Effect of bonding material, etching time and silane on the bond strength of metallic orthodontic brackets to ceramic

Abstract

The purpose of this study was to evaluate the bond strength of metallic orthodontic brackets to feldspathic ceramic with different etching times, bonding materials and with or without silane application. Cylinders of feldspathic ceramic were etched with 10% hydrofluoric acid for 20 or 60 s. For each etching time, half of the cylinders received two layers of silane. Metallic brackets were bonded to the cylinders using Transbond XT (3M Unitek) or Fuji Ortho LC (GC). Light-activation was carried out with total exposure time of 40 s using UltraLume 5. Shear bond strength testing was performed after 24 h storage. Data were submitted to three-way ANOVA and Tukey's test (α=0.05). The adhesive remnant index (ARI) was used to evaluate the amount of adhesive remaining on the ceramic surface at ×8 magnification. Specimens etched for 60 s had significantly higher bond strength compared with 20 s. The application of silane was efficient in increasing the shear bond strength between ceramic and both fixed materials. Transbond XT showed significantly higher (p<0.05) bond strength than Fuji Orth LC. There was a predominance of ARI score 0 (clean ceramic failure surface) for all groups, with an increase in scores 1, 2 and 3 (adhesive material increasingly present on ceramic failure aspect) for the 60-s etching time. In conclusion, 60-s etching time, silane and Transbond XT improved significantly the shear bond strength of brackets to ceramic.

Influence of different treatments of the ceramic surface and thermal cycling on the bond strength of brackets to ceramic

“…However, bonding orthodontic brackets to ceramic surface needs special care because they can exhibit a higher degree of failure in relation to enamel bond 2 . On the other hand, some studies showed no negative effects on ceramic surface, since the most failures was adhesive between the bonding material and the ceramic surface [3][4][5] .…”

“…Normally, hydrofluoric acid (HF) has been used in orthodontics for etching ceramic surfaces for 60 s, where the orthodontic bracket is bonded 3 . HF acid is an efficient surface modification agent that is capable of dissolving the glassy ceramic matrix, increased the roughness 6 , contact surface and wettability 7,8 , promoting higher bond between bonding materials and ceramics [9][10][11] .…”

“…HF acid is an efficient surface modification agent that is capable of dissolving the glassy ceramic matrix, increased the roughness 6 , contact surface and wettability 7,8 , promoting higher bond between bonding materials and ceramics [9][10][11] . The application of hydrofluoric acid followed by a silane solution have been used prior to bonding glass ceramic to increase the bond strength and durability between brackets and ceramic surface 3,12,13 or luting glass ceramic restorations 12 .…”

“…Another fact that can influence the bond strength between the ceramic surface and the bracket surface is the thermal cycling when bonding resin is used 3,16 . The thermal cycling test has been recommended and used to verify if temperature changes may influence the reduction of bond strength values between the ceramic surface, bonding materials and brackets 2 .…”

“…ARI values showed a predominance of debonding failures with score 0 (no bonding resin on the ceramic surface). Clinically, this fact may be advantageous because there is less bonding material to remove from the ceramic surface after bracket debonding [2][3][4] . In summary, the results of this study showed that acid etching before CCP silane influenced significantly the SBS.…”