Mechanical Characterization of Thermoplastic Aligner Materials: Recommendations for Test Parameter Standardization

Table 7

Forces measured for the 0.5-mm and 0.75-mm thick specimens before and after water storage, as well as the forces measured with specimens of the same thicknesses after a 24-hour constant load with and without water storage. All specimens were loaded to the predetermined deflection of 0.15 mm and 0.10 mm for the 0.5-mm and 0.75-mm specimens, respectively. The SD values represent the standard deviation of the corresponding forces.

Original foil thickness (mm)	Deflection depth (mm)	Initial forces		After 24-hour water storage without load		24-hour constant load in dry condition		24-hour constant load in water
		Mean force (N)	SD	Mean force (N)	SD	Mean force (N)	SD	Mean force (N)	SD
0.5	0.15	3.61	0.22	3.05	0.05	3.53	0.25	1.58	0.18
0.75	0.10	7.05	0.22	6.16	0.18	7.01	0.22	4.02	0.14
Average reduction				−1%		−14%		−50%