Introduction
The contours of the crown, the proximal contacts and the embrasures around them steer food away from the gingiva, keep the teeth stable in the arch and give the interdental papilla its space. Every restoration of a proximal, facial or lingual surface must rebuild them; mistakes cause food impaction, gingivitis, secondary caries and bone loss.
Physiological contours
- Height of contour (crest of curvature): the most prominent point of the facial or lingual surface. It lies in the cervical third on the facial surfaces of all teeth and the lingual surfaces of anterior teeth, and in the middle third on the lingual surfaces of posterior teeth.
- The cervical convexity projects only about 0.5 mm beyond the CEJ. It deflects food over the gingival margin while leaving the surface open to self-cleaning and brushing.
- Emergence profile: the contour of the tooth or restoration where it leaves the gingival sulcus. It should be flat, continuing the root surface without a step or bulge.
- Over-contouring creates a plaque-retentive bulge at the gingival margin → gingivitis; under-contouring lets food strike the gingival margin → gingival irritation.
Over-contouring is the more common and more harmful error: in the cervical third a restoration should rather be too flat than too bulky.