Biomedical subjects

Michal Nemec

Publications and source records attributed to Michal Nemec.

3 recordsLinked to original sources

PubMed2004

X-ray opaque waveguide for dentistry.

OBJECTIVE: 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. BACKGROUND DATA: 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. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Equipment Design↗

PubMed2004

Diode laser-activated bleaching.

This study describes a preclinical investigation with laser-activated bleaching agent for discolored teeth. Bleaching techniques involve a broad-spectrum approach utilizing hydrogen peroxide (3-38%) with or without heat or laser, carbamide peroxide (10-30%), or a mixture of sodium perborate and hydrogen peroxide. Extracted human maxillary central incisors were selected. In the bleaching experiment, 38% hydrogen peroxide was used. Two different laser systems and light emission diodes for activation of the bleaching agent were used: diode laser, wavelength 970 nm, and infra-red diode laser, wavelength 790 nm, with eight blue light emission diodes, wavelength 467 nm. The enamel surface was evaluated with the scanning electron microscope. The method of chemical oxidation resulted in a 2-3 shade change in one treatment (15 min). Shorter time (5 min) was not effective. The diode laser, wavelength 970 nm, and the bleaching agent produced the same effect but with a shorter time of bleaching process (5 min - 1 W, 2.5 min - 2 W). Infra-red diode laser, wavelength 790 nm with eight blue light emission diodes, wavelength 467 nm, and the bleaching agent reached the desired color shade also after a shorter time (5 min - 40 mW). Slight surface modification after the bleaching process was detected with scanning electron microscopy. Currently, the laser has been proven the most valuable energy source for power bleaching with simple and short application in the dental office.

Hydrogen Peroxide↗

PubMed2003

Erbium:YAG laser lithotripsy by use of a flexible hollow waveguide with an end-scaling cap.

An Er:YAG laser light delivery system composed of a polymer-coated silver hollow waveguide and a quartz sealing cap has been developed for calculus fragmentation. Sealing caps with various distal-end geometries were fabricated, and the focusing effects of these caps for Er:YAG laser light were measured both in air and in water. Owing to the high power capability of the quartz a beam of sealing caps, Er:YAG laser light with an output energy of 200 mJ and a repetition rate of 10 Hz was successfully transmitted in saline solution by use of the system. Calculus fragmentation experiments conducted in vitro showed that the delivery system is suitable for medical applications in lithotripsy. We also found that the cap with a focusing effect is more effective in cutting calculi. The deterioration of the sealing caps after calculus fragmentation is also discussed.

Equipment Design↗