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HUMAN TEETH HEATING BY LASER IRRADIATION: EXPERIMENTAL AND SIMULATED THERMAL RESPONSES

Carlos E. V. Paiva
Instituto de Pesquisa e Desenvolvimento - Universidade do Vale do Paraíba (UNIVAP), Av. ShishimaHifumi 2911, São José dos Campos, Brasil 12244-000

Paulo D. C. Lobo
Instituto de Pesquisa e Desenvolvimento - Universidade do Vale do Paraíba (UNIVAP), Av. ShishimaHifumi 2911, São José dos Campos, Brasil 12244-000

Marcio Magini
Instituto de Pesquisa e Desenvolvimento - Universidade do Vale do Paraíba (UNIVAP), Av. ShishimaHifumi 2911, São José dos Campos, Brasil 12244-000

Abstract

Laser technology has been widely used in medicine and dentistry for almost four decades. One of these applications is ablation in hard tissues as in the dental material. In the case of the Nd: YAG irradiation, the surface temperature increase can cause a layer of melted substance, which is then solidified, blocking the dentinal tubules, and so reducing the hypersensitivity. However, several studies has shown that this procedure leads to irreversible pulp damage if the temperature rise there is about 6 °C. So, information related to safety parameters applying high power lasers in dental tissues is important. In this study, one of the objectives is to obtain in vitro experimental temperatures at the pulp chamber when human teeth are irradiated at the external surface by the Nd:YAG laser. These results are compared to them obtained applying a two dimensional finite difference scheme (alternating-direction implicit method) in cylindrical geometry. Also, the temperature distribution profiles at subsurface regions were simulated, after the end of the last pulse. In a first experiment, the samples were submitted to the total energy of 1 J in 2, 4 and 5 pulses, with interval of 300 ms and duration of 0.9 ms. Others experiments used the application of 2 pulses with 5 ms width for the same interval. The results showed that the temperature rise is strongly dependent on the pulse energy, pulse duration, pulse interval and exposure time. The theoretical results showed in this present work have a satisfactory relationship with the data obtained in the experimental procedure.

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