Reliability of Orthodontic Miniscrews: Bending and Maximum Load of Different Ti-6Al-4V Titanium and Stainless Steel Temporary Anchorage Devices (TADs).

Temporary anchorage devices (TADs) have been introduced in orthodontic clinical practice in order to allow tooth movements avoiding side effects in the position of adjacent teeth. Miniscrews are available on the market with different diameters and materials. Accordingly, the purpose of the present report was to measure and compare the forces to bend and fracture different mini implants. Ti-6Al-4V Titanium and stainless steel TADs of different manufacturers (Spider Screw – HDC; Mini implants – Leone; Benefit – Orteam; Storm - Kristal) were evaluated. Two different diameters (1.5 mm and 2.0 mm) were tested. Ten unused specimen for each group were blocked in an Instron Universal Testing Machine and a shear load was applied at the neck of the screws. The force to bend the mini implant was measured at 0.1 mm and 0.2 mm deflections. Moreover the maximum load before screw fracture was recorded. Data were submitted to statistical analysis. 2.0 TADs showed significantly higher forces than 1.5 mm screws both at 0.1 mm and 0.2 mm deflections and at maximum load. Moreover, no significant differences were reported between titanium and stainless steel mini implants for equal diameter