Comparison of the mechanical properties of direct printed versus thermoformed aligners

Introduction: Clear aligners have emerged as a popular alternative to traditional braces, offering improved aesthetics and comfort. Aligners can be grouped according to the materials used or mode of fabrication, which can influence the mechanical properties of the aligner. The aim of this research: is to compare the mechanical properties of two different aligner materials fabricated by direct printing (DPA) versus two different aligner materials fabricated by thermoforming (-TFA).Materials and methods: Four materials were utilized to fabricate bar-shaped aligner specimens using two fabrication techniques: TFA and DPA. For the TFA, Zendura FLX and Duran+ were selected, while Dental LT Clear by and Tera Harz TC-85DAC were used for the DPA. Testing was conducted using a Universal Testing Machine (UTM) to determine the tensile strength and calculate the elastic modulus. Additionally, a contact profilometer was employed to assess the surface roughness of the specimens. Results: No significant differences were observed in elastic modulus (MPa) (F = 1.14, p = 0.34). However, tensile strength (MPa) differed among the materials (F = 27.92, p < 0.001). Post-hoc analysis revealed that DPA exhibited higher stress values compared to TFA (p < 0.001). TC-85DAC showed the highest tensile strength of 25.87 MPa, followed by Dental LT Clear 25.38 MPa. Zendura FLX had the lowest tensile strength . Surface roughness of the DPA had a higher value.Conclusion: DPA exhibit superior mechanical strength. However, their increased surface roughness can influence plaque accumulation, wear patterns, and comfort.