S2589
Radiobiology – Normal tissue radiobiology
ESTRO 2026
References: 1 Shanbhag, n. M., Evans, m. D., Mao, w., Nana, a. L., Seeley, w. W., Adame, a., Rissman, r. A., Masliah, e. & Mucke, l. 2019. Early neuronal accumulation of DNA double strand breaks in alzheimer's disease. Acta neuropatholcommun, 7, 7 7. Keywords: cerebellum, radiation, neuropathology
groups, while irradiated and demineralised groups exhibited marked mineral loss.AFM revealed smoother and more homogeneous surfaces in biosilicate and chitosan groups, whereas irradiated and untreated demineralised enamel displayed erosion, porosities, and mineral disorganization.Fluoride maintained surface morphology but showed limited remineralising capacity compared with biosilicate and chitosan-based gel. Conclusion: RT exacerbates enamel softening and surface degradation after demineralisation. Biosilicate and the chitosan-based gel demonstrated superior protective and remineralising effects compared with fluoride, as evidenced by SMH, Raman spectroscopy, and AFM. These biomaterials show promise as preventive adjuncts for enamel stability before and during RT in head and neck cancer patients. References: Dos Santos L et al. Effects of radiotherapy on enamel and dentin: an in vitro analysis. Radiat Environ Biophys. 2024.Arid J et al. Protective effects of biosilicate-based materials on irradiated enamel. Clin Oral Investig. 2024.Sionov L et al. Chitosan-casein formulations and enamel remineralisation under acidic challenge. Caries Res. 2021.IAEA. Absorbed Dose Determination in External Beam Radiotherapy (TRS- 398). 2019.ICRU. Prescribing, Recording and Reporting Photon-Beam Therapy (ICRU-89). 2017. Keywords: biosilicate; chitosan-based; enamel effects
Digital Poster Highlight 5216
Protective and remineralizing effects of biosilicate, chitosan-based gel and fluoride on demineralized and irradiated enamel Kelly Fernanda Molena 1 , Vicente Silva Mattos 2 , Jarbas Caiado de Castro Neto 2 , Francisco Wanderley Garcia de Paula-Silva 1 , HARLEY FRANCISCO de OLIVEIRA 1 , Tatiana Azevedo Pecego 1 , Regina Guenka Palma-Dibb 1 , Fernanda de Carvalho Panzeri Pires-de-Souza 1 , Alexandra Mussolino de Queiroz 1 1 Department of Pediatric Dentistry, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão
Preto, Brazil. 2 São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
Purpose/Objective: Radiotherapy (RT) for head and neck cancer
accelerates enamel demineralisation and reduces its mechanical integrity. This in vitro study evaluated the protective and remineralising effects of biosilicate, a chitosan-based gel, and fluoride on enamel subjected to demineralisation and RT. Material/Methods: One hundred bovine enamel specimens were assigned to 10 groups (n=10): sound enamel (G1), irradiated sound enamel (G2), biosilicate (G3), chitosan-based gel (G4), fluoride (G5), demineralised enamel (G6), demineralised + RT (G7), demineralised + biosilicate (G8), demineralised + chitosan-based gel (G9), and demineralised + fluoride (G10).Artificial caries lesions were induced through pH cycling. Treatments followed manufacturer's instructions. Samples receiving irradiation were exposed to 2 Gy/day until 60 Gy using a clinical 6 MV beam.Surface microhardness (SMH), surface roughness (Ra), Raman spectroscopy (mineral profile), and atomic force microscopy (AFM) were assessed pre- and post-treatment/irradiation. Data were analysed using ANOVA/Tukey ( α =0.05). Results: RT significantly reduced SMH and increased Ra in both sound and demineralised enamel (p<0.05). Biosilicate (G3, G8) and the chitosan-based gel (G4, G9) preserved SMH pre-RT and partially restored SMH post-RT, outperforming fluoride (G5, G10) (p<0.05).Raman analysis showed greater preservation of phosphate and carbonate peaks in biosilicate and chitosan
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