Name: Nayra de Souza Carvalho Lima
Type: MSc dissertation
Publication date: 19/08/2016
Advisor:
Name |
Role |
|---|---|
| Karla Loureiro Almeida Coburn | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| Karla Loureiro Almeida Coburn | Advisor * |
| Priscila Tavares Guedes | External Examiner * |
| Rogério Albuquerque Azeredo | Internal Examiner * |
Summary: 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
