08 April 2022
Since 1998, Park & Bae (Park, 1999; Park et al, 2001; Bae et al, 2002; Bae et al, 2002) have started to use surgical micro-screws (1.2mm in diameter) to retract maxillary anterior teeth after placing them between the roots of upper 2nd premolars and 1st molars. The treatment was very successful without any complications. They also showed that almost all kinds of tooth movement were possible including molar intrusion, molar protraction and whole dentition retraction using small diameter of micro-screws. These micro-screws were inserted into many areas of maxilla and mandible such as in between roots of adjacent teeth and midpalatal suture which were previously unavailable for conventional dental implants. In addition, they showed that micro-screw head can be exposed when it is placed on the attached gingival area. Originally, micro-screw was used to fix mini-plate into bone in surgical fields. So, it was difficult to apply orthodontic elastomers onto the screw head without forming connectional ligature wire loop on the cervical portion of the screw. Thus, there was periodontal involvement which was caused by the location of ligature wire that is under the screw and towards gingival, even though the screw itself was located on the attached gingival area. This micro-screw location allowed gingival embedment of ligature wire producing steady irritation on soft tissue and also caused difficulty for patients in keeping good oral hygiene around the screw.