title: Ti:sapphire femtosecond laser ablation of dental enamel, dentine, and cementum.
abstract: This paper reports an investigation into the characteristics of femtosecond laser (800-nm central wavelength) in the ablation of human dental enamel, dentine, and cementum at various laser fluences from 0.2 to 3.68 J/cm(2) with single and multiple pulses. The femtosecond laser interaction with cementum is reported for the first time. Ablation thresholds were determined to be 0.58, 0.44, and 0.51 J/cm(2) for enamel, dentine, and cementum, respectively. Under the average laser fluences of 1.13 to 3.68 J/cm(2), clean ablated surfaces without debris and microcracks were obtained. Laser fluence was found to influence the ablated diameter and depth, whereas under a certain fluence, pulse number only affects the depth, without affecting the diameter. The ablation mechanism is found to be based on multi-photon absorption, not previously known for femtosecond laser ablation of dental materials. The low thermal loads of 0.708, 1.44, and 0.404 J/cm(3) required for ablating enamel, dentine, and cementum, determined for the first time, are beneficial for minimizing the heat-affected zones and micro-damage. The Raman spectroscopic analysis of phosphate shows that the chemical components of the tooth remain intact before and after the fs-laser ablation. It also shows that different dental tissues respond differently to the laser irradiation.
authors: Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Manchester, UK.
authors: Lingfei
authors: L
authors: Ji
authors: Lin
authors: L
authors: Li
authors: Hugh
authors: H
authors: Devlin
authors: Zhu
authors: Z
authors: Liu
authors: Jiao
authors: J
authors: Jiao
authors: David
authors: D
authors: Whitehead
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