Influence of various surface-conditioning methods on the bond strength of metal brackets to ceramic surfaces

Abstract

With the increase in adult orthodontic treatment comes the need to find a reliable method for bonding orthodontic brackets onto metal or ceramic crowns and fixed partial dentures. In this study, shear bond strength and surface roughness tests were used to examine the effect of 4 different surface conditioning methods: fine diamond bur, sandblasting, 5% hydrofluoric acid, and silica coating for bonding metal brackets to ceramic surfaces of feldspathic porcelain. Sandblasting and hydrofluoric acid were further tested after silane application. A total of 120 ceramic disc samples were produced, and 50 were used for surface roughness measurements. The glazed ceramic surfaces were used as controls. Metal brackets were bonded to the ceramic substrates with a self-curing composite. The samples were stored in 0.9% NaCl solution for 24 hours and then thermocycled (5000 times, 5 degrees C to 55 degrees C, 30 seconds). Shear bond tests were performed with a universal testing device, and the results were statistically analyzed. Chemical surface conditioning with either hydrofluoric acid (4.3 microm) or silicatization (4.4 microm) resulted in significantly lower surface roughness than mechanical conditioning (9.3 microm, diamond bur; 9.7 microm, sandblasting) (P <.001). The surface roughness values reflect the mean peak-and-valley distances. The bond strengths of the brackets bonded to the ceramic surfaces treated by hydrofluoric acid with and without silane (12.2 and 14.7 MPa, respectively), silicatization (14.9 MPa), and sandblasting with silane (15.8 MPa) were significantly higher (P <.001) than those treated by mechanical roughening with fine diamond burs (1.6 MPa) or sandblasting (2.8 MPa). The highest bond strength values were obtained with sandblasting and silicatization with silane or hydrofluoric acid without silane; these fulfilled the required threshold. The use of silane after hydrofluoric acid etching did not increase the bond strength. Diamond roughening and sandblasting showed the highest surface roughness; they can damage the ceramic surface. Acid etching gave acceptable results for clinical use, but the health risks should be considered. The silicatization technique has the potential to replace the other methods; yet cohesive failures were observed in the ceramic during removal of the brackets.

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

“…7 The second highest shear bond strength was seen in the group conditioned with hydrofluoric acid and silane combination. This result is concurrent with the results of a study conducted by Schmage P et al 5 Zachrisson Y, Zachrisson B and Buyukyilmaz T 2 had conducted a study, in which he concluded that silane application after sandblasting the ceramic surface significantly increases the bond strength of metal brackets bonded to ceramic surface, which is concurrent to the results obtained in our study.…”

“…However, the results obtained in the past studies are contradictory, showing that using silane with hydrofluoric acid does not increase the bond strength. 5 Few of the drawbacks of the previous studies are that some of them have used denture teeth, which are burned at considerably higher temperatures and have properties that differ significantly from the feldspathic porcelains commonly used for porcelain crowns. Furthermore, most of the earlier studies have not included storage in artificial saliva before the testing.…”

Adhesion of metal brackets to glassy matrix and hybrid CAD/CAM materials after different physico-chemical surface conditioning

“…In this study, the polished surfaces of VE and LU, and the glazed surfaces of VM and IP, representing the control group, were removed by a fine diamond bur (63 µm). Roughening with diamond burs without silane application was shown to decrease the bond strength compared to roughening with HF acid etching and silane application or Al 2 O 3 air-abrasion and silane application alone [27]. Thus, considering also the low control group results, initial mechanical roughening is crucial prior to bracket bonding.…”

Rapid bonding and easy debonding of orthodontic appliances with 4-META/MMA-TBB resin using thermal heating

“…The shear bond strength of orthodontic brackets bonded with modern bonding materials exceeded 6-8 MPa, thereby rendering sufficient strength for orthodontic treatment [27][28][29][30] . This guideline was based on a report that a minimum bond strength of 5.9-7.9 MPa allowed satisfactory clinical performance and successful clinical bonding in orthodontic treatment 31) .…”