SYSTEMIC EFFECT OF INOCULATION OF RADIOLABELLED BACTERIAL LPS INTO ROOT CANALS

• Grant number: 24/01705-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2024
• End date: December 31, 2024
• Field of knowledge: Health Sciences - Dentistry - Pediatric Dentistry
• Principal Investigator: Raquel Assed Bezerra da Silva
• Grantee: Octavio Augusto de Jesus
• Host Institution: Faculdade de Odontologia de Ribeirão Preto (FORP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

Apical periodontitis (AP) is a disease resulting from the spread of microorganisms in the apical and periapical regions after carious lesion or exposure of pulp tissue. This leads to chronic inflammation and tissue resorption. Studies indicate that AP stimulates a local immune-inflammatory response and may impact other systemic diseases. Bacterial lipopolysaccharide (LPS) plays a crucial role in the pathogenesis of AP, and research aims to understand its distribution in the body and its effects. The overall objective of this study is to evaluate the systemic effect of AP induced by the inoculation of radiolabelled LPS in rat teeth. Ninety-six adult male Wistar rats will be used, divided into 3 groups (n=32): Group I (healthy teeth without periapical lesion induction), Group II (periapical lesion induced without inoculation of radiolabelled LPS), and Group III (periapical lesion induced with inoculation of radiolabelled LPS). Each group will be subdivided into 4 subgroups according to experimental periods: 0, 7, 14, and 21 days (n=8 per experimental period). Induction of AP and inoculation of the [99mTc-LPS] complex will be performed in the root canals of the rats. The in vivo biodistribution of the [99mTc-LPS] complex will be confirmed using photon emission computed tomography (µSPECT/CT). Microscopic analysis of hematoxylin and eosin-stained sections will be conducted to describe the systemic inflammatory process in distant organs where radiolabelled LPS is visualized in the biodistribution analysis. Additionally, a local analysis of the apical and periapical regions of the inoculated teeth will be performed to confirm the presence of apical periodontitis.All data will be analyzed using GraphPad Prism 10 Software. Normality testing will be applied, and if the data exhibit normal distribution, analysis of variance (ANOVA) will be conducted, followed by Tukey's post-test. For all analyses, a significance level of 5% will be adopted.