Tissue effects of the mid-IR Holmium laser (emitting at a wave-length of 2130 nm) were evaluated. This wavelength is attractive because it combines high water absorption and easy transmission through standard optical fibres. The laser was pulsed with pulse durations in the range of 100 microseconds and repetition rates between 2 and 6 Hertz. For all experiments a repetition rate of 2 Hertz was used. The laser beam was coupled into waterfree quartz fibers with core diameters of 200 and 800 microns with an efficiency of 70 and 80%, respectively. Ablation of atherosclerotic plaque has been performed at an ablation threshold of 10J/cm2 for the 800 microns and 40J/cm2 for the 200 microns fibre. Removal of calcified plaque was possible. Ablation efficiency increased in a non-linear fashion with increasing pulse energies. The ablation rate per pulse was approximately 2 mm at energy fluences of 1000J/cm2 for the 200 microns fibre and 1.25 mm at energy fluences of 70J/cm2 for the 800 microns fibre; a further increase in energy densities did not result in higher ablation rates. On macroscopic examination only very limited thermal injury was found in crater adjacent tissue structures. Crater edges were even and did not reveal signs of crater charring or debris in the crater lumen. However, the histologic specimens revealed zones of thermal damage extending 100 up to 1000 microns lateral into adjacent tissue. Thermal damage increased with increasing radiant exposures and depended on the medium used.
The fragmentation response of urinary and ureteral calculi via a single flexible UV quartz/quartz fibre with 320 m core diameter has been studied in-vitro using a Q-switched solid-state alexandrite laser system running simultaneously at two wavelengths in the Blue (380 nm) and Near-JR (760 nm) spectral region with continuously adjustable pulse energy ratios of both laser radiations.It was found that the fragmentation quality -compared to a dye laser system with 1.2 isec pulse duration at 504 mit -is significantly better and faster, and strongly depends on the stone surface color, the acoustic impedance of the exterior/interior stone structure and the energy ratio of the Blue and Near-IR laser beams.
In order to serve as supplements to existing mechanical devices and procedures in dentistry, laser systems and laser procedures may not produce any irreversible damages to the dental hard and soft tissues or to the root canals. For the fast and effective removal of caries lesions, enamel and dentin, or for the preparation of root canals, decisive laser parameters which play a dominant role during these non-mechanical treatments, are the laser wavelength, the pulse duration, the fluence as well as the pulse repetition rate of the applied laser system. We report here of the advantages and technical features of a compact pulsed and frequency-doubled alexandrite laser system for cutting of enamel and dentin, for vaporization and coagulation of soft dental tissue, for preparation and sterilization of root canals and for crystallization of composite material.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.