Department of Orthodontics, Sri Sankara Dental College Varkala, Trivandrum, Kerala, India.
Department of Orthodontics, Sri Sankara Dental College Varkala, Trivandrum, Kerala, India.
Am J Orthod Dentofacial Orthop. 2020 Dec;158(6):816-823. doi: 10.1016/j.ajodo.2019.10.024. Epub 2020 Oct 17.
Periodontal ligament cells (PDLC) respond to the application of mechanical forces by releasing various molecules that participate in bone remodeling. Whether these cellular reactions take place at the same rate in adolescent and adult patients is not known. In this study, we aimed to evaluate differences in genetic expression, if any, between the release of various inflammatory mediators from PDLC in adolescent and adult patients before and after the application of orthodontic forces.
Forty subjects with bimaxillary dentoalveolar protrusion requiring extraction of first premolars for orthodontic treatment were selected and divided into 2 groups. Group A included 20 adolescents (aged 12-20 years), and group B included 20 adults (aged 35-50 years). Then, 35-50 g of force were applied to the maxillary first premolars, and teeth were extracted at different periods: pretreatment (control group), 7 days, 14 days, and 28 days (experimental group). The periodontal ligament was scraped from the middle third of the root, and the beta-galactosidase assay was performed in the control group. RNA extraction, DNase treatment, quantitative polymerase chain reaction, and complementary DNA synthesis were performed in the experimental group.
Adult PDLC exhibited senescent changes through increased beta-galactosidase activity. The increase in the inflammatory response and bone resorption in adult patients was evident by increased prostaglandin E2, IL1B, and acid phosphatase mRNA expression levels. Controlled bone formation response by adolescent PDLC was evident from increased ALP and BGLAP mRNA levels and a balanced receptor activator of nuclear factor kappa-Β ligand/OPG ratio.
The study could identify the reasons behind the differential response of adolescent and adult PDLC to orthodontic mechanics.
牙周膜细胞（PDLC）在受到机械力作用时会释放各种参与骨重塑的分子。但目前尚不清楚青少年和成年患者的这些细胞反应是否以相同的速度发生。本研究旨在评估正畸力作用前后，青少年和成年 PDLC 释放各种炎症介质的遗传表达是否存在差异。
选择 40 名需要拔除第一前磨牙进行正畸治疗的双颌前突患者，分为 2 组。A 组 20 例青少年（年龄 12-20 岁），B 组 20 例成人（年龄 35-50 岁）。然后在每组上颌第一前磨牙施加 35-50g 的力，在不同时期拔牙：预处理（对照组）、7 天、14 天和 28 天（实验组）。从根的中三分之一刮取牙周膜，在对照组中进行β-半乳糖苷酶检测。实验组进行 RNA 提取、DNase 处理、定量聚合酶链反应和互补 DNA 合成。
成年 PDLC 通过增加β-半乳糖苷酶活性表现出衰老变化。成年患者的炎症反应和骨吸收增加，表现为前列腺素 E2、IL1B 和酸性磷酸酶 mRNA 表达水平增加。青少年 PDLC 的受控骨形成反应表现为碱性磷酸酶和骨钙素 mRNA 水平增加，核因子 kappa-B 配体/骨保护素受体激活剂比值平衡。
本研究可以找出青少年和成年 PDLC 对正畸力学反应不同的原因。
