Jha Kanistika, Adhikari Manoj
Lecturer and Consultant Orthodontics, College of Medical Sciences, Bharatpur, Chitwan, 44207, Nepal.
Lecurer and Consultant, Oral and Maxillofacial Surgeon, Nepalese Army Institute of health sciences, College of medicine., Kathmandu, 44600, Nepal.
F1000Res. 2024 Apr 23;11:459. doi: 10.12688/f1000research.109040.2. eCollection 2022.
Class II malocclusions represent anteroposterior dysplasia usually resulting from mandibular retrusion. Along with a retropositioned mandible, it can be associated with either upward or backward jaw rotation. High angle cases are often associated with a short ramal height, steeper mandibular plane, and large gonial angle. Twin block is a commonly used myofunctional appliance that incorporates bite planes that direct the occlusal forces in a more favorable direction for correction of the retrognathic mandible. We aimed to evaluate skeletal, dental, and soft tissue changes following modified twin block appliance therapy in high-angle cases.
A cephalometric study was performed on 15 growing (10-14 years) high angle (Frankfort mandibular angle 28-35°) Class II Division I malocclusion patients undergoing twin block therapy. Skeletal, dental, and soft tissue changes were evaluated by cephalometric analysis using Dolphin software.
Pre- and post-treatment changes in cephalograms were assessed by analysis of variance and paired t-test. Significant changes in the position of the mandible (angle between Sella-Nasion-Point B [SNB] increased by 3.9 degrees, P=0.02), Wits appraisal (decreased by 1.54 mm, P=0.04), maxillo-mandibular relationship (angle between Point A-Nasion-Point B [ANB] decreased by 3.74 degrees, P=0.02) were observed. Soft tissue changes like the nasolabial angle were also significant, increasing by 3.8 degrees (P=0.04) and lower lip relation to E-line (reduction in lower lip protrusion) by 2 mm (P=0.04). Vertical parameters showed non-significant changes, like the Frankfort mandibular angle (FMA) increased by 0.07 degrees, (P=0.67), the angle between Sella-Nasion and Gonion-Gnathion (SN-Go-Gn) increased by 0.33 degrees, (P=0.67), Y-axis increased by 0.2 degrees, (P=0.32). The upper incisor inclination decreased non-significantly from 115.27±1.33 to 113.42±1.65 degrees, (P=0.12) and lower incisor increased non-significantly from 100.13±2.23 to 101.80 ±1.37 degrees, (P=0.08).
Modified twin block appliance can be used to successfully treat Class II Division I high angle cases with good vertical control.
II类错牙合畸形表现为前后向发育异常，通常由下颌后缩引起。除了下颌后缩外，还可能伴有下颌向上或向后旋转。高角病例常伴有升支高度短、下颌平面较陡和下颌角大。双阻板矫治器是一种常用的肌功能矫治器，它包含咬合平面，能将咬合力引导至更有利于纠正下颌后缩的方向。我们旨在评估改良双阻板矫治器治疗高角病例后骨骼、牙齿和软组织的变化。
对15例正在生长发育（10 - 14岁）的高角（Frankfort下颌角28 - 35°）II类1分类错牙合畸形患者进行双阻板治疗，并进行头影测量研究。使用Dolphin软件通过头影测量分析评估骨骼、牙齿和软组织的变化。
通过方差分析和配对t检验评估治疗前后头影测量片的变化。观察到下颌位置有显著变化（蝶鞍 - 鼻根点 - B点[SNB]之间的角度增加3.9度，P = 0.02）、Wits值（减少1.54毫米，P = 0.04）、上下颌关系（A点 - 鼻根点 - B点[ANB]之间的角度减少3.74度，P = 0.02）。软组织变化如鼻唇角也有显著变化，增加3.8度（P = 0.04），下唇与E线的关系（下唇前突减少）减少2毫米（P = 0.04）。垂直参数显示无显著变化，如Frankfort下颌角（FMA）增加0.07度，（P = 0.67），蝶鞍 - 鼻根点与下颌角 - 颏下点（SN - Go - Gn）之间的角度增加0.33度，（P = 0.67），Y轴增加0.2度，（P = 0.32）。上切牙倾斜度从115.27±1.33度非显著降低至113.42±1.65度，（P = 0.12），下切牙从100.13±2.23度非显著增加至101.80±1.37度，（P = 0.08）。
改良双阻板矫治器可成功用于治疗II类1分类高角病例，并能很好地控制垂直方向。
