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SThe biological action of the laser radiation with the wavelength 2.69 tm onto the hard dental tissues and pulp was studied. Modes of laser action, preserving the pulp viability after the odontopreparation of the caries with the various rate, were revealed and chuiically evaluated.One of the basic problems of the therapeutical dentistry always was to realize fast and painless processing of hard dental tissues. Dentist patient's pain is nearly always caused by the pressure, vibration and heating, produced by the manipulations during the teeth preparation with the help of dental drill. Numerous approaches to such a drill creation were studied and evaluated, but even the most progressive high-speed and turbo dental drills does not completely exclude the pain syndrome.Application for these purposes of lasers created, seemingly, the possibility of successful solution of these problems. purposes. However, for a long period of time all the attempts of investigators, working in this direction were unsuccessful, because the experiments, using the lasers, emitting the radiation in the various ranges of spectrum (first of all, emitting such such a wavelengths as 0.69, 1.06, 2.09 or 10.6 .tm) and implementing various modes of action, caused various negative processes during the dental tissues processing, which often has resulted in tooth damage and pulp necrosis.Only recently, after the development of erbium lasers, emitting the radiation with the wavelength 2.94 m (near to one of the main absorption line ofwater), the prospects for such lasers application in clinical practice were established.Dentistry setups, based on this laser, provide rather efficient extraction of the damaged pails of the tooth without damage for the surrounding tissues; tooth heating in this case reveals quite local character.However, radiation with the wavelength in the range nearby 3 .tm can not be transmitted via the flexible optical fiber waveguide -the most convenient mean of radiation transportation. Hence, such a setups have significant disadvantage: radiation transportation to the surgery field is made via the bendable waveguide, flexibility of which is limited.This disadvantage may be eliminated by the use for odontopreparation purposes of the radiation with the wavelength 2.69 tm. One the one hand, this wavelength is close to 2.94 .tm, on the other hand, such a radiation may be (with some losses, indeed) transmitted via the fused silica fiber, providing thus the possibility to make the setup, supplied by the flexible fiber waveguide, enlarging the range of possibilities for the dentist during the treatment.These results were discussed in our previous paper [1], containing the large bibliography. It was fmd out that this laser emission is sufficiently efficiently absorbed in the tooth tissues and makes it possible to prepare caries surfaces without charring, melting and cracking of the enamel and dentin.Here we present the results of further study, devoted to the biological action of the radiation with the wavelength 2.69 tm onto the ...

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Using electronic microscope we have studied the opportunity to apply YAG:Cr,Tm-Er laser irradiation (=2.64 jtm) for preparation of the enamel and dentine in different modes of operation. High efficiency of enamel and dentine preparation was shown when using 50 J/sm2 energy density and frequency of pulses proceeding 3-5 n. There were no damaged effects involved teeth hard tissues in our experiences.The opportunity to apply laser irradiation to odontopreparation in therapeutic stomatology was one of the early ideas in laser applied science4"°"3"5'7. There was a point ofview, that anyone could be able to realize effectively working up of the teeth hard tissues without any pain. Many authors have made several experiences in this theme using hard-materials, gas and eximer lasers, which generated irradiation in lengths of waves in different regions of the spectrum by continuous or pulse-frequently modes of operation5'6'8"2"9'20. The results of these studies did not allow to employ the lasers in therapeutic stomatology for teeth preparation because of influence of laser irradiation results to fissurae and enamel damages, carbonization of the dentine near the zone of incidence of the ray, damages and irreversible alterations in teeth pulp''7'8'18. The search of optimal approaches to solve the problem, result to elaboration of the Er:YAG laser, thich generated irradiation in ?.=2.69 !.tm and X2.69 tm. These irradiation are very similar to one of the basic absorbability maximums of waters, so, they influence both teeth tissues and molecules of water inculcated into the tissue, that allow to its' effectively ablation during preparation, and give the opportunity to avoid chapness ofenamel and dentine, and alteration ofteeth pulp9"4 Resent elaboration in this region of science is creation of YAG:Cr,Tm-Er laser (GOl institute named of SI. Vavilov), which generates irradiation with X=2.64 tm. The of this study is to research the application opportunities of YAG: Cr,TmEr laser irradiation in odontopreparation. MATERIALS AND METHODSThe investigation was performed with 80 human teeth, extracted by different reasons, which were devoted to 16 groups by 5 teeth in each. Preparation of enamel and dentine was made by YAG:Cr,Tm-Er laser irradiation (50 and 120 JIsm2 energy density, 3 and 5 n, pulse time 400 ms ) with teeth water irrigation and without any irrigation. Before experience teeth were kept in 0.9 % solution of natrium chioridi at temperature 37 °C during 24 hours. After preparation the teeth were set into the 2.5 % solution of glutartic aldegidis with cacodilatic buffer at temperature 4 °C during 2 hours. Then, the specimens were put into the 2 % osmium fixing solution, were washed away with saccharose solution and were dehydrated by rising concentration spirits battery. Definitive drying was performed in lipophilic dry chamber. Then teeth were fixed in microscope tables and were coat with copper. To investigate the teeth tissues we used the scanned microscope Hitachi H-300>> (Japan) with 100 A resolution. We have studied 80 ...