## 2 Materials and Methods
### Case Report
In the present case, the maxillary sinus was extended to the mesial side of the maxillary molars, similarly to the distal side. This raised the concern that a large amount of mesial movement through the maxillary sinus could increase the risk of root resorption. A treatment alternative that involved the extraction of the maxillary and mandibular premolars was also presented to the patient. The diagnostic setup model indicated that the required mesial movement of the molars was large and unrealistic. Moreover, the amount of retraction of the incisors was large, and there was a concern that the patient's lip would be retracted too much. The patient had a straight profile with a mildly retrusive upper lip. Because the patient was worried that his lip might retract as a result of the premolar extraction, he refused this option [18]. Therefore, we decided to extract only the maxillary and mandibular third molars and establish the Angle Class I molar relationships with molar distalization. Prior to orthodontic treatment, the patient was referred to a maxillofacial surgeon for extraction of all of his third molars. For initial leveling, the 0.022 in preadjusted edgewise appliances (Tomy international, Tokyo, Japan) that were bonded to his maxillary and mandibular lateral teeth and 0.016 \(\times\) 0.022-in improved super elastic nickel-titanium alloy archwires (ISW) were used. In addition, TADs were inserted between the maxillary first molar and second premolar on both sides to anchor them down better and to move the molars distally (Figure 5A). Four months later, there was clear progressions in the leveling and expansion of the maxillary and mandibular lateral teeth; the brackets were further bonded to the anterior teeth as well. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Variables** & **Japanese Norm** & **Pretreatment** & **Post-Treatment** & **Retention** \\ \hline SNA & 82.3 \(\pm\) 3.5 & 79.8 & 79.8 & 79.8 \\ SNB & 78.9 \(\pm\) 3.5 & 76.3 & 76.0 & 76.0 \\ ANB & 3.4 \(\pm\) 1.8 & 3.5 & 3.9 & 3.9 \\ FMA & 28.8 \(\pm\) 5.2 & 32.4 & 33.0 & 33.0 \\ U1 to FH & 111.1 \(\pm\) 5.5 & 116.5 & 107.2 & 108.0 \\ IMPA & 96.3 \(\pm\) 5.8 & 91.6 & 92.2 & 92.6 \\ FMIA & 54.6 \(\pm\) 6.5 & 56.0 & 54.8 & 55.3 \\ Interincisal & 121.4 \(\pm\) 7.6 & 119.4 & 127.6 & 127.3 \\ angle & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Cephalometric analysis. After leveling the maxillary teeth, the distalization of the maxillary molars was started using 0.018 \(\times\) 0.025 inch stainless-steel archwires (SSWs). The maxillary second molars were distalized using 50 g nickel-titanium open-coil springs placed between the first and second molars on both sides, while tip-forward bends were incorporated into the archive to prevent any further distal tipping of the second molars. In addition, we incorporated a step-up bend, toe-in bend, and torque into the archive to prevent extrusion and rotation. At the same time, distalization of the maxillary first molars was started using 100 g nickel-titanium open-coil springs placed between the second premolars and first molars on both sides. Similar to the movement of the second molars, we controlled the movement of the maxillary first molars using bends. We used long hooks with elastic chains from the TADs that were placed in contact with the mesial aspect of the maxillary first premolars to prevent any reciprocal reaction. These long hooks were loosely crimped to the SSW such that they could slide distally, which successfully moved the maxillary premolars distally (Figure 5B). The maxillary first premolars and canines were also moved distally, in the same order, by the same method (Figure 5C). The buccal inclination of the maxillary second molars was also improved. Additionally, the anterior tooth crowding of the mandible was relieved by expanding and uprighting the molars using intermaximillary Class III elastics and an ISW with a reversed curve (Figure 5B). Finally, moderate stripping was performed on the mandibular anterior teeth to improve crowding and anterior tooth size ratio.