The effect of Er:YAG laser in debris removing after conventional root preparation was tested by optical system in vivo and scanning electron microscope in vitro. The root canal of fifty permanent molars was cleaned in vivo and Er:YAG laser treated. Flexiscope system was used to evaluate the efficacy of laser cleansing at the different stages of endodontic therapy. Forty permanent teeth, extracted for orthodontic or periodontal purposes, were treated in vitro using the same technique an instruments. The in vitro treated teeth were also examined under the SEM. The result of our investigation show an effective improvement of the cleansing of the endodontic surface from pulpal remaining and a smear layer after laser irradiation in vivo and in vitro. The use of Er:YAG laser in organic debris removing and the consequent optical system analysis of the quality of root preparation in vivo seem to be a reliable technique particularly useful in clinical application.

The aim of this study was to evaluate the ability of an Argon laser to eliminate the smear layer after root canal preparation. Thirty three freshly extracted teeth were selected. The working length was established 1.5/2mm short of the apical foramen. The root canals were cleaned and shaped up to a minimum of 30 K file at the working length and flared using a step back technique. Between each file a 2 ml of NaOCl as irrigant was delivered and a final irrigation was conducted. A 300 micrometers fiber was introduced in each root canal, in a wet mood until the working length and the fiber was working in each canal for two times. Each pulse duration was 0.02 sec. and interval between each pulse was 0.2 sec. Five groups of six teeth were selected regarding power delivered: 2W, 1.5W., 1W., 0.75W., 0.5W. plus a group control unlased. Samples were then fixed and prepared for SEM examination and the evaluation of the smear layer removal was conducted using an image analysis system.

The Er:YAG laser has been studied for periodontal therapies, so much for removal of the subgingival calculus and its bactericidal effects. The proposal of this study is to evaluate the effectiveness of the Er:YAG laser in root planning in comparison to the traditional method, not surgical. Six recently extracted due top the disease periodontal, were cut longitudinally tends like this two half of the root. These half were separate in four groups. The first group is the natural tooth, the second group was accomplished to rot planing with Graceycurette. And in the third to Er:YAG laser with a contact tip, using a 45 degree angle in relation to the root; in the fourth group was scraped and planed with Er:YAG laser and complemented rot planing with Graceycurette. The used energy was of 60 to 300mJ and the frequency of 10 Hz accomplished with irrigation. The obtained results were similar in the groups 2 and 3 in comparison to the amount of smear-layer. In group 4 however, better result was obtained, because the image was much more regular and with less amount of smear-layer. The conclusion of the work is that with the association of the Er:YAG laser technique and Graceycurette the results are superior to the conventional treatment.

Aim of the study was to investigate the impact of a new picosecond laser emitting blue light on tooth surfaces in order to remove calculus. The radiation may be comfortably transmitted via 25 micrometers diameter fiber optics. The resulting fluence at the tooth was found to be to low for ablation of calculus via nonlinear effects. Higher absorption of the 446 nm radiation by calculus compared to heathy tissues can provide preferential heating and evaporation of the calculus. The surface of thick calculus is irregular rough thus comprising a large interface to the surrounding cooling medium contra acting the preferential heating. In summary the study indicates the possibility flat layers of calculus by thermal effects. Carbonization in healthy tissues is the major problem concerning removal of subgingival calculus with thermal effects.

In the last six years AlGaAs-Diodelasers have become more and more popular. Due to their small size, their good electro-optical coupling and delicate glass fibers this type of laser fits into most dental offices. The first diode lasers and still most of the devices still on the market work in a continuos wave mode or in a gated mode up to 50 Hz. Using this setting high temperatures in the tissue are inevitable. In this randomized study we tried to evaluate the difference in clinical cutting efficiency, post operative outcome and the histological findings of the excisional biopsies using a new diode laser Ora-laser Jet 20.

Wound infection constitutes a big risk for patients and it is usually associated to increased morbidity, mortality and hospital costs. It is accepted that local treatment of these infections is effective. The aim of this study was to compare histologically the effects of the CO₂ laser and Chlorohexidine Gluconate on Staphylococcus aureus infected cutaneous wounds. Standardized wounds were infected with Staphylococcus aureus and treated during six days as follows: Group I: Chlorohexidine Gluconate, 1 min, six days; Group II: CO₂ Laser, one day, maintaining surface debris; Group III: CO₂ Laser, one day, removing the surface debris. Seven days after wounding the animals were killed and specimens taken for light microscopy. On control wounds, it was observed epithelial ulceration, and neutrophylic and lymphoplasmocitary inflammatory infiltrate. On group II, there was epithelial hyperplasia, areas of ulceration and intense neutrophylic and lymphoplasmocitary inflammatory infiltrate. On the other hand, on group III, there was a neutrophylic inflammatory infiltrate underneath the surface debris and below that intense lymphoplasmocitary inflammatory infiltrate. When the surface debris was removed, there was epithelial ulceration and mild lymphoplasmocitary inflammatory infiltrate and fibroblasts and collagen fibers. The result of this study shows that infected wounds treated with 4 percent Chlorohexidine shows a more pronounced inflammatory reaction when compared to that observed when the CO₂ Laser is used, especially when surface debris are removed; Surface debris removal on Laser treated wounds results ona better and quicker healing; the surface debris may act as a culture medium for bacterial growth, or because of its characteristics, it may act as local irritant and delay healing.

This clinical case report relates to a total of 4 patients, carriers of idiopathic facial paralysis, treated with Low Level Laser Therapy using a Gallium-Aluminum-Arsenide diode laser of 780 nm, 50 mW, continuous wave emission, spot size 3 mm² and total dosage of 20 joules per session distributed to the peripheral trajectory of the injured nerve in a point by point contact mode. Altogether 24 treatment sessions were performed in a period of 12 consecutive weeks twice a week All treated patients presented recovery signs from the initial degree of paralysis.

In addition to our previous report on the effects of LLLT on the proliferation of laryngeal carcinoma cells in which it was found that irradiation H.Ep.2 cells with 670nm laser results in increased cell proliferation, ti was decided to evaluate the effect of increased does of laser light. The aim of this study was to assess the effect off 635 and 670 nm laser irradiation of H.Ep.2 cells in vitro using MTT. The cells, obtained from SCC of the larynx, were routinely processed from defrost to the experimental condition. The cultures were kept either at 5 or 10 percent of FBS. Twenty- four hours after transplantation, the cells were irradiated with laser light at local light doses between 0.04 and 4.8 X 10⁴ Jm^-2. For 670 nm, significant differences in the proliferation were observed between the two concentrations of FBS and between irradiated cultures and controls. Although the results were not significant, 635 nm irradiated cells also proliferated more than non- irradiated ones. This occurred under both conditions of nutrition. It is concluded, that irradiation with 670 nm laser light applied at doses between 0.04 and 4.8 X 10⁴ Jm^-2 could significantly increase proliferation of laryngeal cancer cells.

The relationship between bioptic technique and tissue preservation has been studied in 18 oral biopsies of young patients obtained by electro surgery or CO₂ laser surgery. Biopsies were formalin fixed, paraffin embedded and histologically, histochemically and immunocytochemically treated. All the biopsies show inflammatory cell infiltration, epithelial spongiosis, trichocariosis, supra basal small blisters, and epithelial clefts with lamina detaching from the corium. Histochemistry shows both the presence of edema and acid mucopolysaccharides inside the corium, and variable glycogen content in epithelial cells. Trichocariotic cells show a positive MiB1/Ki67 expression, when they are present. Nevertheless, laser biopsies show a lower amount of basophilic fibrous tissue and of bc12 bodies detection, connected with a higher amount of glycogen, Cytokeratin and MiB1/Ki67 expression in epithelial cells, compared to bovie biopsies. The result show a higher degree of damages in particular at the epithelial level, in electro surgery biopsies rather than laser biopsies. The best epithelial and corium preservation showed by laser biopsies suggest a chance of reversible condition, which can lead to a complete recovery due to its higher capability of restoring tissues.

The aim of this study was to determine the level of fluorescence of seven restorative materials using 655 nm diode laser. The laser fluorescence system has ben used as an auxiliary method for the detection of carious lesions. This new diagnostic method increases information which are important for the choice of treatment by the Dentist. The characteristic of restorative materials and sealers interferes in the values obtained by the apparatus during the detection of secondary carious lesions. The optical properties of each biological tissue or material are related to the interaction with the laser beam. Aware of that, the fluorescence of healthy dentin and enamel is 0-15, the authors determined the fluorescence of seven restorative materials with 10 teeth in each group. The laser reading scale differed according to the materia, ranging from 1 to 22 with several materials, for example the sealer without inorganic filler and the glass ionomer, showing fluorescence values similar to carious enamel which interferes with the readings around the restorations resulting in a false positive. Knowledge of restoration material fluorescence can aid in the detection of secondary carious lesions around the restorations.

In this report of clinical cases of peripheral nerve lesions, we evaluate the efficiency of the diode laser in treating six patients - three female and three male, age ranging from 25 to 36 years - who presented tongue paresthesia after surgical procedures which demanded regional mandible anaesthetic blockage. The patients' presented symptomatology was the absence of gustative sensitivity, the decrease of sensitivity and the increase of the nociceptive threshold on the affected side of the tongue. The treatment was carried out with a diode laser of 50mW, 780nm, continuous wave emission, spot size 3mm, and total dosage of 18 joules per session. We used a verbal scale to measure the intensity of the sensitive response both before and after treatment. The treatment module comprised two weekly sessions over a period of five consecutive weeks. After evaluation of the symptom condition, the patients would undergo another treatment module if necessary. This method of treatment proved to be efficient, resulting in restored sensitivity in al six treated patients. Only one patient reported a residual abnormality sensation concerning the tongue dimension but no discomfort at all. All 6 treated patients were evaluated in a follow-up period of thirty, sixty and ninety days post- treatment.

The changing of tooth shade by whitening agents occurs gradually. Apart from being subjective and affected by the conditions of the surroundings, visual observation cannot detect a very slight change in tooth color. An electronic method, which can communicate the color change quantitatively, would be more reliable. Quantitative Light- induced Fluorescence (QLF) was developed to detect and assess dental caries based on the phenomenon of change of autofluorescence of a tooth by demineralization. However, stains on the tooth surface exhibit the same phenomenon, and therefore QLF can be used to measure the percentage fluorescence change of stained enamel with respect to surrounding unstained enamel. The present study described a technique of assessing the effect of a tooth-whitening agent using QLF. This was demonstrated in two experiments in which either wholly or partially stained teeth were whitened by intermittent immersion in sodium hypochlorite. Following each immersion, the integrated fluorescence change due to the stain was quantified using QLF. In either situation, the value of (Delta) Q decreased linearly as the tooth regained its natural shade. It was concluded that gradual changing of the shade of discolored teeth by a whitening agent could be quantified using QLF.

A direct non-histological means of pulpal diagnosis remains elusive to clinical practice. Clinical vitality testing remains limited to electric, thermal criteria, or laser Doppler flowmetry. The goal of these investigations was to determine the feasibility of using light-induced fluorescence as a non-invasive modality for pulpal evaluation. Such a capability would, for example, permit expanded use of pulpotomy/pulpectomy techniques. Clinically healthy and diseased human extirpated pulpal tissues were used in this study. After excision, they were rapidly frozen and standard cryosections prepared. Measurement of tissue excitation/emission characteristics was performed using spectrographic analysis. A low-light level fluorescence microscopy system was then used to image autofluorescence localization and intensity at optimal excitation/detection parameters. Excitation/detection parameters used in this study included 405/605, 405/635, 405/670, 440/550, and 440/635. Autofluorescence intensities in healthy tissues were significantly stronger than those in diseased tissues at optimal parameters. It is postulated that autofluorescence characteristics are related to pathology- related structural changes in the pulp. This work provides the basis for further investigation into the relation between autofluorescence, histology and clinical symptoms.

3D model calculation on the basis of Finite Elements were carried out to simulate the heat distribution under IR laser ablation. The physical constant of dentin were used for heat capacity, heat conductivity etc. Already for a single pulse the results show the temperature distribution at various times after the laser pulse as well as the temperature gradient and the mechanical stress. The time resolution of a single pulse into 80 equal time step showed the heat deposition during the laser pulse Even more exciting data were obtained for pulse trains. It is clearly obvious that after 10 pulses the system reached a dynamical equilibrium. The amount of heat left over in the tissue by the previous pulse away by the following pulse by removing heated tissue.

Studies have shown that a water spray may augment the laser ablation rate of dental hard tissues in addition to reducing heat accumulation. However, the mechanism of augmentation is controversial and poorly understood. The influence of an optically thick applied water layer on the ablation rate was investigated at wavelengths in which water is a primary absorber and the magnitude of absorption varies markedly. Water was manually applied with a pipette and troughs were cut in enamel blocks using a laser scanning system. Q- switched and free running Er:YSGG and Er:YAG, free running Ho:YAG and 9.6 micrometers TEA CO₂ laser systems were investigated. The addition of water increased the rate of ablation and produced a more desirable surface morphology during enamel ablation with all the erbium systems. Ablation was markedly more efficient for the Q-switched erbium lasers than for the longer free-running laser systems when a water layer was added. Although, the addition of a thick water layer reduced the rate of ablation during CO₂ laser ablation, the addition of the water removed undesirable deposits of non-apatite mineral phases from the crater surface. There was extensive peripheral damage after irradiation with the Ho:YAG laser with and without added water without effective ablation of enamel. The results of this study suggest that water augments the ablation of dental enamel by aiding in the removal of loosely attached deposits of non-apatite mineral phase from the crater surface, thus producing a more desirable crater surface morphology. The non-apatite mineral phase interfere with subsequent laser pulses during erbium laser irradiation reducing the rate of ablation and their removal aids in maintaining efficient ablation during multiple pulses irradiation.

Previous studies have shown that pretreatment of dental enamel by specific carbon dioxide laser conditions inhibited subsequent progression of caries-like lesions in vitro. The aim of the present study was to use an intra-oral model to determine whether similar inhibition is observed in the human mouth. A cross over study with 23 subjects and three regimens was used. Pre-formed varies-like lesions were made in extracted human enamel and exposed intra-orally in partial dentures in each subject to A) placebo dentifrice and no laser treatment, B) placebo dentifrice following laser pretreatment, or C) sodium fluoride dentifrice and no laser treatment during each of three study periods. Samples were assessed by micro radiography to compare the mineral loss before and after each treatment and drive a net change in mineral value. Overall P was not significantly different form L but both P and L were different from F. For those subjects who demineralized in P, L and F were significantly better than P, with L showing an 84 percent inhibition of further demineralization, but no enhancement of demineralization.

The average pathlength of light inside dental enamel and incipient lesions is measured and compared, in order to quantitatively confirm the prediction that incipient lesions have higher scattering coefficients that sound enamel. The technique used, called optical pathlength spectroscopy provides experimental access to the pathlength distribution of light inside highly scattering samples. This is desirable for complex biological materials, where current theoretical models are very difficult to apply. To minimize the effects of surface reflections the average pathlength is measured in wet sound enamel and white spots. We obtain values of 367 micrometers and 272 micrometers average pathlength for sound enamel and white spots respectively. We also investigate the differences between open and subsurface lesions, by measuring the change in the pathlength distribution of light as they go from dry to wet.

FTIR spectroscopy used in the specular reflectance mode is well suited for resolving thermally induced changes in dental hard tissue as a result of laser irradiation. High spatial resolution is achievable with a high brightness synchrotron radiation source such as the ALS at Lawrence Berkeley National Laboratory. IR spectra of modified enamel were acquired after laser ablation using several laser wavelengths from the UV to the mid-IR. Specific areas of laser ablation craters were probed non-destructively with 10-micrometers spatial resolution. The chemical composition of the crater walls deviates markedly from that of hydroxyapatite after Er:YAG and CO₂ laser irradiation without added water. New mineral phases were resolved that have not been previously observed using conventional IR spectroscopy.

The therapy of initial carious lesions aims in a minimal invasive removal of infected dental hard tissue. Typically standard preparation instruments bear the risk of removing a big amount of sound structures as a result of access. On the other hand the competence of Er:YAG lasers for caries removal has been repeatedly proven.

The effects of laser or acid exposure on dentin have been explored for a number of years. Many researchers quite the recrystallization process, therefore there has been no scientific-oriented analysis regarding this issue. The first use of the word 'recrystallization' in laser treated dentin, was done by Dederich et al. They referred to needle-like crystals observed under Scanning Electron Microscopy (SEM) with high magnification. Further researchers continued quoting the recrystallization process in their works even though no evidence of crystals could be seen in their SEM pictures. In this work, four specimens of third human molars were prepared: one specimen was conditioned with 37 percent phosphoric acid, another was irradiated with a 10 Hz Nd:YAG laser at 1,5 W, after receiving the Er:YAG laser treatment. We maintained a control sample with no treatment. The samples were submitted to x-ray diffraction measurements and SEM, performed with the JSM-5900LV microscope of the LME/LNLS.

The present study aimed to test the hypothesis that irradiation of dental enamel by a TEA carbon dioxide laser together with fluoride, can effectively inhibit caries-like progression in sound and demineralized enamel. Blocks of human sound and demineralized dental enamel were divided into 11 treatment groups. Eighty enamel blocks were partially demineralized in a 50 percent HAP/0.1 M lactic acid/carbopol solution. Samples were treated with/without laser and/or F according to the above groups. The blocks were then submitted to 5 days of pH cycling. Microradiography was performed on 100 micrometers thin sections to determine the relative mineral loss as (Delta) Z and the percentage of caries inhibition for the laser and F treated groups. Mean (Delta) Z values for groups I-X were, respectively: 1043; 683; 614; 2294; 1803; 1708; 1547; 1791; 1656;; and 1385. The percent caries inhibition for groups II, III, V-X was respectively: 35, 41; 49; 62; 42; 53 and 76 percent. The combination of this new TEA CO₂ laser and F treatment produced a significant protective effect against lesion progression.

This study was to determine the weight loss caused by the use of Er:YAG laser on enamel and dentine using short and very short pulses and two frequencies. Researchers have reported that the Er:YAG laser ablates dental hard tissues more effectively and efficiently, with less thermal damage to the tooth, than other hard lasers. In this study, one hundred and twenty molars were cut into crown hemisections, were dried for 1 h at 37 degrees C and then weighed with a precision balance. Group 1: enamel short pulse 10 Hz; group 2: dentine short pulse 10 Hz; group 3: enamel very short pulse 10 Hz; group 4: dentine very short pulse 10 Hz; group 5: enamel short pulse 15 Hz; group 6: dentine short pulse 15 Hz; group 7: enamel very shot pulse 15 Hz; group 8: dentine very short pulse 15 Hz. The results of short and very short pulse were statistically similar regardless of the type of tissue and the frequency used. Concluding, enamel ablation with the Er:YAG laser shows lower efficiency than dentin ablation, very short pulse mode ablates dental tissue with the same efficacy than short pulse mode.

Since Buonocore, several researchers have been seeking for the best adhesive system and treatment for the enamel and dentin surfaces. The use of the acid has been presented as one of the best techniques of dentin conditioning, because this promotes the removal of the 'smear layer' and exhibition of dentinal structure, for a best penetration and micro-retention of the adhesive system. However, some conditioning methods have been appearing in the literature, for the substitution or interaction with the acid substances, as the laser. The objective of this work is to evaluate the tensile bond strength of the adhesive system 'self-etching' associated to a composed resin, in dentin surfaces conditioned with the Er:YAG laser. For this study, freshly extracted human teeth were used and in each one the dentinal surfaces, which were treated with three sandpapers of different granulations to obtain a standard of the smear layer, before the irradiation of the laser and of the restoring procedure. After these procedures the specimens were storage in distilled water at 37 degrees for 24 hours. Soon after, they were submitted to the tensile strength test. After analyzing the results, we can conclude that the use of the Er:YAG laser can substitute the drill without the need of conditioning, when using the adhesive system 'self etching' in the dentinal surfaces because there was a decline in the strength of adhesion in the groups conditioned with the laser.

Application of the erbium: YAG laser to periodontal treatment has been attempted and preferable results have been reported for calculus removal, vaporization of granulation tissue, periodontal pocket sterilization and so on. However, it has been difficult to reach and treat some conditions involving complex root morphology and furcated rots with conventional probes. The new broom probe was designed and tested to overcome these obstacles. The probe was made of 20 super-fine optical fibers bound into a broom shape. The experiments were carried out to evaluate the destructive power of a single fiber and to examine the morphology of tissue destruction and the accessibility to a bifurcated root of a human tooth using the broom probe. The Er:YAG laser prototype was used. A flat specimen plate was made by cutting the root of a cow tooth and then attached to an electrically operated table and irradiated under various conditions. The specimens were examined with both an optical and scanning electron microscope. The irradiated surfaces were also examined with a roughness meter. An irradiation applied with a single fiber with an energy level of 1 to 1.5 mJ at its tip results in a destruction depth of 3 to 24 micrometers . The optimum conditions for the fibers of this probe was 1.0 mJ at 10 pps and a scanning speed of 100 mm/min. No part of the tooth surface remained un-irradiated after using the broom probe to cover the surface 5 times parallel to the tooth axis and then five times at a 30 degree angle to the previous irradiation at a power of 20 mJ at 10 pps. Also curved and irregular surface were destroyed to a maximum depth of 19 micrometers . In conclusion, these results suggest that the broom probe would be applicable for periodontal laser treatments even if the tooth surface has a complex and irregular shape.

Frequency-domain IR photothermal radiometry is introduced as a dynamic dental diagnostic tool and its main features are compared with modulated laser luminescence for quantifying sound and carious enamel or dentin. Dental caries found in the fissures or grooves of teeth is very difficult to diagnose or quantify with the present clinical techniques. Visual examination and dental radiographs do not detect the presence of decay until there has been significant carious destruction of the tooth. A high-spatial-resolution dynamic experimental imaging set-up, which can provide simultaneous measurements of laser-induced frequency-domain IR photothermal radiometric and luminescence signals form defects in teeth, was developed. Following optical absorption of laser photons, the new set-up can monitor simultaneously and independently the non-radiative conversion, and the radiative de-excitation in turbid media such as hard dental tissue. This work is intended to show the complementarity between modulated luminescence and photothermal frequency scans in detecting carious lesions in teeth. A sound extracted molar with a dentin-enamel interface was introduced to examine the depth profilometric abilities of the method. Occlusal surfaces of teeth with potential areas of demineralization or carious destruction in the fissures were examined and compared to the signals produced by the sound enamel establishing the depth profilometric abilities of the method. The significance to clinical dentistry lies in the potential of this technique to detect and monitor early carious lesions in the pits and fissures of teeth.

The aim of this study was to determine the effects of varying parameters of Er:YAG laser irradiation with and without water spray cooling on root canal dentin in vitro. After horizontally removing tooth crowns from extracted human teeth, roots were axially sectioned into thin slices, exposing the root canal surface. An Er:YAG laser delivered 10-30 J/cm² into a 0.4-mm diameter laser spot on the root canal surface .Single pulses of different lengths were applied with and without water spray cooling/irrigation, and sequences of 3 pulses at a repetition rate of 30 Hz were applied at selected pulse parameters. The irradiated samples were investigated using confocal laser scanning microscopy (CLSM). At most irradiation conditions, root canal dentin surface was ablated. 3D images from CLSM revealed that the cavity walls were not smooth. Depths, diameters and micro surfaces of the cavities revealed a significant different between the cavities.

The aim of this work was to demonstrate, based upon scientific evidence, the efficacy of dental treatment using the Er:YAG laser. The Er:YAG laser is able of quick cavitation of dental structure with minimal thermal effect. It is also well known that most treatment is carried out without the need of local anesthesia. It is also recognized that its work with no vibration and in a non-contact mode. This paper reports the clinical results of 590 dental procedures carried out with the Er:YAG laser on selected patients. The laser was used for composite removal, cavity enamel preparation, carious dentine removal and conditioning of both dentin and enamel. Dental treatment with the Er:YAG laser as a secure and efficient method of treatment with more comfort for the patients, high acceptance form patients and less need of using local anesthesia.

Various studies have recommended parameters for the use of Er:YAG laser for the treatment of caries of the enamel and dentin without studying the increase in temperature caused by laser in the individual groups of teeth. The Er:YAG laser has been indicated for the removal of caries, cavity preparation and preparation and disinfection of root canals. The authors studied the intrapulpar temperature change in 10 incisors, 10 canines, 10 pre-molars and 10 molars during Class V cavity preparation with focused short pulse and very short pulse Er:YAG laser, using the following parameters: 10 Hz frequency, 500 mJ per pulse, 6 s, 10 mm distance, 25 ml/min water flow, at 23 degrees C and 65 percent humidity. The greatest increase in temperature was found in the incisors and the least increase in the molars at both pulse modes. The very short pulse mode caused less of an increase in temperature in the pulp chamber in all teeth than the short pulse mode.