INTRODUCTION
- Acid etching is a process by which naturally smooth tooth surface is roughend to create micromechanical interlocking of surfaces.
- the end point of etching is creation of irregular tooth surface that appears frosty white due to light refraction.
- recommended etching time to prepare the enamel surface for bonding is 15-20 sec.
- primary teeth-60 sec.
- teeth effected by fluorosis-60-120 sec.
- 37% phosphoric acid is ideal concentration for the purpose.
Types
- liquids
- gels
LIQUIDS- useful when-
- larger surface area is to be etched as they flow easily.
- surfaces have deep grooves or fissures as it easily penetrates the irregularities.
- applied using-
- small cotton pellets
- foam sponges
- micro sponges
- special applicator tips
GELS-
- They were developed by adding small amount of micro fillers or cellulose as thickening agents.
- they show less flow and higher viscosity.
- useful when controlled applications are required such as preparation walls, bevels and margins.
- applied using-
- brushes
- paper points
- syringe applicators.