Hypothesis: Essix-ACERTM and Essix-C+RTM have no differences in long-term translucency, flexibility, or surface-roughness from 8 different cleaning methods.

Objective: To evaluate if there are significant differences in initial translucency, flexibility, or surface-roughness between Essix-ACERTM and Essix-C+RTM. To evaluate if there are significant differences in translucency, flexibility, or surface-roughness after long-term exposure to different cleaning methods in Essix-ACERTM and Essix-C+RTM.

Methods: For a 6-month period, 10 specimens (2x0.5x0.04in) of Essix-ACE RTM and Essix-C+RTM (Dentsply-Raintree-Essix) were exposed to 8 different cleaning methods (InvisalignRTM Cleaning Crystals, Retainer BriteRTM, PolidentRTM, ListerineRTM, 2.5% vinegar, 0.5% NaOCl, 3% H2O 2, and toothbrushing) twice a week. The specimens were stored in 37°C artificial saliva when not being cleaned. At baseline and 6-months, translucency, flexibility, and surface-roughness of the specimens were quantified. Qualitative evaluation of surface-roughness of specimens from each cleaning method was evaluated after 6-months using a scanning-electron-microscope. Student t-tests and ANOVA statistical analyses were used at a significance level of 0.05.

Results: There were differences in translucency, flexibility, and surface-roughness between Essix-ACERTM and Essix-C+RTM before exposure to different cleaning methods. Both Essix-ACERTM and Essix-C+RTM demonstrated statistically significant less translucency between baseline and 6-month in all cleaning methods. Essix-ACE RTM showed statistically significant differences in flexibility in all cleaning methods except InvisalignRTM Cleaning Crystals and Retainer BriteRTM. ListerineRTM affected the translucency of Essix-ACERTM significantly more than other methods except toothbrushing, while there was no difference in translucency among the methods in Essix-C+RTM. Qualitative study did not show any distinctive surface-roughness differences when compared to untreated materials.

Conclusions: Over the 6-month period, the translucency of Essix-ACE RTM and Essix-C+RTM were significantly decreased between 6-months and baseline for all different cleaning methods. The results of flexibility and surface-roughness were varied. None of the cleaning methods were ideal for Essix ACERTM or Essix C+RTM.