The term bicuspid refers to eight of the 32 permanent teeth. There are no bicuspids in primary teeth, and they grow in to replace primary molars. Two bicuspids are on each side of the upper and lower jaw, behind the canine teeth and in front of the molars. They are also commonly known as premolars, due to their placement in the jaw. The bicuspids typically grow in at 10 to 12 years of age.
Dental notation systems describe teeth by noting their location in the mouth, either with a numerical designation or by name. The mouth can be divided into quadrants to specify location by describing upper or lower, left or right. The upper and lower designations are also referred to by the name of the jawbone, with the upper term being maxillary and the lower being mandibular. When specifying a location-based name for the bicuspids, it is common to refer to the first and second bicuspid, with the first being the tooth closer to the front of the mouth.
Cusps or cuspals are the high points on a tooth, which are used for chewing and tearing. Canine teeth, bicuspids, and molars all have cusps. Bicuspids typically have two cusps, one on the cheek or buccal side of the tooth, and one on the tongue or lingual side. Although bi is the prefix for two, a bicuspid tooth will sometimes have three cusps, with two on the lingual side.
Bicuspid teeth are described as transitional teeth, as their function is between that of the canines and the molars. Teeth have a specialized function for handling food as it is transferred from the front to the back of the mouth while chewing. The shape of the incisors and canines is ideal for cutting or tearing food, while the bicuspids are ideal for crushing and the molars for grinding. Bicuspids are shorter than the canines and smaller than the molars.
The primary molars are larger than the bicuspids that eventually replace them. Their smaller size may naturally correct overcrowding of teeth in smaller mouths. It is not unusual for one or more to be missing naturally, and they are also commonly removed to correct ongoing issues with overcrowding. They are usually the first choice if removal is necessary because they are not as prominent or visible as teeth in the front of the mouth, and their absence has less of an impact on the appearance of the smile.
Most bicuspid teeth have one root. Two is not uncommon, particularly in the upper teeth. In rare cases, the first bicuspid in the upper jaw, also known as the maxillary first bicuspid, can present with three roots. Additional roots can make extractions more complicated.
As they are permanent teeth, bicuspids should not wiggle in the mouth. A dentist should be consulted if a bicuspid appears to be loose. As with any tooth, a dentist should also be consulted if there is pain or any evidence of damage following an impact or injury.