Malocclusion as a Trigger for Changes in the Matrix of Articular Cartilage of the Mandible

Malocclusion alters the biomechanical environment of the temporomandibular joint (TMJ), potentially affecting the extracellular matrix of the mandibular articular cartilage (ACM). Understanding these changes is essential to elucidate adaptive mechanisms and possible degenerative processes. This study aimed to evaluate proteoglycan deposition and type I collagen (Col I) expression in ACM under experimentally induced malocclusion. Twenty-four 8-week-old female Wistar rats were divided into control and experimental groups with two treatment periods (2 and 4 weeks). Sagittal malocclusions were induced orthodontically, promoting mesial movement of the first molars and distalization of the third molars on opposite sides of the arches. Sagittal sections of ACM were stained with toluidine blue/fast green for proteoglycans and analysed by Col I immunohistochemistry. A reduction in proteoglycans in the territorial zone of the posterior third of the ACM was observed after 2 weeks, followed by new deposition in the 4-week group. Differences in Col I distribution and fibre organization were also observed in the posterior third, particularly in animals treated for 2 weeks. In conclusion, occlusal disorder induced changes in ACM, particularly in the early stages of overload, suggesting tissue remodelling associated with altered functional demands.