Effect of mechanical loading on the metabolic activity of cells in the temporomandibular joint: a systematic review

Abstract

ObjectivesThe purpose of this systematic review was to elucidate how different modalities and intensities of mechanical loading affect the metabolic activity of cells within the fibro-cartilage of the temporomandibular joint (TMJ).Materials and methodsA systematic review was conducted according to PRISMA guidelines using PubMed, Embase, and Web of Science databases. The articles were selected following a priori formulated inclusion criteria (viz., in vivo and in vitro studies, mechanical loading experiments on TMJ, and the response of the TMJ).A total of 254 records were identified. After removal of duplicates, 234 records were screened by assessing eligibility criteria for inclusion. Forty-nine articles were selected for full-text assessment. Of those, 23 were excluded because they presented high risk of bias or were reviews. Twenty-six experimental studies were included in this systematic review: 15 in vivo studies and 11 in vitro ones.ConclusionThe studies showed that dynamic mechanical loading is an important stimulus for mandibular growth and for the homeostasis of TMJ cartilage. When this loading is applied at a low intensity, it prevents breakdown of inflamed cartilage. Yet, frequent overloading at excessive levels induces accelerated cell death and an increased cartilage degradation.Clinical SignificanceKnowledge about the way temporomandibular joint (TMJ) fibrocartilage responds to different types and intensities of mechanical loading is important to improve existing treatment protocols of degenerative joint disease of the TMJ, and also to better understand the regenerative pathway of this particular type of cartilage.Electronic supplementary materialThe online version of this article (doi:10.1007/s00784-017-2189-9) contains supplementary material, which is available to authorized users.

Effects of loading on chondrocyte hypoxia, HIF‐1α and VEGF in the mandibular condylar cartilage of young rats

“…The TMJ is a load bearing joint and covered by fibrocartilage which is composed of four different layers: the fibrous, proliferative, hypertrophic, and calcified cartilage . Stimuli induced by loading are essential to the development of TMJ cartilage . It has been speculated that the cartilage obtains oxygen by the invasion of new vasculature, which promotes cartilage replacement by bone growth and remodeling .…”

Condylar repair and regeneration in adolescents/young adults with early‐stage degenerative temporomandibular joint disease: A randomised controlled study

“…Biomechanical overload has been commonly assumed to be an important pre‐disposing factor for degenerative changes in TMJs . While physiologic loading of the TMJs could prevent fibrocartilage breakdown and provide stimulus for fibrocartilaginous cell proliferation, biomechanical overloading may ruin joint lubrication and increase intra‐articular pressure, resulting in temporary hypoxia and consequent degradation of TMJ structure . In our recent quantitative study, ARS moves the condyle significantly forward‐downward by 2 to 3 mm and may cause biomechanical unloading of the TMJ facilitating regenerative condylar bone remodelling …”

“…4,28,29 While physiologic loading of the TMJs could prevent fibrocartilage breakdown and provide stimulus for fibrocartilaginous cell proliferation, biomechanical overloading may ruin joint lubrication and increase intra-articular pressure, resulting in temporary hypoxia and consequent degradation of TMJ structure. 30,31 In our recent quantitative study, ARS moves the condyle significantly forward-downward by 2 to 3 mm 16 and may cause biomechanical unloading of the TMJ facilitating regenerative condylar bone remodelling. 11,13,14 Many previous studies determined the possible cause and effect relationship between DDw/oR and TMJ DJD.…”

“…As non‐surgical and surgical treatments seldom restore damaged joints once advanced osteoarthritic changes occur, the possibility of TMJ cartilage and bone regeneration presents an attractive new area of basic science and clinical research. The articular surface of TMJ is lined with dense fibrocartilage, which has greater propensity for repair than hyaline cartilage present on most synovial joints . Accordingly, the capacity of active remodelling on condyles may be higher than other load‐bearing joints .…”

“…13,34 In the fibrocartilage, which has greater propensity for repair than hyaline cartilage present on most synovial joints. 31 Accordingly, the capacity of active remodelling on condyles may be higher than other loadbearing joints. 11,13 The concept of biomechanical condylar regeneration offers an alternative paradigm and justification for the early management of TMJ DJD in younger patients.…”