Relation between the potency of the Delboeuf illusion (relative inducer size) in teeth supplied to each endodontist to how much he or she cut into the tooth along the long axis of the root (adjusted length – canal length).

<p>Each graph shows the regression equation, the correlation coefficient for the relationship, and whether the relationship is statistically significant (*<i>p</i><.05; ****<i>p</i><.0001). In general, endodontists increased the length of cavities more in teeth showing a strong Delboeuf illusion than in teeth showing a weak Delboeuf illusion.