Assessment of enamel and dentin caries lesions provoked by microcosm biofilm model by optical coherence tomography and cross-sectional microradiography: a comparative study

• Grant number: 24/20716-5
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree
• Start date: April 01, 2025
• End date: September 30, 2025
• Field of knowledge: Health Sciences - Dentistry - Social and Preventive Dentistry
• Principal Investigator: Ana Carolina Magalhães
• Grantee: Rafaela Ricci Kim
• Supervisor: Marcella Esteves Oliveira
• Host Institution: Faculdade de Odontologia de Bauru (FOB). Universidade de São Paulo (USP). Bauru , SP, Brazil
• Institution abroad: University Hospital Tübingen, Germany
• Associated to the scholarship: 24/05183-0 - Assessment of enamel and dentin caries lesions provoked by microcosm biofilm model by optical coherence tomography and cross-sectional microradiography: a comparative study, BP.MS

Abstract

The objective of the project will be to compare the mineral loss and depth of caries lesions in enamel and dentin by Spectral Domain Optical Coherence Tomography (SD- OCT) and cross-sectional microradiography (TMR) as well as to analyze cariogenic bacteria present in the microcosm biofilm used for the proposal. Three hundred and eighty-four samples of bovine enamel and dentin (enamel: 192 and dentin: 192; 4 mm x 4 mm) will be cut and polished. For the formation of the microcosm biofilm, the pool of saliva collected from 10 healthy individuals will be used. In 24-well plates, samples will be allocated according to two factors under study: Biofilm formation time (1, 3, 5 and 7 days) and Treatment (0.12% CHX-positive control and PBS-negative control). The samples will be exposed to 1.5 mL of inoculum (human saliva - glycerol + McBain saliva, 1:50), for 8 h. After the initial 8 h, the inoculum will be removed, the samples will be washed with PBS (5 s) and will receive 1.5 mL of fresh medium (McBain's artificial saliva with 0.2% sucrose) for 16 h, completing 24 h. From the 1st to the 7th day, depending on the formation time, the samples will be treated for 1 minute with CHX or PBS (n=12, biological triplicate n=4) and the medium containing sucrose will be changed. The response variables will be: CFU/mL count for cariogenic microorganisms (Streptococcus mutans/ S. sobrinus and Lactobacillus spp.) present in the biofilm, quantification of live/dead bacteria and extracellular polysaccharides (EPS) of the biofilm by confocal fluorescence microscopy, q-PCR for Streptococcus mutans and quantification of caries lesion by OCT and TMR (mineral loss and lesion depth). The data will be subjected to appropriate statistical analysis (parametric or non-parametric test), considering p<0.05. During BEPE, the samples will be analyzed by OCT at the University of Tübingen, Germany.