Femtosecond laser for cavity preparation in enamel and dentin: ablation efficiency related factors.

H Chen,Pj Lü,Y Wang,Yc Sun,H Li

doi:10.1038/srep20950

Abstract

To study the effects of laser fluence (laser energy density), scanning line spacing and ablation depth on the efficiency of a femtosecond laser for three-dimensional ablation of enamel and dentin. A diode-pumped, thin-disk femtosecond laser (wavelength 1025 nm, pulse width 400 fs) was used for the ablation of enamel and dentin. The laser spot was guided in a series of overlapping parallel lines on enamel and dentin surfaces to form a three-dimensional cavity. The depth and volume of the ablated cavity was then measured under a 3D measurement microscope to determine the ablation efficiency. Different values of fluence, scanning line spacing and ablation depth were used to assess the effects of each variable on ablation efficiency. Ablation efficiencies for enamel and dentin were maximized at different laser fluences and number of scanning lines and decreased with increases in laser fluence or with increases in scanning line spacing beyond spot diameter or with increases in ablation depth. Laser fluence, scanning line spacing and ablation depth all significantly affected femtosecond laser ablation efficiency. Use of a reasonable control for each of these parameters will improve future clinical application.

Highlights

To study the effects of laser fluence, scanning line spacing and ablation depth on the efficiency of a femtosecond laser for three-dimensional ablation of enamel and dentin
Ablation efficiencies for enamel and dentin were maximized at different laser fluences and number of scanning lines and decreased with increases in laser fluence or with increases in scanning line spacing beyond spot diameter or with increases in ablation depth
The harsh noises produced by high-speed turbo drills commonly used in traditional tooth preparation tends to make the patients uncomfortable, and the pain caused by mechanical friction and heat requires the use of a local anesthetic[1,2,3] mechanical preparation of dentin produces a contamination layer[4,5,6,7] on its surface, affecting bond strength

Summary

Introduction

To study the effects of laser fluence (laser energy density), scanning line spacing and ablation depth on the efficiency of a femtosecond laser for three-dimensional ablation of enamel and dentin. Laser fluence, scanning line spacing and ablation depth all significantly affected femtosecond laser ablation efficiency. An Er:YAG laser, which is a representative waterlaser, can effectively cut dental hard tissues[11,12,13,14]; its results do not always meet the strict accuracy requirements of tooth preparation for oral inlays, crowns and other restorations. The ablation rate, AR, is defined as the volume of dental hard tissue cut by the laser per unit time (AR = V/t, mm3/s). The ablation efficiency, AE, is defined as the volume of dental hard tissue cut by the laser per unit energy (AE = V/E, mm3/J). As a clinically-prepared dental tissue cavity typically has a www.nature.com/scientificreports/

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Conclusion