What concentration of phosphoric acid is typically used in acid etch technique?

The acid etch technique commonly employed in dentistry utilizes a concentration of phosphoric acid around 35%. This concentration is effective for creating a proper surface profile on enamel and dentin, enhancing the bond between the tooth structure and the subsequent dental materials, such as composites and sealants. A 35% phosphoric acid solution provides an optimal balance: it is strong enough to effectively remove the smear layer and create micro-retentive features on the enamel and dentin, but not so strong that it risks damaging the underlying tooth structure due to excessive demineralization.

Lower concentrations, such as 10% or 20%, may not sufficiently prepare the surface for bonding, resulting in inadequate retention. Conversely, while a 50% concentration could be effective for etching, it carries a higher risk of damaging the tooth structure and potentially causing sensitivity or other complications. Therefore, the 35% concentration is the standard used in dental practices for preparing surfaces in restorative procedures.