When using composite resin, what must be done to the tooth surface?

When using composite resin, etching the tooth surface is a critical step in the bonding process. Etching typically involves applying an acid solution, commonly phosphoric acid, to the enamel and dentin. This process creates micro-roughness on the surface of the tooth, allowing for better mechanical retention of the composite material once it is applied.

This roughened surface increases the surface area available for adhesion and helps to create a more stable bond between the composite resin and the tooth. The resin can flow into the microscopic pores and irregularities that are created through etching, making the bond stronger and more durable, which is essential for the longevity of the restoration.

Other methods, such as polishing, coating with fluoride varnish, or ensuring the tooth is dried thoroughly, do not fulfill the primary requirement for creating an effective bond with composite resin. While drying may be necessary prior to etching or applying the resin, it does not contribute to the actual bonding process like etching does. Therefore, etching the tooth surface is a fundamental and indispensable step in the successful placement of composite resin materials.