Background: The persistent stresses of modern life have a serious negative impact on the psychological wellbeing of
a considerable number of the current population. Nowadays, many researchers reported a positive correlation between
psychological stress (PS) and TMD. However, a proven causative relationship is difficult to be justified on clinical basis. Thus,
we designed an experimental model that compares the effect of psychological stress on two discrete joints, in order to prove the
substantial influence of PS on TMJ when compared to the knee joint.
Study Design.: The study was conducted on 32 albino rats randomly divided into 3 groups control group (Ctrl), foot shock
group (SH) and psychological stress (PS) group. PS was induced to PS group by communicating with the suffering of the SH
group during their electric shock periods. After 1-month Synovial fluids from both joints were compared regarding inflammatory
mediators (IM).
Results: Synovial levels of TNF- α and IL-6 were significantly higher in TMJ of the PS group versus Ctrl group (P<0.05).
Whereas, knee joints levels were comparable in their corresponding groups.
Conclusion: PS exclusively affects the TMJ by elevating its synovial inflammatory mediators. Moreover, PS can solely induce
TMJ synovitis