Abstract
Abstract Objective To evaluate in vitro the effect of different treatments of the ceramic surface and thermal cycling on the shear bond strength (SBS) of metallic brackets bonded to feldspathic ceramic. Material and method Ceramic cylinders were divided into four groups (n=4) according to the treatment of ceramic surface: G1-Clearfil Ceramic Primer silane and Transbond XT (CCPT); G2-etched with 10% hydrofluoric acid (HFA) for 60 s, CCP and Transbond XT (ACCPT); G3-etched with 10% HFA for 60 s, Ambar Adhesive and Transbond XT (AAAT); and, G4 - etched with 10% HFA for 60 s, RelyX Ceramic Primer silane -RCP, adhesive primer Transbond and Transbond XT (ACPPT). Brackets were bonded to the cylinders with Transbond XT and light-activated for 40 s with LED Radii Plus. All specimens were stored in deionized water at 37 °C for 24 h, and two cylinders from each group were subject to 7,000 thermal cycles in a thermal cycler (5 °C/55 °C). After storage and thermal cycling, the SBS test was performed at a crosshead speed of 1 mm/min. Data were subjected to two-way ANOVA and Tukey’s post hoc test (α=0.05). Result The SBS of ACCPT was significantly higher than the other groups (p<0.05). The specimens submitted to thermal cycling showed significantly lower SBS than those without thermal cycling (p<0.05), regardless the ceramic surface treatment. The ARI showed predominance of score 0 for all groups. Conclusion Acid etching, CCP silane and Transbond XT method obtained the best results for bracket bonding. Thermal cycling reduced SBS for all groups. Score 0 was predominant for ARI in all groups.
Highlights
In the last years, older patients have looking for orthodontic treatment and many of these have ceramic restorations
After bonded to ceramic surface, the orthodontic brackets are exposed to the oral environment and failure may occur at interface among orthodontic brackets, bonding material and dental ceramic due to thermal changes and heavy forces produced by the archwire in the oral cavity[4]
The Adhesive Remaining Index (ARI) was used to classify the failure modes[17] as follows: Score 0: no bonding resin on the ceramic; Score 1: less than half of the bonding resin remained on the ceramic; Score 2: half of the bonding resin was left on the ceramic; and, Score 3: all bonding resin was left on the ceramic, with clear impression of the bracket mesh
Summary
Older patients have looking for orthodontic treatment and many of these have ceramic restorations. Some studies showed no negative effects on ceramic surface, since the most failures was adhesive between the bonding material and the ceramic surface[3,4,5]. Previous study showed that the use of adhesive improves adaptation and bond strength of substrates along the resin cement/ceramic interface[9]. After bonded to ceramic surface, the orthodontic brackets are exposed to the oral environment and failure may occur at interface among orthodontic brackets, bonding material and dental ceramic due to thermal changes and heavy forces produced by the archwire in the oral cavity[4]. The purpose of this study was to evaluate the effect of different treatments and thermal cycling on the SBS of metallic brackets bonded to feldspathic ceramic. The hypotheses tested were: 1) Different treatments on the ceramic surface would not affect the shear bond strength; and 2) Thermal cycling would not affect the shear bond strength
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