How malocclusion interferes with tissue inhibitor of metalloproteinase-1 expression and morphology of the articular cartilage of the mandible in female rats

• Published in: Archives of oral biology 2025-01, Vol.169, p.106117, Article 106117
• Main Authors: Mathias, Carolina Brioschi, Badaró, Rebeca Ferreira, Bautz, Willian Grassi, da Gama-de-Souza, Leticia Nogueira
• Format: Article
• Language: English
• Subjects: Animals; Cartilage, Articular - metabolism; Cartilage, Articular - pathology; Chondrocytes - metabolism; Chondrocytes - pathology; Female; Immunohistochemistry; Malocclusion; Malocclusion - pathology; Mandible - pathology; Osteoclasts - pathology; Rats; Rats, Wistar; Temporomandibular joint; Tissue inhibitor of metalloproteinase-1; Tissue Inhibitor of Metalloproteinase-1 - metabolism
• ISSN: 0003-9969; 1879-1506; 1879-1506
• DOI: 10.1016/j.archoralbio.2024.106117

The purpose of this study was to investigate morphological alterations and tissue inhibitor of metalloproteinase-1 expression in the articular cartilage of the mandible under conditions of experimentally induced malocclusion. Twenty-four 8-week-old female Wistar rats were used and divided into control and experimental groups with two different treatment periods (2 and 4 weeks). Sagittal malocclusions were orthodontically created, causing mesial movement of the first molars and distalization of the third molars unilaterally and on opposite sides of the arches. Sagittal sections of the articular cartilage of the mandible were subjected to hematoxylin and eosin and immunohistochemistry for tissue inhibitor of metalloproteinase-1. Chi-square and MannWhitney U tests were applied. Animals treated for 2 and 4 weeks showed morphological alterations in articular cartilage of the mandible. The main findings were thickening of the posterior third, layer derangement, osteoclast activity and osteophyte formation. Among the cellular aspects, the presence of chondrocytes with condensed nuclei and cytoplasm reduction were observed. The enzyme in control animals was observed only in the mature layer. Treated animals showed immunopositive cells in the proliferative and mature layers, and in the 2-week treated group, the posterior third of the cartilage had more immunolabeled cells than control (P=0.0291). The occlusal disorder caused morphological changes in articular cartilage of the mandible, probably due to the attempt to adapt to the new condition. Tissue inhibitor of metalloproteinase-1 expression may play a role as an initial modulator in the biological events observed in articular cartilage of the mandible. •Occlusal disorder induced morphological changes in the articular cartilage.•The structural aspects observed are tissue adaptation to overload.•TIMP-1 expression increased in response to malocclusion.•TIMP-1 seemed to modulate the early stages of adaptative process in cartilage.