Editor's Comment and Q&A: Comparison of Twin-block and Dynamax appliances for the treatment of Class II malocclusion in adolescents: A randomized controlled trial

Introduction The aim of this study was to compare the effectiveness of Twin-block and Dynamax appliances for the treatment of Class II Division 1 malocclusion. Methods This was a randomized controlled trial involving 32 boys and 32 girls aged 10 to 14 years with Class II Division 1 malocclusion. They were randomly allocated to either the Dynamax appliance group or the Twin-block appliance group. Treatment was provided by 4 clinicians at 2 centers. Records were taken at the start and the end of the functional phase and after all treatment. In addition, incisal overjet, the number of appliance breakages, and adverse events or side effects of the treatment were recorded at each patient visit. Results The data monitoring committee in an interim analysis at 18 months after the start of the trial found significantly greater overjet reduction in the Twin-block group than in the Dynamax group and more breakages and adverse events with the Dynamax appliance. As a result, treatment with the Dynamax appliance was terminated, and those patients completed treatment with the Twin-block or a fixed appliance. Regression analysis showed a statistically significant difference in the performance over time between the Twin-block and Dynamax appliances in terms of reduction in overjet, with the Twin-block appliance performing significantly better than the Dynamax. The incidence of adverse events was greater in the Dynamax group (82%) than in the Twin-block group (16%), with a statistically significant difference (P <0.001) between the 2 groups. Conclusions The Twin-block appliance was more effective than the Dynamax appliance when overjet was evaluated and the Dynamax appliance patients reported greater incidence of adverse events with their appliance than those who were treated with the Twin-block appliance.

引言 本研究的目的是比较Twin - block矫治器和Dynamax矫治器治疗安氏Ⅱ类1分类错颌的有效性。 方法 这是一项随机对照试验，涉及32名男孩和32名女孩，年龄在10到14岁之间，患有安氏Ⅱ类1分类错颌。他们被随机分配到Dynamax矫治器组或Twin - block矫治器组。由2个中心的4名临床医生提供治疗。在功能矫治阶段开始和结束时以及所有治疗结束后进行记录。此外，在每次患者就诊时记录切牙覆盖、矫治器损坏次数以及治疗的不良事件或副作用。 结果 在试验开始18个月后的中期分析中，数据监测委员会发现Twin - block组的覆盖减少量明显大于Dynamax组，并且Dynamax矫治器的损坏次数和不良事件更多。因此，Dynamax矫治器的治疗被终止，那些患者使用Twin - block矫治器或固定矫治器完成治疗。回归分析显示，在覆盖减少方面，Twin - block矫治器和Dynamax矫治器随时间推移的表现存在统计学上的显著差异，Twin - block矫治器的表现明显优于Dynamax矫治器。Dynamax组不良事件的发生率（82%）高于Twin - block组（16%），两组之间存在统计学上的显著差异（P <0.001）。 结论 在评估覆盖时，Twin - block矫治器比Dynamax矫治器更有效，并且使用Dynamax矫治器的患者报告的不良事件发生率高于使用Twin - block矫治器治疗的患者。