Surface pretreatment in orthodontic bonding

With the advent of acid etching to dental enamel in 1950 adhesion was introduced to dentistry .Acid etching creates a selective dimeralization and increases the free surface energy,enamel porosity and surface area Adhesion to enamel is dependent on resin capacity to penetrate between rods and crystals which results in micromechanical retention.Infiltrated resin encapsulates individually hydroxyapetite crystals and creates micro tags and constitutes the hybrid layer which promotes nanoretetention mechanism between dental structure and dental material