# An Orthodontic Treatment Case of a TMD Patient with Maximly Posterior Intrusion Using TsADs
## 2 Materials and Methods
### Case Report
Full fixed Roth prescription 0.018 in preadjusted edgewise orthodontic appliances (Tomy, Tokyo, Japan) were bonded on both arches for alignment and leveling. At six months of treatment, the retraction of the maxillary anterior teeth and intrusion of the maxillary posterior teeth was started. Two TSADs (diameter, 1.4 mm; length, 8 mm; Orlus, Seoul, Korea) were placed in the buccal alveolar bone between the roots of the maxillary first molars and second molars to intrude the posterior teeth and to retract the anterior segments. A transpalatal arch (TPA) was installed 5 to 6 mm away from the midpalatal soft tissue for the tongue exercise to intrude the posterior teeth more effectively. An additional TSAD between the roots of the maxillary central incisors beneath the anterior nasal spine (ANS) was implanted to control the root movement of the maxillary anterior teeth, in the expectation that this intrusive force would promote the bodily movement of the anterior teeth [11]. Two more TSADs were also placed in the posterior area of the plate for the intrusion of the maxillary molars. For the retraction of the anterior teeth, 100 g of orthodontic forces were applied on the elastomeric chains between each TSAD and 0.016 \(\times\) 0.022-in stainless steel archive. The same forces were also applied to the TPA and palatal TSADs for the intrusion of the posterior segments. These forces were reactivated and regulated until the proper overbite and overjet were achieved (Figures 3 and 4). The total treatment time was 29 months. Posttreatment analysis discovered that both overbite and overjet were in normal ranges, and no TMD symptoms or discomfort was found after using the stabilization splint. A panoramic radiograph indicated no significant signs of progressed condylar resorption. The lateral cephalometric analysis presented minor skeletal changes (ANB, 11.5\({}^{\circ}\) to 8.5\({}^{\circ}\)), which were mostly induced by a counterclockwise rotation of the mandible, followed by the intrusion of the maxillary posterior dentition. On the superimposition of the lateral cephalograms, it was measured that there was a 3 mm maxillary molar intrusion with the use of TPA and TSADs. Inferring from the mandibular inferior border before and after treatment, it seems that the intrusion was symmetrical on both sides. Figure 3: _Cont._  
Moreover, the intrusion of the posterior teeth provided the patient with a more esthetic smile line, as her flat maxillary occlusal plane angle was improved. To reduce overjet, her maxillary anterior teeth were retroclined (U1-FH, 100.0\({}^{\circ}\)). These changes contributed not only to the correction of the anterior open bite but to the improvements in the facial profile (Figure 5; Table 1). Figure 4: Treatment progress: (**a**) a single TSAD installed beneath the ANS and two buccal TSADs between the molars were used for the retraction and intrusion of anterior teeth. (**b**) Intrusion force was applied to the maxillary posterior teeth with a combination of TPA and maxillary buccal TSADs. Figure 3: Treatment mechanics: (**a**) TSADs were implanted between the maxillary first and second molars for absolute anchorage. During the retraction of the anterior segment, the moment is produced at the distance between the center of resistance (the point in the alveolus between the maxillary lateral incisors and canines) and the retraction forces for the anterior segment, which led to the clockwise rotation of the anterior teeth. Since the entire dentition was connected with a continuous heavy archive, clockwise rotation of the full maxillary dentition occurred at the center of resistance, generally located 11 mm apical to and 26.5 mm posterior from the incision edge of the maxillary central incisor, which resulted in the mild intrusion of the maxillary molars. (**b**) For additional root moment and palatal root movement of the anterior teeth, 100 g of distointrusive force passed through the center of resistance of the full maxillary arch with the help of a single TSAD installed beneath the ANS.