A patient arrives at your office with their full gold crown in hand. They explain to you that another dentist delivered it last week. You then examine the crown and the preparation. Which of the following hand instruments is used for creating retentive features in dentin ?
A special type of excavator is the angle former. It is used primarily for sharpening line angles and creating retentive features in dentin in preparation for gold restorations. It also may be used when placing a bevel on enamel margins. The angle former is mon-angled and has the primary cutting edge at an angle (other than 90 degrees) to the blade.
 
Ref:   Sturdevant's art and science of operative dentistry page e4
Enamel hatchet
Angle former
Straight chisel
GMT