Comparison of Three Different Orthodontic Adhesives Bonded to Metallic and Ceramic Brackets: SEM and SEM/EDX Analysis (In Vitro Study)

Abstract

Objectives: To compare three different orthodontic adhesives (Transbond XT Light Cure Adhesive,Heliosit Orthodontic, Fuji Ortho LC) bonded to two types of orthodontic brackets: ceramic brackets(Fascination Roth 0.22) and metallic brackets (Topic Roth 0.22, Dentaurum). Materials and methods:The study was performed on 18 human teeth (6 for each adhesive). The prepared teeth weredivided into three groups according to the examination time. Subsequently, they were observed after1, 2 and 3 weeks following bonding. After the experimental procedure, the teeth samples werecut in half along the longitudinal axis in the vestibulo-oral direction, fixed with conductive carboncement, placed in a high-vacuum evaporator and then coated with carbon. One half of each samplewas observed under a Field-emission gun scanning electron microscope (FEG-SEM Hitachi SU 8030,Japan), while on the second half of the samples qualitative (X-ray line-scans) and semi-quantitativepoint X-ray energy dispersive analyses (EDX) were performed with Thermo Noran (USA) NSS System7, equipped with Ultra Dry detector (30 mm2 window). Results: Transbond XT had an ideal bond withthe enamel and the bracket base, with rare presence of microgaps and cracks in the enamel. HeliositOrthodontic demonstrated a better bond relationship with the bracket base than the enamel, whereasin the latter the presence of microgaps in the bond was observed. The microphotographs of FujiOrtho LC demonstrated many cracks inside the adhesive, and some of them continued to move forwardinto the enamel surface. Therefore, an impression of a very solid bond relationship with theenamel exists, with cracks being present in the enamel surface and never at the enamel-adhesive interface.Microgaps also appeared at the bracket-adhesive interface. Conclusion: Transbond XT is ahighly filled composite resin and is an ideal orthodontic adhesive in each aspect examined, with anideal enamel-adhesive and bracket-adhesive interface. Heliosit Orthodontic provides better bracketadhesive interface compared to the enamel. Fuji Ortho LC as a solid resin-modified GIC provides abetter enamel-adhesive interface, compared to the bracket base.