Geometric Shape of the Crown

Facial & Lingual View

The geometrical shape of the crowns from the facial and lingual view is trapezoidal. The shorter of the two parallel sides is adjacent to the cervix. This geometrical shape is the same for the facial (and lingual) views of all crowns in both the secondary and primary dentitions. This basic geometrical shape means that all crowns taper towards the cervix. The mesial and distal crests of curvature vary amongst the teeth in the dentition, but this basic shape indicates that the mesial and distal crests of curvature of all teeth are either in the middle to incisal (occlusal) thirds of the crowns.

Mesial & Distal (Proximal) View Crown

The geometrical shape of the crowns of the maxillary central and lateral incisors from the mesial and distal view is triangular. The base of the triangle is adjacent to the cervix (or CEJ or cementoenamel junction). This geometrical shape is the same for the proximal (mesial and distal) views of all anterior teeth in both dentitions.

Incisal View

The geometrical shape of the crowns of the maxillary central and lateral incisors from the incisal view is triangular. All of the incisors (maxillary and mandibular) have this basic geometrical shape. The base of the triangle is positioned labially and the apex of the triangle is lingual due to the lingual taper of the crown.

This differs from the canines, which are diamond-shaped from this view, due to their highly developed middle labial lobe.

Dimensionally, the crown of the permanent maxillary central incisor is larger mesiodistally and labiolingually than the permanent maxillary lateral incisor.