STRESS RELAXATION OF SMARTEE CLEAR ALIGNER MATERIAL

Abstract

Smartee is a brand that manufactures its own proprietary PET-G-based thermoplastic materials. Stress relaxation is critical for clear aligner materials. It directly impacts orthodontic treatment efficiency. This study aimed to examine stress relaxation properties of thermoplastic polymer materials manufactured by Smartee. Twelve samples (5 mm × 9 mm) were sectioned from the upper central incisor of aligners and divided into unused (n = 6) and 7-day worn (n = 6) groups. Testing was performed blindly. Using a DMA1 (Mettler-Toledo, Greifensee, Switzerland) at 37°C, a constant extension of 0.3 mm was applied to each sample, and the resulting force decay was recorded over 1 hour. Data was recorded and analyzed using the STARe software. Result, the measured force was 0.32 ± 0.09 N for the unused group and 0.27 ± 0.09 N for the 7-day worn group, with corresponding stress relaxation values of 2.41 ± 1.16 MPa and 2.00 ± 0.15 MPa, respectively. Statistical comparison using independent t-tests showed no significant difference between groups for either force or stress (p > 0.05). Conclusions, there was no significant difference in force and stress relaxation between unused and 7-day worn Smartee clear aligners material.

Keywords: Orthodontic Thermoplastic Materials, Mechanical Properties, Stress Relaxation, Clear Aligners