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  1. 1. HEAT TRANSMISSION ON DENTIN IRRADIATED BY Er,Cr:YSGG LASER FOR CARIES PREVENTION Valter Valentim Lula Jnior1, Profa. Dra. Denise Maria Zezell2, Profa. Dra. Patrcia Aparecida da Ana1 1Universidade Federal do ABC (UFABC) - Av. dos Estados, 5001, Santo Andr, SP 2Instituto de Pesquisas Energticas e Nucleares (IPEN) - Av. Lineu Prestes 2242, Cidade Universitria, So Paulo, SP valter.junior@ufabc.edu.br, zezell@usp.br, patricia.ana@ufabc.edu.br Advanced School On Modern Trends Of Biophotonics For Diagnosis And Treatment Of Cancer And Microbial Control, April 11 to 19, 2013 Abstract. The temperature changes on root dentin surface and pulp chamber of uniradicular teeth were analysed during Er,Cr:YSGG laser irradiation at low fluences, aiming to determine a promissory parameter for future clinical application for caries prevention in dentin. Keywords: Er,Cr:YSGG laser, temperature, caries prevention. INTRODUCTION Dentin exposure by gingival recession makes teeth more sensible to pain and more susceptible to caries lesions (Fig. 1). MATERIAL AND METHODS Fig. 1 A) Healthy gingiva showing knife-edge border of the free gingiva that is scalloped in shape; B) Gingival recession, with dental root exposure due to gingival margin migration apical to the cemento-enamel junction (SCHEID and WEISS, 2012). RESULTS CONCLUSION According to the obtained results, the fluence of 2.8 J/cm can be a promissory parameter for caries prevention on root dentin. ACKNOWLEDGMENTS To IPEN for the laboratorial and CEPOF for the accomodation support. REFERENCES ANA, P. A. Estudo in vitro da resistncia desmineralizao e da reteno de flor em esmalte dental irradiado com laser de Er,Cr:YSGG. 2007. Tese (Doutorado) Instituto de Pesquisas Energticas e Nucleares, So Paulo. SCHEID, R. C.; WEISS, G. Woelfel's Dental Anatomy. 8. ed. Philadelphia: LWW, 2012. ZACH, L.; COHEN, G. Pulp response to externally applied heat. Oral Surg., v. 19, n. 4, p. 515-30, 1965 Gingival recession Root and dentinal tubules exposure Severe root caries and hypersensitivity Hi-power laser heating (Fig. 2) Chemical changes in dentin (Fig. 3) Risk of pulpal damage Dentin surface and pulpar chamber heating analysis Safe and effective parameters for caries prevention X Fig. 2 Absorbance spectrum of the main componentes of biological tissues, related to the main laser wavelenghts used in dentistry. (ANA, 2007). Fig. 3 Chemical changes in dental hard tissues after laser heating. According to the temperature, it is possible to note changes in water, carbonate and organical material content, as well as the transformation of phosphate in pirophosphate, increase of hydroxyl and formation of new crystallographic phases, which leads to decrease of acid solubility (ANA, 2007). 20 incisor human teeth Pulp removal Opening of teeth lingual surfaces Placing of thermocouple (Fig. 4) 10 teeth in group A 10 teeth in group B Group A: 2,8 J/cm2 Group B: 5,6 J/cm2 Er,Cr:YSGG pulsed laser irradiation for 20s Thermocouple and thermographic camera heat analysis (Fig. 5) Statistical analysis (Table 1) Fig. 4 Thermocouple placing. Fig. 5 Root dentin irradiation. Fig. 5 Infrared images during radicular dentin irradiation; a) at beginning, b) during irradiation; c) imediatelly after irradiation; d) during tooth cooling. Fig. 6 Surface temperature changes during Er,Cr:YSGG laser irradiation at 2.8 J/cm2. Fig. 7 Pulpal temperature changes during laser irradiation detected with thermocouple Dentin surface temperature data evidences Er,Cr:YSGG laser potential on trigger chemical changes in dentin when irradiated with 5.6 J/cm fluence, due to temperature raises above 100C. Nevertheless, even with less chemical changes due to lower temperature raises, 2.8 J/cm fluence suggests to be more indicated because it was not induced intrapulpal temperature raises higher than 5.5C, without pulpal damage risk (ZACH and COHEN, 1965). Laser Thermocouple Thermographic camera Tooth Dental wax 0 20 40 60 80 100 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 T( o C) Time (s) 2.8 J/cm 2 5.6 J/cm 2 0 20 40 60 80 20 30 40 50 60 70 Temperature( o C) Time (s) 2.8 J/cm 2