Lip Competence
The ability to achieve an anterior oral seal with the lips in a relaxed, natural posture, without muscular strain.
Full Definition
Lip competence describes a state in which the upper and lower lips meet at rest without active muscular effort, providing an anterior seal for the oral cavity. Lip incompetence, by contrast, occurs when there is a gap between the lips at rest, often associated with increased overjet, vertical facial excess, or dentoalveolar protrusion. The distinction is clinically important in treatment planning and is documented in soft-tissue assessments. Editors must distinguish 'lip competence' (a soft-tissue assessment finding) from 'lip seal', which may be used more broadly. In case reports, the findings are typically styled as 'competent lips' or 'incompetent lips'.
Usage
Usage note: Use 'competent lips' or 'incompetent lips' as adjectival forms in clinical descriptions. Do not conflate 'lip incompetence' with habitual mouth breathing, which may co-exist but is a distinct finding.
In Context
- "Clinical examination revealed lip incompetence with a 4 mm interlabial gap at rest." — Orthodontic clinical examination record
- "The soft-tissue assessment should document lip competence separately from mentalis strain." — Case report editorial note