Investigation of carbon dioxide laser 'lambda' = 10.6 µm, fluoride and dental biofilm effects on enamel demineralization. In vitro and in situ studies

Author(s)

Bruna Raquel Zancopé

• Document type: Doctoral Thesis
• Press: Piracicaba, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba
• Defense date: 2016-02-29

Examining board members

Marinês Nobre dos Santos; Paulo Nelson Filho; Patricia Moreira de Freitas; Fernanda Miori Pascon; Silvia Amelia Scudeler Vedovello

• Advisor: Marinês Nobre dos Santos

Abstract

Carbon Dioxide Laser (CO2) has been used to morphologically and chemically modify the dental enamel surface as well as to make this substrate more resistant to demineralization. The general objective of this thesis was to investigate the CO2 laser, fluoride (F) and dental biofilms effects on enamel demineralization. Four studies were developed and are presented in four chapters. Chapter 1 evaluated the effects of dental biofilm and CO2 laser (? = 10.6 µm) irradiation on enamel lesion progression of bovine tooth enamel. For biofilm formation, 10 volunteers wore palatal appliances containing 06 specimens of bovine enamel each. The laser irradiation was performed before and after biofilm removal. The specimens were submitted to microhardness test and scanning electron microscopy analysis (MEV). This study showed that biofilm covering enamel surface did not reduce the CO2 laser irradiation effect on reduction progression of dental caries lesion. Chapter 2 evaluated, in vitro, the CO2 laser (? = 10.6 µm) irradiation effects on biofilm formation in dental enamel. In this study, 96 bovine enamel specimens were divided into 2 groups: Control and CO2 laser. The biofilms were grown on the enamel specimens for 1, 3 and 5 days under intermittent cariogenic condition in the irradiated and not irradiated surface and were evaluated by dry weigh, counting of the number of microorganisms through viable colonies counting, polysaccharides analysis, quantitative real-time-PCR as well as by contact angle. The biofilms morphology was characterized by fluorescence microscopy and Field Emission Scanning Electron Microscopy. In conclusion CO2 laser irradiation modified the surface energy and disrupted the initial biofilm formation. Chapter 3 investigated the CO2 laser (? = 10.6 µm) effects and of the fluoridated products in calcium fluoride (CaF2) formation on the enamel surface and subsurface lesion progression. Demineralized primary enamel specimens were allocated in groups (n=15): Acidulated Phosphate Fluoride (APF) gel, fluoride foam and fluoride varnish and CO2 Laser. The specimens were submitted to microhardness test and MEV. Laser irradiation alone or combined with fluoridated products inhibited lesion progression However, no synergistic effect was observed, Chapter 1 evaluated, in situ, the CO2 laser (? = 10.6 µm) and APF effects on CaF2 and fluorapatite (FAp) formation on the surface of previously demineralized enamel specimens. It was also the aim of this study to evaluate these effects on carious lesions progression and on fluoride biofilm formation. An in situ study was conducted with 04 double-blind phases of 14 days each. Specimens were subjected to microhardness test, CaF2 and FAp concentration analysis and of the F on biofilm. The higher formation of CaF2 and FAp due to CO2 laser irradiation rendered the enamel more resistant to subsurface caries lesion progression (AU)

• FAPESP's process: 12/02885-7 - Evaluation of the effects of acidulated phosphate fluoride on the effectiveness of CO2 laser in reducing demineralization of dental enamel - in situ study
• Grantee: Bruna Raquel Zancopé
• Support Opportunities: Scholarships in Brazil - Doctorate