Fig. 1. Measurement and classification of the impacted third molar. Spatial relationship was classified based on the angle measured between the long axis of the impacted third molar and adjacent second molar (yellow line and an asterisk mark). Depth was classified based on the line connecting the cervico-enamel junction (CEJ) of the adjacent second molar (dotted blue line). Ramus relationship/space available was subcategorized based on the ratio between the distance from the ascending ramus to the distal of second molar (a) and the diameter of the impacted third molar (b) (pink arrows).