A formula to determine the amount of retraction of mandibular canines

Moderate to severe protrusion of anterior teeth often necessitates the extraction of 4 premolars to retract anterior teeth into their space. We present a formula that determines how far the mandibular canines should be retracted to provide adequate space for correction of lower incisor protrusion. To test the accuracy of the formula, 23 mandibular setups were made and the results of the formula were compared with those of the setups. Paired t-tests at a confidence level of 95% did not show any statistically significant differences between the results.