Occlusal plane: the bite line and the smile
Quick facts
- Definition
- Imaginary plane passing through the edges of the incisors and the cusps of the molars in the bite.
- Relationship with the smile
- Its tilt influences tooth exposure and the design of the smile arc.
- Reference
- In prosthetics, it is usually oriented by Camper's plane.
- Use in HOF
- Helps understand smile asymmetry, tooth exposure and lip position.
The occlusal plane is an imaginary plane that passes through the edges of the incisors and the cusps of the molars when the teeth meet in the bite. For the dentist, it is a reference for oral rehabilitation. For the HOF professional, it is a clue to how the smile and the lip are organized over the teeth.
How does it relate to the smile?
The tilt of the occlusal plane relative to the horizontal of the face influences three things the patient sees: how many teeth show, how much gum shows and whether the smile looks level. An asymmetric tilt, in which one side sits higher, usually produces a crooked smile, even when the lips are symmetrical.
| Situation | Visible effect on the smile |
|---|---|
| Plane level with the bipupillary line | More balanced smile |
| Plane tilted to one side | Asymmetric smile, with one corner higher |
| Plane tilted steeply upward at the front | Greater incisor exposure |
| Flatter or downward-sloping plane | Fewer teeth visible |
The way to orient the plane in the assessment is to use a clinical reference, such as Camper's plane, which also orients prostheses.
Why does it matter in HOF?
Harmonization is often done together with dentistry, and the occlusal plane is the point where the two meet.
- Smile asymmetry: before blaming the lip or the muscle, check whether the cause is dental. Filling or injecting toxin in an asymmetric smile of occlusal origin does not fix the cause.
- Lip support: the position of the incisors defines lip support. A dental change can alter the contour, and lip filler can end up out of proportion if the tooth changes later. See lips.
- Smile line: the design of the smile arc and the smile line depend on the relationship between teeth, lip and gum.
- Mouth corners: the intercommissural line and the position of the corners relate to the occlusal plane, which matters for the mouth corners.
What about the bite?
Bite changes, such as malocclusion, alter the plane and the facial support. In such cases, aesthetic treatment may be only a complement, and the patient should be guided toward orthodontic or surgical assessment when it makes sense.
Also known as: bite plane, plane of occlusion.
Frequently asked questions
Does the occlusal plane influence the appearance of the lip?
Yes. The position and tilt of the teeth support the lip and define how much shows at rest and in the smile. Dental changes can alter the lip contour.