skip to main content

Leeway Space — NDEB AFK MCQ

Instant feedback + full explanation. One question, done properly.

ModerateOrthodonticsLeeway SpaceNDEB AFK

The 'leeway space' in the mixed dentition refers to which of the following?

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

Reveal the answer and explanation

Correct answer: D — The difference in mesiodistal width between the primary canines + molars and their permanent successors (canines + premolars)

Leeway space (Nance) is the difference in combined mesiodistal widths between the primary canine + first molar + second molar (C + D + E) and their permanent successors (canine + first premolar + second premolar, 3 + 4 + 5). The primary teeth are larger, leaving approximately 1.7 mm of excess space per side in the mandible and 0.9 mm in the maxilla. This space is available for mesial drift of the first permanent molar and late lower incisor alignment.

Reference: Proffit – Contemporary Orthodontics, 6th ed., 2019