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Pell and Gregory Classification — MFDS Part 1 MCQ

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ModerateOral Surgery PrinciplesPell and Gregory ClassificationMFDS Part 1

On a panoramic radiograph, which pair of relationships is used in the Pell and Gregory classification of an impacted mandibular third molar?

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

Reveal the answer and explanation

Correct answer: A — Vertical depth relative to the adjacent second molar and available space relative to the anterior border of the ramus

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

The correct answer is A. The Pell and Gregory classification has two components. Positions A, B and C describe the vertical depth of the third molar relative to the occlusal plane and cervical level of the adjacent second molar. Classes I, II and III describe the space available between the distal aspect of the second molar and the anterior border of the mandibular ramus. Angulation relative to the second molar is assessed by Winter’s classification, so B combines a different classification with inferior alveolar canal risk assessment. Follicular width, crown or root morphology, root number and buccolingual position may be relevant to radiographic or surgical assessment but do not define the Pell and Gregory system.

Reference: García AG, Sampedro FG, Rey JG, Vila PG, Martin MS. Pell-Gregory classification is unreliable as a predictor of difficulty in extracting impacted lower third molars. British Journal of Oral and Maxillofacial Surgery. 2000;38(6):585–587. https://pubmed.ncbi.nlm.nih.gov/11092770/