Stress relaxation properties of four orthodontic aligner materials: A 24-hour in vitro study

Abstract

Objective: To investigate the stress release properties of four thermoplastic materials used to make orthodontic aligners when subjected to 24 consecutive hours of deflection. Materials and Methods: Four types of aligner materials (two single and two double layered) were selected. After initial yield strength testing to characterize the materials, each sample was subjected to a constant load for 24 hours in a moist, temperature-regulated environment, and the stress release over time was measured. The test was performed three times on each type of material.

Effects of thermoforming on the physical and mechanical properties of thermoplastic materials for transparent orthodontic aligners

“…The majority of current aligner manufacturers use modified polyethylene terephthalate glycol (PETG), although polypropylene, polycarbonate, thermoplastic polyurethanes, copolyester, and many other materials are also used 202122…”

Class II subdivision correction with clear aligners using intermaxilary elastics

“…From a biomechanical perspective, the dental movements occurred as planned, thanks to the fact that they were planned within the correct range of predictability [13] and the excellent properties of the material that the F22 aligners are made of [11]. …”

“…The last pair of aligners was used for retention due to the elastic propriety of the thermoplastic material [11]. …”

Influence of constant strain on the elasticity of thermoplastic orthodontic materials

“…To investigate aligner orthodontic devices formed from thermoplastic materials, the optimal composition of the physical properties of the thermoplastic materials must be determined and they must be extremely effective in vitro without the measurement of the orthodontic force. However, there have only been a few studies of the physical properties of the thermoplastic orthodontic materials 4,[16][17][18][19][20] and the orthodontic force exerted by the aligner [21][22][23][24][25] . There has been no study to investigate the relationship between the behavior of the orthodontic force exerted by the aligner and the change in the physical properties of the thermoplastic materials over a two week period.…”