A patient repeatedly bites the lips. What is the most likely cause?

Patient case: Counselling, implant planning and occlusal vertical dimension

Scenario: Four items.

Show answer and explanation

Correct answer: B. Inadequate overjet

A. A deep overbite can traumatise the palatal mucosa or the labial gingiva of the lower incisors, but it does not trap the lip.
B. Correct. When the upper anterior teeth do not project sufficiently in front of the lowers, the lip has nowhere to sit and gets caught between the teeth during closure and speech.
C. Inadequate freeway space produces the same overclosure-related complaints, again through a different mechanism.
D. An excessive vertical dimension causes a strained appearance, difficulty closing the lips, clicking teeth and soreness — not repeated lip biting.

Note: Cheek biting has the analogous cause in the posterior segment — insufficient horizontal overlap of the buccal cusps.