Angle Orthod. 2021 Nov 1;91(6):843-855. doi: 10.2319/081720-723.1.
Ankylosis of a molar during active growth leads to a significant vertical bone defect, extrusion of the opposing molar, and inclination of adjacent teeth. Treatment timing is an essential factor for the patient's quality of life. Early extraction of the ankylosed molar and protraction of the second molar is challenging because of the difficulty of tooth movement and the uncertainty of the normal eruption of the third molar. In view of the uncertainty of eruption of the mandibular third molar, it is essential to assess the potential for eruption according to the developmental stage of the third molar and to secure sufficient space for eruption. In this case report, a girl with an ankylosed right mandibular first molar and an advanced vertical bone defect was treated via early extraction of the ankylosed molar along with the intrusion of the maxillary molar and mesial root movement of the second molar before the initiation of third molar root formation. Restoration of the vertical bone defect was noted at the end of treatment. In addition, spontaneous eruption of the third molar was observed, which was in contrast to the mesioangular impaction of the contralateral third molar. This case emphasizes the importance of treatment timing to increase the chance of utilization of the third molar.
在活跃生长期，磨牙的骨粘连会导致明显的垂直骨缺损、对颌磨牙的外凸以及邻牙倾斜。治疗时机是患者生活质量的一个重要因素。由于牙齿移动的难度以及第三磨牙正常萌出的不确定性，早期拔除粘连的磨牙并进行第二磨牙的牵引是具有挑战性的。鉴于下颌第三磨牙萌出的不确定性，根据第三磨牙的发育阶段评估其萌出的可能性，并为其萌出提供足够的空间是非常重要的。在本病例报告中，一名女孩的右侧下颌第一磨牙发生骨粘连，并伴有严重的垂直骨缺损，我们通过早期拔除粘连的磨牙，并在上颌磨牙内收和第二磨牙近中根移动的同时，在第三磨牙牙根形成之前进行治疗。治疗结束时，观察到垂直骨缺损得到了恢复。此外，还观察到第三磨牙的自发性萌出，与对侧第三磨牙的近中阻生形成对比。这个病例强调了治疗时机的重要性，以增加利用第三磨牙的机会。
