Dentists use a standardized numbering system to precisely identify specific teeth, preventing confusion about which tooth requires attention. This systematic method is common in the United States, where professionals rely on numbers rather than general names. Tooth 31 refers to a permanent tooth that plays a significant role in chewing. Understanding its classification helps clarify its function and why it may be prone to certain issues.
Understanding Dental Numbering Systems
Dentists primarily use the Universal Numbering System (UNS) in the United States to chart the 32 teeth of the adult permanent dentition. This system assigns a unique number from 1 to 32 in a predictable, clockwise sequence. The count begins in the upper jaw with the upper right third molar (tooth 1) and continues across the upper arch to the upper left third molar (tooth 16). The numbering then drops to the lower jaw, starting with the lower left third molar (tooth 17) and moving across the lower arch to the lower right third molar (tooth 32). Teeth 25 through 32 occupy the lower right quadrant.
Identifying Tooth 31
Following the Universal Numbering System, tooth 31 is identified as the permanent mandibular right second molar. “Mandibular” indicates its position on the lower jaw, and “right” specifies the side of the mouth. As the second molar, it is the second of the three large grinding teeth located furthest back in the jaw, often called the 12-year molar due to its typical eruption time. Tooth 31 is positioned deep within the dental arch, located between the lower right first molar (tooth 30) and the lower right third molar (tooth 32). Anatomically, the crown of the second molar features four distinct cusps, two on the cheek side (buccal) and two on the tongue side (lingual).
Role in Chewing and Common Issues
The primary purpose of tooth 31, like all molars, is crushing and grinding food during mastication. Its broad, robust chewing surface is designed to withstand the significant forces generated when breaking down tough foods. This tooth helps maintain the correct bite alignment by working with the upper second molar.
Susceptibility to Decay
Because of its location at the back of the mouth, the second molar is difficult to clean effectively, making it susceptible to dental decay and plaque buildup. This poor accessibility often leads to cavities that may require deep fillings or root canal therapy if the decay reaches the pulp chamber.
Pressure and Impact
Tooth 31 absorbs immense pressure from chewing, which can result in micro-fractures, chips, or general wear over time, especially in individuals who clench or grind their teeth. Its proximity to the third molar (wisdom tooth) can cause issues if the wisdom tooth is impacted or erupts at an angle. An impacted wisdom tooth may push against the second molar, causing pain, damage, or contributing to decay. Due to its deep location and complex root structure, treatments like root canals can be more challenging and may require specialized care from an endodontist.