ABSTRACT
Preventing enamel demineralization around brackets is a concern for orthodontists. Fluoride releasing materials have been recommended to overcome this problem. The aim of this study was to evaluate the effect of incorporating nanohydroxyapatite [NHA] into resin modified glass ionomer cements [RMGIC] on ceramic bracket debonding. In this experimental study, 80 human premolars were divided into 4 bonding groups as follows: group 1: Transbond XT [TBXT] [control group], group 2: Fuji II LC [RMGIC], group 3: 5% NHA added to RMGIC and group 4 10% NHA added to RMGIC. After enamel etching, ceramic brackets were bonded. The shear bond strength [SBS] and the adhesive remnant index [ARI] were calculated for each group. The data were analyzed using one-way ANOVA, Tukey's post hoc HSD test and the Kruskal Wallis test. According to ANOVA, 10% NHA added to RMGIC had a significantly lower SBS compared to other groups [11.93 +/- 2.11] but no significant difference was found among the remaining groups. The mean SBS was 17.33 +/- 4.07 MPa in group 1, 17.22 +/- 3.55 MPa in group 2 and 16.56 +/- 2.59 MPa in group 3. According to ARI, the predominant failure mode in RMGIC groups was cohesive. Resin modified glass ionomer cements containing 5% NHA can be as effective as composite resins for bonding ceramic brackets