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Parallax Technique — NDEB AFK MCQ

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ModerateRadiology & ImagingParallax TechniqueNDEB AFK

Which radiographic technique is most useful for evaluating the buccolingual position of an impacted maxillary canine?

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

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Correct answer: APeriapical with parallax (tube-shift technique)

The parallax (tube-shift/Clark's rule/SLOB) technique uses two periapical radiographs taken with different horizontal tube angulations. If the impacted tooth moves in the same direction as the tube shift, it is palatal (Same Lingual, Opposite Buccal = SLOB rule). This 2D technique is effective for determining buccolingual position. CBCT provides the definitive 3D assessment but is not always the first investigation.

Reference: White & Pharoah – Oral Radiology: Principles and Interpretation, 8th ed., 2019