ISO-3950 system for primary dentition

The ISO-3950 system is a two-digit notation system where the first digit describes the quadrant:

  • Upper right quadrant (maxillary) - 5
  • Upper left quadrant (maxillary) - 6
  • Lower left quadrant (mandibular) - 7
  • Lower right quadrant (mandibular) - 8


The second digit corresponds to the sequence number for each tooth in a quadrant:


For example, the primary lateral incisor in the lower left quadrant has a numbering of 72 where:

  • 7 is used for describing the lower left quadrant;
  • 2 refers to the lateral incisor as it is the second tooth from the midline of the lower jaw.