Professor Emeritus, Sections of Orthodontics and Pediatric Dentistry, School of Dentistry, University of California at Los Angeles, Los Angeles, CA.
J World Fed Orthod. 2020 Oct;9(3S):S45-S53. doi: 10.1016/j.ejwf.2020.09.004.
Mesially impacted mandibular second molars are a common occurrence in orthodontic practices, especially those using the lingual arch or lip bumper for alleviating anterior crowding. Horizontally impacted second molars, on the other hand, occur so infrequently that most practitioners have limited experience in treating such a patient. Because of this there is little consensus on the management of these cases. As opposed to vertically impacted molars that may be associated with ankylosis or other factors preventing eruption, the mesially angulated, horizontally impacted mandibular second molar usually has eruption potential, because its impaction is more commonly due to lack of space and/or abnormal eruption path. Hence, orthodontic uprighting shows the most promise and can commonly be done without extracting the third molar or surgically exposing the impacted second molar. Modern clinicians have at their disposal a myriad of biomechanical choices that can be used to successfully reposition these teeth and enable finishing with an optimal occlusion.
临床上常见上颌阻生的下颌第二磨牙,尤其是应用舌弓或唇挡来解除前牙拥挤的病例。然而,水平阻生的下颌第二磨牙却很少见,多数医生对此类病例的处理经验有限。由于缺乏共识,此类病例的处理方法也不尽相同。与可能因粘连或其他阻止萌出的因素而导致垂直阻生的磨牙不同,近中倾斜的水平阻生的下颌第二磨牙通常具有萌出潜力,因为其阻生多由于缺乏空间和/或异常萌出路径所致。因此,正畸直立是最有希望的方法,通常可以不拔除第三磨牙或通过手术暴露来实现。现代临床医生可以使用各种生物力学方法来成功地重新定位这些牙齿,并获得最佳的咬合关系。