Thursday, March 29, 2012

Near-UV laser treatment of extrinsic dental enamel stains

This research looks promising on removing stain from teeth using a laser. MJ

 

Schoenly, J., Seka, W., Featherstone, J. and Rechmann, P. (2012), Near-UV laser treatment of extrinsic dental enamel stains. Lasers Surg. Med.. doi: 10.1002/lsm.22017

Abstract

Background and Objectives

The selective ablation of extrinsic dental enamel stains using a 400-nm laser is evaluated at several fluences for completely removing stains with minimal damage to the underlying enamel.

Study Design/Materials and Methods

A frequency-doubled Ti:sapphire laser (400-nm wavelength, 60-nanosecond pulse duration, 10-Hz repetition rate) was used to treat 10 extracted human teeth with extrinsic enamel staining. Each tooth was irradiated perpendicular to the surface in a back-and-forth motion over a 1-mm length using an ∼300-µm-diam 10th-order super-Gaussian beam with fluences ranging from 0.8 to 6.4 J/cm2. Laser triangulation determined stain depth and volume removed by measuring 3D surface images before and after irradiation. Scanning electron microscopy evaluated the surface roughness of enamel following stain removal. Fluorescence spectroscopy measured spectra of unbleached and photobleached stains in the spectral range of 600–800 nm.

Results

Extrinsic enamel stains are removed with laser fluences between 0.8 and 6.4 J/cm2. Stains removed on sound enamel leave behind a smooth enamel surface. Stain removal in areas with signs of earlier cariogenic acid attacks resulted in isolated and randomly located laser-induced, 50-µm-diam enamel pits. These pits contain 0.5-µm diam, smooth craters indicative of heat transfer from the stain to the enamel and subsequent melting and water droplet ejection. Ablation stalling of enamel stains is typically observed at low fluences (<3 J/cm2) and is accompanied by a drastic reduction in porphyrin fluorescence from the Soret band.

Conclusion

Laser ablation of extrinsic enamel stains at 400 nm is observed to be most efficient above 3 J/cm2 with minimal damage to the underlying enamel. Unsound underlying enamel is also observed to be selectively removed after irradiation. Lasers Surg. Med. © 2012 Wiley Periodicals, Inc.

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