Introduction
Every denture edge, every crown margin and every impression meets the soft tissues of the mouth. Knowing their landmarks tells you where a prosthesis may rest, where it must stay clear and where it can be dislodged.
Borders and divisions
The dental arches and alveolar processes split the cavity in two:
- Oral vestibule: the space between the arches and the lips and cheeks. Its depth (lower jaw) or height (upper jaw) is the vestibular fornix.
- Oral cavity proper: everything inside the arches.
The lining
The oral mucosa has two layers: stratified squamous epithelium on the surface and connective tissue underneath. How thick and how keratinized it is depends on the job it does.
Lips
- Upper and lower lips meet at the left and right commissures.
- The nasolabial groove runs from each nostril to the corner of the mouth; the labiomental groove runs across, between lower lip and chin.
- The vermilion border is the red zone of the lip; its junction with facial skin is the mucocutaneous margin.
- The tubercle is the small bulge in the middle of the upper lip; the groove from it up to the nose is the philtrum.