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Selective ablation of dental enamel and dentin using femtosecond laser pulses

机译:飞秒激光脉冲选择性剥蚀牙釉质和牙本质

摘要

The study of the interaction of intense laser light with matter, as well as transient response of atoms and molecules is very appropriated because of the laser energy concentration in a femtosecond optical pulses. The fundamental problem to be solved is to find tools and techniques which allow us to observe and manipulate on a femtosecond time scale the photonics events on and into the matter. Six third human extracted molars were exposed to a femtosecond Ti:Sapphire Q-switched and mode locked laser (Libra-S, Coherent, Palo Alto, CA, USA), emitting pulses with 70 fs width, radiation wavelength of 801 nm, at a constant pulse repetition rate of 1 KHz. The laser was operated at different power levels (70 to 400 mW) with constant exposition time of 10 seconds, at focused and defocused mode. Enamel and dentin surfaces were evaluated concerned ablation rate and morphological aspects under scanning electron microscopic. The results in this present experiment suggest that at the focused mode and under higher average power, enamel tissues present microcavities with higher depth and very precise edges, but, while dentin shows a larger melt-flushing, lower depth and melting and solidification aspect. In conclusion, it is possible to choose hard or soft ablation, under lower and higher average power, respectively, revealing different aspects of dental enamel and dentin, depending on the average power, fluence and distance from the focal point of the ultra-short pulse laser on the tooth surface.
机译:由于飞秒光脉冲中的激光能量集中,研究强激光与物质的相互作用以及原子和分子的瞬态响应非常适合。要解决的根本问题是找到工具和技术,使我们能够在飞秒时间尺度上观察和操纵物质上和物质中的光子事件。六分之三的人类提取的磨牙暴露于飞秒的Ti:Sapphire Q开关和锁模激光(Libra-S,Coherent,Palo Alto,CA,美国),发出70 fs宽度的脉冲,辐射波长为801 nm。 1 KHz的恒定脉冲重复频率。在聚焦和散焦模式下,激光以不同的功率水平(70至400 mW)操作,恒定的曝光时间为10秒。在扫描电子显微镜下评估牙釉质和牙本质表面的消融速率和形态方面。本实验的结果表明,在聚焦模式下和较高的平均功率下,牙釉质组织呈现出具有较高深度和非常精确的边缘的微腔,但牙本质显示出较大的熔体冲洗,较低的深度以及熔融和凝固方面。总之,可以根据平均功率,通量和距超短脉冲焦点的距离,分别在较低和较高的平均功率下选择硬性或软性消融,以揭示牙釉质和牙本质的不同方面。激光照射牙齿表面。

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