University of São Paulo, Physics Institute of São Carlos, São Carlos, USP/Grupo de Óptica, Brazil.
J Biomed Opt. 2012 Apr;17(4):048001. doi: 10.1117/1.JBO.17.4.048001.
Femtosecond lasers have been widely used in laser surgery as an instrument for contact-free tissue removal of hard dental, restorative materials, and osseous tissues, complementing conventional drilling or cutting tools. In order to obtain a laser system that provides an ablation efficiency comparable to mechanical instruments, the laser pulse rate must be maximal without causing thermal damage. The aim of this study was to compare the different morphological characteristics of the hard tissue after exposure to lasers operating in the femtosecond pulse regime. Two different kinds of samples were irradiated: dentin from human extracted teeth and bovine femur samples. Different procedures were applied, while paying special care to preserving the structures. The incubation factor S was calculated to be 0.788±0.004 for the bovine femur bone. These results indicate that the incubation effect is still substantial during the femtosecond laser ablation of hard tissues. The plasma-induced ablation has reduced side effects, i.e., we observe less thermal and mechanical damage when using a superficial femtosecond laser irradiation close to the threshold conditions. In the femtosecond regime, the morphology characteristics of the cavity were strongly influenced by the change of the effective number of pulses.
飞秒激光已被广泛应用于激光手术中，作为一种非接触式去除硬组织（如牙体硬组织、修复材料和骨组织）的工具，可补充传统的钻削或切割工具。为了获得一种激光系统，其烧蚀效率可与机械仪器相媲美，激光脉冲率必须达到最高而不会造成热损伤。本研究旨在比较飞秒脉冲作用下硬组织暴露后的不同形态特征。对两种不同的样本进行了照射：来自人离体牙的牙本质和牛股骨样本。应用了不同的程序，特别注意保护结构。牛股骨的孵化因子 S 计算值为 0.788±0.004。这些结果表明，在飞秒激光烧蚀硬组织时，孵化效应仍然很显著。等离子体诱导烧蚀的副作用较小，即在接近阈值条件的浅层飞秒激光照射下，我们观察到较少的热和机械损伤。在飞秒激光作用下，空化腔的形态特征受到有效脉冲数变化的强烈影响。
