Final answer:
Enamel etching with phosphoric acid is used to roughen the surface and open enamel pores before applying sealants, enhancing the adhesive bond for better retention and protection against decay.
Step-by-step explanation:
The retention of the sealant is obtained by etching the enamel with phosphoric acid, which is used to roughen and to open the pores in enamel. This process significantly improves the adhesive bond between the tooth surface and the sealant.
When the enamel is etched, it becomes rougher at a microscopic level. This rougher surface increases the surface area available for the bonding agent often part of the sealant to adhere to. Additionally, the etching process opens the pores in the enamel, allowing the sealant to penetrate more deeply and bond securely to the tooth.
The purpose of etching before applying sealant is akin to sanding a wall before painting: to ensure a stronger bond and to maximise retention of the sealant. It is a critical step in the application of sealants and is essential for the prevention of dental caries and the protection of the underlying dentin and pulp cavity from bacterial acids that cause decay.