Özet:

he challenges the orthodontist face is how to increase bond strength between the brackets and tooth, various ceramic restorations or porcelain crowns. Bond strength can be affected by bracket type and design of their base, bonding adhesive, or etching technique. Aim: To evaluate and compare the effects of sandblasting and hydrofluoric acid etching on shear bond strength (SBS) of metallic orthodontic brackets, bonded to porcelain crowns surfaces used for prosthetic restorations. Silane coupling agent was used as bond strength enhancer in both the cases. Methodology: Thirty porcelain maxillary central incisor crowns were used in the study. The crowns were divided randomly into two groups: Group H- the porcelain crowns were etched with 9% hydrofluoric acid followed by application of silane and the brackets were bonded with a composite adhesive, Group S the porcelain crowns were microetched with 50 microns Al2O3 particles followed by silane application and metal brackets were then bonded with the composite adhesive. All bonded crowns were stored in distilled water for 1 week at 37.8 0C before debonding. Result: The mean Shear bond strength values were significantly higher (p=0.001) in Sandblasting group than 9% Hydrofluoric acid with the mean±SD values as 12.6493±1.15084 and 7.4540±.54742 respectively. However, all SBS values in the present study were above the optimal range for orthodontic bonding (6-8MPa), rendering them clinically acceptable

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