Análise micromorfológica de esmalte e dentina expostos ao laser de Nd: YAG em regime de picossegundos

Abstract

The efficiency of the ablation obtained with a picosecond-pulsed laser system minimizes material collateral damage because of the etching and plasma formation mechanism. It prevents the excessive generation of shock waves and promotes a considerable decrease of mechanical side effects. In this study, a Nd:YAG picosecond-pulsed Q-switched and mode-locked laser (Antares 76-s, Coherent, Palo Alto, CA) was used. Fifteen microcavities were prepared in the enamel, and nine microcavities were prepared in the dentin of three recently extracted human molars. The parameters for irradiating enamel followed a fixed frequency of 100 Hz and an average power level of 1.3 W; for dentin, the frequency was fixed in 15 Hz, and the average power level varied between 800, 700 and 600 mW. Enamel proved more capable to dissipate shock waves than dentin, since cracks originating from microcavities were more frequent in dentin. In conclusion, it seems that in order to keep defined edges, it is important to choose shorter irradiation periods when average power levels are kept high, which results in lower and best-localized total energy delivery.

Study of the morphological alterations to enamel and dentin in human and bovine teeth after irradiation with Er:YAG laser

“…In this study we attested that the Z2 layer was more broadly and clearly defined when there was an increase in the energy density irradiated, in human as well as in bovine enamel and dentin. A similar outcome was attained by Lizarelli and Bagnato [6] employing Nd:YAG laser, in which Z2 is said to be the result of abrasion of the edges, making them so fragile that they simply detach. This phenomenon may have been caused by the strong shock waves brought on by the higher energy output.…”

“…Many morphological studies involving Er:YAG laser and human teeth have been published [1][2][3][4][5][6][7][8][9][10][13][14][15]. Nevertheless, not a single study comparing the effects of this infrared laser in human and bovine teeth has been reported.…”

“…To better understand this morphological study, let us consider that, according to Lizarelli and Bagnato [6], the microcavities are divided into three zones: Z1, center of the microcavity; Z2, an intermediate zone that may or may not exist; Z3, area unaffected by the irradiation (Fig. 1).…”

“…Much has been published about the morphological alterations to human enamel and dentin after irradiation with Er:YAG laser [1][2][3][4][6][7][8][9]10,[13][14][15]. However, not a single comparative study on the morphology of human and bovine enamel and dentin after Er:YAG laser irradiation could be found in the current literature.…”

Temperature Response in the Pulpal Chamber of Primary Human Teeth Exposed to Nd:YAG Laser Using a Picosecond Pulsed Regime

“…[1][2][3][4][5][6][7] One of the reasons is the absence of commercial models specific for medical application. Nevertheless, ultra-short laser pulses are an important tool whose clinical applicability is yet to be discovered.…”