Influence of cortical thickness on the stability of mini-implants with microthreads

The objective of this study was to assess the influence of cortical thickness and bone density on the insertion torque of a mini-implant (MI) with microthreads. Mini-implants with lengths of 6 and 8 mm in the active part were inserted into synthetic bone blocks (polyurethane resin). The density of these blocks was 20 pounds per cubic foot (pcf), simulating bone marrow, and that of blocks 1, 2, and 3-mm-thick blocks was 40 pcf, simulating cortical bone. Blocks with uniform density of 40 pcf were also used to simulate bone areas of greater density. Insertion torque was quantified with a universa...