[Osteosynthesis of the middle third of the face. A comparative analysis of screws inserted with or without...

Results of osteosynthesis of middle third of face were compared after insertion, with or without pre-tapping, of more than 400 miniscrews (AO, 2 mm diameter). The parameters measured were the torque, the screw/bone interface and the morphology of the implant bed. The screw/bone area of contact was large and the torque superior in the absence of pre-tapping. Greater screw retention values were also be gained by applying the miniscrews without pre-tapping in cases where bone thickness does not exceed 5 mm. Pre-tapping would appear to be indicated when the bone is thicker, to make screw insertion easier and to prevent its fracture during insertion.