Bond Strength of Metallic or Ceramic Orthodontic Brackets to Enamel, Acrylic, or Porcelain Surfaces.

Mónica Pinho,Conchita Martin,Afonso Pinhão Ferreira,Ricardo Faria Almeida,Júlio C M Souza,Filipe Silva,Bruno Henriques,Óscar Carvalho,Maria C Manso

doi:10.3390/ma13225197

Abstract

Bonding strategies within different brackets and dental materials are still a challenge concerning adhesion and dental surface damage. This study compared the shear and tensile bond strength of orthodontic ceramic and metallic brackets to enamel, acrylic, and ceramic surfaces after thermal cycling. Dental surfaces were divided into three groups: enamel, ceramic, and acrylic. Each group received stainless-steel and ceramic brackets. After thermal cycling, specimens were randomly divided into two subgroups considering tensile (TBS) or shear bond strength (SBS) test. After the mechanical testing, scanning electron and optical microscopy were performed, and the adhesive remnant index (ARI) was determined. The two-way ANOVA full factorial design was used to compare TBS, SBS, and ARI on the surface and bracket type (α = 0.05). There were significant differences in TBS, SBS, and ARI values per surface (p < 0.001 and p = 0.009) and type of bracket (p = 0.025 and p = 0.001). The highest mean SBS values were recorded for a ceramic bracket bonded to an acrylic surface (8.4 ± 2.3 MPa). For TBS, a ceramic bracket bonded to acrylic showed the worst performance (5.2 ± 1.8 MPa) and the highest values were found on a metallic bracket bonded to enamel. The adhesion of metallic or ceramic brackets is enough for clinical practice although the damage of the enamel surface after debonding is irreversible and harmful for the aesthetic outcome of the teeth.

Highlights

The increasing demand for orthodontic treatment keeps orthodontists chasing the optimal bonding strategy considering different brackets and surfaces [1,2,3]
Surfaces were randomly divided into two subgroups, according to the tests to which they were submitted: subgroup 1 included the brackets subjected to shear bond strength test; and subgroup 2 included the brackets subjected to tensile bond strength test
The upper incisor brackets were bonded to maxillary first molar teeth or prosthetic crowns with this same shape to avoid bias withing groups. For both shear bond strength (SBS) and tensile bond strength (TBS), the mean values of adhesive remnant index (ARI) in this study showed a heterogeneous distribution for the three surfaces with percentages below 35.8 ± 22.3 in all groups

Summary

Introduction

The increasing demand for orthodontic treatment keeps orthodontists chasing the optimal bonding strategy considering different brackets and surfaces [1,2,3]. Materials 2020, 13, 5197 restorations and/or prostheses, the bond strength of brackets to enamel and restorative material is a major concern during orthodontic treatment and later at the bracket removal [4]. Another concern is that the removal of the bracket may result in irreversible damage to the restorative and enamel surfaces [5,6]. The most common ceramic-based materials for veneering prosthetic structures include feldspar and leucite-based porcelain [7,8] Such materials can be manufactured by traditional laboratory methods or by CAD-CAM [9]. Chemical bonding can be achieved by applying a silane coupling prior to the resinous adhesive [15,16]

Objectives

Methods

Discussion

Conclusion