Mestrado Profissional em Clínica Odontológica

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Navegando Mestrado Profissional em Clínica Odontológica por Autor "Bautz, Letícia Nogueira da Gama de Souza"

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    Análise da remodelação tecidual e da expressão de MMP-9 durante a erupção dentária
    (Universidade Federal do Espírito Santo, 2016-08-19) Lima, Nayra de Souza Carvalho; Bautz, Letícia Nogueira da Gama de Souza; Coburn, Karla Loureiro Almeida; Guedes, Priscila Tavares; Azeredo, Rogério Albuquerque
    The tooth formation results from the interaction between the oral epithelium and the underlying ectomesenchyme. As these elements develop, ossification and tissue remodeling occurs around them, so that they are surrounded by a bone crypt. The tooth eruption is a complex process which depends on the release of several signaling molecules and growth factors that enable the tooth to cross tissue barriers in order to emerge into the oral cavity. Studies have shown intense bone remodeling around the developing tooth, consisting on bone resorption in the coronal area of the crypt, accompanied by bone formation in the basal area, promoting tooth movement. These events, followed by disruption of the connective tissue of the lamina propria, are essential steps of the eruptive movement and seems to be dependent of effector cells such as osteoclasts and mast cells, which release matrix metalloproteinases (MMPs) responsible for the degradation of the extracellular matrix of these tissues. This study aimed to carry out an analysis of tissue remodeling and MMP-9 expression throughout the eruptive process in rat molars. For this purpose, a histomorphometric analysis was conducted and included the measurement of bone surface area in the basal and apical area of the bone crypt, the quantification of the osteoclasts and mast cells and the expression of MMP-9 on the tooth germ and surrounding tissues. Our results demonstrated a reduction of bone area on the apical region of bone crypt, followed by a decreased number of osteoclasts lying on the bone surface. In parallel there was a progressive increase in bone area at the base of the bone crypt. High number of mast cells were quantified at the lamina propria of nine days old rats, and those cells showed cytoplasmic expression of MMP-9, suggesting a possible role of these cells in the recruitment of osteoclast precursors, whose peak activity occurs at that same time. The same expression pattern was also observed in osteoclasts, osteoblasts and osteocytes, suggesting a combined action of bone cells and mast cells in the cellular events that result in tissue remodeling during the eruptive process.
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    Avaliação da deposição de proteoglicanos e colágeno tipo i na matriz extracelular da cartilagem articular da mandíbula em condição de má oclusão experimental
    (Universidade Federal do Espírito Santo, 2019-11-07) Nardotto, Ludimilla Rocha Dutra; Bautz, Willian Grassi ; https://orcid.org/0000-0003-2365-4851; http://lattes.cnpq.br/0501863452453459; Bautz, Letícia Nogueira da Gama de Souza; https://orcid.org/0000-0001-6330-996X; http://lattes.cnpq.br/; https://orcid.org/0009-0007-1933-1255; http://lattes.cnpq.br/; Pacheco, Marcos da Silva ; https://orcid.org/; http://lattes.cnpq.br/1102062219427157; Bertollo, Rossiene Motta ; https://orcid.org/0000-0002-8536-6719; http://lattes.cnpq.br/2474104532832056
    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