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
ABSTRACT
Simplification of the self-etching process may affect durability; therefore, long-term durability of these systems in oral conditions has been attended. The aim of this study was to evaluate the effect of 6-month water storage on microleakage of two-component self-etch adhesive systems and to compare these systems with etch and rinse adhesive systems in class V cavities. In this in-vitro study, class V cavities were prepared at buccal and lingual surfaces of ninety-six human molars and the enamel margin was beveled [0.5 mm width]. The teeth were randomly assigned into four groups [N=24]. Twelve teeth were assessed after one day and 12 after 6 months. The adhesive groups were scotch bond multi-purpose, single bond, clearfil SE bond and all-bond SE. After thermocycling, immersion in dye solution and sectioning, the samples were examined using a stereomicroscope. The data were analyzed by Kruskal-Wallis, Dunn, Mann-Whitney U and Wilcoxon tests [p<0.05]. In the one day samples, A-B SE adhesive system showed higher microleakage at the occlusal margin [p<0.05]. However, there was no significant difference between four adhesive systems at the gingival margin. In the 6-month samples there was no significant difference between four adhesive systems at the occlusal margin, while at the gingival margin etch and rinse adhesive systems [SMP and SB] presented significantly higher microleakage [p<0.05]. Pass of time did not affect microleakage of the self-etch adhesive systems at the gingival margin