Chemical and morphological alterations of dental enamel irradiated by femtosecond laser with sub-ablative parameters

• Grant number: 19/21683-5
• Support type: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): March 01, 2020
• Effective date (End): February 28, 2021
• Field of knowledge: Physical Sciences and Mathematics - Physics - General Physics
• Principal Investigator: Michelle Alexandra Chinelatti
• Grantee: Heitor Hussni Casarin
• Home Institution: Centro Universitário Central Paulista (UNICEP). Associação de Escolas Reunidas (ASSER). São Carlos , SP, Brazil

Abstract

Considering the chemical structure of dental enamel, especially the carbonate band in the role of caries prevention, and the absence of studies using femtosecond laser in dental enamel in order to prevent caries lesions, the objective of the present study is to evaluate the chemical changes of enamel irradiated by femtosecond laser with sub-ablative parameters, using Raman spectroscopy, and morphological analysis by Scanning Electron Microscopy (SEM). Thirty (30) freshly extracted bovine incisors teeth will be used to obtain enamel specimens (5 mm X 5 mm). The chemical composition of the non-irradiated specimens will be analyzed by means of Raman spectrometry to acquire the absorption spectrum, being delimited the areas under the absorption bands of carbonate and phosphate. This analysis will be used to evaluate the change in enamel chemical composition post-irradiation. Enamel surfaces will be irradiated by a femtosecond Ti: Sapphire laser system (Libra S, Coherent), pulsed mode (approximately 70 fs), and focused mode (focal length 20 cm). In order to establish appropriate sub-ablative parameters for caries prevention, the samples will be irradiated with different mean powers (0-1 W), different energies per pulse (<1 mJ), and exposure times of 10 seconds and 15 seconds. After irradiation, the areas under the absorption bands of carbonate and phosphate will be delimited in each sample. The final carbonate/phosphate area ratios will be calculated from the difference of the areas under the bands of the irradiated and non-irradiated specimens, corresponding to the relative concentration of carbonate and phosphate. The analysis of surface morphology by SEM will be performed on non-irradiated and irradiated specimens, being recorded the most representative areas of morphological alterations on irradiated enamel when compared to non-irradiated ones.