Which technique is used to enhance the bond of sealants to the tooth surface?

Etching the enamel is the correct technique used to enhance the bond of sealants to the tooth surface. This process involves applying a mild acid, typically phosphoric acid, to the enamel. The acid creates microscopic irregularities on the tooth's surface, increasing the surface area and providing a more conducive environment for the sealant to adhere properly. This improved mechanical retention is crucial for the long-term success of the sealant in protecting against decay.

The etching process is essential because it enhances the bonding strength, ensuring that the sealant remains in place and effectively shields the tooth from bacteria and food particles that can lead to cavities. By creating this textured surface, the sealant can penetrate into the enamel, which significantly improves retention.

Other techniques listed do not effectively enhance the bond in the same way. Frictional cleaning refers to a method for cleaning the tooth surface, which may remove debris but does not improve the chemical or mechanical bonding of sealants. Chemical bonding generally involves chemical interactions that can occur with certain materials but requires specific properties not applicable in this context. Mechanical smoothing might contribute to aesthetics or comfort but does not enhance the bond strength as etching does. Thus, etching the enamel is the established best practice for sealant application.