Which of the following is not an etchant used in dental procedures?

In dental procedures, etchants are substances used to create a roughened surface on teeth or dental materials to promote better adhesion for restorative materials. Citric acid, malic acid, and phosphoric acid are all types of acids that can act as etchants in dentistry.

Citric acid is often used for its ability to remove enamel layer to increase enamel surface roughness for bonding processes. Malic acid can also serve a similar purpose, promoting chemical etching and enhancing bonding efficacy. Phosphoric acid is one of the most widely used etchants in dentistry, specifically for etching enamel and dentin when preparing for adhesive procedures.

On the other hand, Bis GMA (bisphenol A-glycidyl methacrylate) is not an etchant; it is a resin used in dental composite materials. Bis GMA serves as a matrix for restorative materials but does not perform any etching of tooth surfaces. This delineation highlights the differences in functionality among the substances, affirming that Bis GMA is not an etchant used in dental procedures.