Pell Gregory Class III — MFDS Part 1 MCQ

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ModerateOral Surgery PrinciplesPell Gregory Class IIIMFDS Part 1

On panoramic radiographic assessment, which relationship between an impacted mandibular third molar and the anterior border of the ascending ramus defines Pell and Gregory Class III?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: C — Most or all of the third-molar crown lies within the ramus

Explanation lettering: C = shown as A · E = shown as B · A = shown as C · B = shown as D · D = shown as E

Pell and Gregory Class III means that most or all of the mandibular third molar lies within the ascending ramus, reflecting minimal or absent space distal to the second molar. Adequate space for the complete mesiodistal crown width describes Class I, whereas reduced space with only partial ramus overlap describes Class II. Options D and E describe the separate depth component of the Pell and Gregory system: positions A and C, respectively, rather than the Class I–III ramus relationship. Although Class III anatomy may complicate access, it should not automatically be described as the most difficult extraction because UK Faculty of Dental Surgery guidance notes that the Pell and Gregory classification alone is an unreliable predictor of operative difficulty.

Reference: Fernandes IA et al. Pathologic conditions associated with impacted third molars: A retrospective study of panoramic radiographs in a Southern Brazilian population, Pell and Gregory classification figure, 2024. https://www.rcseng.ac.uk/-/media/files/rcs/fds/guidelines/3rd-molar-guidelines--april-2021.pdf