Lip Competence
The ability of the lips to achieve a comfortable, unstrained seal at rest, an important aesthetic and functional outcome measure in orthodontic treatment.
Full Definition
Lip competence describes a resting state in which the upper and lower lips meet naturally along their full width without muscular effort. Incompetent lips — those that fail to meet at rest — are associated with increased overjet, a hyperdivergent skeletal pattern, or bimaxillary proclination, and carry implications for long-term stability of orthodontic treatment outcomes. The term is distinct from 'lip seal', which can occur even with some strain (a 'lip trap' is a related but separate phenomenon). In editorial contexts, 'competent' and 'incompetent' are clinical descriptors and should not be interpreted in their lay sense.
Usage
Usage note: In clinical writing, 'competent' and 'incompetent' are technical descriptors. Flag any usage where these terms appear in a lay evaluative sense.
In Context
- "Lip competence was restored following retraction of the upper incisors and reduction of the overjet." — Treatment outcome report
- "The patient demonstrated lip incompetence at rest, with the lower lip trapped behind the upper incisors." — Clinical examination record