Figure 3. Comparison of Knoop hardness values before thermoforming (BT) and after thermoforming (AT) and among different thermoplastic materials. All tests were performed for 1.0-mm-thick Duran, Essix A+, Essix ACE, and 0.75-mm-thick eCligner. The same capital letter indicates no difference between materials at the 1% significance level. The same lower case letters indicate no difference between BT and AT at the 1% significance level.

See Table 1 for the manufacturer of each product.