Livas Christos, Delli Konstantina
Assistant Professor, Department of Orthodontics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
Oral Medicine Specialist, Department of Oral and Maxillofacial Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
J Oral Maxillofac Surg. 2017 Mar;75(3):475-483. doi: 10.1016/j.joms.2016.10.035. Epub 2016 Nov 4.
To systematically assess the available evidence on the effect of orthodontic extractions on third molar (M3) angulation.
Three databases were searched up to April 25, 2016 to identify orthodontic studies comparing M3 angular changes in patients with and without extraction. Information on methodology, treatment procedures, and outcome was retrieved from each study. Assessment of overall and individual quality of the included studies was performed using validated criteria.
Fourteen retrospective studies were considered eligible for this systematic review. Two studies achieved a moderate evidence score, whereas the lowest grade was assigned to 12 studies. The overall evidence level was classified as limited. Meta-analysis was not feasible because of the high heterogeneity across studies. Based on the best available evidence, premolar extraction followed by fixed orthodontic appliances can substantially improve the angular position of M3s by 10° to 18°.
There is limited evidence that orthodontic extractions can substantially enhance the uprighting of M3s. Clinicians should be aware of the potentially beneficial effect of orthodontic extraction treatment on M3 development, although well-designed prospective studies are necessary to strengthen this statement.
系统评估正畸拔牙对第三磨牙（M3）倾斜度影响的现有证据。
检索截至2016年4月25日的三个数据库，以确定比较拔牙和未拔牙患者M3角度变化的正畸研究。从每项研究中获取有关方法、治疗程序和结果的信息。使用经过验证的标准对纳入研究的总体和个体质量进行评估。
十四项回顾性研究被认为符合本系统评价的要求。两项研究获得中等证据评分，而十二项研究被评为最低等级。总体证据水平被归类为有限。由于各研究之间存在高度异质性，因此无法进行荟萃分析。根据现有最佳证据，拔除前磨牙后使用固定正畸矫治器可使M3的倾斜位置显著改善10°至18°。
正畸拔牙能显著促进M3直立的证据有限。临床医生应意识到正畸拔牙治疗对M3发育可能存在的有益影响，不过需要设计良好的前瞻性研究来强化这一观点。
