Micro-structural Changes of the Temporomandibular Joint in Type2-diabetic (T2DM) Animal Model

Objectives: The association between diabetes mellitus (DM) and osteoporosis remain controversial. Among patients with fractures, there is an increase prevalence of DM but among patient with DM there is no increased risk for fractures. Although the metabolic abnormalities of DM potentially affect bone metabolism, structures and mineral density, the extent of their contribution to osteoarthritis with T2DM is still under debated. So the objective of this study was to investigate bone and cartilaginous changes in TMJ of in vivo T2DM model.
Methods: TMJ from sixteen weeks old Wistar (WS) rats (n=12) and age- matched T2DM using Goto-Kakizaki (GK) rats (n=12) were analyzed. A combined approach of micro-CT technique and histological analysis were used to evaluate the bone morphological and cartilaginous alterations in the condylar bone of the TMJ.
Results: The Micro-CT analysis demonstrated a significant reduction of BMD in GK rat-condyles. Other parameters such as BV/TV, BS/BV and Tb.N remained lower but did not bring statistical difference. In the histological analysis, fibrous apposition was less observed in the superficial layer of the condyle of the GK rats. The superficial and transitional layers were thinner in GK articular cartilage. Given by those, the total height of GK articular cartilage (superficial, transitional, deep zones) was shorter than that of WS. In cellular morphological analysis, the proliferating chondrocytes of GK articular cartilage were observed in smaller size when compared to that in WS articular cartilage, suggesting a delayed differentiation.
Conclusions: The information presented in this study provides an understanding of TMJ articular pathology as well as its trabecular structural changes in T2DM. Our results should alert the dentist and therapists to exercise caution with T2DM patients in order to avoid a complication from TMD by acquired inflammation or overusing.