Comparison of Shear Bond Strength of Metal Brackets Bonded to Porcelain Surface using Different Surface Conditioning Methods: An in vitro Study

Abstract

Aim: To evaluate and compare the shear bond strength of metal brackets bonded to ceramic surfaces using different conditioning methods and to assess the site of bond failure after debonding. Materials and methods:A total of 70 ceramic surfaces were produced with uniform shape, size and composition. The samples were divided into 7 groups (each of 10 samples).Group 1 was the control group (untreated surface); in group 2 the surface were roughened with a diamond bur; in group 3 the surface were etched with hydrofluoric acid; in group 4 the surfaces were sandblasted; in group 5 the surfaces roughened with bur and silane applied; in group 6 the surfaces were etched with hydrofluoric acid and silane applied and in group 7 the surfaces were sandblasted and silane applied.To all the above groups, metal orthodontic brackets were bonded with light cure adhesive. The brackets were later stored in artificial saliva and incubated at 37°C (24 hours). The samples were then subjected to shear bond strength test using an Instron universal testing machine. The debonded porcelain surfaces were then studied under stereomicroscope to assess site of bond failure.Results: Sandblasting the ceramic surface and silane application showed the highest bond strength. Stereomicroscope examination after debonding showed that the bond failure is at bracket-adhesive interface in four groups namely hydrofluoric acid, sandblasting, hydrofluoric acid with silane and sandblasting with silane. Conclusion:Sandblasting with silane combination produced the highest shear bond strength, so it is a clinically suitable method for bonding orthodontic metal brackets onto ceramic surface.Clinical relevance: Bonding orthodontic brackets to ceramic crowns of patients has been a tough task. In this study, different conditioning methods were used to treat the ceramic surfaces before bonding. The results showed that sandblasting the ceramic surface prior to application of silane produced the highest shear bond strength which is clinically suitable to reduce bond failures.

Shear bond strength of ceramic brackets after different pre-treatments in porcelain surface

“…It is possible that the micro-retentions generated by CoJet system, whose particles are 30 ìm in size, could be lower than those created by the aluminum oxide blasting (50 ìm particles). These findings agree with Girish et al 21 (2012), who reported that blasting with larger particles (110 ìm) produced higher bond strength values than those found with CoJet. Ozcan 22 (2014), who evaluated the CoJet in ceramic, metal-ceramics, metal-mechanics and metallic substrates, achieved the best results with metallic substrates.…”

Effect of Femtosecond Laser Treatment on the Shear Bond Strength of a Metal Bracket to Prepared Porcelain Surface

“…17 Aluminum oxide sandblasting has been widely used to promote micromechanical retention of ceramics (madani 2000). Many studies 27,28 have shown that Al 2 O 3 sandblasting, combined with silane, significantly increased the bond strength of bracket-to-porcelain surface. Girish et al 27 showed that 50 lm Al 2 O 3 SB for 10 sec without thermocycling enhanced to SBS value (15.18 MPa).…”

“…Many studies 27,28 have shown that Al 2 O 3 sandblasting, combined with silane, significantly increased the bond strength of bracket-to-porcelain surface. Girish et al 27 showed that 50 lm Al 2 O 3 SB for 10 sec without thermocycling enhanced to SBS value (15.18 MPa). This finding is concurrent with results from the current study, because thermocycle can decrease the SBS value.…”

“…However, these results were not consistent with a previous report that the SBS of an SB porcelain surface was higher than that after HF treatment. 27 Using HF may also lead to damage to soft tissue. Therefore, the orthodontist must be careful during HF application.…”

The evolution of bonding in orthodontics

“…This mechanical preparation has been shown to increase adhesion to these surfaces by as much as 100%. 15 After microetching a porcelain crown, the surface was chemically etched with 8% hydrofluoric acid to further increase the adhesive strength. Silane then was applied followed by a bonding adhesive.…”