Collagen is the building component of temporomandibular joint (TMJ) discs and is often affected by inflammation in temporomandibular disorders. The macromechanical properties of collagen are deteriorated by chronic inflammation. However, the mechanism by which inflammation influences disc function remains unknown. The relationship between the ultrastructure and nanomechanical properties of collagen in inflamed discs should be clarified. Seven-week-old female Sprague–Dawley rats were randomly divided into two groups. Chronic TMJ inflammation was induced by intra-articular injection of complete Freund’s adjuvant, and samples were harvested after 5 weeks. Picrosirius staining revealed multiple colours under polarized light, which represented alternative collagen bundles in inflamed discs. Using atomic force microscopy scanning, the magnitude of Young’s modulus was reduced significantly accompanied with disordered collagen fibril arrangement with porous architecture of inflamed discs. Transmission electron microscopy scanning revealed a non-uniform distribution of collagen fibres, and oversized collagen fibrils were observed in inflamed discs. Fourier transform infrared microspectroscopy revealed a decrease in 1 338 cm⁻¹/amide II area ratio of collagen in different regions. The peak positions of amide I and amide II bands were altered in inflamed discs, indicating collagen unfolding. Our results suggest that sustained inflammation deteriorates collagen structures, resulting in the deterioration of the ultrastructure and nanomechanical properties of rat TMJ discs.

胶原蛋白是颞下颌关节（TMJ）椎间盘的建筑成分，在颞下颌疾病中通常会受到炎症的影响。胶原蛋白的宏观力学性能会因慢性炎症而恶化。然而，炎症影响椎间盘功能的机制仍然未知。应阐明发炎椎间盘中胶原蛋白的超微结构与纳米机械性能之间的关系。将七周大的Sprague-Dawley雌性大鼠随机分为两组。关节内注射完全弗氏佐剂可诱发慢性TMJ炎症，并于5周后收集样品。Picrosirius染色在偏振光下显示多种颜色，代表发炎椎间盘中的替代胶原束。使用原子力显微镜扫描，杨氏模量的幅度显着降低，伴有发炎椎间盘多孔结构的胶原蛋白原纤维排列紊乱。透射电子显微镜扫描显示胶原纤维分布不均匀，并且在发炎的椎间盘中观察到过大的胶原纤维。傅立叶变换红外光谱表明减少了1338厘米^-1 /酰胺II在不同区域的胶原蛋白的面积比。在发炎的椎间盘中，酰胺I和酰胺II谱带的峰位置发生了变化，表明胶原蛋白展开。我们的研究结果表明持续的炎症会破坏胶原蛋白结构，从而导致大鼠TMJ椎间盘的超微结构和纳米机械性能下降。