Quadrant
Definition
One of four sections of the dentition: upper right, upper left, lower left, lower right. The midline divides left from right; the occlusal plane divides upper from lower.
- Total quadrants
- Four
- Divided by
- Midline and occlusal plane
- Names
- Upper right, upper left, lower left, lower right
- Used in
- Tooth numbering systems
Common questions
Why do different tooth numbering systems assign quadrants different codes or numbers?+
The FDI system numbers quadrants 1 to 4 as a prefix digit, the Universal system numbers all teeth 1 to 32 continuously without quadrant prefixes, and the Palmer system uses bracket symbols per quadrant, so the same physical quadrant is represented differently depending on which system a report uses.
How does quadrant identification help in bite mark or dental identification casework?+
Locating a mark or restoration to its correct quadrant narrows comparison to the corresponding region of a suspect's or decedent's dental records, letting an odontologist match tooth position, spacing, and wear patterns against a specific quarter of the arch rather than the whole dentition.
Related terms
- FDI Notation
- The two-digit system published by the Federation Dentaire Internationale. The first digit (1-4 for permanent, 5-8 for deciduous) encodes the quadrant; the...
- Midline
- The anatomical midpoint of the dental arch dividing it into left and right halves. In notation systems, position 1 is always the...
- Palmer Notation
- A grid-based system where a bracket symbol indicates the quadrant and a number 1-8 (or letter A-E for deciduous) indicates position from...
- Universal Numbering System
- The North American standard. Permanent teeth are numbered 1-32 running clockwise from the maxillary right third molar. Deciduous teeth are lettered A-T...