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Grant number: 23/10679-2
Support Opportunities:Regular Research Grants
Duration: February 01, 2024 - January 31, 2026
Field of knowledge:Health Sciences - Dentistry - Pediatric Dentistry
Principal Investigator:Raquel Assed Bezerra Segato
Grantee:Raquel Assed Bezerra Segato
Host Institution: Faculdade de Odontologia de Ribeirão Preto (FORP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil
Associated researchers:Léa Assed Bezerra da Silva ; Paulo Nelson Filho


Apical periodontitis (PA) is a disease resulting from the spread of microorganisms in the apical and periapical regions after dental caries lesion or exposure of the pulp tissue. This causes chronic inflammation and tissue resorption. Studies show that PA stimulates a local immune-inflammatory response and may impact other systemic diseases. Bacterial LPS (lipopolysaccharide) plays a significant role in the pathogenesis of PA, and research aims to understand its distribution in the body and its effects. The overall objective of this study is to evaluate the local and systemic effects of PA induced by inoculation of radiolabeled LPS into rat teeth. Ninety-six adult male Wistar rats will be used and divided into 3 groups (n=32): Group I (healthy teeth without induction of apical periodontitis), Group II (induced apical periodontitis without inoculation of radiolabeled LPS), and Group III (induced apical periodontitis with inoculation of radiolabeled LPS). Each group will be subdivided into 4 subgroups, according to experimental periods: 0, 7, 14, and 21 days (n=08 per experimental period). The study will consist of 2 stages. In stage 1, a protocol for radiolabeling LPS and producing the complex [99mTC-LPS] will be developed. Additionally, an in vitro study of macrophage culture will validate the complex [99mTC-LPS] compared to non-radiolabeled LPS as a stimulator of pro and anti-inflammatory cytokines (TNF-±, IL-6, IL-4, and IL-10). In stage 2, apical periodontitis will be induced, and the complex [99mTC-LPS] will be inoculated into the rat root canals. Microscopic analysis of hematoxylin and eosin-stained sections will describe the inflammatory process locally and systemically in different organs. The area of PA will be measured through micro-computed tomography (µ-CT). In vivo biodistribution of the complex [99mTC-LPS] will be investigated using micro-single-photon emission computed tomography (µSPECT/CT). All data will be analyzed using GraphPad Prism 10.0 software. Normality testing will be applied, and if the data show a normal distribution, analysis of variance (ANOVA) will be performed, followed by Tukey's post-test. For all analyses, a significance level of 5% will be adopted. (AU)

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