STABILITY OF HAND VERSUS ELECTRICALLY DRIVEN TEMPORARY ANCHORAGE DEVICES

Abstract

Objectives: Temporary anchorage devices (TADs) provide skeletal anchorage for orthodontic tooth movement. TAD stability is defined as device retention during treatment. Insertion of TADs can either be hand-driven, relying on tactile sensation, or electric-driven, with established presets with specific torque and speed. Although device manufacturers claim that electric-driven insertion provides greater stability, this is currently unsubstantiated. The aim of this study was to compare stability, as measured by resistance to deflection, and insertion time of TADs placed using these two methods.Methods: Twenty TADs (Rocky Mountain Orthodontics; 1.6mm x 8mm) were inserted into synthetic bone blocks mimicking palatal bone: 20 PCF with a 1mm cortical plate of 40 PCF (Sawbones USA). TADs were inserted by two methods, hand-driven (n=10) and electric-driven (n=10; at 10 N•cm, 15 RPM) perpendicular to the surface of the bone blocks. All TADs were subjected to a tangential force using an Instron machine until their deflection measured 2.5mm. The force versus displacement over time was recorded and the slope was calculated to determine resistance to deflection. The insertion time was recorded for each TAD. Results: Hand-driven TADs had a mean resistance to deflection (76.30 N/mm ± 11.70), yield point (43.61 N ± 4.34), and insertion time (28.929 s ± 3.47). Electric-driven TADs had a mean resistance to deflection (79.34N/mm ± 17.95), yield point (40.81N ± 4.58), and insertion time (77.642 s ± 7.21). An independent samples t-test revealed no significant difference in TAD resistance to deflection (p=0.658) or yield point (p=0.177) between the two groups. Hand insertion time was on average 2.68 times faster (p=0.000) than electric insertion time. Individual measurements had small standard deviations, indicating reliability to the experimental approach. Conclusion: There are no significant differences in stability between hand-driven and electric-driven TADs when studied by this method. These results indicate that electric drivers may require more operating time and do not necessarily provide more TAD stability.