Low intensive laser irradiation is widely used for the treatment of many stomatological diseases. The caries static activity of HNL light and infrared lasers, its influence on the activation of microcirculation of the pulp enzyme system and on the increase of enamel permeability became clear. These data allow us to suppose that the low intensive laser irradiation may potent the activity of the initial caries by the increase of teeth stability to the factors provoking the caries.

Favorable clinical data at the absence of positive dynamics microbiological research findings in the treatment of caries and their complications give a reason to consider the treatment insufficiently effective and it is necessary to reduce the terms of an additional prophylactic observation and an antirelapse treatment of the disease. That is why researchers all over the world search for new effective methods of influence on the microflora of carious foci. Using the experience of the treatment of 40 patients with caries, 40 patients with chronic pulpitis, and 40 with chronic periodontitis high bactericidal properties of low intensive laser radiation are shown. If after the traditional treatment of foci microflora was inoculated in 62.3% of the cases, after the laser therapy session -- in 26.3% of the cases. The efficiency, ease of handling, and low expenditure of time allow us to recommend this method for a massive use in the treatment of caries and their complications.

Biological responses of cells to visible and near IR (laser) radiation occur due to physical and/or chemical changes in photoacceptor molecules, components of respiratory chains (cyt a/a₃ in mitochondria). As a result of the photoexcitation of electronic states, the following physical and/or chemical changes can occur: alteration of redox properties and acceleration of electron transfer, changes in biochemical activity due to local transient heating of chromophores, one-electron auto-oxidation and O'₂- production, and photodynamic action and ¹O₂ production. Different reaction channels can be activated to achieve the photobiological macroeffect. The primary physical and/or chemical changes induced by light in photoacceptor molecules are followed by a cascade of biochemical reactions in the cell that do not need further light activation and occur in the dark (photosignal transduction and amplification chains). These reactions are connected with changes in cellular homeostasis parameters. The crucial step here is thought to be an alteration of the cellular redox state: a shift towards oxidation is associated with stimulation of cellular vitality, and a shift towards reduction is linked to inhibition. Cells with a lower than normal pH, where the redox state is shifted in the reduced direction, are considered to be more sensitive to the stimulative action of light than those with the respective parameters being optimal or near optimal. This circumstance explains the possible variations in observed magnitudes of low- power laser effects. Light action on the redox state of a cell via the respiratory chain also explains the diversity of low-power laser effects. Besides explaining many controversies in the field of low-power laser effects (i.e., the diversity of effects, the variable magnitude or absence of effects in certain studies), the proposed redox-regulation mechanism may be a fundamental explanation for some clinical effects of irradiation, for example the positive results achieved in treating wounds, chronic inflammation, and ischemia, all characterized by acidosis and hypoxia.

Luminol-amplified chemiluminescence was recorded after irradiation with laser radiation at 632.8 and 820 nm. The following cellular systems were used as objects of irradiation: blood of healthy donors, blood of patients with colon cancer or acute respiratory illness, blast cells of patients with acute leukemia. The irradiation was suppressing the oxidative metabolism of cellular systems under study.

The effect of light on calcium transport in mammalian sperm mitochondria and plasma membrane was studied. Digitonin treated bovine spermatozoa and plasma membrane vesicles were irradiated with a He-Ne laser and a 780 nm diode laser at various intensities and energy doses and Ca²⁺ uptake was measured by the filtration method. It was found that there is an accelerated Ca²⁺ uptake by the mitochondria after low He-Ne light and inhibition after high intensity irradiation. The ATP-dependent Ca²⁺ uptake by the sperm plasma membrane vesicles was not changed due to He-Ne irradiation. It was enhanced due to 780 nm irradiation.

Low level He-Ne laser radiation (633 nm) is currently used as an aiming beam in carbon dioxide laser surgery. However no systematic study was published yet concerning the interaction of He-Ne laser radiation with blood cells and tissues under surgery. In view of this, in the present paper, several methods were used to follow up the changes in the properties of the human erythrocyte membrane during and/or following the low level exposures to He-Ne laser beam compatible with those currently used in laser surgery (3 mW beam power, 2 mm beam diameter). It was found that no significant modification of membrane permeability to hemoglobin is obvious after short irradiation (up to 30 minutes) while osmotic fragility and membrane fluidity is increased (more in young than in old erythrocytes) even at these irradiation times.

We previously described the influence of low-level laser therapy (LLLT) on the primary fibroblast ATCC CRL1471 CCD-19SK passage 7 in culture, metabolic changes and statistical significance absorption of ³[H]Hydroxyproline after 2 irradiations (12 hour intervals) with Ar:DYE Laser, 633 nm wavelength, output power 38 mw, spot size 3.5 cm, power density 4 mw/cm², energy density plus or minus 2 J/cm². The aim of this work is to investigate, by using the same procedure, the behavior of the confluence monolayer fibroblasts culture when a central scratch of 0.4 - 1 mm and 2 irradiations is performed, by means of the study of the colony formation, haptotaxis (direction) and chemotaxis- chemokinesis (movement). The results indicate that all these phenomena appear sooner in the LLLT cultures than in non-treated cultures. Thus we can confirm that LLLT induces fibroblast biological effects.

Influence of He-Ne laser irradiation (lambda - 632.8 nm, power density - 1.5 mW/cm²) on polytene chromosomes of salivary glands cells of Chironomus plumosus in different conditions of exposure was studied. Living larvae or isolated salivary glands were exposed to irradiation. He-Ne laser irradiation was stated to influence the functional activity of polytene chromosomes. The response of the genetic apparatus to the laser light action was shown to depend on the irradiation dose and fractional character of the dose exposure, on the initial functional state of chromosome loci and may be manifested both by activation and inhibition of definite regions of the genome. The phenomenon of adaptation of the genetic system to He- Ne laser irradiation is revealed.

The actions of physico-chemical mechanisms of low power light, applied in medicine are discussed. The investigations were prepared both in experiment on laboratory animals and in emergency-care clinics, where I worked with physicians as the theory-investigator. In this message I propose the theory of permeability increasing effects of low power light. Proton- permeability increasing effects on membranes go to the bioenergetic mechanism of low power light action. Sodium-permeability increasing effects on excitable membranes go to the reflex mechanism of low power light action. We suppose the medical mechanism of laser irradiation effects on the blood to be connected with water-permeability increasing effects because of blood cell membrane depolarization and shaking. We measured the dependence of red blood cell membrane water-permeability coefficient upon the low power light irradiation wavelength in the range 625 - 645 nm. So it was proved that He-Ne laser irradiation with 633 nm wavelength excites dissolved molecular oxygen from the ground triplet state to the singlet state. Fast relaxation of singlet oxygen to triplet state in water medium near membrane with the time 10^-6 sec go to the membrane purification mechanism of low power light action.

The incidence of inferior alveolar nerve (IAN) damage following removal of 3rd molar teeth or saggital split osteotomy has been reported as high as up to 5.5% and 100% respectively. Sensory aberrations in the IAN persisting for longer than 6 months leave some degree of permanent defect. Low level laser treatment (LLL) has a reported beneficial effect on regeneration of traumatically injured nerves. The purpose of this double blind clinical trial was to examine the effects of LLL using a GaAlAs laser (820 nm, Ronvig, Denmark) on touch and temperature sensory perception following a longstanding post surgical IAN injury. Thirteen patients were divided into two groups, one of which received real LLL (4 by 6 J per treatment along the distribution of the IAN to a total of 20 treatments during a time period between 36 - 69 days) and the other equivalent placebo LLL. The degree of mechanoreceptor injury as assessed by Semmes Weinstein Monofilaments (North Coast Medical, USA) were comparable in the two groups prior to treatment (p equals 0.9). Subsequent to LLL the real laser treatment group showed a significant improvement in mechanoreceptor sensory testing (p equals 0.01) as manifested by a decrease in load threshold (g) necessary to elicit a response from the most damaged area. The placebo LLL group showed no significant improvement, In addition, the real LLL group reported a subjective improvement in sensory function too. The degree of thermal sensitivity disability as assessed using a thermotester (Philips, Sweden) was comparable between the two groups prior to LLL p equals 0.5). However, there was no significant improvement in thermal sensitivity post LLL for either the real or placebo laser treated groups. In conclusion, GaAlAs LLL can improve mechanoreceptor perception in longstanding sensory aberration in the IAN.

Two types of laser diode (LD) based equipment for rheumatology are introduced. The first is a portable device which contains single LD emitting at 890 nm laser pulses (time full width 100 nsec) of reprate tunable within (0.5 - 1.5) kHz; the laser beam average power is 0.7 mW at 1 kHz reprate. The second is computer controlled, contains one HeNe laser and 5 LD allowing 6 modes of patient irradiation (placebo effect evaluation included). HeNe laser works in cw at 632.8 nm; the LD works each as described for the portable equipment. HeNe and LD beams are superposed so that HeNe laser spot in the irradiation plane has a 60 mm diameter and the LD spots covers a 50 mm diameter disc centered on the HeNe laser spot. Clinical applications using the second type of equipment are reported; 1287 patients were treated between October 1991 and October 1994. Female/male ratio was 4:1 and their age distribution was between 18 and 85 years. The average number of exposures was 10 and the mean exposure time was 7 minutes. Studies were made on the treatment of rheumatoid arthritis, seronegative arthritis, degenerative joint diseases, abarticular rheumatism, osteoporosis pain and pains and edema after fractures.

The low energy laser (LEL) biostimulatory effects on nervous tissue regeneration are well known. Thirty two patients with medial and/or radial nerve traumatic forearm lesion after surgical suture were divided into two groups: A-18 patients were treated with LEL; B-14 patients, witness, were treated with placebo lasers and classical medical and physical therapy. Lasers used were: HeNe, 632.5 nm wavelength, 2 mW power, and GaAlAs diode laser, 880 nm wavelength, pulsed emission with an output power 2 mW. Before, during, and after treatment EMG was done in order to measure objectively the efficiency of the treatment. We obtained good results after 4 - 5 months at 14 patients (77.7%) from group A and about the same results at 10 patients (71.3%) from group B, but after at least 8 months the good results were noticed concerning the improvements of EMG registration and on movements and force of the fingers. Finally we can say that the favorable results were obtained in at least twice shorter time with LEL treatment than with classical therapy.

The influence of preliminary transcutaneous He-Ne laser irradiation (lambda - 632.8 nm, power density - 5 mW/cm²) on the development of cerebro- and cardiovascular disturbances was studied in experiments on white male rats in conditions of combined pathological stress (rigid immobilization plus sound stimulus for 2 hours). Ischemic and hemorrhagic damages of the heart and brain were shown to decrease after laser exposure, it being revealed at the pathomorphologic investigation.

Results on laser induced fluorescence (LIF) properties of collagen, cholesterol and chlorophyll a (chl a) when excited at 337.1 nm are reported. The collagen and cholesterol florescence was studied in connection with atherosclerotic plaques diagnostics and/or removal within the cardiovascular system. The fluorescence signal excitation and collection were made using optical fibers, for liquid samples at concentrations between 0.1 mg/ml and 5.0 mg/ml for both collagen and cholesterol, their fluorescence lifetime being 5 nsec and 6 nsec, respectively. Chl a LIF concerned the stimulated emission of radiation considering the pigment as laser active medium. Chl a concentrations varied, in different solvents between 5 multiplied by 10^-3 M/l and 10^-5 M/l. For chl a at 0.62 mM/l and pumping photon densities higher than 5 multiplied by 10¹⁶ photons/cm² and pulse, fluorescence linewidth narrowing from 28 nm to 5 nm in ethanol and from 25 nm to 4 nm in DMSO were obtained. Lasing maxima at 672 nm in acetone, 674 nm in ethanol and 678 nm in DMSO were observed. At lasing conditions for chl a in DMSO (1 mM/l) the measured fluorescence lifetime was 2 nsec instead of 5 nsec for normal fluorescence. The results on chl a stimulated emission show a lower lasing threshold at 10¹⁶ photons/cm² and pulse, than previously reported, if DMSO solvent is used.

The widespread use of lasers in medicine has raised the awareness about the mutagenic effect of ultraviolet laser radiation. Although it is well known that the major target for UVC (200 - 290 nm) and UVB (290 - 320 nm) wavebands on cells and tissues is nuclear DNA, the information about UVA radiation (320 - 400 nm) is controversial, as far as some researchers present evidence that this waveband should be 1000-fold less cytotoxic and mutagenic than UVC, while others present evidence about its lethality and mutagenicity. In addition the mechanism of cell killing in the UVA range remains unclear. This work presents an extensive study of UVA-laser radiation (355 nm) effects on Chinese hamster ovary cells. The experiments were performed with an Nd:YAG/KD^*P laser (third harmonic, 355 nm), operating at the Q-switch mode, 6 nsec pulse duration. Chinese hamster ovary cells (CHO cells) from a frozen cell line, were suspended in McCoy's 5A culture medium, washed with PBS, and after centrifuging at 200 g the pellet irradiated by UVA-laser beam. Cell viability studies were done in a range of fluences from 0 - 75 J/cm², 5 Hz repetition rate. Direct effects of laser irradiation were evaluated by the Trypan Blue test, and post-effects by the cell survival assay. The degree of cell damage was related to the fluence and it was concluded that increasing fluences of radiation resulted in decrease rate of cell survival. Also, it was noticed that the survival fraction 8 days after irradiation was decreased in relation to the survival fraction just after irradiation. Direct and post-effects are discussed and related with pertinent mechanisms of damage and repair by UVA light.

In the present paper speckle-interferometrical technique utilizing strongly focused Gaussian beam (SFGB) diffraction has been proposed for the analysis of microcirculatory parameters. The method has been applied for the investigation of lymph motion characteristics in microvessels in vivo. Spectra of scattered intensity fluctuations in the statistically inhomogeneous speckles formed at the diffraction in lymph microvessels have been presented. It has been shown that the alterations of the spectra envelope depend on peculiarities of lymph motion in microvessels. Physical parameters of determination both of temporal changes of a mean velocity and of spatial-temporal velocity distribution in lymph microvessels have been proposed. An application of lymphotropic drug on the lymph microvessels has been studied. Temporal changes of lymph flow parameters have been analyzed in the paper.

In recent years we have been working out a new method of treatment of steroid-resistant asthma -- extracorporeal He-Ne-laser blood irradiation. The procedures gave good clinical effect and allowed reduction of steroid dose in a majority of patients. The monocytes were investigated by luminol-dependent chemiluminescence and the method of living cell microcopy. Extracorporeal He-Ne laser blood irradiation normalized both monocytes chemiluminescence and cell oscillation in asthmatic patients significantly earlier than in cases of ordinary treatment, although the mechanisms of action of He-Ne-laser irradiation upon blood steroid-resistant asthmatics were not fully determined.

We discuss light-induced stimulation and inhibition of biological activity by means of three types of competing processes. In the visible region, these competing processes are the formation by photosensitization of reactive oxygen species (ROS) which stimulate the redox activity of the respiratory chain (RC) on the one hand, and intramolecular electronic- vibrational energy transfer from an endogenous photosensitizer to an enzyme of the RC, thereby bringing this enzyme into an inactive configuration and paralyzing the RC, on the other hand. Moreover, there is competition between stimulation of the redox activity of the RC by the ROS and a slower process where the enzymes of the RC react with the ROS, again paralyzing the RC. This paralysis of the RC plays a dominant role in photodynamic therapy, where exogenous photosensitizers together with a sufficiently large visible light-energy dose lead to overproduction of ROS. Finally, in the far-red region, there is competition between reactivation of the ATPase ion pumps in the cell membrane and inhibition of the enzymes in the RC as a result of vibrational overtone excitation. Photobioactivation is shown to lead to enhanced transient Ca²⁺ concentration increase (calcium oscillations) in the cytosol, thereby triggering further biological activity such as afflux of intercellular messengers which open gated ion channels in neighboring cells, producing calcium waves. Addition of ROS scavengers or quenchers such as SOD in the presence of catalase neutralizes photobiomodulation induced by visible light.

Sixty patients (greater than 16 yrs old) suffering primary or relapse genital herpes simplex viruses (HSV) and relapse labial HSV were appointed for this study. Three or more relapses were experienced per year. Patients (under treatment) were divided into two groups (distribution areas), corresponding to either labial herpes or genital herpes. These groups were sub-divided into 3 groups. The total number of labial or facial HSV patients was 36 (10 in group 1, 12 in group 2, 14 in group 3) and 24 for genital, buttocks, or 'area pudenda' HSV patients (6 in group 1, 8 in group 2, 10 in group 3). The design was a randomized, double- blind study. The setting was hospital and outpatient. The patients diagnosed as having the HVS disease were sent to the dermatology department and were assigned to a group at random. Treatment was begun as follows: During the treatment signs and symptoms were assessed and after the treatment, the relapses were also assessed (biochemical and hematological tests before and after the treatment) and the diagnosis of the HSV type I and II. The statistical evaluation of the results was performed and carried out with the SPSS and BMDP program. The relapses of the herpes infection in the lips and the face were significantly reduced (p less than 0.026) in patients treated with laser He-Ne and laser He-Ne plus Acyclovir. The interim between the relapses also increased significantly (p less than 0.005) in relation with the group treated with Acyclovir. The duration of the herpetic eruptions was clearly reduced in all locations in patients treated with laser He-Ne plus Acyclovir. No differences were noted between patients treated with laser He-Ne only or Acyclovir only. Therefore it is probable that therapeutic synergism took place. In relation with this, laser He-Ne shows the same therapeutic efficacy as Acyclovir taken orally. The association of Acyclovir and laser Ne-Ne could be an alternative method for the treatment of HSV in the face. The number of relapses of the herpes infection in the genital, buttocks or 'area pudenda' and the interim between the relapses were not substantially modified with the treatment of laser He-Ne or laser Ne-Ne plus Acyclovir. Although a little difference exists in comparison with the patients treated with Acyclovir alone, a survey or an increased number of patients should be necessary.

Interest in the interaction of low power light with tissues has increased in the last few years. Very often, the stimulating effects of irradiation have been explained by the role of the coherence of laser radiation as it acts upon biological objects. This argument is not convincing and the purpose of the present report is to describe the experiences during two years working with infrared (IR) GaAs light emitting diodes (LED) as clinical light for the therapy of some dental diseases. Equipment was designed and built, FOTOTER, which was approved by the National Health Office (registration No. 7910B). The treatment was practiced on 360 patients. They presented pain on buccal or facial structures and disorders on buccal tissues. Pathologies, number of patients treated, application time in each trigger point, number of sessions, and the relief pain patients are summarized. We conclude that the therapy with IR LED has the same effects as the HeNe and GaAs laser therapy on the biological buccal tissues. We recommend LED therapy for the treatment of these dentistry diseases.