) and D uncan's test (P < .05) indicated significant differences in depth and area of demineralized enamel such that lesion size was: Transbond XT no brush > Transbond XT brush > Advance no brush = Advance brush = Fuji Ortho LC no br ush = Fuji Ortho brush. The promising results of this in vitro study warran t further clinical investigation of hybrid glass ionomer adhesives as ortho dontic bonding agents to minimize enamel demineralization.