Patient-friendly definition from the DentistsDirectory.org dental glossary.
Canines — also called cuspids or eye teeth — are the four pointed teeth located at the corners of the mouth, one in each quadrant. They are the longest teeth in the human dentition, with roots extending deep into the jaw, and are among the strongest and most stable teeth in the mouth. Their pointed single cusp is designed for gripping and tearing food.
Beyond tearing food, canines play a critical role in guiding the bite. In a healthy bite, when the jaw moves sideways, the upper and lower canines come into contact first and separate the back teeth from touching each other — a protective mechanism called canine guidance. This protects the molars and premolars from the lateral forces of sideways chewing movements, which those teeth are not designed to withstand. Loss of canines or significant wear to them can shift these lateral forces onto the back teeth, contributing to cracking and accelerated wear.
Canines are the cornerstone of smile aesthetics — they mark the "corners" of the smile frame. Orthodontists pay particular attention to canine position because they are frequently impacted (especially the upper canines) and because their relationship to the incisors defines smile width and balance. Impacted upper canines are among the most common orthodontic problems seen in adolescents and young adults, often requiring surgical exposure and orthodontic traction to bring into proper position.