Table 1.

Koerner difficulty index scale for removal of mandibular impacted third molar.

Classification difficulty index	Value
Angulation
Mesioangular	1
Horizontal	2
Vertical	3
Distoangular	4
Depth
Level A	1
Level B	2
Level C	3
Ramus relationship
Class I	1
Class II	2
Class III	3
Difficulty index
Slightly difficult	3–4
Moderately difficult	5–7
Very difficult	8–10