Previous studies have shown that reflectance imaging at wavelengths greater than 1200-nm can be used to image demineralization on tooth occlusal surfaces with high contrast and without the interference of stains. In addition, these near-IR imaging systems can be integrated with laser ablation systems for the selective removal of carious lesions. Higher wavelengths, such as 1950-nm, yield higher lesion contrast due to higher water absorption and lower scattering. In this study, a point-to-point scanning system employing diode and fiber lasers operating at 1450, 1860, 1880, and 1950-nm was used to acquire reflected light images of the tooth surface. Artificial lesions were imaged at these wavelengths to determine the highest lesion contrast. Near-IR images at 1880-nm were used to demarcate lesion areas for subsequent selective carious lesion removal using a new compact air-cooled CO2 laser prototype operating at 9.3-μm. The highest lesion contrast was at 1950-nm and the dual NIR/CO2 laser system selectively removed the simulated lesions with a mean loss of only 12-μm of sound enamel.
Kenneth H. Chan, Nathaniel M. Fried, and Daniel Fried, "Selective ablation of carious lesions using an integrated multispectral near-IR imaging system and a novel 9.3-µm CO2 laser," Proc. SPIE 10473, Lasers in Dentistry XXIV, 104730E (Presented at SPIE BiOS: January 28, 2018; Published: 8 February 2018); https://doi.org/10.1117/12.2296025.
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