Hu Yun, Li Hegang
Department of Orthodontics, Stomatological Hospital, School of Stomatology, Southern Medical University, No. 366, South Jiangnan Avenue, Haizhu District, Guangzhou, 510280, Guangdong, China.
Clin Oral Investig. 2023 Jul;27(7):3695-3703. doi: 10.1007/s00784-023-04985-5. Epub 2023 Apr 3.
This study was aimed at resolving the controversy over the wearing time of mandibular advancement (MA) appliances by comparing the differences between part-time and full-time MA (PTMA and FTMA) from the perspective of promoting H-type vessel coupling osteogenesis in the condylar heads.
Thirty 30-week-old male C57BL/6J mice were randomly divided into 3 groups: the control (Ctrl), PTMA, and FTMA groups. The mandibular condyles were analyzed by morphology, micro-computed tomography, histological staining, and immunofluorescence staining to investigate the changes of the condylar heads in the PTMA and FTMA groups after 31 days.
Both PTMA and FTMA models promoted condylar growth and achieved stable mandibular advancement at day 31. However, compared with PTMA, FTMA has the following characteristics. First, new bone formation in the condylar head was detected in the retrocentral region in addition to the posterior region. Second, the condylar proliferative layer was thicker, and the number of pyknotic cells in the hypertrophic and erosive layers was higher. Moreover, endochondral osteogenesis of the condylar head was more active. Finally, the retrocentral and posterior regions of the condylar head had more vascular loops or arcuate H-type vessel coupling Osterix osteoprogenitors.
While both PTMA and FTMA induced new bone formation in the condylar heads of middle-aged mice, FTMA promoted more osteogenesis by volume and region. Furthermore, FTMA presented more H-type vessel coupling Osterix osteoprogenitors in both the retrocentral and posterior regions of the condylar head.
FTMA is better at promoting condylar osteogenesis, especially in non-growing patients. We suggest that enhancing H-type angiogenesis could be an effective strategy to achieve favorable MA outcomes, especially for patients unable to meet the FT-wearing requirement or being non-growing.
本研究旨在通过比较部分时间佩戴和全时间佩戴下颌前伸（MA）矫治器（PTMA和FTMA）在促进髁突头部H型血管耦联成骨方面的差异，解决关于MA矫治器佩戴时间的争议。
将30只30周龄雄性C57BL/6J小鼠随机分为3组：对照组（Ctrl）、PTMA组和FTMA组。通过形态学、显微计算机断层扫描、组织学染色和免疫荧光染色对下颌髁突进行分析，以研究31天后PTMA组和FTMA组髁突头部的变化。
PTMA和FTMA模型均促进了髁突生长，并在第31天实现了稳定的下颌前伸。然而，与PTMA相比，FTMA具有以下特点。首先，除后部区域外，在髁突头部的中央后区域检测到新骨形成。其次，髁突增殖层更厚，肥大层和侵蚀层中的固缩细胞数量更高。此外，髁突头部的软骨内成骨更活跃。最后，髁突头部的中央后区域和后部区域有更多的血管袢或弓形H型血管耦联Osterix骨祖细胞。
虽然PTMA和FTMA均诱导中年小鼠髁突头部形成新骨，但FTMA在体积和区域上促进了更多的成骨。此外，FTMA在髁突头部的中央后区域和后部区域均呈现出更多的H型血管耦联Osterix骨祖细胞。
FTMA在促进髁突成骨方面更好，尤其是在非生长型患者中。我们建议增强H型血管生成可能是实现良好MA效果的有效策略，特别是对于无法满足全时间佩戴要求或为非生长型的患者。
