Olefin Polymer-coated Silver Hollow Research Articles

X-ray opaque waveguide for dentistry.

The aim of this study is the design, realization, and examination of a new x-ray contrast hollow waveguide which will be suitable for x-ray diagnostics or treatment required in medicine, as dentistry, maxiollofacial surgery or oncology. With the growing usefulness of laser radiation therapeutic interventions, a strong demand for radiation delivery from the laser source to the interaction place has appeared. For more complicated surgery, especially for internal intervention, an x-ray is necessary. In such cases, as a minimum, the end of the delivery system must be x-ray contrasted to distinguish where the interaction of radiation with tissue would take place. Up to now, neither fiber, hollow waveguide, nor other delivery system have been x-ray opaque. A new type of hollow glass waveguide was designed, fabricated, and examined as a delivery system for an endodontic treatment. The system is composed from the cyclic olefin polymer coated silver hollow glass waveguide with special covering for x-ray visibility. The inner diameter of the waveguide was 320 microm, the outer diameter was 630 microm, and its length was 100 mm. After the delivery system was created, the hollow waveguide was checked under an x-ray machine and its opacity was measured. For actual treatment, an Er:YAG laser system generating a mid-infrared radiation was used. The root canals of 10 molars were treated endodontically, and the result of that treatment was compared with the common cleaning methods. During treatment, digital x-ray images were taken with conventional files, using this new designed hollow waveguide. The position of a metal instrument demonstrates the quality of opacity after conventional step-back technique. The hollow waveguide is visible in the left tooth canal. A bone density analysis shows no differences between a left (waveguide) and right (tooth) canal. It was demonstrated that no differences exist between x-ray opacity of the metal instrument used for endodontic treatment and a special hollow waveguide. The digitalized, three-dimensional image helps to detect a precise position of customary instrument or waveguide in root canal.

Comparative evaluation of HP oxide glass fibers for Q-switched and free-running Er:YAG laser beam propagation

The radiation transmission of a Q-switched and a free-running Er:YAG laser, emitting at 2.94 μm, through high power (HP) oxide glass fibers of 450 μm and 250 μm core diameter was studied. Attenuation measurements were obtained as a function of the laser energy input and as a function of the curvature. The output beam quality was also studied using a beam profiler. Experiments with the same Er:YAG laser but with a 1000 μm core diameter cyclic olefin polymer coated silver hollow glass (COP/Ag) waveguide as the delivery system were performed for comparison. The results are promising as far as the delivery of Q-switched Er:YAG laser radiation is concerned. The fibers exhibited an attenuation below 0.7 dB/m, good output beam profiles, while no damage was observed after extended use.

Q-switched Er:YAG radiation transmission through fluoride glass fibers and dielectric-coated metallic hollow waveguides

The radiation transmission of a Q-switched Er:YAG laser, through fluoride glass fibers of 450 and 600 μm core diameter, and through a cyclic olefin polymer coated silver hollow glass waveguide (COP/Ag), of 1 mm inner diameter, was investigated. Attenuation measurements were obtained as a function of the laser energy input and as a function of curvature, at 90° and 180° bending angle. The results are promising for the delivery of Q-switched Er:YAG laser radiation, as the fibers exhibited attenuation of 0.9 dB/m and the waveguide 1.9 dB/m, and no damage of them was observed.