Mechanoresponsive and lubricating changes of mandibular condylar cartilage associated with mandibular lateral shift and
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ORIGINAL ARTICLE
Mechanoresponsive and lubricating changes of mandibular condylar cartilage associated with mandibular lateral shift and recovery in the growing rat Wu Yang 1 & Katarzyna Anna Podyma-Inoue 2 & Ikuo Yonemitsu 1 & Ippei Watari 1 & Yuhei Ikeda 1 & Xiyuan Guo 1 & Tetsuro Watabe 2 & Takashi Ono 1 Received: 2 September 2019 / Accepted: 23 January 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Objective 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 2week treatment reversal (TR). Materials and methods 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). Results 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. Conclusion 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. Clinical relevance Our study supports that the adaptive changes of MCC, which are caused by mandibular functional deviation, could be largely recovered by early treatment. Keywords Mandibular condylar cartilage . Mandibular lateral shift . Proteoglycan 4 . Indian hedgehog . Transforming growth factor beta-1
Introduction The temporomandibular joint (TMJ) is a bilateral joint in which the right and left joints function together as a unit and * Ikuo Yonemitsu [email protected] 1
Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Bunkyo City, Tokyo, Japan
2
Department of Biochemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Bunkyo City, Tokyo, Japan
are connected to the mandible. It is also a synovial joint that permits the articulation of mandibular condyle and glenoid fossa/articular eminence in the temporal bone. Articular tissues in the TMJ display frictionless movement and
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