These barrier envelopes also help to protect the x-ray plates. The premium plastic material is tough and prevents the plates from getting scratched, dented, or damaged while in the patient’s mouth. By using dental X-ray barriers. You can maximize the service life of each plate, which helps cut down on the practice’s expenses as well.

  • Effectively removes the smear layer.
  • Demineralizes enamel and dentin.
  • Perfect viscosity.
  • Highly visible.
  • Rinses away cleanly.

Moreover, phosphoric acid is not only used for etching enamel and dentin surfaces within dental bonding procedures but can also be used as an intra- and extra-oral cleaning agent for tooth structure and dental restorations. One of the major advantages of a phosphoric acid gel etchant in dentistry is its superior control during placement procedures.

Characteristics Of Phosphoric Acid Etching Gel

Etching gel has non-slumpy consistency, allows precise application and is generally blue in colour which makes it highly visible. Moreover, it is easily rinsed with minimum effort. Etching gel roughens the surface, increases retention of sealant, and promotes mechanical retention for composite restorations for inlays, crowns, bridges, veneers, root canal posts splints, orthodontic brackets, and pit and fissure sealing.

Types of acid:

The concentration of etching gel usually contains phosphoric or hydrofluoric acid.


The actual concentration percentage varies depending on whether it is phosphoric or hydrofluoric. However, phosphoric acid is commercially available in concentrations between 30% and 40%, with 37% being the most common. On the other hand, hydrofluoric acid is usually used in concentrations between 5% and 10%.

The Viscosity:

The ideal etching gel should have an appropriate viscosity that facilitates its precise application. The etching gel having the property of thixotropy allows it to flow and become more viscous when it is applied and does not run off the tooth’s surface.


The etching gel can be presented in both liquid and gel form. In both cases, they can be in syringe or canister format.

Directions For Etching Gel:

The etching gel is a water-based, 40% phosphoric acid gel. The gel is blue in colour for better visibility and easy identification against tooth structure. Etching gel is generally applied using a syringe with a dispensary needle attached. The gel is applied directly to the tooth enamel, covering all the angles and keeping the acid from the dentin. Then the acid gel is left in place for 15 seconds. 

Usually, a 90 to 120-second etch is recommended on primary teeth with high fluoride content. After that, the gel is rinsed thoroughly for 20 seconds. Then dried with air that is water and oil-free.


What Does Etching Gel Do To Teeth?

Etching gel dissolves some of the minerals in the dentin and enamel, the two outer layers of teeth. This steady erosion creates rough features called “tunnels and tags” that can absorb bonding resin chemically and can physically lock it into place on the dentin and enamel surface.

Why is An Etching Gel Required?

Unlike amalgam fillings that use mechanical retention and undercut, composites are chemically bonded to the tooth surface. Since the tooth’s enamel is extremely hard and shiny, bonding agents do not adhere, requiring the tooth surface to be conditioned. The conditioning is performed using etching gels.

The etching gel is placed on the enamel portions of the tooth and is left in place for 15 seconds. When it is washed off, the shiny surface appears frosted or chalky. Under a microscope, the surface looks rough and jagged. These microscopic irregularities are filled with a bonding agent that hardens in place.

What Are The Different Acid Etching Techniques?

After deciding the type of etching gel, it is important to select the technique that best suits the type of treatment one carries out. There are different techniques depending on the procedure, the size of the restoration, and according to the material the restoration is made of. There are generally 3 different basic acid etching techniques:

Total Acid Etching:

The total acid etching technique refers to dentin and enamel etching. In enamel, the acid etching pattern creates micromechanical retention. In dentin, due to its tubular structure and organic composition, the effect is to expose its collagen matrix so that hydrophilic monomers can penetrate.

Selective Etching:

This refers only to applying phosphoric acid to the surface of the superficial enamel rim. It is perfect for patients who tend to have sensitivity in the deep areas of their teeth.


The universal adhesive includes the etchant, which should be applied on dentin or enamel that was not previously etched.

Can Etching Gels Harm Your Teeth?

The demineralization of the enamel in the tooth, caused by acid etching, does not usually damage or harm the form and function of teeth. However, one should follow some precautionary measures to prevent potential risks. Always make sure to wear protective gloves while applying the etching gel, and use clothing and eye/face protection. If swallowed, rinse your mouth immediately. If it falls on the skin or hair, remove all contaminated clothing and wash it thoroughly.

Why is The Concentration of Phosphoric Acid 37% in Etching Gels?

Using 37% phosphoric acid for orthodontic bonding yields high bond strength and causes enamel loss during etching and debonding. It provides adequate bond strength with a more conservative etch pattern and enables easy debonding, reducing enamel damage.

How Long Should The 37% Phosphoric Acid Etchant Be Applied Simultaneously To Enamel and Dentin?

The acid etchant in the form of liquid or gel should be at least applied on the tooth surface for about 10 to 15 seconds. However, deciduous teeth require a longer time for etching than permanent teeth because of the presence of aprismatic enamel. After that, the etching gel should be washed continuously for 10 to 15 seconds.

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