## 3 Discussion  
This article described the successful outcome of the early treatment for the child patient with anterior crossbite and MNTI, which is a very rare tumor. We had another plan initially. The alternative was chin-cup therapy to improve anterior crossbite. The chin-cup was considered an effective treatment appliance to control mandibular growth in patients with anteriorly positioned mandibles [25; 26; 27]. However, this approach would have a significant influence over the tumor compared to other appliances because the chin-cup directly applied a force to her mandible with MNTI. Therefore, we did not recommend it and offered this alternative to the patient and her family. Presently, her occlusion was corrected and stabilized by our selected therapy. We think that we should keep the skeletal relationship and the eruption of permanent teeth under observation until completion of growth. Several reports indicated the difficulties of the early treatment and retention of skeletal Class III malocclusion in children due to their inability to predict mandible growth [10; 28; 29]. Therefore, follow-up is necessary and important to retain her collected skeletal or dental occlusion. Furthermore, this girl and her parents hope the additional orthodontic treatment of the mandibular anterior crowding in permanent dentition stage. For the treatment of this malocclusion, we will have to extract the malposed tooth or another one in MNTI. Therefore, she is cautiously determined whether it can be treated at the timing of second phase treatment using the multiple bracket method. In the present case, symptoms produced by MNTI were almost same ones as previous reports, but the subsequent process was not completely different. Triggers that her parents noticed were swelling of her alveolar ridge in the left mandibular region and following facial asymmetry. At the age of 8 months, she was referred to our department. On clinical examination, smooth swelling extended from the right mandibular primary canine to the left mandibular molar region (Figure 7). It was firm without ulceration or discharge and caused her neither pain nor feeding difficulties. MRI and CT showed a large and widespread mass on the mandible (Figure 8). The definitive diagnosis of MNTI was made by biopsy. After we were provided it, we consulted with pediatricians, cranio-facial surgeons, and radiologists about treatment options, complications, and prognosis. Though surgical resection had high possibilities of serious complications and interfering with her life, we recommended surgery because we expected a complete cure. However, her parents did not approve of surgery, as was discussed above. In addition, the result of CT and MRI indicating the reduction in the size of the tumor after biopsy encouraged their decision (Figure 8). \begin{table}
\begin{tabular}{c c c c c} \hline
**Variables** & **Japanese Norm** & **SD** & **Pretreatment (7 Years 4 Months)** & **Posttreatment (9 Years 11 Months)** \\ \hline Angles (\({}^{\circ}\)) & & & & \\ ANB & 2.8 & 2.4 & \(-\)2.0 & 0.5 \\ SNA & 80.8 & 3.6 & 80.5 & 80.5 \\ SNB & 77.9 & 4.5 & 82.5 & 80.0 \\ Mandl.l.–SN pl. & 37.1 & 4.6 & 34.2 & 34.4 \\ U1-SN pl. & 105.9 & 8.8 & 97.0 & 118.0 \\ L1-Mand. pl. & 93.4 & 6.8 & 80.6 & 82.0 \\ Interincisal angle & 123.6 & 10.6 & 148.2 & 125.6 \\ Linear (mm) & & & & \\ Wits value & \(-\)1.92 & 2.52 & \(-\)7.0 & \(-\)4.2 \\ Overjet & 3.1 & 1.1 & \(-\)2.0 & 3.5 \\ Overbite & 3.3 & 1.9 & 3.0 & 3.0 \\ \hline \end{tabular}
\end{table} 
Table 1: Cephalometric summary [23; 24]. Figure 8: Sequential radiographic changes for MNTI by CT on the left side and MRI on the right side. (**A**) Before the start of treatment at the age of 8 months; (**B**) 1 month later, after the biopsy; (**C**) 4 years and 6 months later, after the biopsy; (**D**) 6 years and 6 months later, after the biopsy. Figure 7: Pictures of the patient at the age of 8 months. (**A**) Facial frontal view; (**B**) intraoral view showing swelling in the left mandibular region.