Prof. Denise Zezell

OSA/OPTICA FELLOW since 2022. Bachelor in Physics (1984), MSc in Physics (1987) and PhD in Sciences from Universidade Estadual de Campinas (1991). Postdoc at the International Center for Theoretical Physics – Trieste, Italy (1992) and at the Center for Lasers and Applications at IPEN / CNEN-SP (1992-1995). She has been a full researcher at the Nuclear and Energy Research Institute of the Nuclear Energy National Commission (CNEN) since 1995, where she was Manager of the Lasers and Applications Center in 2008. From 2009 to 2013 she was the Coordinator of the Professional Master Program in Lasers in Dentistry at IPEN, together with School of Dentistry- University of Sao Paulo (USP). From 2013 to 2015 she was Vice-Coordinator of the Master’s and Doctorate Program in Nuclear Technology at USP. She was principal investigatior in a number of FAPESP (CEPID Optics and Photonics) and other National projects (CNPq INCT Photonics) a member of the Medical Physics Commission of the Brazilian Society of Physics from 2008-2014. She was Vice President of the Brazilian Association of Lasers in Dentistry (ABLO) 2010-2014. Participated in the Capes-CA Engineering II Quadrennial Evaluation Committee 2013-2016. She was the creator and since 2019 is the Dean of the Professional Master Course in Radiation Technology in Health Sciences, IPEN. Since 2017, she has been appointed OSA Traveling Lecturer, a member of Education Commission from CNEN. Member of the Deliberative Council of the Brazilian Photonics Society (2021-current) and its Newsletter editor for Biophotonics (2018-2019). During 2019 she was member of the Techinical Group 9 of the Brazilian Committee for the Development of Nuclear Program. Since 2020 is member of the Committee of Photonics – Ministry of Science, Technology and Innovation (MCTI), and Brazilian representative for the IAEA Arcal RL 069 project, on training human resources in the nuclear area. Work in the following fields: Physics, Biophotonics, in the study of Optical and Spectroscopic Properties of biological tissues mainly by micro-FTIR and fluorescence, infrared thermography, aiming at the development of new diagnostic and therapeutic processes for clinical applications of lasers in dentistry and medicine. She has been dedicated to the search for biomarkers to determine the effects of ionizing radiation on biological tissues as well as to study the early diagnosis of skin and breast tumors by vibrational spectroscopy (FTIR optical biopsy).

Title: Importance of Heat Generation and Propagation on Dental Tissues Due to High-Intensity Laser Irradiation for safe clinical use

Erbium lasers are strongly absorbed by water and hydroxyapatite, which are the main components of hard tissues (enamel, dentin and bone). Consequently, these lasers can be efficiently used for cutting hard tissue, for cavity preparation, for caries removal, caries and erosion prevention, when laser irradiation should change chemically the structure of dental hard tissue in order to increase their resistance to demineralization. More recently erbium lasers are being used for debonding ceramics. Only using proper irradiation conditions, minimally invasive procedures with low thermal or mechanic damages to the tissues can be achieved. For these applications, erbium lasers can increase temperatures up to 1200 °C on dentin and enamel surface, and the thermal effects must be controlled to avoid thermal damages, such as carbonization and cracks that can weak the irradiated tissue or even damage the pulp or periodontal tissue. For that, it is strongly required to know the thermal effects of laser irradiation on target tissues, with depends on the laser parameters and refrigeration methods. Studies regarding superficial thermal changes promoted by Er,Cr:YSGG laser irradiation on enamel will be described, according to the experimental measurements performed by infrared thermography. Fast-response thermocouples were also used to determine the temperature increase inside the pulp chamber and at periodontal tissue during laser irradiation simulating a clinical protocol. These studies were useful for determining laser energy densities and time of irradiation. The characteristics of laser irradiation, such as wavelength, laser absorption and optical properties of enamel were strictly considered. These studies demonstrate the strong effects of a higher-absorbed laser wavelength on biological tissues and how the practitioners can avoid possible thermal damages due to laser irradiation. The knowledge of optical changes on biological tissues due to heat is also an important point to be considered for determining laser parameters in a future clinical practice.

Acknowledgements: This work was supported by CNPq (INCT-INTERAS 406761/2022-1 and INCT-INFO 465763/2014-6; Sisfoton 440228/2021-2 and PQ 314517/2021-9); FAPESP (17/50332-0 and 21/00633-0).