Alteration of BMP‐4 and Runx2 expression patterns in mouse temporomandibular joint after ovariectomy

Objective:  Temporomandibular disorder (TMD) includes a number of clinical conditions involving the masticatory musculature or the temporomandibular joint (TMJ) and associated structures. Previous studies have shown the presence of high‐affinity estrogen receptors in the TMJ articular cartilage. The aim of this study was to evaluate the developmental changes in mouse TMJ under estrogen deficiency. Materials and methods:  Four‐month‐old ovariectomized mice were killed after certain weeks. We examined the significant alterations of the expression patterns of bone morphogenetic protein (BMP)‐4, Runx2 , and bone sialoprotein (BSP) after ovariectomy. Results:  In the control group, BMP‐4, Runx2 , and BSP expressions showed no definite difference at any stage. In the ovariectomy group, the intensity of BMP‐4 and Runx2 expression increased after ovariectomy. BSP immunoreactivity, however, increased slightly at 2 weeks but then decreased gradually. Conclusions:  Estrogen plays important roles in the metabolism and maintenance of TMJ via regulations of signaling molecules such as BMP‐4, Runx2 , and BSP. Our results suggest that estrogen deficiency is a candidate cause of TMD. This study revealed further osteogenetic properties of estrogen that may be useful in the clinical treatment and prevention of TMD.