Objective: The purpose of this research is to review the four issues about TADs such as stability, reinforcement of orthodontic anchorage, distalization of upper and lower molars, intrusion of incisors and molars.
Methods: Keywords about each issue were selected. Using PubMed and Cochrane Database, literature retrieval was carried out. Excluding a case report, this study dealt with case control study, retrospective cohort study, randomized controlled trial, Meta analysis. In each four issues, the evidences of various levels from weak to strong evidence were provided.
Result: In stability, age could be considered a factor that influences the success of TADs, and younger patients had higher failure rate than older age group. Also bone density and the thickness of cortical bone play major roles in mechanical retention of TADs. In anchorage reinforcement, compared with conventional anchorage, TADs were more effective with moderate quality of evidence. In molar distalization, there was scientific evidence that both conventional and TADs systems are effective for distalization; however, with TADs, there was no anchorage loss when direct anchorage was used. In upper molar intrusion, current weak evidence suggests that molar intrusion with TADs may cause mandibular counterclockwise autorotation. Need to prevent continuous eruption of lower first and second molars.
Conclusion: Many studies suggested that the tooth movement with TADs were effective, and it is necessary to know about the anatomical and the physiological limitation about stability of TADs and orthodontic tooth movement.