Department of Orthodontics, Faculty of Dentistry, Alexandria University, Champollion St., Azarita, P. O. Box: 21521, Alexandria, Egypt.
BMC Oral Health. 2024 Aug 6;24(1):899. doi: 10.1186/s12903-024-04622-x.
Posttreatment changes after orthodontic treatment are challenging. One of the main reasons for such a phenomenon is the lack of patient compliance with removable retainers especially in the maxillary arch, due to palatal coverage, deterioration of speech, decreased masticatory efficiency, and loss of retainers. Fixed retainers have been introduced to overcome patient compliance and provide longer stable results. However, teeth still show movements when a six-unit fixed retainer is in place. Thus, in this study, an eight-unit fixed retainer was evaluated in an attempt to eliminate unwanted movements. THE AIM OF THIS RESEARCH: was to assess short-term positional changes associated with an eight-unit extended maxillary fixed retainer.
A single-arm clinical trial was conducted to address the aim of the study. This research was approved by the institutional review board of the Faculty of Dentistry, Alexandria University (IORG:0008839, No-0479-8/2022). The registration date of this study was 5/06/2023. Twenty-eight patients (19.8 ± 4.5 years) who had finished the active orthodontic phase and started retention had an eight-unit extended maxillary fixed retainer that was bonded to the palatal surface of the maxillary incisors, canines, and the first premolars or the second premolars. Pre-retention and one-year post-retention intra-oral scans were made to produce STL files that were superimposed to determine the amount of tooth change. Additionally, analysis of digital casts and lateral cephalometric radiographs was performed.
Statistically significant changes in all planes and the rotation of teeth after one year of retention were found. The upper right lateral incisor exhibited the most evident change in the vertical plane, while the upper right central incisor exhibited the greatest change overall. Minimal changes in the cast measurements were observed. Lateral cephalometric measurements showed minimal changes after one year of retention, and these changes were not statistically significant except in the interincisal angle and the angle between the upper incisor and the line connecting the A-point to the pogonion.
Increasing the extension of maxillary fixed retainers did not eliminate unwanted tooth movement in the first year of retention.
正畸治疗后的治疗后变化具有挑战性。出现这种现象的主要原因之一是由于腭覆盖、言语恶化、咀嚼效率降低和保持器丢失，患者对上颌弓的可摘保持器的依从性较差。固定保持器的引入是为了克服患者的依从性，并提供更长时间的稳定结果。然而，当放置六单位固定保持器时，牙齿仍然会出现移动。因此，在这项研究中，评估了八单位固定保持器以试图消除不需要的运动。本研究的目的是评估与上颌八单位扩展固定保持器相关的短期位置变化。
进行了一项单臂临床试验以解决研究目的。本研究得到了亚历山大大学牙科学院机构审查委员会的批准（IORG：0008839，No-0479-8/2022）。本研究的注册日期为 2023 年 6 月 5 日。28 名患者（19.8±4.5 岁）完成了正畸活跃阶段并开始保持治疗，在上颌切牙、尖牙和第一前磨牙或第二前磨牙的腭表面粘结了八单位扩展上颌固定保持器。进行保留前和保留一年后的口腔内扫描以产生 STL 文件，然后将这些文件进行叠加以确定牙齿变化的数量。此外，还进行了数字模型分析和侧位头颅侧位片分析。
在保留一年后，所有平面和牙齿的旋转都发现了统计学上显著的变化。右上侧切牙在垂直平面上表现出最明显的变化，而上颌右侧中切牙总体上变化最大。在模型测量中观察到最小的变化。侧位头颅侧位片测量在保留一年后显示出最小的变化，除了切牙间角和上颌切牙与 A 点到颏顶点连线之间的角度外，这些变化没有统计学意义。
增加上颌固定保持器的扩展并没有在保留的第一年消除不需要的牙齿移动。
