In Vitro Study aboutthe Effect of Dual-Thread and Diameter onthe Orthodontic Miniscrews Primary Stability

The aim of the study was to determine the effect of Dual-Thread and diameter on the orthodontic miniscrew primary stability, and define the best shape and diameter of miniescrew can be used to give the best stability. The study sample consisted of (24) orthodontic miniscrews made of (Ti-6Al-4V) alloy with 2 shapes (regular and Dual-Thread) , and 2 diameters (1.6 , 1.8mm). The experiment has been divided into 3 tests : measuring the maximum insertion torque , the Periotest value , the maximum removal torque. The results showed that the maximum insertion and removal torque were statistically higher while the Periotest values were statistically lower when using the Dual-Thread and the diameter of 1.8 mm than the regular shape and the diameter of 1.6 mm(P>0.01)