The angle of divergence in the preparation of cast-metal intracoronal restorations:

Cast-metal intracoronal restorations, referred to as inlay restorations, rely on diverging vertical walls that are almost parallel and a luting cement to provide retention of the casting in the tooth . During the initial tooth preparation, the preparation walls are designed not only to provide for draw (for the casting to be placed into the tooth) but also to provide for an appropriate small angle of divergence (2–5 degrees per wall) from the line of draw (to enable retention of the luted restoration). The path of draw is usually designed to be perpendicular to the horizontal features of the preparation. Reference: Sturdevant operative dentistry. 7th edition pg no 128