Objective To survey and compare the thickness-change of different thickness thermoplastic materials under different test condition and make sure the relationship between the thickness-change and the material initial thickness in order to provide a guide in selecting the suitable thickness thermoplastic in practice. Methods To choose Biolon, the thickness include 1.0 mm, 0.75 mm, 0.5 mm. Used Electron Vernier caliper to measure the thickness- change of different thickness thermoplastic materials under different processing mode. The data was analyzed by SPSS 10.0. Results After thermoforming the thickness of thermoplastic became thinner, the thickness of Biolon 0.75 mm decreased by 0.14 mm, Biolon 1.0 mm decreased by 0.22 mm and Biolon 0.5 mm decreased by 0.14 mm. After saliva immersion the thickness became thicker. The thickness of Biolon 0.75 mm increased by 0.02 mm, Biolon 1.0 mm increased by 0.03 mm and Biolon 0.5 mm increased by 0.02 mm. Conclusion 1）The influence of different processing mode to the thickness-change had relation to the material initial thickness. 2）The Biolon 0.75 mm had certain superiority in thickness stability compared to the homogeneous brand through the above research.
