ANGULATION
Proper Angulation ensures the sharp edge of the Instrument's cutting surface is at the optimum cutting angle to remove calculus as the Instrument is pulled up (see cross section and End View).
Angulation (shown in red in figure) is the angle between the instrument's cutting surface and the tooth surface (see 'end view' looking straight into the tip of instrument). Rotating the Instrument as shown by the large blue arrow increases the Angulation (larger angle).
A typical ideal value is 70 degrees and varies depending on the instrument.
ADAPTATION
Proper Adaptation ensures the Instrument will remove material from the tooth and not harm the patient. Proper Adaptation ensures the Instrument tip is not pointing into the tooth or into the gum too much.
Adaptation (shown in red in figure) is the angle between the Tip center line CL and the tooth surface (see 'top view' looking down at the cutting surface). Rotating the Instrument as shown by the large blue arrow increases the Adaptation Angle (more positive). When CL is parallel with the Tooth Surface then Adaptation Angle is zero degrees. When the Tip points into the tooth (as illustrated) then the Adaptation Angle is negative (-22° in this example) and it is positive when the tip is pointing into the gum (away from the tooth surface).
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It varies depending on the instrument but a typical ideal value is -1 degrees so the first 1 to 2 mm of the tip is in contact with the tooth.
Top View - looking down at the top of the cutting surface along side the tooth surface.