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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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AbstractsThe paper summarizes the results of the experiments on the study of the changes in tooth and its pulp, caused by the odontopreparation by the pulsed erbium laser in comparison with the conventional and turbine dental drills. The results evident for the advantages of the laser dental drill application in some cases.Teeth preparation is the old, but widely used in the therapeutical and orthopedic dentistry surgery procedure. It provides the successful treatment of the damaged teeth andjaws. In the therapeutical dentistry this procedure is used for the extraction of the damaged dental tissues and clearing the healthy regions. The role ofthis procedure grows with the improve of the attitude to the dental health of the nation and with the wider use of the high speed and turbine dental drills with the rotation rate of the surgeiy tool as high as 30000 rounds per minute. However, preparation ofthe hard dental tissues and other dentistry procedures cause the negative reaction of the patient due to the pain, fear and other emotions. Hence one of the basic problems is the reduce of the pain and other negative effects.Application of lasers to the odontopreparation made it possible to realize the painless treatment of the non complicated and complicated caries. However, the ruby, neodymium, holmium and COz-lasers are not widely used in the dentistry, for the wavelength of their radiation (0.69; 1.06; 2.09; 10.6 pm) has the possibility to penetrate deep into the dental tissues; the heating of the large zone inside the tooth leads to the overheat and necrosis of its pulp and to the cracking and melting of the harddental tissues, resulting in turn in the secondary caries.It was found out, that the use of the eibium laser with the wavelength 2.94 tm for the hard dental tissues preparation is free ofthe said disadvantages [1].However, the transportation of the radiation with the wavelength of 2.94 tm to the surgery field can be carried out only using the inconvenient mirror waveguide. That is why in the Institute for Laser Physics there was made up the erbium laser dental setup, using the radiation with the wavelength of 2.69 tm. Such a radiation is also sufficiently efficiently absorbed in dental tissues, but it can be transported to the surgery field via the fused silica optical fiber and can be thus used for the processing of the caries cavities of any class according to Black.So we had the possibility to carry out the comparative experimental study of the consequences of the preparation by the conventional, turbine and ethium laser dental drills ofthe enamel, dentin and pulp ofthe animal and the extracted humane teeth.Three series of the odontopreparation of the central incisors (rabbits, "shenshilla" breed) were carried out using the conventional dental drill (10000 rounds per minute), turbine dental drill (30000 rounds per minute) and erbium laser (wavelength 2.69 im repetition rate 3 Hz and energy fluency 50-60 J/cm2. Each series of animals was divided into two groups, the incisors of the animals of the first grou...