The superior border of a mandibular lingual bar major connector should be located at least how far from the free gingival margin?

Correct answer: A. 3 mm

• A. CORRECT. A minimum of 3 mm of clearance between the superior border of the lingual bar and the free gingival margin prevents impingement on the marginal gingiva, allows food clearance and permits oral hygiene access. Closer than this and the connector traumatizes the gingiva and drives inflammation.
• B. 7 mm is well beyond the floor-of-mouth depth available in most patients.
• C. 1 mm places the connector directly against the gingival margin and will produce tissue damage.
• D. 5 mm is more clearance than required and would push the connector unnecessarily far into the floor of the mouth, compromising comfort.

Note: The arithmetic that matters: a lingual bar needs a half-pear cross-section about 4–5 mm in height, plus 3 mm of gingival clearance, so you need at least 8 mm of vertical depth from the floor of the mouth to the free gingival margin. Measure it with a periodontal probe with the tongue elevated. Under 8 mm, switch to a lingual PLATE.