When a dental professional calls out a number during an examination, these numbers are part of a standardized system used by dentists and insurance providers to communicate clearly about specific teeth. This article explains the logic behind this notation, focusing on the system commonly used in the United States, and precisely locates the tooth designated as Number 5.
The Logic of the Universal Numbering System
The standard notation method used by most dental practices in the United States is the Universal Numbering System (UNS). This system assigns a unique number to each of the 32 permanent teeth in the adult mouth. The numbering sequence follows a consistent, systematic path through the mouth rather than the order teeth appear.
The counting begins with the patient’s upper right third molar (Tooth Number 1). The numbering proceeds sequentially along the upper arch, moving from the back toward the front and continuing around to the upper left third molar (Tooth Number 16).
From the last tooth in the upper arch, the count drops to the lower jaw, beginning with the lower left third molar (Tooth Number 17). The sequence continues around the lower arch, moving from the left side to the right. The final tooth is the lower right third molar (Tooth Number 32).
Identifying Tooth Number 5
Following the Universal Numbering System’s clockwise path, Tooth Number 5 is the permanent upper right first premolar. Located in the upper jaw on the right side, it sits between the upper right second premolar (Tooth Number 4) and the upper right canine (Tooth Number 6). This location places it in the transition zone between the sharper front teeth and the broader chewing teeth.
The first premolar is a transitional tooth type that shares features with the teeth on either side. It is commonly referred to as a bicuspid because its chewing surface typically features two prominent pointed structures, or cusps. The function of Tooth Number 5 is to assist the canines in tearing food while beginning the process of grinding and crushing it before it moves to the molars.
How Baby Teeth Are Numbered
The Universal Numbering System uses a separate notation for primary (baby) teeth to prevent confusion with permanent teeth. Instead of numbers 1 through 32, the 20 primary teeth are designated using the uppercase letters A through T. This system is important because children often have a mix of primary and permanent teeth for several years.
The lettering follows the same general clockwise pattern as the permanent teeth, beginning in the upper right quadrant. The count starts with the upper right second molar (Letter A) and proceeds along the upper arch to the upper left second molar (Letter J). The count then drops to the lower left second molar (Letter K).
The sequence continues around the lower jaw to the lower right second molar, the final tooth (Letter T). This distinct alphabetical system ensures that dental records clearly differentiate between a primary tooth and a permanent tooth.