What is the threshold for classifying severe crowding in orthodontics?

Severe crowding in orthodontics is typically classified as 5 mm or more of irregularity per quadrant. This standard is based on the amount of space discrepancy between the available arch length and the space required for the teeth, indicating a significant challenge in alignment that may necessitate comprehensive orthodontic treatment. Identifying severe crowding is crucial for planning interventions and can influence the choice of treatment modality, whether it be extraction, expansion, or other orthodontic approaches.

The thresholds for crowding below this level—3 mm or 4 mm—are generally classified as moderate or mild crowding and usually don't require the same level of intervention as severe crowding. A threshold of 6 mm would reflect an even greater degree of crowding that may also be classified as severe, but it is not the standard definition typically used. Therefore, 5 mm accurately reflects the recognized cutoff for identifying severe crowding in orthodontic practice.