Artificial teeth: cuspal inclination is chosen before the shade

The choice of artificial teeth focuses almost always on shade and form, and almost never on cuspal inclination. That is the reverse of the order determining how the denture will function.

Available cuspal degrees typically range from zero to thirty-three. The number indicates the angle of the cusps relative to the horizontal plane, and determines how the denture behaves during movement.

Thirty-three-degree teeth have pronounced cusps, good masticatory efficiency and a natural appearance. They require favourable intermaxillary relationships and well-preserved ridges, however, because steep cusps generate horizontal force components that destabilise the base.

Zero-degree teeth, without cusps, generate no lateral force at all. They are indicated on severely resorbed ridges and in unfavourable intermaxillary relationships, where stability matters more than efficiency.

Twenty degrees represents the most used compromise: acceptable masticatory efficiency with contained lateral forces. It is the reasonable choice when nothing pushes towards either extreme.

On an implant overdenture the logic changes. Implants supply the stability a conventional denture lacks, which permits teeth with more pronounced cusps without the risk of unseating the base.

Among materials, acrylic teeth have the advantage of bonding chemically to the base, itself acrylic. It is a true bond, not mechanical, and the reason a tooth detaching from the base is rare.

The limitation is wear: acrylic abrades faster than enamel and, in dentures worn for years, this produces a progressive loss of vertical dimension.

Composite teeth offer superior wear resistance while retaining the chemical bond to the base. They are the most balanced choice for dentures intended to last, and for patients with natural antagonists.

Porcelain teeth have the lowest wear of all, but do not bond chemically: retention is mechanical, via pins or cavities. They are brittle and wear the natural antagonist, and for these reasons their use has greatly declined.

The form of anterior teeth is selected in relation to the face, with a practical rule that survives scrutiny: the inverted outline of the central incisor tends to match the contour of the face.

Setting, however, matters more than selection. Excellent teeth set without respecting the midline, occlusal plane and lip support give a poorer result than ordinary teeth set with judgement.

In summary: choose cuspal degree first, according to ridges and intermaxillary relationships; then material, according to the antagonist and expected service life; then form and shade. The reverse order produces dentures that look good and are unstable.