ABSTRACT
In this work, we studied the effects of C0(2), Nd:YAG and diode lasers on the enamel and dentin of deciduous human teeth. After the irradiations, the samples were duly prepared and set up on metallic bases, covered with gold and examined in the scanning electron microscope. The results showed that the irradiation with the C0(2) mode locked laser with 1.0 W power caused melting and irregularities with small cavities on the surface of the enamel. The irradiated area on the dentin surface appeared circular and well delimited, containing blocks of dentin and cracks. By using the pulsed Nd:YAG laser with 1.0 W mean power and 10 Hz frequency, the enamel surface presented granules of molten enamel, with a typical melting look. The irradiated dentin surface presented a cavity with a margin elevated with granules and holes, and its bottom presented dentinary tubules with globules of melted dentin. Irradiation with the mode locked of diode laser with 1.0 W mean power, showed the formation of a melted and evenly resolidified enamel surface, and the dentin surface presented a block of melted dentin with adjacent regions of normal dentin, evidently with a relatively smooth surface.
El estudio presenta algunos resultados del efecto del láser de C0(2), Nd:YAG y Diodo sobre el esmalte y dentina de dientes deciduos humanos. Después de las irradiaciones, se prepararon las muestras y se montaron sobre bases metálicas, cubiertas con oro y examinadas en el microscopio electrónico de barrido. Los resultados mostraron que la irradiación con el láser C0(2) en modo conmutado con 1,0 W de potencia, provoca fusión e irregularidades con pequeños cráteres en la superficie del esmalte. En la superficie de la dentina, el área irradiada se mostró circular y bien definido, con bloques de dentina y grietas. Con el uso del láser Nd: YAG en el modo pulsado con 1,0 W de potencia media y frecuencia de 10Hz, la superficie del esmalte presentó granulos de esmalte fundido, dándole el aspecto de "melting" (derretido). La superficie de dentina irradiada presentó un cráter con borde elevado con gránulos y agujeros, y su fondo presentó túbulos dentinarios con glóbulos de dentina derretida. La irradiación del láser de Diodo en el modo conmutado con potencia media de 1,0 W, provocó la formación de una superficie de esmalte fusionada y resolidificada uniforme y la superficie de la dentina presentó un bloque de dentina fundida en la regiones adyacentes de dentina normal, mostrando una superficie bastante lisa.
Subject(s)
Humans , Child, Preschool , Child , Tooth, Deciduous/anatomy & histology , Tooth, Deciduous , Tooth, Deciduous , Dentin/anatomy & histology , Dentin , Dentin , Dental Enamel/anatomy & histology , Dental Enamel , Dental Enamel , Lasers, Solid-State/adverse effects , Lasers, Gas/adverse effects , Microscopy, Electron, Scanning/methodsABSTRACT
OBJECTIVE: This investigation evaluated the variation of the intrapulpal temperature when dentine was irradiated by the Er:YAG laser. BACKGROUND DATA: The effect of preparation with the Er:YAG laser on the intrapulpal temperature is probably the biggest problem in using the laser for preparation of dental hard tissue. MATERIALS AND METHODS: Seventy-two bovine incisors were studied that had the enamel and dentine of the buccal surface polished to a thickness of 2.0 mm. The teeth were divided into three groups, according to the repetition rate used (Group I = 2 Hz, Group II = 4 Hz, and Group III = 6 Hz), and irradiated, with or without water cooling, using 250, 300, and 350 mJ of energy per pulse. Thermocouples were introduced inside the pulp chamber through the palatine opening of the samples and fixed to the vestibular wall of the pulp chamber using a thermal paste. RESULTS: It was verified that there was a decrease of the intrapulpal temperature for all of the parameters in the Group I irradiated with water cooling and for the parameters of 350 mJ/4 Hz with water cooling. The other irradiations showed an increase of the intrapulpal temperature, varying from 0.03 degrees to 2.5 degrees C. CONCLUSION: We conclude that the use of the Er:YAG laser promoted acceptable temperature increases inside the pulp chamber. However, we do not recommend this procedure without water cooling because macroscopic observations of the dentine irradiated without water cooling showed dark lesions, suggesting carbonization of this tissue.
