Effects of aging on the tensile strength and surface condition of orthodontic aligners: a comparative study of five models.

Background/objective: The objective of this study is to determine the effect of aging on tensile strength and surface condition of orthodontic aligners on days 0, 1, 5, 7, 10, and 14.

Materials/methods: The total sample of 80 aligners included five brands (Accusmile®, Angel®, GRAPHY®, Invisalign® and Suresmile®) were placed in a thermocycler to imitate the temperature variations of the oral cavity and accelerate aging for 50, 250, 350, 500, and 700 cycles. The mechanical tensile properties (Young's modulus E, yield strength YS, maximum elastic stress MES, Ultimate Tensile Strength UTS, and maximum stress MS) were measured by Universal Testing Machine at a rate of 5 mm of deformation per minute for 4 minutes.