Radiographic Position of Impacted Mandibular Third Molars and Their Association with Pathological Conditions

Figure 3

Pell and Gregory classification of ramus relation. (a) Class I: sufficient space available between the anterior border of the ascending ramus and distal side of the second molar for third molar eruption. (b) Class II: the space available between the anterior border of the ascending ramus and distal side of the second molar is less than the mesiodistal width of third molar’s crown. It indicates that ascending ramus bone is covering the distal portion of the third molar crown. (c) Class III: absolute lack of space is observed; the third molar is totally embedded in the ascending ramus bone.

(a)

(b)

(c)