阻生下颌第三磨牙部分萌出时,常易并发冠周炎,食物嵌塞,龋病和龈炎,甚至造成切牙拥挤。由于这些并发症,常常拔除第二磨牙以利第三磨牙萌出。有人主张在牙冠开始钙化前拔除第三磨牙,来避免上述 Impacted mandibular third molar part of the eruption, often complicated by pericoronitis, food impaction, dental caries and gingivitis, and even cause incision crowded. Due to these complications, the second molars are often removed in order to facilitate the eruption of the third molars. Some people advocate the removal of the third molar before the tooth crown calcification to avoid the above