Which of the following etching pattern is optimal for bonding?
Three types of etched patterns are noted. They are:

 Type I: Etched enamel surface in which the center of enamel rods is dissolved with periphery intact
 Type II: There is peripheral dissolution of enamel rods
 Type III: It is a combination of the above two patterns

For optimum bond strength, Type I pattern is preferred.
Type 1
Type II
Type III
Type IV