All of the following increase primary stability of miniscrew implants EXCEPT:

 # All of the following increase primary stability of miniscrew implants EXCEPT: 

A. Cortical predrilling

B. Cortical bone thickness

C. Spongy bone thickness

D. Length or diameter

The correct answer is A. Cortical predrilling

• Studies about various miniscrew designs to improve primary stability are increasing. Different changes in screw diameter, length and the design of the threads have been investigated

• Primary stability is influenced and increased by optimum loading, good bone density, more cortical bone thickness, advance screw design and root proximity. 

• Drill free method of MSI insertion is much better than pre-drilled method for primary stability of mini screw implants as in case of pre drilled method more heat is produced which leads to compromised bone regeneration hence jeopardize implant stability.