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 were divided into three groups according to the examination time. Subsequently, they were observed after 1, 2 and 3 weeks following bonding. After the experimental procedure, the teeth samples were cut in half along the longitudinal axis in the vestibulo-oral direction, fixed with conductive carbon cement, placed in a high-vacuum evaporator and then coated with carbon. One half of each sample was 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-quantitative point X-ray energy dispersive analyses (EDX) were performed with Thermo Noran (USA) NSS System 7, equipped with Ultra Dry detector (30 mm² window).

Results: Transbond XT had an ideal bond with the enamel and the bracket base, with rare presence of microgaps and cracks in the enamel. Heliosit Orthodontic demonstrated a better bond relationship with the bracket base than the enamel, whereas in the latter the presence of microgaps in the bond was observed. The microphotographs of Fuji Ortho LC demonstrated many cracks inside the adhesive, and some of them continued to move forward into the enamel surface. Therefore, an impression of a very solid bond relationship with the enamel 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 a highly filled composite resin and is an ideal orthodontic adhesive in each aspect examined, with an ideal enamel-adhesive and bracket-adhesive interface. Heliosit Orthodontic provides better bracket-adhesive interface compared to the enamel. Fuji Ortho LC as a solid resin-modified GIC provides a better enamel-adhesive interface, compared to the bracket base.

Keywords: Adhesive; Bracket; Composite Resins; Composite resin; Dental Bonding; Dental Cements; EDX; MeSH Terms: Orthodontic Brackets; Resin modified glass ionomer cement; SEM.

Figure 1

Micro-photographs of samples tested 1 week after bonding: 1a) Metallic bracket bonded with Transbond XT; 1b) Ceramic bracket bonded with Transbond Xt; 1c) Metallic bracket bonded with Heliosit Orthodontic; 1d) Ceramic bracket bonded with Heliosit Orthodontic; 1e) Metallic bracket bonded with Fuji Ortho LC adhesive; 1f) Ceramic bracket bonded with Fuji Ortho LC adhesive.

Figure 3

Micro-photographs of samples tested 3 weeks after bonding: 3a) Metallic bracket bonded with Transbond Xt; 3b) Ceramic bracket bonded with Transbond Xt; 3c) Metallic bracket bonded with Heliosit Orthodontic; 3d) Ceramic bracket bonded with Heliosit Orthodontic; 3e) Metallic bracket bonded with Fuji Ortho LC adhesive; 3f) Ceramic bracket bonded with Fuji Ortho LC adhesive.

Figure 2

Microphotographs of samples tested 2 weeks after bonding: 2a) Metallic bracket bonded with Transbond XT; 2b) Ceramic bracket bonded with Transbond XT; 2c) Metallic bracket bonded with Heliosit Orthodontic; 2d) Ceramic bracket bonded with Heliosit Orthodontic; 2e) Metallic bracket bonded with Fuji Ortho LC adhesive; 2f) Ceramic bracket bonded with Fuji Ortho LC adhesive.

Figure 4

Micro-photographs of the selected areas for semi-quantitative EDX analysis of the adhesives: a) Transbond XT Light Cure Adhesive (3M Unitek Orthodontic Products, USA) b) Heliosit Orthodontic (Ivoclar Vivadent, Schaan, Liechtenstein) c) Fuji Ortho LC (GC Corporation, Japan.

Figure 6

Overview of the elements found in the selected surface of the samples (y-axis: number of counts, x-axis: energy in keV: a) Transbond XT Light Cure Adhesive (3M Unitek Orthodontic Products, USA): presence of carbon (C), oxygen (O), sodium (Na), silicon (Si), phosphorus (P), molybdenum (Mo), chlorine (Cl) and calcium (Ca); b) Heliosit Orthodontic (Ivoclar Vivadent, Schaan, Liechtenstein): presence of carbon (C), oxygen (O), sodium (Na), aluminum (Al), silicon (Si), phosphorus (P), sulphur (S), chlorine (Cl) and calcium (Ca); c) Fuji Ortho LC (GC Corporation, Japan): presence of carbon (C), oxygen (O), fluorine (F), sodium (Na), aluminum (Al), silicon (Si), phosphorus (P), sulphur (S), chlorine (Cl) and calcium (Ca).

Figure 5

Micro-photographs of the point selection in the enamel for the semi-quantitative EDX analysis: a) Transbond XT Light Cure Adhesive (3M Unitek Orthodontic Products, USA) b) Heliosit Orthodontic (Ivoclar Vivadent, Schaan, Liechtenstein) c) Fuji Ortho LC (GC Corporation, Japan)