Bicortical titanium screws for critical orthodontic anchorage in the mandible: a preliminary report on clinical applications.

Critical anchorage during orthodontic treatment in the mandible needs both time and effort and patient compliance. In 8 patients, 12 bicortical titanium screws (BIS) were used as anchorage units for orthodontic molar protraction. The criteria for patient selection were: critical anchorage in the lower jaw (i.e. retraction of anterior teeth undesirable) and molar extraction sites. After insertion of the screws in local anesthesia, orthodontic forces were applied immediately. One screw worked loose and had to be removed before the end of treatment. Problems encountered included impingement of the screw head and slight inflammatory reactions of the surrounding mobile mucosa, which necessitated premature removal of two screws. After healing, a new insertion site was chosen. Further treatment was uneventful. Anchorage for orthodontic forces as described offers several advantages. The total treatment time is reduced as the screws can be loaded immediately. The line of action of the orthodontic force coincides with the level of the center of resistance of the molar resulting in a favorable translatory tooth movement. Treatment does not depend on patient cooperation.