Master of Clinical Science of Stomatology Jia Yu
Faculty and research unit
University of Oulu Graduate School,
Faculty of Biochemistry and Molecular Medicine,
Oral health sciences
Field of study
Oral Development and Orthodontics
Date and time of the thesis defence
Place of the thesis defence
Remote access: https://oulu.zoom.us/j/5154558853
Topic of the dissertation
Effects of loading, estrogen level, and aging on rat mandibular condylar cartilage
Docent Janna Waltimo-Sirén, University of Helsinki
Professor, Ph.D. Pertti Pirttiniemi, University of Oulu
Sufficient loading and physiological estrogen level are beneficial for the temporomandibular joint
The temporomandibular joint (TMJ) enables complex movements and is mechanically loaded during function. The mandibular condylar cartilage (MCC), which plays a crucial role as a stress absorber during function. The MCC is composed of chondrocytes surrounded by extracellular matrix (ECM) that mainly contains collagens and proteoglycans.
TMJ degenerative disease (TMJ-DD) is characterized by degeneration of soft and hard tissues of the TMJ. The etiology of TMJ-DD is multifactorial. Loading, estrogen, and aging have been presented as potential risk factors for TMJ-DD.
The aim of the current study was to investigate the effects of loading, estrogen level, and aging on the histomorphology of rat MCC and on the expression of various biomolecules (HIF-1α, VEGF, MMP-3, MMP-8, type I, II, and X collagens) of the condylar cartilage. Loading and aging were found to be associated with histomorphological changes in the MCC, being the main factors for the thickness changes of the anterior and central parts of the MCC. Aging was also the main factor for these changes in the posterior part of the MCC.
Increased loading upregulated the expression of HIF-1α, VEGF, MMP-3, as well as the expression of type II and X collagens in the condylar cartilage. Estrogen deficiency was associatedwith lower expression of MMP-8, type II and X collagens. Aging increased the expression of type I collagen but decreased the expression of MMP-8.
The results of this study show that sufficient loading and physiological estrogen level are beneficial for the development and remodeling of the MCC, while aging is likely to increase susceptibility to reduced capacity for adaptation of the MCC.Dissertation
Last updated: 29.5.2020