Acid-etch technique

Smith, D. C. (1975). Approaches to adhesion to tooth structure. In Silverstone, L. M. Dogson, I. L. (eds.) The Acid Etch Technique, pp. 119-38. St Paul, Minnesota North Central Publishing Company. 

Simonsen, R. J. "Clinical Applications of the Acid Etch Technique," Quintessence Publishing Co., Chicago, 1978. 

The acid-etch technique of Buonocore cannot be easily applied to dentine, because the process alters the surface of dentine unfavourably. It removes the mineral phase, and leaves behind a coUagen-rich structure that is soft, and which tends to collapse when dried with air. The matted collagen fibre surface that is thereby formed forms weak bonds with organic substances, and this results in low values of bond strengths. These typically lie in the range 5-10MPa [3]. 

Glass-ionomer cements have taken a major place in dental treatments as restorative filling materials and also in a range of more adhesive applications due to their ability to bond to both dentine and composite fillers. Acid-etching techniques are well established for the bonding of resins to enamel. 

An important chromate-free acid etching technique is also available, it is designated the P2 [24] process. Here, as ferrous sulphate replaces the dichromate salts used in the more conventional chromic-sulphuric acid pickling, it is seen as being more friendly to the environment. Although not currently specified as the principle etching process, specifications for pretreatments such as phosphoric acid... 

Direct bonding of orthodontic brackets uses the acid-etch technique, with phosphoric acid gel to etch the surface and deliver the initial pretreatment (Kitayama et al. 2007). This is followed by the application of bonding agents or of lightly filled or completely unfilled resins to the surface. These form attachments to the surface mechanically by flowing into the irregularities created in the etching step. 

While polymeric surfaces with relatively high surface energies (e.g. polyimides, ABS, polycarbonate, polyamides) can be adhered to readily without surface treatment, low surface energy polymers such as olefins, silicones, and fluoropolymers require surface treatments to increase the surface energy. Various oxidation techniques (such as flame, corona, plasma treatment, or chromic acid etching) allow strong bonds to be obtained to such polymers. 

There are numerous metal pretreatment techniques that can be used in addition to solvent degreasing. To obtain metal/polymer systems which exhibit strong initial adhesion it is usually sufficient to wash the metal with a solvent followed by an acid etch or sandblasting technique to remove any weak oxide layers and roughen the surface simultaneously. 

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