For individuals with cancer risk factors, reducing tissue inflammation may reduce the risk of developing cancer. This is the basis of several clinical trials evaluating potential chemoprevention drugs. These trials require quantitative assessments of inflammation which, for the oral epithelium, are traditionally provided by punch biopsies. To reduce patient discomfort and morbidity, we have developed a non-invasive alternative using diffuse reflectance spectroscopy. Though any optical system has the potential for probing near-surface structures, traditional methods of accounting for scattering of photons are generally invalid for typical epithelial thicknesses. We have previously developed a theory that is valid in this regime and validated it with Monte Carlo simulations. We use a differential measure with acute sensitivity to small changes in layer scattering coefficients. To assess the capability of the approach to quantify epithelial thickness, detailed Monte Carlo simulations and measurements on phantom models of a two layered structure have been performed. Preliminary results from this work show that our key feature varies less than 20 percent despite four-fold changes in scattering coefficients and ten-fold changes in absorption coefficients. This indicates that the method will be of practical clinical value for quantifying epithelial thickness in vivo.

Historically, 810nm has been the predominant wavelength used for intraoral surgery, when diode lasers have been discussed, due to their large numbers in the market place. The techniques used intraorally with the 810nm diode have been relatively similar in most cases. Low powers, 1 or 2 watts, using continuous wave, are employed. The purpose of this study is to compare the thermal damage of the technique of using continuous wave at low powers, to using higher powers with a pulse mode and water for coolant, with the 980nm diode wavelength. During the study the laser fiber was held immobile eliminating surgical manipulation as an error. The resultant histology proves, while the volume of vaporization dramatically increases, thus giving the clinician the ability to reduce the time for destructive conduction of excess heat for a given procedure, the amount of coagulation actually decreases in width and depth. As an added benefit charring, which has been implicated in delayed healing is virtually eliminated. This evidence, coupled with excellent clinical results, lends validity to the use of pulsed higher powers and water coolant for the 980nm diode laser.

The purpose of this investigation was to measure the maximum temperature at the Nd:YAG and Diode lasers fiberoptic tips as a function of air/water coolant, during soft tissue ablation in pig jaws. A pulsed Nd:YAG laser (1064nm) and a Diode laser (800-830 nm) were used varying parameters of power, conditioning or not of the fiber tip, under 4 settings of air/water coolant. The maximum temperature at the fiber tip was measured using an infra-red camera and the interaction of the fiber with the porcine soft tissue was evaluated. A two-factor ANOVA was used for statistical analysis (p≤0.05). Nd:YAG laser interaction with soft tissues produced temperatures levels directly proportional to power increase, but the conditioning of the fiber tip did not influence the temperature rise. On the other hand, conditioning of the fiber tip did influence the temperature rise for Diode laser. The addition of air/water coolant, for both lasers, did not promote temperature rise consistent with cutting and coagulation of porcine soft tissue. Laser parameters affect the fiberoptic surface temperature, and the addition of air/water coolant significantly lowered surface temperature on the fiberoptic tip for all lasers and parameters tested.

The aim of this study was to assess the effect of LLLT (λ830nm, Thera lase, DMC Equipmentos, Sao Carlos, SP, Brazil, 40mW, CW, spot size 0.60mm, 16J/cm² per session) on the repair of bone defects on the femur of Wistar albinus rats which were grafted with anorganic bovine bone associated or not to bovine bone membrane. Five randomized groups were studied: I (Control); II (anorganic bovine bone); III (anorganic bovine bone + LLLT); IV (anorganic bovine bone + bovine bone membrane) and V (anorganic bovine bone + bovine bone membrane + LLLT). The animals were irradiated at every 48h during 15 days, the first irradiation was performed immediately after the procedure. The animals were irradiated transcutaneuosly in four points around the defect. At each point a dose of 4J/cm² was given (f~0,60mm, 40mW) totaling 16J/cm² per session. The animals were sacrificed 15, 21 and 30 days after surgery. The specimens were routinely processed to wax and stained with H&E and Picrosírius stains and analyzed under light microscopy. The results showed evidence of a more advanced repair on the irradiated groups when compared to non-irradiated ones. The repair of irradiated groups was characterized by both increased bone formation and amount of collagen fibers around the graft within the cavity early, considering the osteoconductive capacity of the anorganic bovine bone and the increment of the cortical repair in specimens with membrane. It is concluded that LLLT had a positive effect on the repair of bone defect submitted the implantation of graft associated or not to the use of biological membrane.

The purpose of the study is to evaluate the effect of various laser techniques for bleaching teeth in office vital whitening. Hydrogen peroxide (30% concentration) and carbamide peroxide (10% solution) were used for chemical activation of bleaching process. Extracted non-carcious upper central incisors were exposed to laser radiation. Four different laser systems (Nd:YAG laser SHG, wavelength 0.53 μm, CTE:YAG laser, wavelength 2.7 μm, Nd:YAG laser, wavelength 1.06 μm, and alexandrite laser, wavelength 0.75 μm) were applied to accelerate the speed of the process. The end of chemical exposition was verified by the change of bleaching agent color. The color change was determined by stereomicroscope (Nikon SMZ 2T, Japan), the quality of surface structure was checked by scanning electron microscope Joel (Japan). The speed of bleaching rnaged from 630 s (chemical methods only) to 250-340 s (chemicals + alexandrite laser radiation). The Alexandrite laser application was considered an elective process to decrease the time of bleaching without modifying the surface.

The aim of this study was to compare histologic and microbiogically the use of the CO₂ Laser and Chlorohexidine Gluconate (0.5% and 2%) on cutaneous wounds infected by Staphylococcus aureus. Wound infection constitutes a risk for the patients and it is usually associated to increase morbidity, mortality and hospital costs. It is accepted that local treatment of these infections is effective. Standardised wounds created on the dorsum of Wistar rats were infected with Staphylococcus aureus and treated as follows: Group 1: control; Group 2: Chlorohexidien Gluconate (0.5%), 1 min, six days; Group 3: Chlorohexidine Gluconate (2%), 1 min, six days; Group 4: CO₂ Laser, CW, RSP, 8W, 10s, single application, maintaining surface debris; Group 5: CO₂ Laser, CW, RSP, 8W, 10s, single application, removing surface debris. Eight days after wounding material from the surface of the wound was collected for microbiology and the animals were sacrificed and specimens taken for light microscopy. Microbiological examinations showed that on group 2 the bacteria were not found on 50% of the animals. On group 3 83% were germ-free, on group 4 50% and on group 5 66%. Histological examination showed a better result for CO₂ laser treated wounds compared to others. It is concluded that the use of a 2% Cholohexidine solution was more effective on decontaminating the wounds. However, wounds treated with the CO₂ laer and with the removal of surface debris healed better than the others.

The aim of this study was to compare microbiologically the effects of the CO₂ Laser and Chlorohexidine Gluconate (4%) on Staphylococcus aureus infected cutaneous wounds. 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. Standardized wounds created on the dorsum of 36 rats were infected with Staphylococcus aureus and treated during six days as follows: Group I: Chlorohexidine Gluconate applied to the wound surface during one minute during six days; Group II: Single CO₂ Laser irradiation (8W,CW, unfocused, 8cm focal distance, 81530W/cm²), maintaining surface debris; Group III: Single CO₂ Laser irradiation (8W,CW, unfocused, 8cm focal distance, 81530W/cm²), removing the surface debris. Daily samples were taken for microbiological analysis. Seven days after wounding the animals were killed a final sample taken. The use of Chlorohexidine Gluconate solution and the CO₂ laser with the removal of the surface debris result in a significant reduction on the infectability of the Staphylococcus aureus when compared to non-treated infected wounds (p=0.00 e p=0.02). However, if the debris is left on the wound surface the resolution of the infection is less significant and results in non-significant differences on the number of Staphylococcus aureus when compared to non treated controls (p=0.14). No difference on infectability of the Staphylococcus aureus was detectable when the debris was removed of the surface of the wounds and when the Chlorohexidine solution was used (p=0.05). Therefore, the use of the CO₂ laser would improve the resolution of the infection without further irradiating the tissue and consequently without further impairing wound healing. The fact that significant differences were observed between the two modalities of CO₂ treatment indicates that the surface debris acts as a culture medium for bacterial growth keeping a higher infectability of the wound in which the debris was not removed (p=0.04).

The healing time of surgical wounds is of extreme importance and it is usually associated to a post-operative period free of infection and with less pain and inflammation. The aim of the present study was to compare histologically the effect of the GaAlAs (λ830nm, Thera Lase, DMC, Sao Carlos, SP, Brazil, spot size 0.60mm, 35mW) and InGaAlP (λ685nm, Thera Lase, DMS, Sao Carlos, SP, Brazil, spot size 0.60mm, 35mW) isolated or in association with doses of 20 and 50J/cm² on cutaneous wounds in the dorsum of the Wistar Rat. The animals were divided into seven groups: Group I - Control (non-irradiated), Group II -λ685nm, 20 J/cm², Group III - λ830nm, 20 J/cm², Group IV -λ685nm and λ830nm, 20 J/cm²; Group V - λ685nm,50J/cm²), Group VI - λ830nm,50 J/cm², and Group VII - λ685nm and 830nm, 50 J/cm². The animals were sacrificed three, five and seven days after surgery. Light microscopic analysis using H&E and Picrosírius stains showed that, at the end of the experimental period, irradiated subjects showed increased collagen production and organization when compared to non-irradiated controls. Inflammation was still present on all groups at this time. Groups IV (l830nm and λ685nm,20J/cm²) presented better results at the end of the experimental period. It is concluded that LLLT had a positive biomodulatory effect end the repair of cutaneuos wounds.

Wound healing is a complex process that involves several metabolic and cellular responses. Several methods of improving wound healing have been suggested. Polarized light was suggested as a new method of biostimulation, improving the quality of the healing process. The aim of this work was to investigate the effects of polarized light (λ400 - λ2000nm) on the healing of cutaneous wounds using immunohistochemical analysis. Eighteen healthy male young adults Wistar rats were used. Standardized wounds were created on the dorsum of the rat. The wounds were illuminated with the polarized light source at doses of 20 or 40J/cm². Non-illuminated animals acted as controls. The first application of the light was performed immediately after the surgical procedure and repeated at every 48 hours during seven days. Twenty-four hours after the last irradiation the animals were humanely sacrificed. The slices were immunomarked by α SMA and by Picrosírius stain. The results of the histological analysis shows that the healing process on illuminated subjects was characterized by increased amount of collagen fibers when compared to control wounds. On the other hand, expressive amounts of myofibroblasts were also observed on illuminated specimens, when compared to non-irradiated animals, especially with a dose of 20J/cm². It is concluded that the use of polarized light had influence on the proliferation of myofibroblasts as well as on the amount of collagen fibers, being this best observed when small doses are used.

Tissue repair is an integration of dynamic interactive processes that involves soluble mediators, blood components, production of extra-cellular matrix and mesenchymal cells. Many studies involving the use of LLLT shows that the healing process is favored by such therapy. The aim of this work was to evaluate, through histological analysis, the tissue effects of cutaneous wounds submitted to different intensities and a same irradiation dose with lasers in λ670 or λ685nm. Eighteen animals were divided in two experimental groups according to wavelength used (λ670 or λ685nm). Each one of these groups was divided still in three subgroups of three animals each, related to the intensity of applied irradiation (2, 15 or 25mW). Twelve animals acted as untreated controls and were not irradiated. The irradiation was carried out during seven days. The animals were sacrificed eight days after surgery. The specimens were removed, kept in 4% formaldehyde for 24 hours, routinely prepared to wax, stained with H&E and analyzed under light microscopy. The histological characteristics observed, so much in the irradiated animals, as in the control, they are indicative of a substitution repair process, however, the LLLT modulatory positive effect was observed, in the healing process, mainly associate to the use of the shorter wavelength and low power. The results of the present study indicate that LLLT improves cutaneous wound repair and best results are achieved when higher potencies associated to short wavelengths or lower potencies associated to higher wavelengths are used.

The aim of the present investigation was to assess histologically the effect of LLLT (λ830nm, Thera Lase, DMC, Sao Carlos, SP, Brazil, 40mW, CW, spot size 0.60mm, 16J/cm² per session) on the repair of surgical defects created in the femur of the Wistar Albinus rat. The defects were filled to lyophilized organic bovine bone associated or not to GTR (decalcified cortical osseous membrane). Surgical bone defects were created in 42 animals divided into five groups: Group I (control - 6 animals); Group II (organic bovine bone - 9 animals); Group III (organic bovine bone + LLLT - 9 animals); Group IV (organic bovine bone + decalcified cortical osseous membrane - 9 animals); Group V (organic bovine bone + decalcified cortical osseous membrane + Laser - 9 animals). The animals on the irradiated groups received 16J/cm² per session divided into four points around the defect (4J/cm²) being the first irradiation immediately after surgery and repeated seven times at every 48h. The animals were humanely killed after 15, 21 and 30 days. The results of the present investigation showed histological evidence of improved amount of collagen fibers at early stages of the bone healing (15 days) and increased amount of well organized bone trabeculae at the end of the experimental period (30 days) on irradiated animals compared to non irradiated ones. It is concluded that a positive biomodulative effect on the healing process of one defect associated or not to the use of organic lyophilized bone and biological bovine membrane on the femur of the rat.

Healing is important for the success of the insertion of implants and for treating traumatic or pathologic injuries of the bone. Lasertherapy has been suggested as a mean of improving bone healing. Near infrared Raman spectroscopy was used to assess the amount of both inorganic and organic components of irradiated and control bone around dental implants inserted in to the tibia. Fourteen rabbits received a titanium implant on the tibia; eight of them were irradiated with λ830nm laser (Thera Lase, DMC, Sao Carlos, SP, Brazil, 21.5 J/cm², 10mW, spot size 0.60mm) and six acted as controls. The animals were sacrificed 15, 30 and 45 days after the surgery, and specimens were prepared for Raman spectroscopy, which was collected at every four points from each three thirds of the bone around the implants. The results showed significant differences in the concentration of inorganic components in irradiated specimens between 15 and 30days (p < 0.05), 15 and 45 (p < 0.01); between irradiated and controls 30 and 45 days after surgery (p <0.01). Concentration of organic components was also significantly different between irradiated and controls in periods of 30 to 45 days after surgery. It is concluded that LLLT does improve bone healing and Raman Spectroscopy can safely assess this.

The sealing cements commonly used for endodontic applications are of the type cured through chemical reactions. During the polymerization process, mechanical contractions are not uncommon, leading to a non-perfect sealing. Photopolymerizable cements usually presents superior performance as compared to those chemically activated. However, difficulties in carrying the light to difficult-to-reach regions like the dental apex preclude those material of being accepted in the dental office routine. This work reports on a novel technique which allow the light curing of photopolymerizable cements in endodontic applications. A special light guide had been developed to allow the curing light to reach and polymerize the sealing cement in the apex region. The technique was tested by using single-root human teeth with normal canal morphology. The Ultradent EndoREZ root canal sealer and a resin-based photopolymerizable filler specially developed for the current application had been used. The cone-shaped light guide was introduced into treated canals filled with the photopolymerizable material, up to the apical region. Light from an argon laser was launched onto the light guide for polymerization. All test samples were immersed in methylene-blue solution for microleakage testing. All samples treated with the self-polymerizable material presented dye penetration to some extent. No sample within the group which had the filling material polymerized by using the light guide presented dye penetration through the canal wall.

The degree of conversion (DC) of Z100 (3M) composite resin photoactivated by both Light-Emitting Diode and halogen lamp was evaluated by FT-Raman Spectroscopy. Eighteen circular blocks of resin (Φ 6mm X 3mm) were cured either by the LED (λ = 470nm, 190mW/cm²,Φ = 8mm) and by the halogen lamp (λ = 400-500nm, 600mW/cm²,Φ = 7mm) varying the irradiation time (20, 40 and 60s). The resin surfaces were analyzed immediately after curing by FT-Raman Spectroscopy. The FT-Raman results showed the reduction in monomer trough changes in the intensity of the peak at 1640cm^-1 as a function of irradiation time. The samples that were cured by 60s with LED source reached the maximum degree of conversion of 52% and 50% for the irradiated and non-irradiated surface, respectively. Whereas the samples cured by the same irradiation time, but with halogen lamp, those values were around only 4% higher for each surface with no statistically significant difference. It was observed no statistically significant differences in the DC values between both light sources used with 40s of irradiation. Therefore we conclude that, despite of their reduced irradiance, LEDs can cure composite resin ensuring a DC without statistically significant differences from the halogen lamp.

Cavities in human teeth were fabricated by means of Er:YAG laser and compared with samples processed by using conventional drill. The cavities of lased and unlased samples were cured with two different composite resins ( Bis-GMA vs PEX) to investigate differences in their adhesion properties. Morphological characterization of the sample surfaces by SEM analysis was performed. The same samples were then examined by micro-Raman spectroscopy by using He-Ne laser visible light excitation, in order to characterize the dentin/resin interfaces. The Raman spectra exhibited typical peaks of dentine. Resin contributions to the Raman spectra were also detected and have been used to monitor the interface properties of the boundary region. The dependence of the Raman spectrum on spatial position has been monitored. In both lased and unlased samples the PEX diffusion in dentine is limited in a region of order of 10 μm depth. A larger interdiffusion region is observed at the boundary of dentine and Bis-GMA resin.

The smear layer removal of root canal walls irradiated with Er:YAG laser after nickel-titanium rotary instrumentation was evaluated by scanning electron microscopy. Thirty mesial roots of human mandibular molars were selected and randomly distributed in three groups, according to treatment. Group 1 was instrumented with rotary nickel-titanium files 1 mm from the anatomical apex and irrigated with 2.5% sodium hypochlorite. Group 2 received the same treatment as Group 1, but after instrumentation the root canals were irradiated with Er:YAG laser. Group 3 received the same treatment as Group 1, but irrigation was performed with 2.5% sodium hypochlorite alternated wtih 17% EDTA during instrumentation. Photomicrographs were obtained from middle and apical thirds and submitted to qualitative evaluation. Statistical analysis showed that 2.5% sodium hypochlorite associated with 17% EDTA (Group 3) removed smear layer more efficiently than 2.5% sodium hypochlorite al one (Group 1) (p<0.05). Root canals irradiated with Er:YAG laser occupied an intermediary position regarding smear layer removal. There were no statistical differences between the evaluated radicular thirds (p>0.05).

This study evaluated smear layer removal of 40 mesio-distal flattened root canals after rotary instrumentation. Teeth were divided into 4 goups: Group 1: 2.5% sodium hypochlorite was used as an irrigating solution; Group 2: instrumented as Group 1 followed by Er:YAG laser irradiation (140mJ input/10Hz, withdrawn at 2mm/s from the apical to the cervical region touching the buccal wall; the procedure was then repeated for the lingual wall); Group 3: instrumented as Group 1 and followed by Er:YAG laser irradiation (250mJ input/10Hz, in the same way as described for Group 2) and Group 4: instrumented as Group 1 and alternated with 17% EDTA. Teeth were then split longitudinally and prepared for examination under the scanning electron microscope. Scores from 1 to 4 were given to the fotomicrographs by three independent evaluators, and these data were submitted to statistical analysis. Teeth where alternated 17% EDTA was used (Group 4) showed less amount of smear layer, followed by the group irradiated with 250mJ input/10Hz (Group 3), the group irradiated with 140mJ input/10Hz(Group 2) and the group where only sodium hypochlorite was used (Group 1). The apical third presented more smear layer than the middle third (p<00.1)

This study evaluated in vitro the external temperature increase at the three root thirds using five different fiberoptic tip withdrawal techniques in 50 human canines. Er:YAG laser was applied with a 50/28 fiberoptic tip with 250 mJ input, 112 mJ output, 10 Hz, 1 mm from the apical foramen: group 1: each third was irradiated starting at the apex for 1 s on each wall, with the irradiation turned off between thirds; group 2: apical third irradiated without movement for 2 s and tip withdrawn with continuous radiation up to the cervical third; group 3: tip activated at the apex and removed to the canal entrance in a straight line; group 4: tip activated at the apex and removed to the canal entrance with circular movements touching all walls; group 5: tip activated at the apex and removed to the canal entrance with clockwise circular movements for 6 s adn then reinserting and removing with counter-clockwise circular movements for another 6 s, touchgin all walls. Group 1 had significantly lower external temperature (p<0.01). The middle third had the greatest temperature increase (p<0.01). We conclude that the withdrawl techniques caused an increase in external root temperature that would not damage adjacent tissues.

This study evaluated smear layer removal in apical and middle root thirds using five different fiberoptic tip withdrawal techniques. Thirty human canines were instrumented using 2.5% sodium hypochlorite, with a final irrigation of distilled water, and divided randomly in 6 different groups. Er:YAG laser was applied in 5 groups with a 50/28 fiberoptic tip (250 mJ input, 112 mJ output, 10 Hz, 1 mm from apex) with distinct withdrawal techniques. Group 6 did not receive laser irradiation. Two pieces of each root canal (middle and apical thirds) were obtained under the SEM and analyzed for the amount of smear layer. Results showed statistical differences (p<0.05) between treatments and significant differences (p<0.01) between radicular thirds. It can be concluded that 1) all withdrawal techniques produced the same results on smear layer removal and 2) the middle third presented less smear layer t han the apical third after Er:YAG laser irradiation.

The purpose of this study was to analyze the environment microbial contamination produced by Er:YAG laser irradiation in infected root canals. A total of 20 human anterior teeth were prepared, sterilized and, then, inoculated with a mixture of the following microorganisms: S. Aureus, E. Faecalis, P. Aeruginosa, B. Subtilis and C. Albicans. After the contamination period (28 days), the teeth were irrigated with sterile distilled water or 1% sodium hypochlorite and, then, irradiated with an Er:YAG laser with two different laser parameters: 52 mJ or 110 mJ output at the fiber tip. Eighteen Petri dishes with 20 ml of BHI Agar were used in the study. For each group, 3 plates with BHIA were used for the analysis of the microbial contamination of the environment during the activation of the laser in infected root canals. The plates were positioned in differing distances away from the irradiated tooth (plate 1 - distance of 15 cm, plate 2 - distance of 50 cm and plate 3 - distance of 3 meters). After the analysis of the results, it was observed that the larger microbial contamination occurred in Group 1 (teeth irrigated with sterile distilled water and irradiated with Er:YAG laser with 52 mJ output at the fiber tip), plate 1 (positioned 15 cm away from the irradiated tooth), with values greater than 30 Colony-Forming Units (CFU).

This study evaluated in vitro the antimicrobial action of Er:YAG laser in infected root canals. A total of 36 human anterior teeth were prepared, sterilized and inoculated with suspensions of S. aureus, E. faecalis, P aeruginosa, B. subtilis and C. albicans. After the contamination period (28 days), the teeth were irrigated with sterile distilled water or 1% sodium hypochlorite and, then, irradiated with an Er:YAG laser (wavelength 2094 nm) with two different evaluation parameters: 52 mJ and 110 mJ laser output at the fiber tip. After the irradiation, the teeth were irrigated with sterile distilled water and the solutions were collected with sterile paper points and incubated in Letheen Broth for 48 hours. After this period 0,1 ml of this solution was transferred to 10 ml of Brain Heart Infusion and incubated for 48 hours. After 72 hours a new collect ion was done and incubated again. Based on the data, it was concluded that the distilled water or 1% sodium hypochlorite irradiated or not with an Er:YAG laser with two different parameters: 10 Hz, 110 mJ input and 52 mJ output, and 10 Hz, 250 mJ input and 110 mJ output had no antimicrobial activity in the root canals contaminated with the following microorganisms: Enterococcus faecalis, Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis and Candida albicans.

The present study evaluates the seal quality in apex delta of single root human teeth filled with light-curing materials (Ultrablend Calcium-hydroxide, Vitremer glass ionomer and Flow-Fill Magic composite). 45 roots prepared by the endo PTC/Dakin technique were used. All prepared samples received photopolymerization with the blue 488 nm argon ion laser light. A 200 μm optical fiber introduced into the root canal delivered 100 mW of light power to the light-curing material. The fiber tip was positioned 5 mm away from the apex. Light was applied for 20 seconds. After curing, the samples received impermeabilization with ethyl-cyanoacrylate, leaving only the apex exposed, and then immersed in a methylene-blue dye solution for 24 hours. The samples were cut longitudinally and analyzed under a stereoscopic microscope for dye infiltration. It was found that those samples sealed with Ultrablend Calcium-hydroxide or the glass ionomer presented the best results, as compared to those samples sealed with the Flow-Fill Magic composite. No statistically significant difference was observed between the group treated with Ultrablend Calcium-hydroxide and the group treated with the glass ionomer, for a significance level of 0.05.

In this work is presented the use of Photoacoustic as an alternative technique to monitor the curing process of odontological materials, emphasizing the resins chemically activated (RCA). Through photoacoustic measurements, it is possible to study optical and thermal properties of samples, and to obtain information on the characteristic times involved in the curing processes. For this study the samples were analyzed to evaluate the polymerization of the RCA for different temperature. The results obtained show the viability of applying the Photoacoustic Techinques to monitor the polyermization kinetic of odontological resins, allowing for a qualitative and quantitative interpretation.

The aim of this work was to characterize the degree of photoactivation of the Z250 resin through photoacoustics. In this technique, the signal detected is proportional to the heat produced in a sample as a consequence of light absorption. This technique has been used for more than 20 years as a work tool in diverse fields of biological and biomedical sciences. Through photoacoustic measurements, it is possible to study optical and thermal properties of samples, and to obtain information on the characteristic times involved in photoinduced processes, as the photoactivation of composed resins. After application on the surface, the Z250 resin is photoactivated by incidence of continuous light (λ = 475 ± 15 nm) coming from a photodiode. This leads to the polymerization of the resin, modifying its thermal properties. The experimental method employed in this work was the following: a) the resin was applied on an aluminum sheet placed in contact with the photoacoustic cell (front incidence); b) modulated white light was applied in the lower surface of the aluminum sheet, black-painted to increase the light absorption; c) the photothermal signal was observed. Polymerization was evaluated through the alteration of the photoacoustic signal caused by the activation of the resin promoted by the incidence of the continuous light, for different activation times. The results show that the polymerization of the resin substantially modifies the photoacoustic signal, indicating that the degree of photoactivation can be evaluated through photoacoustic measurements.

Raman Spectroscopy was used in the present investigation to evaluate the degree of conversion of composite resin, photoactivated by the Halogen lamp, the Argon Laser beam and by the Light Emitting Diode. Eighteen circular blocks of resin (7mm X 2,5mm) were cured by the Halogen light source (n = 9, λ = 400-500nm, Power density = 478 mW/cm²), by the Argon laser beam (n = 9, λ = 488nm, Power density = 625 mW/cm²) and nine blocks (6mm X 3mm) by the LED (n = 9, λ = 475 ± 15nm, Power density = 190mW/cm²) using the same irradiation time (20, 40 and 60 seconds). The resin surfaces were analyzed immediately after curing by Raman and FT-Raman Spectroscopy. The Raman results show changes of the relative intensities between the peaks at 1610 and the 1640cm^-1, as a function of irradiation time. After 60s of irradiation time, the maximum degree of conversion reached for the samples cured either by the Argon laser, the Halogen lamp and LED were 66,4%, 62,2% and 52%, respectively. The Argon laser was more effective and shown a better biocompatibility, with less residual monomer in the bottom.

To generate the three-dimensional grid net for a real tooth, an extracted tooth was grinded in steps of some millimetres from the top to the root. After each grinding step the displayed cross section was documented by photography showing clearly all transition lines between enamel, dentin and the pulp. The photographic reprints were used to determine the x-y-z-coordinates of selected points to represent the transition lines. In a fairly large-scale procedure these points were combined to a three dimensional net. FEM calculations were carried out to solve the heat equation numerically for the boundary condition that an IR laser pulse hits the surface for laser ablation. Since all the information of the various types of tissue is included in this model, the results give a huge variety of information. For example: the outer shell of enamel could be displayed exclusively to show its inner surface and which temperature distribution as well as mechanical stress got build up there.

Several studies have shown that the addition of an optically thick water layer (~1-mm) to the surface of dental enamel before each incident Er:YAG laser pulse, profoundly influences the rate and efficiency of ablation and the resulting surface morphology. In this study, a calibrated syringe pump, and a motion control system were used to uniformly treat areas of the enamel surface. The rate of water delivery that resulted in the most efficient ablation was determined by profiling the resulting laser incisions using optical coherence tomography. In addition, enamel surfaces of 5 x 5 mm² were uniformly treated and the resulting surface morphology was examined using synchrotron radiation-FTIR spectroscopy, and optical and electron microscopy. The influence of the modified surface morphology on the adhesion of composite was also investigated. The shear-bond strength of composite bonded to enamel surfaces irradiated at intensities clinically relevant for caries removal approached values measured for conventional acid etching when the water delivery rate was optimized. This study demonstrates that composite restorative materials can be directly bonded to laser prepared surfaces without the necessity of further surface preparation and acid etching and that the addition of a thick water (~1-mm) prevents the formation of undesirable CaP phases that compromise adhesion to restorative materials.

For non-invasive laser dental treatmet, a real-time and non-contact monitoring technique is needed. We have investigated the extent of the surface modification of root dentin using photoacoustic spectroscopy (PAS) and pulsed-photothermal radiometry (PPTR), and have discussed the applicability of each technology to in vivo monitoring during laser treatment. Root dentins were used as specimens. The wavelength, average power density, and exposure time used were varied within the ranges λ = 9.0-10.6 μm, P_av = 7-28 W/cm², and τ = 0-10 s respectively. The temporal behaviors of the laser-induced acoustic waves and the temperature rise were measured with an audible microphone and a radiation thermometer, respectively. The extent of the surface modification was evaluated by using information on the ablation depth and the absorption spectrum of the irradiated dentin. The morphological and chemical changes of the irradiated dentin can be made available to assist in dentinal tubule sealing and increased acid resistance for root surface caries therapy. It was found that time-resolved measurements of the acoustic waves and the temperature are useful for a real-time understanding of the extent of the morphological and chemical changes, respectively. We have demonstrated that applicability of an in vivo monitoring technique using PAS and PPTR for root surface caries therapy.

Previous studies have shown that pretreatment of dental enamel by specific carbon dioxide laser conditions inhibited subsequent acid dissolution of the enamel surface. The aim of the present study was to examine the dissolution profiles following irradiation by a new short pulse carbon dioxide laser treatment. Bovine enamel blocks were irradiated at 9.6 μm with a 5-8 μs or a 20-30 μs pulse duration laser using overlapping spots, and a range of fluences. Dissolution profiles were measured in an acetate buffer. Higher fluences produced rapid initial dissolution followed by a plateau with a low dissolution rate. For caries inhibition purposes the high solubility decomposition phases need to be avoided or removed.

This study was performed to examine the possibility of Er:YAG laser for dentine hypersensitivity treatment using a novel laser probe; broom type probe. The morphological change of dentinal tubules of bovine dentine plate after low power laser irradiation (5 or 10 mJ, 10 pps) or boiling was observed by SEM. Fifty teeth from 13 patients aged 31-54 years with complain of dentine hypersensitivity were treated by laser irradiation at 25-35 mJ, 10 pps using the broomed probe. Clinical effect of laser irradiation was verified by the examination of sensitivity rate to cold water, air blow and mechanical stimuli of explorer at before, immediately after, and 1,3,5 and 12 weeks after laser irradiation. The ratio of blockade and reduction of dentinal tubules after laser irradiation was 16-61%. The accumulation due to vaporization of water in dentinal tubules and degeneration or coagulation of organinc elements at the site of blockade and reduction were superficially described by SEM. Remarkable clinical improvement of dentine hypersensitivity by laser was admitted but relapse was also detected partially. The present study suggests low power irradiation of Er:YAG laser would be effective on dentine hypersensitivity, but a partial limitation of laser treatment for dentine hypersensitivity may be exited.

Dental hypersensitivity has been studied for several years and it is reported as a striking painful condition that originates from the exposition of dentinal tubuli as a result of the reduction of the thickness of the enamel or cement. Usually the exposed area is subjected to several kinds of stimuli, resulting in a rapid sharp acute pain. The aim of this study was evaluated the efficiency of LLLT in the treatment of patients with dental hypersensitivity. 1102 teeth of 388 patients from the Laser Center of the Camilo Castelo Branco University were treated with LLLT between 1995-2000. 98 males and 290 females aged 30 to 45 years old were treated. For LLLT, a diode laser was used at 780nm, CW, 40mW, elliptical area of the beam 2mm², exposure time per point 25s. This corresponds to an equivalent dose of 50 J/cm² at each point (considering the area of the spot). If a 1cm² area is considered, the total dose per tooth is 4J/cm². With the diode laser 830nm, CW, 50mW, elliptical area of the beam 2mm², exposure time per po int of 20s. This corresponds to an equivalent dose of 50J/cm² at each point (considering the area of the spot). If a 1cm² area is considered, the total dose per tooth is 4J/cm². The results showed 403 (36.57%) out of 1102 teeth required a single session for complete remission of the symptoms. 255 (23.14%) needed two sessions; 182 (16.51%) three sessions; 107 (9.7%) four sessions; and 59 (5.35%) five sessions. 96 (8.71%) did not respond to LLLT and the patients were re-assessed and treatment changed. The more affected tooth was the lower premolar (301 - 27.4%), followed by lower molars (163 - 14.8%), upper premolar (149 - 13.5%), and upper molars (52 - 4.7%), upper canine (119 - 10.7%), upper incisive (108 - 9.9%), lower canine (62 - 5.6%), and upper molars (52 - 4.7%). The result of the present investigation demonstrates indeed that LLLT, when based on the use of correct irradiation parameters, is effective in treating dentinal hypersensitivity as it quickly reduces pain and maintains a prolonged painless status. The authors concluded that the use of LLLT was effective on 91.27% of the cases. Previous studies were carried out by the authors to evaluate histologically the reaction of the dentinal pulp in rats after application of LLLT. The LLLT was shown to be efficient in the stimulation of odontoblast cells, producing reparative dentin and closing dentin tubuli.

Utilizing Fourier Transform Infrared Spectroscopy (FTIR) in specular reflectance mode chemical changes of root cement surfaces due to laser radiation were investigated. A total of 18 samples of root cement were analyzed, six served as controls. In this study laser energies were set to those known for removal of calculus or for disinfection of periodontal pockets. Major changes in organic as well as inorganic components of the cementum were observed following Nd:YAG laser irradiation (wavelength 1064 nm, pulse duration 250 μs, free running, pulse repetition rate 20 Hz, fiber diameter 320 μm, contact mode; Iskra Twinlight, Fontona, Slovenia). Er:YAG laser irradiation (wavelength 2.94 μm, pulse duration 250 μs, free running, pulse repetition rate 6 Hz, focus diameter 620 μm, air water cooling 30 ml/min; Iskra Twinlight, Fontona, Slovenia) significantly reduced the Amid bands due to changes in the organic components. After irradiation with a frequency doubled Alexandrite laser (wavelength 377 nm, pulse duration 200 ns, q-switched, pulse repetition rate 20 Hz, beam diameter 800 μm, contact mode, water cooling 30 ml/min; laboratory prototype) only minimal reductions in the peak intensity of the Amide-II band were detected.

Previous studies have shown that pretreatment of dental enamel by specific carbon dioxide laser conditions inhibited progression of caries-like lesion progression in vitro. The aim of the present study was to determine whether irradiation by a new shorter pulse carbon dioxide laser would inhibit caries-like lesion progression in dentin. Dentin blocks were irradiated at 9.6 μm with a 20 μs pulse duration laser using overlapping spots, 5 pulses per spot, and fluences from 0.2 - 1.0 J/cm². The blocks were subjected to pH-cycling to produce subsurface caries-like lesions including control groups, one with daily fluoride treatments. Lesion severity was assessed by cross-sectional microhardness measurement. Neither low fluences nor fluences in the optimum range for enamel significantly (p>0.05) inhibited lesion progression in dentin in this model. Only the fluoride treatment group significantly (p<0.05, ANOVA/Tukey) inhibited lesion progression by 33%.

A mesoscopic simulation of the process of human enamel laser ablation by Er:YAG and CO₂ lasers is being developed using the finite element method, taking into account the complex structure and chemical composition of this material. A geometric model that allows studying in detail the temperature, stress and displacement distribution within a few enamel rods is presented. The heat generation that takes place inside the enamel at the centre of the laser spot, caused by a non-ablative laser pulse emitted by CO₂ and Er:YAG lasers, was simulated. The sensitivity of our model to the estimated material parameters was studied. Temperature, displacement and stress distribution maps obtained for both lasers are presented. These preliminary results suggest that the temperature distribution across the enamel rods is different in the two situations considered; thermally induced stresses in the material are higher in the regions that are richer in hydroxyapatite (HA), and the higher displacements are observed in the regions that are rich in water. The rod tails inside enamel present higher stresses in the direction perpendicular to the surface of enamel than the ones that are created at the surface of our simulated structure. We conclude that the mesostructure plays a crucial role in the accurate modelling of dental laser ablation.

This study evaluated the influence of different storage solutions on teeth from a tooth bank, using DIAGNOdent laser fluorescence at 3 time periods. The storage solutions used in the study were: refrigerated water, saline, and 10% formol. Eighteen visually intact deciduous incisors were divided into three groups of six samples each. The teeth were previously cleaned, dehydrated and measured using DIAGNOdent at the most prominent buccal region of each tooth. Three subsequent measurements were taken at 1, 7 and 15 days. All measurements were taken by the same examiner and averages were recorded for each time period. Results showed that the three solutions had similar responses to laser. ANOVA was applied to verify the correlation between measurements, time periods, and storage solutions. Statistically significant differences were found only between the time periods. In this in vitro study, all three storage solutions influenced the DIAGNOdent measurement results as time elapsed until the 24 h period.

Mouth breathing unbalances the physiological mechanisms of the dental surface hydration by compromising lip closure, and, very often, causing the vestibular positioning of upper incisors. That variance leads to the interruption of the dental demineralization and remineralization feedback, prevailing a demineralized condition of the dental surface which increases caries risk. The laser fluorescence examination allows an early demineralization diagnosis, thus it makes possible through preventive measures to minimize the risk factor - dental mineral structure loss - in the bacterial infection of the demineralized area, and hence, preventing invasive therapeutical procedures. A DIAGNOdent apparatus was used to evaluate the mineralization degree of the upper central incisors in 40 patients - twenty of them with a mouth breathing diagnosis; the remaining twenty were nasal breathers (control group). Age ranging from 6 to 12 years, both male and female. To measure the vestibular surface of the incisors, it was divided into 3 segments: cervical, medial and incisal. The average of the results pertaining to the mouth breathing patients was as follows: tooth 11 cervical third - 5.45, medial third - 7.15, incisal third - 7.95, and tooth 21 - cervical third - 5.95, medial third - 7.25, incisal third - 8.15. The control patients, nasal breathers, presented the following results: tooth 11 cervical third - 1.75, medial third - 2.30, incisal third - 1.85, and tooth 21 - cervical third - 1.80, medial third - 2.20, incisal third - 2.15. The mouth breathing patients showed demineralization in the teeth examined at the initial stage, subclinical, comparing with the control patients, nasal breathers, who did not present any mineral deficit in these teeth.

The authors have verified the efficiency and safety of laser and high-frequency gingivectomy in non-periodontal indications. Within a prospective, non-selective study, they treated and monitored 357 dental areas in 139 teeth.Out of the total number, 248 areas were treated wtih a diode laser, 980nm; 109 areas with high-frequency electrocautery. The following parameters were monitored: a) regeneration of the marginal gingiva; b) generation of iatrogenic recessions or periodontal pockets; c) bleeding from gingival sulcus during probing; d) changes in tooth vitality; e) patient's subjective evaluation. The authors identified a high degree of safety in both laser and high-frequency gingivectomy, with no significant difference between these two methods. Laser gingivectomy appears to have a wider indication range, while high-frequency gingivectomy requires lower financial expenses.

Exact color matching of dental restorative materials to vital teeth is a difficult task. There are several reasons for this difficulty and they will be elaborated upon in the presentation. One of the most important reasons is the fact that teeth, as well as dental restorative materials are translucent, and thus the color impression is a product of light scattering, back scattering, transmission, and spectral modifications inside of these objects. Classic colorimetry is insufficient to provide an exact color match. Additional information about the translucency factor of the considered object (material and geometry) is necessary to provide full reproducibility. Translucency has a direct effect on perceived brightness. In this article we describe the TransluDent, a complementary product to ColorDent, which measures translucency of teeth and dental materials. TransluDent determines translucency by measuring light transmitted through an object and light scattered inside of the object. The translucency measurements were performed on two groups of subjects. One group consisted of people in their twenties and the second group of subjects was in fifties. For comparison several sets of dental shade-guides were also tested. The great discrepancy in translucency factor between human teeth and popular on the market shades may explain difficulty in color matching of dental restorative materials to teeth.