Effect of the sterilization cycle on the flexural strength of titanium orthodontic mini-screws: an in vitro study

The aim of this study was to investigate the effect of sterilization cycles on the flexural strength (FS) of titanium mini-screws used in orthodontics. The study was conducted between 2024 and 2025 at the Department of Orthodontics, Faculty of Dentistry, Van Yüzüncü Yıl University, using 1.8 × 8 mm titanium mini-screws. A total of 30 specimens were used and divided into three equal groups: Group 1 received one sterilization cycle; Group 2 received 10 sterilization cycles; and Group 3 received 25 sterilization cycles. The screws were then embedded in acrylic blocks and tested. FS measurements were performed using a universal testing machine. Mini-screws fixed in acrylic blocks were placed parallel to the ground, and a force perpendicular to the length was applied to induce deformation. The significance of the results was assessed at p < 0.05. The mean FS values ​​were 278.00 ± 61.62 N in Group 1, 243.80 ± 51.26 N in Group 2, and 286.60 ± 41.91 N in Group 3. The FS values ​​of sterilized miniscrews did not differ statistically significantly according to the number of sterilization cycles (p > 0.05). The study found that the FS of titanium miniscrews, which have a wide range of applications in orthodontic practice, was not affected by repeated sterilization cycles of up to 25 cycles.