This PDF file contains the front matter associated with SPIE Proceedings Volume 6846, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

The use of low levels of visible or near infrared light for reducing pain, inflammation and edema, promoting healing of wounds, deeper tissues and nerves, and preventing tissue damage by reducing cellular apoptosis has been known for almost forty years since the invention of lasers. Despite many reports of positive findings from experiments conducted in vitro, in animal models and in randomized controlled clinical trials, LLLT remains controversial. Firstly the biochemical mechanisms underlying the positive effects are incompletely understood, and secondly the complexity of choosing amongst a large number of illumination parameters has led to the publication of a number of negative studies as well as many positive ones. This review will focus on the role of nitric oxide in the cellular and tissue effects of LLLT. Red and near-IR light is primarily absorbed by cytochrome c oxidase (unit four in the mitochondrial respiratory chain). Nitric oxide produced in the mitochondria can inhibit respiration by binding to cytochrome c oxidase and competitively displacing oxygen, especially in stressed or hypoxic cells. If light absorption displaced the nitric oxide and thus allowed the cytochrome c oxidase to recover and cellular respiration to resume, this would explain many of the observations made in LLLT. Why the effect is only seen in hypoxic, stressed or damaged cells or tissues? How the effects can keep working for some time (hours or days) postillumination? Why increased NO concentrations are sometimes measured in cell culture or in animals? How blood flow can be increased? Why angiogenesis is sometimes increased after LLLT in vivo?

There have been numerous reports describing the phenomena of biostimulation and bioinhibition using low-level laser therapy (LLLT) and other light and IR sources within the laboratory and in clinical trials. Stimulation or inhibition employed correctly has been shown clinically to reduce pain, improve tissue repair, resolve inflammation and stimulate the immune system. All these effects are sensitive to different irradiance and / or different energy (sometimes described as dose rate or fluence rate effects). The typical ranges for biostimulation and bioinhibition will be examined and a 3D Arndt Schulz style model proposed to illustrate possible 'dose sweet spots' for the intended clinical effects.

The immune system is a complex group of cells, tissues and organs that recognize and attack foreign substances, pathogenic organisms and cancer cells. It also responds to injury by producing inflammation. The immune system has peripheral components that include skin-associated lymphoid tissues (SALT) and mucosa-associated lymphoid tissues (MALT), located where pathogens and other harmful substances gain access to the body. Phototherapy, delivered at appropriate treatment parameters, exerts direct actions on the cellular elements of the peripheral part of the immune system since it is readily accessible to photons.

It has been proposed that photodynamic therapy (PDT) can inactivate microbial cells. A range of photosensitizers and light sources were reported as well as different fluence parameters and dye concentrations. However, much more knowledge regarding to the role of fluences, irradiation time and irradiance are required for a better understanding of the photodynamic efficiency. The aims of this study were to investigate the role of light parameters on the photoinactivation of yeast cells, and compare cell survivors in different growing phases following PDT. To perform this study, a suspension (10⁶cfu/mL) of Candida albicans ATCC-90028 was used in log and stationary-phase. Three irradiances 100mW/cm², 200mW/cm² and 300mW/cm² were compared under 3min, 6min and 9min of irradiation, resulting in fluences of 18, 36, 54, 72,108 and 162J/cm². The light source used was a laser emitting at 660nm with output power of 30, 60 and 90mW. As photosensitizer, 100μΜ methylene blue was used. PDT was efficient against yeast cells (6 log reduction) in log and stationary-phase. Neither photosensitizer nor light alone presented any reduction of cell viability. The increase of irradiance and time of irradiation showed a clearly improvement of cell photoinactivation. Interestingly, the same fluences in different irradiances presented dissimilar effects on cell viability. The irradiance and time of irradiation are important in PDT efficiency. Fluence per se is not the best parameter to compare photoinativation effects on yeast cells. The growing-phases presented the same susceptibility under C. albicans photoinactivation.

The role of low visible or near infra-red laser intensity in suppressing metabolic activity of malignant human brain cancer (glioblastoma) cells was investigated through the application of either a continuous wave 633nm HeNe or a pulsed picosecond 1,552nm wavelength laser. Human glioblastomas were exposed in their growth culture medium with serum for several energy doses. For both types of laser exposures the glioblastomas exhibited a maximal decline in the metabolic activity relative to their respective sham control counterparts at 10 J/cm². The cellular metabolic activities for various treatment doses were measured through the colorimetric MTS metabolic assay after the laser exposure. Interestingly, addition of (the enzyme) catalase in the growth medium prior to the laser exposure was found to diminish the laser induced metabolic suppression for all fluence treatment conditions, thus suggesting a functional role of H₂O₂ in the metabolic suppression. Taken together, our findings reveal that visible or near infra-red low level light exposures could potentially be a viable tool in reducing the metabolic activity of cancers; evidence at hand implicates a role of light induced H₂O₂ in bringing about in part, suppression in the metabolic activity. Due to the cellular "biphasic" response to the laser exposure, further research needs to be undertaken to determine exposure parameters which would optimize metabolic and cellular growth suppression in-vivo.

Photodymanic antimicrobial therapy (PAT) has been proposed to treat oral infections and the phenothiazinic compound Methylene Blue (MB) has been considered as a suitable photosensitizer for this application. MB is a known methachromatic compound and the dimerization process may lead to different photochemical reactions, into the oral cavity, where the complete isolation of the saliva may not be possible. The aim of this study is to monitor the dimerization process of MB in the presence of human saliva through absorption spectroscopy. Absorption spectra of 30μM MB solutions in water and in human saliva were recorded in the wavelengths ranging from λ=400nm to λ=700nm. The spectra were recorded immediately after mixture and 1 min, and 5 minutes after blending. The results were evaluated by spectral analyses and through the calculus of the dimer/monomer ratio. The results demonstrated that immediately after mixture a hypochromic effect characterized by the diminishing on the total absorption in the visible range of the spectrum (λ= 400nm - 700nm) is observed, but the aggregation process is not detectable. After 1 minute the ratio between dimer and monomer absorption increase and this increase became higher upon increasing the contact time. The results indicate that the addition of saliva into the mixture leads to and hypochromic effect follow by the dye aggregation. Aggregation is probably an important variable to be analyzed when choosing the pre-irradiation time in oral cavity application, because it may lead to different photochemical routes.

Laser phototherapy has proven to improve treatment of several pathologies in dentistry. The aim of the present study was to analyze the low power laser phototherapy effects comparing multiple irradiations with the same total energy at once. This in vitro study focuses on the biostimulation of cellular growth of pulp fibroblasts (FP5 cell lineage). The cells were grown in Dulbecco's Modified Eagle's (DME) medium with either 5% (nutritional deficit) or 10% fetal bovine serum (FBS). Laser irradiation was carried out with diode lasers with the following parameters: 685 nm, 40 mW, spot size 0.019 cm². The groups were: G1(6.3J/cm², 3 s, 0.12J), G2 (12.6J/cm², 6 s, 0.24J), G3 (18.9J/cm², 9 s, 0.36J), G4 (2 irradiations of 6.3J/cm², 0.24J), G5 (3 irradiations of 6.3J/cm², 0.36J), G6 (5% SFB, negative control, without irradiation), and G7 (10% SFB, positive control, without irradiation). On groups G4 and G5 the irradiation was performed with 6h-intervals. For growth analysis, the MTT test was used 24 hours after the last irradiation. The data from spectrophotometer were analyzed by ANOVA followed by the Tukey's test. The groups submitted to multiple irradiations presented significantly higher cell growth than the groups with single irradiation. This cell growth was similar to that of positive control group. The laser phototherapy with multiple irradiations is more effective on cellular growth.

Severe burns cause extensive damage and are complicated by loss of body fluids, injury in the cutaneous vasculature and delayed wound healing. Low-intensity laser therapy (LILT) has been studied as an alternative method to accelerate wound healing. This study was carried out to evaluate LILT effects (λ= 660 nm) in rat burned skin with two different dose regimens. Thirty-six male adult Wistar rats with two burns created on their back using steam water were divided into 3 groups. In the fractioned dose laser group (FG), the lesions were irradiated with 1J/cm² on days 1, 3, 8 and 10; in the single dose laser group (SG), the lesions were irradiated with 4J/cm² on day 1. On control group (CG), lesions were not irradiated. Three animals per group were sacrificed on days 1, 3, 8, 10, 15 and 21 post-wounding and skin specimens were collected and processed to histomorphometry. At days 1, 3 and 8, statistical significant differences were not observed among groups. On the 10^th day, mean values of the number of blood vessels for FG was significantly higher than CG. Irradiated groups showed a peak of new blood vessels formation at day 15 while for CG the peak was at day 21. The number of vessels in CG was significantly higher than FG and SG at day 21. These findings suggest that LILT may accelerate angiogenesis compared to control group, however, no significant differences were observed between laser groups with fractioned or single dose during all experiment.

The aim of the experiment was to estimate the effect of repeated simultaneous exposures to infrared laser radiation and μT variable magnetic field used in magnetostimulation on pain perception in rats, as well as the involvement of endogenous opioid system in the mechanism of this effect. In experimental group clean-shaven scull of male Wistar rats placed individually in a specially designed plastic chamber were simultaneously exposed to infrared laser radiation (wavelength - 855 nm, mean power - 4,1 mW, energy density - 30 J/cm²) and variable magnetic field of saw-like shape of impulse, at a frequency of basic impulse 180-195 Hz and mean induction value of 120 μT generated by magneto-laser applicator of device for magnetostimulation Viofor JPS (Med & Life, Poland) 12 minutes daily for 2 periods of 5 consecutive days, with 2 days-lasting break between them, while control animals were sham-exposed. The pain perception was determined by means of "hot plate" test on the basis of calculated analgesic index. As a result of repeated exposures a significant increase in analgesic index persisting also till 14^th day after the end of a cycle of exposures was observed. This analgesic effect was inhibited by prior i.p. injection of opioid antagonist - Naloxone.

The aim of this study was to determinate the efficiency of methylene blue (MB) to kill cultures of Aggregatibacter actinomycetemcomitans under red light and to investigate MB photobleaching by optical absorption spectroscopy. Bacteria were diluted in aqueous solution, putted in glass tubes and distributed in 5 groups: (L-MB-) control group; (L+MB-) laser alone by 5min; (L-MB+) MB alone through 5min; (3L+MB+) MB+laser 3min; (5L+MB+) MB+laser 5min. Laser parameters were P=30mW, λ=660nm, E=9J in 5min and E=5.4J in 3min. The samples were diluted and bacterial colonies were counted and converted into colony forming units (CFU). Absorption spectra of the MB-stained bacterial suspension and photosensitized bacterial suspension were obtained. Groups L-MB-, L+MB-, and L-MB+ did not show a decrease in CFU/mL. L+MB+ groups showed a significant decrease in CFU/mL but no statistically significant differences were observed between 3min and 5min. Spectroscopy showed that MB is photodegraded after irradiation and that dimer species are more notably consumed than monomeric species. These results suggest that MB is a suitable photosensitizer to reduce A. actinomycetemcomitans, and that 3min of irradiation are enough to produce a significant effect. Due to the spectral changes observed on MB solution after irradiation a type I mechanism may be involved.

This study compares the antimicrobial effect of photodynamic therapy (PDT) combined to endodontic treatment with conventional endodontic treatment alone in patients with necrotic pulp and has a 6-month radiographic follow up comparing the healing of periapical lesions. Fifteen patients with periapical lesion and requiring root canal treatment were selected. Microbiological samples were taken after accessing the root canal, conventional manual endodontic therapy (group 1 n=5) and after accessing the canal, endodontic therapy and PDT (group 2 n=10). All the root canals were filled with a calcium hydroxide paste for 1 week. Radiographs were taken after obturation and following 6 months. Endodontic therapy alone presented an 87% reduction in microorganisms while the combination with PDT had a 95% reduction. Radiographic follow up showed 32% higher reduction in the lesion area in PDT group. Results suggest that the use of PDT added to conventional endodontic treatment leads to a further major reduction of microbial load. PDT is an efficient alternative to chemical antimicrobial agents. It is a non-cumulative local treatment, which may be an appropriate approach for the treatment of infections in the oral cavity.

Optical Coherence Tomography (OCT) is a noninvasive method for imaging dental microstructure which has the potential of evaluating the health of periodontal tissue. OCT provides an "optical biopsy" of tissue 2-3 mm in depth. Optical biopsy is a measurement of the localized optical properties based on tissue type and pathology. This sixth modality of imaging was pioneered at Lawrence Livermore National Laboratory. OCT is based on the optical scattering signatures within tissue structure. With the use of a broad spectrum bandwidth light source, high resolution images, 10 times the resolution of radiographs, can detect important tissue interfaces within the periodontal sulcus and its' relationship to the attachment apparatus of the tooth. Multiple cross-sectional tomograms can be stacked to create two and three dimensional images providing information as to health of periodontal tissue important to both the clinician and researcher.

This manuscript is intended to demonstrate the important role that dentistry plays in regulating the balance of the Autonomic Nervous System (ANS) through the proprioceptive feedback of the posterior teeth to the brain. An old paradigm called Dental Distress Syndrome, relatively unknown in dentistry today, has at its core, the importance of the height of the posterior (back) teeth and its impact on total body health which is greatly aided by low level laser energy. The rationale behind the belief that the alteration of the posterior teeth affects the ANS begins with basic concepts in embryology. The functioning of the ANS will support the fact of Dental Distress Syndrome. Health practitioners of all disciplines can learn to recognize Dental Distress Syndrome and initiate non-invasive treatment and team with a trained dentist to enhance the wellness and health of the patient if they so desire. A synopsis of my oral paper presented to the Academy of Laser Dentistry demonstrating temporary balancing of the Autonomic Nervous System with three minutes of cold laser energy, as well as my rationale as to why results vary with different cold lasers will be discussed. Clinical case studies will be presented.

A single, open and non comparative study was conducted at Anwar Shah Trust for C.P. & Paralysis in collaboration with the Departments of Neurology and Neurosurgery, Children Hospital Lahore, Pakistan to evaluate the effects of ACULASER THERAPY in childern suffering from Cerebral Palsy (C.P.) and associated Neurological Disorders like epilepsy, cortical blindness, spasticity, hemiplegia, paraplegia, diplegia, quadriplegia, monoplegia, sensory-neural deafness and speech disorders. In all 250 childern were treated and the data was gathered during a period of 3 years from December 2003 till December 2006. These children were further classified according to the type of C.P. (spastic, athetoid, mixed) they suffered from and associated Neurological Disorders. This article shows results in C.P. childern who were treated with ACULASER THERAPY for minimum 6 weeks and more or had minimum of 15 treatment sessions and more. This article also shows that those childern who were given a break in the treatment for 1 month to 1 year did not show any reversal of the signs and symptoms. Analysis of the data showed that out of 171 children with Spasticity and Stiffness 147 showed marked improvement showing 87% success rate, out of 126 children with Epileptic fits, there was a significant reduction in the intensity, frequency and duration of Epileptic fits in 91 children showing 72% success rate, out of 48 children with Cortical Blindness 30 children showed improvement accounting for 63% efficacy rate, out of 105 children with Hearing Difficulties, 63 showed marked improvement accounting for 60% improvement rate, out of 190 children with Speech Disorders 122 showed improvement reflecting 64% improvement rate, out of 96 children with Hemiplegia 71 showed improvement in movement, tone and power accounting for 74% improvement rate, out of 76 children with Quadriplegia 52 showed improvement in gross and fine motor functions showing 69% success rate and out of 58 children with Paraplegia of lower limbs 44 showed improvement in weight bearing, standing and movement accounting for 76% improvement rate.