Which is a clinical extra-oral sign specific for deep bite?

Which is a clinical extra-oral sign specific for deep bite?

• A. Increased lower 1/3 face
• B. Leptoprosop facial type
• C. Diminished lower 1/3 face
• D. Forced lip competence

Answer: (C)

The main idea here is that deep bite often alters the vertical relationship between the teeth and the lower facial soft tissues. When there is an excessive vertical overlap of the incisors, the visible height of the lower third of the face is reduced, so the lower facial region appears shortened. This diminished lower 1/3 of the face is a distinctive extra-oral sign of a deep bite because it directly reflects the vertical constriction created by the occlusion. In contrast, a longer lower face (increased lower facial height) is typical of vertical excess or an open bite pattern, not a deep bite. Leptoprosopic refers to a long, narrow facial type, which isn’t specific to deep bite. Forced lip competence describes lip posture and can occur with various occlusions, so it isn’t specific to deep bite either.

The main idea here is that deep bite often alters the vertical relationship between the teeth and the lower facial soft tissues. When there is an excessive vertical overlap of the incisors, the visible height of the lower third of the face is reduced, so the lower facial region appears shortened. This diminished lower 1/3 of the face is a distinctive extra-oral sign of a deep bite because it directly reflects the vertical constriction created by the occlusion.

In contrast, a longer lower face (increased lower facial height) is typical of vertical excess or an open bite pattern, not a deep bite. Leptoprosopic refers to a long, narrow facial type, which isn’t specific to deep bite. Forced lip competence describes lip posture and can occur with various occlusions, so it isn’t specific to deep bite either.