Enamel, acid etching pretreatment

Acid etching pretreatment of enamel, such as the use of buffered 50% phosphoric acid solutions, has found clinical applications to bond enamel to restorative materials, sealants and orthodontic brackets (4, ). The etching creates an increased enamel surface area and opens pores into which the resin can flow. Greater porosity of the substrate allows an easier ingress of un-... 

Acid etching pretreatment of dentin prior to application of a resin restorative leaves the collagenous component of this substrate substantially untouched. The collagen at the dentin surface interferes with the mechanical adhesion of the hydroxyapatite, (the inorganic constituent of dentin) to the adhesive. Thus, in contrast to its successful use with enamel, etching pretreatment produces a bond between dentin and restorative resin that is too weak to withstand the forces encountered at the interface under clinical conditions. 

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