Long-term Comparison of Maxillary Protraction with Hybrid Hyrax-Facemask vs Hybrid Hyrax-Mentoplate Protocols Using Alt-RAMEC: A 5-Year Randomized Controlled Trial

Background: The study aimed to compare the short- and long-term effectiveness of hybrid Hyrax (HH) -Facemask (FM) and HH-mentoplate (MP) treatment protocols for maxillary protraction using Alt-RAMEC. Methods: A single-center 2-arm parallel randomized controlled trial. Participants: 28 skeletal class III patients (female: 14, male: 14; average age: 9.7 ± 1.3 years;) were included Interventions: Two treatment groups where protraction therapy was combined with Alt-RAMEC. Group 1: Facemask group (Hybrid Hyrax + Facemask) and Group 2: Mentoplate group (Hybrid Hyrax + Mentoplate). Objective: To compare skeletal and dental changes between groups using low dose computed tomography (CT) scan from which virtual lateral cephalograms were generated. Outcome: Outcomes include changes in Wits appraisal (primary outcome), and cephalometric analysis of skeletal and dental changes (secondary outcomes) at 1 year and 5 years after treatment initiation. Randomization: 28 patients were allocated to either treatment-protocols using sequentially numbered opaque, sealed envelopes. The randomization sequence was generated with a 1:1 allocation ratio. Blinding: Due to the nature of the trial, the operator and children could not be blinded to the treatment allocation. However, blinding was used when assessing the outcomes. Results: Follow-up: one patient was lost at the one-year follow-up and an additional three patients were lost at the 5-year follow-up. Outcomes: Both treatment protocols effectively improved intermaxillary relationship. Wits measurements showed improvements of 4.42 mm (FM) and 2.86 mm (MP) at T1, decreasing slightly to 3.33 mm (FM) and 1.50 mm (MP) at T2. While vertical control and incisor inclination were comparable between groups long-term, short-term differences were noted in upper and lower incisor inclination. Results remained equally stable after five years (T2). Harms: minor harms were encountered with the anchor hooks (fracture or mucosal irritation), however none led to treatment cessation Conclusions: Early class III treatment with HH + MP provided similar outcomes and stability to that of HH + FM suggesting that the choice between FM and MP should be based on individual patient factors rather than presumed mechanical advantages.研究背景：本研究旨在采用Alt-RAMEC技术（Alt-RAMEC），比较混合式Hyrax扩弓器（Hybrid Hyrax）-面罩（Facemask, FM）与混合式Hyrax扩弓器（Hybrid Hyrax）-颏板（Mentoplate, MP）两种上颌前牵引治疗方案的短期与长期疗效。 研究方法：本研究为单中心、双臂平行随机对照试验。 研究对象：纳入28例骨性Ⅲ类错𬌗患者（女性14例，男性14例；平均年龄9.7±1.3岁）。 干预措施：设置两个治疗组，均采用联合Alt-RAMEC技术的前牵引治疗方案。组1：面罩组（混合式Hyrax扩弓器+面罩）；组2：颏板组（混合式Hyrax扩弓器+颏板）。 研究目的：通过低剂量计算机断层扫描（computed tomography, CT）生成虚拟头颅侧位片，比较两组患者的骨性与牙性改变。 结局指标：主要结局指标为Wits值评估（Wits appraisal）变化，次要结局指标为治疗启动后1年及5年时的头颅侧位头影测量分析，以评估骨性与牙性变化。 随机分组：采用按顺序编号的不透光密封信封，将28例患者按1:1分配比例随机分配至两种治疗方案组。 设盲情况：由于本试验的干预性质，操作者与患儿无法对治疗分配设盲，但在结局评估环节采用了盲法。 研究结果： 随访情况：1年随访时失访1例，5年随访时额外失访3例。 结局指标：两种治疗方案均有效改善了颌间关系。T1时，Wits值分别改善4.42mm（FM组）与2.86mm（MP组），至T2时分别小幅下降至3.33mm（FM组）与1.50mm（MP组）。尽管两组长期的垂直向控制与切牙倾斜度无显著差异，但短期随访时上下颌切牙倾斜度存在差异。治疗后5年（T2）疗效仍保持稳定。 不良事件：牵引锚钩出现轻微不良事件（断裂或黏膜刺激），但均未导致治疗中止。 研究结论：早期骨性Ⅲ类错𬌗采用HH+MP治疗的疗效与稳定性与HH+FM方案相当，提示临床选择面罩与颏板时应基于患者个体因素，而非假设的机械优势。