Objectives: To evaluate the effects of a Twin-block appliance on the condyles of patients with ClassⅡmalocclusion by conducting a systematic review and a Meta-analysis.
Methods: Pubmed, Embase, Cochrane Library, Chinese BioMedical Literature Database, China National Knowledge Infrastructure, and VIP Database were electronically searched. Randomized controlled trials, controlled clinical trials, and single-arm trials on condylar changes produced by a Twin-block appliance in patients with ClassⅡmalocclusion were included. Two reviewers independently extracted and assessed the risk of bias. Meta-analyses were conducted with Review Manager 5.3.
Results: Eight studies were included; among which, seven were of high quality. After treatment with a twin block appliance, condyles moved anteriorly. The anterior joint spaces decreased (P<0.000 01), whereas the posterior spaces increased (P<0.000 01). The superior spaces were not changed (P=0.11). Moreover, a significant difference was observed in the increase of the condylar space index (P<0.000 01). After treatment, the anteroposterior diameters of the condyles and condylar height increased (P=0.000 2 and P<0.000 01, respectively). By contrast, no significant changes were discovered in the medial external diameters of the condyles (P=0.42).
Conclusions: A Twin-block appliance can promote the growth of a condyle in the posterior and upper direction and move it forward in favor of the correction of Class Ⅱ malocclusion.
目的: 评价Twin-block矫治器对安氏Ⅱ类错牙合患者髁突生长改建及位置的影响。方法: 计算机检索Pubmed、Embase、Cochrane library、中国生物医学文献数据库（CBM），中国知网（CNKI）、维普（VIP）等数据库，纳入所有应用Twin-block矫治器治疗安氏Ⅱ类错牙合畸形患者并对其髁突进行评估的随机对照试验、临床对照试验及单臂临床试验。2位评价者独立纳入文献、进行偏倚风险评估并提取数据，运用Revman 5.3软件进行统计分析。结果: 最终纳入文献8篇，共8项研究，其中7项为高质量研究。Meta分析结果显示：Twin-block矫治后，髁突向前移位，关节前间隙减小（P<0.000 01），关节后间隙增大（P<0.000 01），而关节上间隙未发现具有统计学意义的改变（P=0.11）；关节间隙指数的增大具有统计学意义（P<0.000 01）。治疗后髁突前后径增大（P=0.000 2），髁突高度增大（P<0.000 01），而髁突内外径的增大不具有统计学意义（P=0.42）。结论: Twin-block矫治器能够促进髁突向后上方的生长改建，并引导其向前移位从而使髁突-关节盘重新定位，达到良好的下颌位置并改善安氏Ⅱ类咬合关系。.
Keywords: Class Ⅱ malocclusion; Meta-analysis; Twin-block appliance; condyle; systematic review.