What Are Dental Quadrants?
Before we discuss tooth numbering systems, you need to understand some vocabulary that is going to be used. The mouth is divided into four different sections, known as quadrants. The quadrants are used to help dental professionals identify which teeth are causing problems and to plan dental treatments. Each quadrant contains a different mix of teeth, including incisors, canines, premolars, and molars. Incisors are the closest to the midline of your teeth, while molars are the farthest.
What Are Mandibular and Maxillary Arches?
Teeth that are on the upper arch are maxillary. Consequently, the lower arch is called mandibular. Therefore, the top two quadrants (the right and left maxillary) contain the upper teeth, while the bottom two quadrants (the right and left mandibular) contain the lower teeth.
The Three Tooth Numbering Systems
There are three different systems for tooth numbering: the Universal, the Palmer notation, and the FDI World Dental Federation notation. The FDI system is the most commonly used tooth numbering system, and it assigns a two-digit number to each tooth depending on the quadrant and the number of the tooth in regard to the midline.
The Universal system is mostly used in the United States, and it starts on the upper right side and goes left. Then starts again with the mandibular third molar (tooth number 17) and goes sequentially until it reaches the last tooth on the right. The Palmer system is used mostly in the United Kingdom, and it contains four sets of number 1-8 with 1 always being a tooth at the midline. While there is no “correct” tooth numbering system, these three do provide a coherent way to identify each individual tooth.
FDI Tooth Numbering System
The FDI World Dental Federation notation, also known as ISO 3950, is a system used to describe the shape and position of teeth. It is the most widely used tooth numbering system. The system uses two sets of numbers to identify each tooth, for both primary and permanent dentition.
The permanent teeth are given four quadrants, with 1 representing the patient’s upper right side, 2 upper left, 3 lower left, and 4 lower right. The next number corresponds with the type of the tooth. Number 11 is the maxillary right central incisor, and number 18 is the maxillary right third molar. The FDI World Dental Federation notation is an essential tool for dentists when communicating about dental treatment plans.
The American Dental Association Universal Numbering System
- the upper right – ┘;
- the upper left –└;
- the lower right – ┐;
- the lower left –┌.
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