Avaliação da deposição de proteoglicanos e colágeno tipo I na matriz extracelular da cartilagem articular da mandíbula em condição de má oclusão experimental

• Autor(a) principal: Dutra, Ludimilla Rocha
• Data de Publicação: 2019
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/13585
• topic: Odontologia; Articulação Temporomandibular; Cartilagem Articular da Mand; Cartilagem articular da mandíbula; Osteoartrite; Má oclusão; Proteoglicanos; Colágeno tipo I; Temporomandibular joint; Mandible articular cartilage; Osteoarthritis; Malocclusion; Proteoglycans; Type I Collagen; subject.br-rjbn

Introduction: The mandible articular cartilage (MAC) is recognized for its differential adaptive capacity against overload situations due to its structural organization, in which the superficial layers present cells that secrete an extracellular matrix (ECM) rich in type I collagen, while the type II collagen matrix is secreted by the chondrocytes in the underlying layers. Nevertheless, anomalous conditions that promote functional demand that exceeds the adaptive properties of CAM may trigger temporomandibular joint (TMJ) disorders such as osteoarthritis (OA). The objectives of the study were to evaluate the deposition of proteoglycans and collagen type I in the CAM of rats under normal conditions and submitted to malocclusion in two experimental times. Methods: Twenty-four 8-week-old female Wistar rats were divided into control and treated groups. Two experimental times (2 and 4 weeks) were defined. In the treated groups, sagittal malocclusions were orthodontically created, generating mesial movement of the first molars and distalization of the third molars unilaterally and on opposite sides of the arches. For microscopic analysis, sagittal sections of the TMJs were obtained and submitted to the toluidine blue / fast green staining method for proteoglycans evaluation and immunohistochemical technique to evaluate collagen type I. For protein expression analyzes, we obtained MAC images and defined fraction of marked area, then control and treated groups were compared by Student's t-test. Results: Animals that did not underwent occlusal interference maintained microscopic patterns compatible with the normal aspects of MAC. Proteoglycan deposition was observed in areas of the halo-like territorial matrix around the chondrocytes. In animals treated for 2 weeks, the cartilaginous matrix presented reduction or even absence of proteoglycans, especially in the territorial matrix of the posterior third of the MAC. In the group treated for 4 weeks, a new deposit was detected. In relation to type I collagen, in the fibrous layer of the posterior third of the animals treated for 2 weeks the protein deposition was higher than in the animals treated for 4 weeks (p = 0.0351). In addition, animals from the 2 week control group also had a smaller fraction of type I collagen area compared to those treated for 2 weeks (p = 0.0020). In the experimental time of 4 weeks no difference was detected in the expression of type I collagen between control and treated groups. Conclusion: Experimental malocclusion seems to have the capacity of inducing alterations in MAC ECM, with initial effects regarding proteoglycan reduction in the territorial matrix and increase of type I collagen fraction, and late of new proteoglycan deposition. These findings demonstrate that the tissues responded to functional changes, probably in order to adapt to occlusal maladjustment, without the establishment of OA. However, it should be emphasized that the time factor is important so the process occurring is no longer physiological and results in the appearance of degenerative lesions.