This meta-analysis showed a very low prevalence rate of PDD in TMD patients. The limited literature did not allow conclusions to be drawn about the PDD-related features.

Conservative treatment was effective in managing the patient. A follow-up for 9 months with a repeat MRI was undertaken to monitor the progress.

Tumor necrosis factor-alpha (TNF-α) is an infl ammatory cytokine known to cause bone resorption, swelling and edema during tissue organization. Conversely, TNF-α has also been shown to participate in tissue regeneration during the wound healing process. We have previously investigated the eff ects of TNF-α on human dental pulp cell diff erentiation. Dental pulp cells are composed of diff erent cell types including primary odontoblasts and fi broblasts. We determined that the ratio of stem cells within the pulp cell population was increased following short-term stimulation with TNF-α. The aim of this study therefore was to investigate the eff ect of short-term stimulation with TNF-α on osteoblast-like MC3T3-E1 cell growth and diff erentiation. MC3T3-E1 cells were cultured in standard growth medium and on reaching sub-confl uence were exposed to recombinant TNF-α (10 and 100 ng/ml) for 2 days prior to assessing their cell proliferation and diff erentiation properties in comparison to non-stimulated MC3T3-E1 cells (control). Although no signifi cant diff erences in cell proliferation were observed between the TNF-α-stimulated and control groups, cell diff erentiation was delayed in the TNF-α-stimulated groups. In summary, short-term stimulation of cultured MC3T3-E1 cells with TNF-α had only minimal eff ect on their growth and diff erentiation.

Bone marrow-derived mesenchymal stem cells (BMSCs) have considerable potential for self-renewal and multi-differentiation. Tumor necrosis factor-α (TNF-α) is an inflammatory cytokine and is involved in tissue regeneration during wound healing. It was already reported that cultured human dental pulp cells acquire stem cell properties following short-term stimulation by TNF-α. However, it has not been clarified if BMSCs acquire stem cell properties after TNF-α treatment. The purpose of this study was to investigate the effect of short-term stimulation with TNF-α on BMSCs. Rat BM-SCs were cultured up to 60% confluence and then incubated with 1-100 ng/ml of recombinant rat TNF-α (rTNF-α) for a further 2 days. After reaching subconfluence, cells were passaged once to remove rTNF-α completely before subsequent assays. Cells in the control group were passaged without stimulation. Expression levels of Nanog and Oct4 stem cell markers were significantly increased in the rTNF-α 10 ng/ml stimulation group. rTNF-α stimulation did not affect cell proliferation compared with the control group. However, rTNF-α stimulation led to a delay in cell differentiation. This study suggests that short-term TNF-α stimulation of BMSCs significantly increased their stem cell phenotype, but delayed their osteogenic cell differentiation.

No abstract