premolars

Premolars, also known as bicuspids, are a class of permanent teeth located between the canines and molars in the upper and lower jaws of most mammals, including humans. They serve as transitional teeth that help convert the tearing action of canines into the grinding function performed by molars.

Function and anatomy: Premolars assist in chewing by both tearing and crushing food. They typically have one or two cusps on the occlusal surface, with shapes that support both shearing and grinding motions. In humans, maxillary first premolars commonly have two cusps and two roots, while maxillary second premolars often have two cusps and a single root. Mandibular premolars usually have one root, though root anatomy can vary. Each premolar develops from dental tissue and contains a pulp chamber with nerves and blood vessels, protected by enamel and dentin.

Eruption and development: In humans, premolars replace deciduous teeth and typically erupt in late childhood to early adolescence. The first premolars appear around ages 10 to 11, and the second premolars around ages 11 to 12. Variations in root number, cusp pattern, and presence of accessory canals are common among individuals.

Clinical relevance: Premolars are common sites for dental caries and fractures due to their position and occlusal load. They are often involved in orthodontic treatment planning and restorative procedures because their location bridges the canine and molar regions.

Evolution and variation: Across mammals, premolars vary in number, cusp arrangement, and size, reflecting dietary adaptations. In some species, premolars are more specialized for grinding, while in others they retain more of a piercing function similar to canines.