Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Bunkyo City, Tokyo, Japan.
Department of Biochemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Bunkyo City, Tokyo, Japan.
Clin Oral Investig. 2020 Oct;24(10):3547-3557. doi: 10.1007/s00784-020-03225-4. Epub 2020 Feb 7.
The in vivo mechanoresponsive and lubricating changes of the mandibular condylar cartilage (MCC) associated with mandibular lateral shift (MLS) and recovery are poorly understood. Using growing rats, we investigated whether the expression of mechanoresponsive factors, including proteoglycan-4 (PRG4), Indian hedgehog (Ihh) and transforming growth factor-β1 (TGF-β1), would be affected by MLS. We also investigated whether these changes could recover to the control level after a 2-week treatment reversal (TR).
The MLS appliances were placed for 2 or 4 weeks in 5-week-old rats and removed from 7-week-old rats in the TR group. The MCC was analysed histomorphometrically by toluidine blue staining. Reverse transcription-polymerase chain reaction and immunohistochemistry were performed to evaluate the expression of PRG4, Ihh, PTHrP (parathyroid hormone-related protein), TGF-β1, Matrix metallopeptidase 13 (MMP-13) and a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS-5).
A thickened superficial layer and an enhanced expression of PRG4 were detected in MLS groups. PTHrP-Ihh expression correlated positively with the up-regulation of PRG4. TGF-β1 expression decreased in the early stage of MLS but recovered to the control level in the TR group. A significantly enhanced expression of MMP-13 in MLS groups was detected.
MLS treatment, which acted on the growth stage of rats, affected the morphology and expression of lubrication factor in the MCC. Elimination of this mechanical stimulus may help MCC recover to normal conditions.
Our study supports that the adaptive changes of MCC, which are caused by mandibular functional deviation, could be largely recovered by early treatment.
下颌髁突软骨（MCC）与下颌侧移（MLS）及其恢复相关的体内力学反应和润滑变化知之甚少。本研究使用生长中的大鼠，研究 MLS 是否会影响机械反应因子，包括蛋白聚糖 4（PRG4）、印度刺猬（Ihh）和转化生长因子-β1（TGF-β1）的表达。我们还研究了这些变化在 2 周的治疗逆转（TR）后是否可以恢复到对照水平。
5 周龄大鼠放置 MLS 矫治器 2 或 4 周，TR 组 7 周龄大鼠去除 MLS 矫治器。甲苯胺蓝染色分析 MCC 的组织形态计量学。逆转录聚合酶链反应和免疫组织化学评估 PRG4、Ihh、甲状旁腺激素相关蛋白（PTHrP）、TGF-β1、基质金属蛋白酶 13（MMP-13）和整合素金属蛋白酶与凝血酶敏感蛋白 5（ADAMTS-5）的表达。
MLS 组可见浅层增厚和 PRG4 表达增强。PTHrP-Ihh 表达与 PRG4 的上调呈正相关。MMP-13 在 MLS 组表达增强。
作用于大鼠生长阶段的 MLS 治疗改变了 MCC 的形态和润滑因子表达。消除这种机械刺激可能有助于 MCC 恢复正常状态。
本研究支持下颌功能偏斜引起的 MCC 适应性变化可以通过早期治疗得到很大程度的恢复。
