Structural and chemical analyses of irradiated root dentin treated with carbodiimide (EDC), chitosan, proanthocyanidin, and remineralization potential of epigallocatechin-3-gallate (EGCG) and EDC in artificially induced caries

• Grant number: 24/13223-2
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: March 16, 2025
• End date: March 15, 2026
• Field of knowledge: Health Sciences - Dentistry - Endodontics
• Principal Investigator: Fabiane Carneiro Lopes Olhê
• Grantee: Helena Cristina de Assis
• Supervisor: Ana Karina Barbieri Bedran-Russo
• Host Institution: Faculdade de Odontologia de Ribeirão Preto (FORP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil
• Institution abroad: University of Illinois at Chicago (UIC), United States
• Associated to the scholarship: 23/08497-3 - Longevity of enzymatic activity and bond strength in dentin treated with EDC, chitosan and proanthocyanidin prior to cementation of fiberglass posts in teeth submitted to radiotherapy, BP.DR

Abstract

Abstract Part A: The aim of this study is to investigate the chemical changes in root dentin resulting from ionizing radiation and their impact on interaction with conventional resin cement. Eighty single-rooted teeth were randomly divided into two groups (n=40): non-irradiated and irradiated. Root lengths were standardized, and canals were prepared and filled. Post spaces were then prepared, and the samples were redistributed according to dentin treatment (n=10): distilled water, 0.2% chitosan, EDC 0.5 mol/l, and 5.0% proanthocyanidin. After drying the post space, fiberglass posts were cemented with RelyX ARC¿. Cross-sectioned slices were obtained. The most apical slices will undergo analysis for collagen crosslinking using FTIR (n=5), evaluation of interfacial micro-permeability and thickness of the hybrid layer using fluorescence microscopy (n=5), and assessment of adhesive interface quality using scanning electron microscopy (n=3). The equality of variances and normal distribution will be assessed using Levene's. and Shapiro-Wilk tests (p>0.05). If these assumptions are met, a three-way ANOVA will be used for data analysis. If assumptions are not met, the Kruskal-Wallis test will be employed. Statistical analyses will be performed using SPSS software, with a significance level set at 95%. Abstract Part B: The aim of this study is to evaluate the remineralization potential of epigallocatechin-3-gallate (EGCG) and carbodiimide (EDC) in artificially induced root caries on irradiated teeth. Sixty maxillary canines will be selected and assigned to 2 groups (n=30): non-irradiated and irradiated. To separate the crown from the radicular portion, the teeth will be sectioned, resulting in 60 root remnants, yielding root dentin specimens (5 x 4 x 2 mm). Root caries lesions will be induced by exposure to a demineralization solution (pH 5.0) for 144 h at 37 °C. After that, dentin specimens will be allocated to 3 groups (n=20 each) according to the solution used for dentin treatment: EGCG 0.5%, EDC 0.5 mol/l, and neutral buffer (control). Treatments will be done for 1 h and then, specimens will undergo remineralization regimen for 14 days. Remineralization solution will be renewed every 2 days. Dentin treatments will be repeated in the day 7 of the remineralization regimen for 1 h. Mineral density, reduced modulus of elasticity, nanohardness and micro porosity, as well as the chemical composition of the remineralized lesions will be estimated using microcomputed tomography (n=6), nanoindentation (n=4), fluorescence microscopy (n=10), and Raman spectroscopy (n=3). The equality of variances and normal distribution will be assessed using Levene's and Shapiro-Wilk tests (p>0.05). If these assumptions are met, a two-way ANOVA will be used for data analysis. If assumptions are not met, the Kruskal-Wallis test will be employed. Statistical analyses will be performed using SPSS software, with a significance level set at 95%.