First clinical application of a liquid-core light guide connected to an Er:YAG laser for oral treatment of leukoplakia.

For medical applications, erbium lasers are usually equipped with articulated mirror arms or special glass fibers. However, only with mirror arms is it so far possible to transmit high average powers or pulse energies in the region of 1 J to achieve suitable energy densities for fast tissue preparation. An alternative to the glass fiber systems mentioned above are liquid-core light guides. An extremely flexible liquid-core light guide was used to connect a dental Er:YAG laser system to an especially adapted dental laser applicator. The core liquid was continuously circulated during laser irradiation to transmit pulse energies up to 1.1 J. A modified laser handpiece was used for exemplary clinical treatment. The experimental setup with the highly flexible light guide was completed successfully, and its ease of handling for a dental surgeon was demonstrated in the clinical treatment of leukoplakia of the oral cheek mucosa. Complete ablation of the epithelium with the laser was performed. One year postoperatively, the patient remains disease-free. This article describes the technical realization of a liquid-core light guide system for medical applications. We report about the first successful clinical treatment of oral hyperkeratosis using this new light guide technology.