bicuspids

Bicuspids, also known as premolars, are the teeth located between the canines and the molars in the human permanent dentition. The term bicuspid reflects their typical two-cusp crown morphology. There are four premolars in the permanent dentition: the maxillary first and second premolars and the mandibular first and second premolars.

In the upper jaw, premolars usually have two cusps and two roots, though variations occur. In the lower jaw, premolars typically have one root, with the first premolar often possessing two roots less commonly. The crowns are generally shorter and broader than canines, with a buccal (facial) and a lingual cusp serving as the main occlusal elevations. Some premolars may present an additional accessory cusp or a three-cusp morphology in rare cases.

Developmentally, premolars replace the deciduous first and second molars, not the canines. Eruption typically occurs in late childhood to early adolescence, around ages 10 to 12, with the first premolars erupting before the second premolars in most individuals.

Functionally, bicuspids assist in tearing and grinding food and help maintain vertical dimensions of the dental arch during chewing. They also participate in guiding occlusion and distributing bite forces between the canines and molars.

Clinical relevance includes their susceptibility to caries and wear at the cusps, their common involvement in orthodontic space management, and standard endodontic procedures when necessary. Variations in cusp number, root anatomy, and eruption timing may influence diagnosis and treatment planning.