The interest in endodontic use of dental laser systems is increasing. Developing laser technology and a better understanding of laser effects widened the spectrum of possible endodontic indications. Various laser systems including excimer-, argon⁺-, diode-, Nd:YAG-, Er:YAG- and CO₂-lasers are used in pulp diagnosis, treatment of hypersensitivity, pulp capping, sterilization of root canals, root canal shaping and obturation or apicoectomy. With the development of new delivery systems - thin and flexible fibers - for many different wavelengths laser applications in endodontics may increase. Since laser devices are still relatively costly, access to them is limited. Most of the clinical applications are laser assisted procedures such as the removing of pulp remnants and debris or disinfection of infected root canals. The essential question is whether a laser can provide improved treatment over conventional care. To perform laser therapy in endodontics today different laser types with adopted wavelengths and pulse widths are needed, each specific to a particular application. Looking into the future we will need endodontic laser equipment providing optimal laser parameters for different treatment modalities. Nevertheless, the quantity of research reports from the last decade promises a genuine future for lasers in endodontics.

Objective of the study was the evaluation of X-ray image quality of cyclic olefin polymer-coated silver hollow glass waveguide (COP/Ag) in root canal, using a dental digital radiography method for an endodontic treatment. Er:YAG laser system was used. The wavelength generated was 2.94 micrometers and the length of the generated pulses was around 250 usec. The radiation was delivered to the investigated tissue by a cyclic olefin polymer-coated silver hollow glass waveguide (COP/Ag) with an inner diameter equal to 700 micrometers and the length of 10 cm. The fluence used in the experiments was in the range of 19 up to 45 J/cm². The root canal systems of 10 extracted premolars and molars were treated endodontically using a step-back technique with K-type endodontic files. Isometric X-ray images were captured via fixed-point measurement method. Digital images were taken before treatment, with conventional files and with an insertion of the COP/Ag hollow glass waveguide. A density histogram, characterizing the density spread across the image was established. An aluminum step wedge, 50 mm long x 20 mm wide, having thickness range from 0.5 mm to 5 mm was used as a marker to check the quality of radiopacity. The overall dimensions were adjusted in relation to the sensor size as a control. COP/Ag hollow glass waveguide was slightly visible in root canal system. An isometric image, histogram, and pseudocolor picture help to detect the position of waveguide in the root canal.

Raman Spectroscopy was used on the present investigation to monitor the degree of conversion of microparticled composite resin (Z100-3M), polymerized by both the conventional halogen light and the Argon Laser beam. Circular blocks of composite 6mm diameter and 3mm of thickness were used on this study. The tip of the halogen light source ((lambda) = 400-500nm, 478mW/cm²) or the Argon laser beam ((lambda) = 488nm, 624mW/cm²) was positioned on the surface of the composite resin and both activated for different irradiation times (5, 10, 20, 30, 40 and 60 seconds). The top surface which was directly irradiated and the non-irradiated (inferior) surface were analyzed immediately after curing by Raman Spectroscopy. The Raman results show systematic changes of the relative intensities between the peaks at 1610 (aromatic C=C stretching mode) and the 1640 cm^-1 (methacrylate C=C stretching mode), as a function of irradiation time. The degree of conversion was calculated based on the relative intensity change of these two modes and compared for each light source. The change in the relative intensity shows that Raman Spectroscopy can be used as an effective method to study the degree of conversion of composite resins.

The aim of the study was to investigate temperature elevations in the implant surface and the peri-implant bone during simulated surface decontamination of endosseous dental implants with an 809 nm semiconductor laser. Stepped cylinder implants were inserted into bone blocks cut from resected pig femurs. An artificial peri-implant bone defect provided access for the irradiation of the implant surface. A 600 micron optic fiber was used at a distance of 0.5 mm from the implant surface. Power output varied between 0.5 and 2.5 W in the cw-mode. Power density was between 176.9 and 884.6 Wcm^-2. The bone block was placed into a 37 degree(s)C water bath in order to simulate in vivo thermal conductivity and diffusitivity of heat. Temperature elevations during irradiation were registered by means of K-Type thermocouples and a short wave thermocamera. In a time and energy-dependant manner, the critical threshold of 47 degree(s)C was exceeded in the peri-implant bone. Surface peak temperatures in the focus of up to 427.8 degree(s)C were observed. Implant surface decontamination with an 809 nm GaAlAs laser must be limited to a maximum of 10 s at an energy density below 350 wcm^-2 to ensure a safe clinical treatment.

Laser interaction with oral tissues is dependent upon the tissues physical properties. Previous studies measured the absorbance coefficient of individual components of the tissues. The purpose of the present study was to determine the reflectance, transmittance and absorbance of the whole tissue: porcine gingiva. Therefore, 2x4 mm sections consisting of attached and free gingiva from porcine mandibles, 1.2+/- 0.2 mm thickness, were measured using a spectrometer for reflectance (R) and transmittance (T), and the absorbance (A) was calculated. In order to fully characterize the optical properties of the soft tissue, the color of porcine gingiva was also measured utilizing the L*a*b* system. The average R, T and A among the specimens were determined for each wavelength (200-2500 nm) and the respective spectral curves determined at 95% confidence level. For the laser emission wavelength frequency-doubled Alexandrite (377nm) the average values were: R=25.8%; T=0.6%; A=73.6%. For the laser emission wavelength Nd:YAG (1064nm) the average values were: R=25.8%; T=66%; A=3%. For the laser emission wavelength diode (980nm) the average values were: R=30%; T=58%; A=12%. Color of the gingival tissue measured in reflectance had higher L*, a* and b* values as compared to color measured in transmittance.

A variety of lasers are used for many oral soft tissue procedures. Each dental laser has specific parameters giving a wide range of operation. Lasers such as the carbon dioxide, argon and diode operate in continuous wave, while Nd:YAG, Er:YAG, Ho:YAG, and Er,Cr:YSGG are free-running pulsed lasers with high peak power and very short pulse duration. Laser tissue interaction is basically a photothermal effect and the biologic effect is dependent on the laser operating parameters, such as emission wavelength, power, emission mode, pulse duration, energy/pulse, energy density, duration of exposure, total energy and tissue characteristics. This article reviews current knowledge of laser parameters, laser-tissue interaction and applied preclinical and clinical safety and effectiveness scientific support.

Three dimensional model calculations using Finite Elements were carried out to simulate the heat distribution under IR laser ablation. The thermodynamic constants of dentin were used for heat capacity, heat conductivity etc. Compared to earlier results, the anisotropy of these constants is now considered; i.e. the heat conduction for example is not necessarily independent of the direction but depends on the orientation of the inner structure of the dental tissue. While the results of CO₂ laser ablation were discussed last year, new calculations have been performed for the optical constant of dentin at a wavelength of 2.9 micrometers . Since the penetration length of 2.9 micrometers radiation is significantly shorter than that of 10.6 micrometers , the thermally influenced zone around the laser crater is thinner.

Thermal damage in dental pulp during Nd:YAG laser irradiation have been studied by several researchers; but due to dentin inhomogeneous structure, laser interaction with dentin in the hypersensitivity treatment are not fully understood. In this work, heat distribution profile on human dentine samples irradiated with Nd:YAG laser was simulated at surface and subjacent layers. Calculations were carried out using the Crank-Nicolson's finite difference method. Sixteen dentin samples with 1,5 mm of thickness were evenly distributed into four groups and irradiated with Nd:YAG laser pulses, according to the following scheme: (I) 1 pulse of 900 mJ, (II) 2 pulses of 450 mJ, (III) 3 pulses of 300 mJ, (IV) 6 pulses of 150 mJ; corresponding to a total laser energy of 900 mJ. The pulse interval was 300ms, the pulse duration of 900 ms and irradiated surface area of 0,005 mm². Laser induced morphological changes in dentin were observed for all the irradiated samples. The heat distribution throughout the dentin layer, from the external dentin surface to the pulpal chamber wall, was calculated for each case, in order to obtain further information about the pulsed Nd:YAG laser-oral hard tissue interaction. The simulation showed significant differences in the final temperature at the pulpal chamber, depending on the exposition time and the energy contained in the laser pulse.

It has been established that the ability of erbium lasers to ablate hard dental tissue is due primarily to the laser- initiated subsurface expansion of the interstitial water trapped within the enamel and that by maintaining a thin film of water on the surface of the tooth, the efficiency of the laser ablation is enhanced. It has recently been suggested that a more aggressive ablative mechanism, designated as a hydrokinetic effect, occurs when atomized water droplets, introduced between the erbium laser and the surface of the tooth, are accelerated in the laser's field and impact the tooth's surface. It is the objective of this study to determine if the proposed hydrokinetic effect exists and to establish its contribution to the dental hard tissue ablation process. Two commercially available dental laser systems were employed in the hard tissue ablation studies. One system employed a water irrigation system in which the water was applied directly to the tooth, forming a thin film of water on the tooth's surface. The other system employed pressurized air and water to create an atomized mist of water droplets between the laser hand piece and the tooth. The ablative properties of the two lasers were studied upon hard inorganic materials, which were void of any water content, as well as dental enamel, which contained interstitial water within its crystalline structure. In each case the erbium laser beam was moved across the surface of the target material at a constant velocity. When exposing material void of any water content, no ablation of the surfaces was observed with either laser system. In contrast, when the irrigated dental enamel was exposed to the laser radiation, a linear groove was formed in the enamel surface. The volume of ablated dental tissue associated with each irrigation method was measured and plotted as a function of the energy within the laser pulse. Both dental laser systems exhibited similar enamel ablation rates and comparable ablated surface characteristics. The results of the study suggest that, although the manner in which the water irrigation was introduced differed, the mechanism by which the enamel was removed appeared basically the same for both dental laser systems, namely rapid subsurface expansion of the interstitially trapped water. It is the conclusion of this study that if the proposed hydrokinetic effect exists, it is not effective on hard materials, which are void of water, and it does not contribute in any significant degree in the ablation of dental enamel.

Infrared lasers have been used for several clinical applications in dentistry, including laser ablation, oral surgeries and dentin hypersensitivity treatment. Despite of dentin low absorption coefficient in the near infrared spectrum, Nd:YAG laser radiation ((lambda) = 1064 nm) is able to melt the human dentin surface resulting in dentin tubules closure that can suppress the symptoms of dentin hypersensitivity pathology. Objectives: This study aims to analyze, through SEM technique, the morphological changes in dentin surface after Nd:YAG laser irradiation using different parameters in energy distribution. Materials and Methods: In this study sixteen human dentin samples were submitted to Nd:YAG laser radiation using a total energy of 900mJ distributed in one, two, three or six laser pulses with energy for each pulse of 900, 450, 300 or 150 mJ respectively. All the samples were irradiated with laser pulse width of 90ms, pulse intervals of 300 ms and spot size area of 0,005 cm². Results: SEM analysis suggests that differences in energy distribution results in morphological differences even though the same energy is used for all the samples.

In order to stop or prevent the progression of dental disease, early detection and quantification of decay are crucially important. Dental decay (caries) detection methods have traditionally involved clinical examination by eye, using probes and dental radiography, but up to 60% of lesions are missed. What the dentist requires is a cheap, reliable method of detection of early disease, ideally with information on the depth and rate of growth or healing. Conventional commercial scanning confocal microscopes are unsuitable for use on dental patients. We report on a fibre optic based confocal microscope designed for in vivo examination of caries lesions. The system utilizes a common fibre both as the source and to detect the reflected confocal signal. The initial system has been optimized using dielectric mirrors and the thickness of the stack has been measured with high precision. Dental samples have been examined and the system has been demonstrated to provide information on the depth and mineral loss of a lesion. Fibre optic microscopy (FOCM) demonstrates a practical route to developing an in vivo caries profiler. In this paper, the FOCM and its applications in caries detection are described and the potential of this scheme as a practical dental probe is discussed.

The ability of an en-face Optical Coherence Tomography (OCT) system to detect and quantitatively monitor the demineralization of teeth to produce enamel and dentine (root) caries was determined and validated with an established method of quantifying demineralization, transverse microradiography (TMR). We used an OCT system which can collect A-scans, B-scans (longitudinal images) and C-scans (en-face images). The development of enamel and root caries, by 3-day demineralization in acidic buffer solution, was assessed quantitatively every 24 hours. Caries lesions were shown as volumes of reduced reflectivity in both the transversal and longitudinal images. The A-scan, which showed the levels of reflectivity versus the depth of penetration into the tissue, was used for the quantitative analysis of the lesions. Results demonstrated that the reflectivity of tooth tissue decreased with increasing demineralization time. A linear correlation was observed between the mineral loss in enamel (r=1.0) and dentine (r=0.957) measured by TMR and the percentage reflectivity loss measured by OCT. We concluded that OCT could detect incipient enamel and root caries and quantitatively monitor the demineralization of the tissue. The reflectivity loss in tooth tissue during demineralization, measured by OCT, could be related to the amount of mineral lost during the demineralization.

TeraHertz Pulse Imaging (TPI) is a relatively new imaging modality for medical and dental imaging. The aim of the present study was to make a preliminary assessment of the potential uses of TPI in clinical dentistry, particularly in relation to caries detection and the detection and monitoring of erosion. Images were obtained in vitro using a new TPI system developed by TeraView Ltd. We present data showing that TPI in vitro images of approximal surfaces of whole teeth demonstrate a distinctive shadowing in the presence of natural carious lesions in enamel. The thickness of this enamel shadowing appears to be related to lesion depth. The use of non-ionizing radiation to image such lesions non-destructively in vitro represents a significant step towards such measurements in vivo. In addition, data is presented which indicates that TPI may have a potential role in the detection and monitoring of enamel erosion. In vitro experiments on whole incisor teeth show that TPI is capable of detecting relatively small artificially induced changes in the buccal or palatal surface of the enamel of these teeth. Imaging of enamel thickness at such a resolution without ionizing radiation would represent a significant breakthrough if applicable in vivo.

New diagnostic tools are needed for the characterization of dental caries in the early stages of development. If carious lesions are detected early enough, they can be arrested without the need for surgical intervention. The objective of this study was to demonstrate that polarization sensitive optical coherence tomography (PS-OCT) can be used for the imaging of early caries lesions and for the monitoring of lesion progression over time. High-resolution polarization resolved images were acquired of natural caries lesions and simulated caries lesions of varying severity created over time periods of 1 to 14 days. Linearly polarized light was incident on the tooth samples and the reflected intensity in both orthogonal polarizations was measured. PS-OCT was invaluable for removing the confounding influence of surface reflections and native birefringence and for resolving the surface structure of caries lesions. This study demonstrated that PS-OCT is well suited for the resolution of interproximal and occlusal caries, early root caries, and secondary caries around composite fillings. Longitudinal measurements of lesion progression established a strong correlation (p<0.001) between the reflected light from the lesion area and the square root of time indicating that PS-OCT is well suited for monitoring changes in enamel mineralization over time.

Lasers are used for several procedures involving hard and soft tissues of the oral cavity. Included in those procedures is the use of the CO₂ laser to alter the surface structure of tooth enamel to render it more resistant to caries. A new 9.6micrometers wavelength TEA CO₂ laser (Argu Photonics, Jpiter, FL) has been investigated as a device that can be used for this procedure without harming the dental pulp. Erupted, caries and restoration free third molars (n=24) were used in the experiment. Teeth were irradiated at an incident fluence of 1.5J/cm² and a repetition rate of 10Hz and a spot size 1mm in diameter. At the low and high settings, 200 to 400 pulses were delivered at 12mJ per pulse for a total energy of 2.4 or 4.8J delivered for 20 or 40 seconds respectively. Other teeth were subjected to a sham dental procedure (positive control) or no procedure (negative control). Prior to testing, radiographs were taken of all teeth, and they were tested pulpally using heat, cold and electricity to determine vitality. The teeth were removed either immediately or at one week or one month after testing. They were bioprepared and examined histologically for signs of inflammation. Only one tooth developed symptoms of sensitivity to cold for 10 days following exposure to the high power level. The sensitivity was of fleeting duration and was judged to be reversible pulpitis. All teeth tested responded normally at pretesting and pre-extraction time periods. Histological examination disclosed no indication of an inflammatory response in the pulp tissue. All sections appeared normal with no changes seen in the normal pulpal morphology. We conclude that the 9.6 micrometers wavelength laser causes no pulpal damage at the energy levels used and can be used safely for caries prevention treatments.

The purpose of this study was to investigate the effect of a new TEA carbon dioxide (CO₂) laser (.9.6 micrometers , 5-8 microsecond(s) pulse duration) combined with fluoride (F), on the inhibition of caries-like progression in occlusal surfaces in sound and demineralized enamel. Of 120 occlusal tooth surfaces (10 per group), 90 were partially demineralized in a 50% HAP/0.1 M Lactic acid/carbopol solution (pH 5.0). Samples were treated with/without the laser (2.0 j/cm² or 3.0 J/cm²) and/or F (as APF). Caries-like progression was tested by 5 days of pH cycling. Results were assessed by cross-sectional quantitative microradiography. The percent inhibition of caries progression with laser and/or F ranged from 87-170%. This new TEA CO₂ laser produced significant protective effect against lesion progression, and in combination with fluoride treatment lesion reversal occurred.

This study determine, in vitro, the coronal leakage of root canals evaluating the effect of smear layer removal by either EDTA or laser. Two sealers were also compared. Sixty- four canines were instrumented with the step-back technique and irrigated with 10 ml of 1% sodium hypochlorite. In Group 1, 10 teeth were sealed with Sealer 26 and 10 teeth were sealed with Grossman cement with no attempt of smear layer removal. Group 2 received a final irrigation of 15 ml of 15% ETA, and was sealed as in group 1. Group 3 received Er:YAG laser application (2940 nm, 140 mJ, 15 Hz and 42 J, 300 pulses, 500milli-sec pulse duration), and sealed as in group 1. Root canals sealed with Sealer 26 has significantly less coronal leakage than Grossman cement (p<0.05). Coronal leakage after smear layer removal with 15% EDTA or Er:YAG laser was not statistically different (p>0.01).

The present study examined root canal cleaning, using the optic microscope, after rotary instrumentation with ProFile.04 with or without laser application with different output energies. Cleaning and shaping can be accomplished manually, with ultra-sonic and sub-sonic devices, with rotary instruments and recently, increasing development in laser radiation has shown promising results for disinfection and smear layer removal. In this study, 30 palatal maxillary molar roots were examined using an optic microscope after rotary instrumentation with ProFile .04 with or without Er:YAG laser application (KaVo KeyLaser II, Germany) with different output energies (2940 nm, 15 Hz, 300 pulses, 500 milli-sec duration, 42 J, 140 mJ showed on the display- input, 61 mJ at fiberoptic tip-output and 140 mJ showed on the display-input and 51 mJ at fiberoptic tip-output). Statistical analysis showed no statistical differences between the tested treatments (ANOVA, p>0.05). ANOVA also showed a statistically significant difference (p<0.01) between the root canal thirds, indicating that the middle third had less debris than the apical third. We conclude that: 1) none of the tested treatments led to totally cleaned root canals; 2) all treatments removed debris similarly, 3) the middle third had less debris than the apical third; 4) variation in output energy did not increase cleaning.

The effects of two endodontic irrigants associated or not with Er:YAG laser on a smear layer created by hand instrumentation were evaluated in vitro in the middle and apical thirds of root canals. Twenty five human maxillary canines with a single root were distributed randomly into five groups of five teeth each. Group 1 was irrigated with sodium hypochlorite 1.0%, Group 2 received EDTAC 15% as irrigating solution and Group 3 received both NaClO 1.0% and EDTAC 15%. Group 4 was irrigated with distilled water and irradiated with Er:YAG laser. Group 5 received NaClO 1.0% as irrigating solution and was irradiated with Er:YAG laser. Teeth were split longitudinally and prepared for examination under scanning electron microscopy. The teeth irrigated with NaClO (Group 1) showed the higher amount of smear layer, with statistically significant differences (p<0.05) from the teeth irrigated with distilled water and irradiated with Er:YAG laser (Group 4), which showed intermediate amounts of smear layer. The teeth irrigated with EDTAC 15%, NaClO 1.0% associated with EDTAC 15% and NaClO 1.0% with Er:YAG laser (Groups 2,3 and 5) showed the lowest amounts of smear layer, being statistically similar between them and different (p<0.05) from Groups 1 and 4. There were no differences between the radicular thirds. It can be concluded that irradiation with Er:YAG laser can be as effective as EDTAC 15% when used associated with 1.0% sodium hypochlorite, but not as effective when used together with distilled water.

The aim of this in vitro study was to determine whether low-level laser light in the presence of a photosensitizer could kill Streptococcus mutans and Streptococcus sobrinus. Suspensions of these microorganisms were exposed to a gallium-aluminium-arsenide laser light (660 nm) in the presence of photosensitizer toluidine blue O. Viable microorganisms were counted on brain heart agar plates after incubation at 37 degree(s)C in partial atmosphere of 10% CO₂ for 48 hours. Their exposure to the laser light in the absence of the dye or the dye in the absence of the laser light presented no significant effect on the viability of the microorganisms. However, a decrease in the number of viable microorganisms was only verified when they were exposed to both the laser light and the dye at the same time. Their total growth inhibition was achieved with a dye concentration of 100 mg/mL and a light energy density of 28.8 J/cm², after being exposed to laser light for 900 seconds. In conclusion, these results imply that these bacteria can be killed by low-power laser light in the presence of the photosensitizer.

The purpose of this in vitro study was to determine whether low-level laser light in the presence of a photosensitizer can kill streptococci in human saliva. Samples of stimulated saliva were collected from ten healthy subjects. These samples were mixed and exposed to a gallium-aluminium-arsenide laser light (660 nm) in the presence of toluidine blue O. Viable total streptococci and mutans streptococci were counted on plates with MSA and MSB, respectively, following incubation at 37 degree(s)C, 10% CO₂ for 48 hours. The exposure of saliva to laser light in the absence of the dye, or the dye in the absence of the laser light showed no significant effect on the viability of the microorganisms. A decrease in the number of viable microorganisms was only verified when they were exposed to both the laser light and the dye at the same time. A total inhibition growth of the mutans streptococci and a substantial killing rate of total streptococci were achieved with a dye concentration of 100 mg/mL and an energy density of 28.8 J/cm². These results imply that total streptococci and mutans streptococci present in human saliva can be killed by low-level laser light in the presence of toluidine blue O.

Presence of more dental alloys in oral cavity often causes pathological symptoms. Due to various and multi-faced symptomatology, they tend to be a source of significant problems not only for the patient but also for the dentist. Metal ions released from alloys can cause subjective and objective symptoms in mouth. The aim of this study was detection of metal elements presence in saliva. There were 4 groups of examined persons: with intact teeth (15 individuals) with metallic restorations, pathological currents 5-30 (mu) A, multi-faced subjective symptomatology and uncharacteristic objective diagnosis (32 patients), with metallic restorations and no subjective symptoms (14 persons) and with metallic restorations, without pathological currents and with problems related to galvanism (13 patients). Presence of 14 metal elements was checked by inductively coupled plasma mass spectrometer with laser ablation. Nd:YAG laser detector was used. There were significant differences in content of silver, gold and mercury between persons with intact teeth and other three groups. There were no differences found between subjects with and without galvanic currents, and presence of subjective and objective symptoms.

In this comparative clinical study, we aimed at evaluating the immediate and late analgesic effect of GaAlAs diode lasers of 660 nm and 830 nm in treatment of dentine pain. We used GaAlAs diode lasers of 660 nm and 830 nm with 35 mW, continuous wave emission, spot size 1 mm² and a dosage of 4 joules/cm² applied to the cervical dentine surface. In total 4 treatment sessions were performed at intervals of 7 days in a period of 4 consecutive weeks. A total of 40 teeth treated were divided into two groups comprising 20 teeth each: one group irradiated with a 660 nm wavelength laser, and the other one with a 830 nm wavelength laser. By means of a quantitative visual analogue scale (V.A.S.), we measured the sensitive responses to cold stimulus pre- treatment, and at a follow-up period of 15 and 30 minutes post-treatment in both groups in order to evaluate the immediate analgesic effect. The late effect was evaluated at a follow-up period of 15 and 30 days. Using the GaAlAs diode laser of 660 nm wavelength resulted in better levels of dentine desensitization, at both immediate and late analgesic effect analysis compared with the use of the GaAlAs diode laser of 830 nm wavelength.

We evaluated the effect of LLLT in 68 patients who presented hypoesthesia due to odontological surgery procedures: dental implant surgeries (N=51); extraction of impacted lower third molars (N=10); endodontics in lower first molars (N=7). Lesions treated within 30 days after the nerve injury had occurred were part of the immediate group, and lesions with more than 30 days from the occurrence of the injury were part of the late group. Treatments were carried out with an infrared diode laser of 40 mW-830nm, continuous wave emission, spot size 3 mm², and a total dosage of 18 joules per session in a contact mode of application, 20 sessions altogether. The efficacy of laser therapy in peripheral nerve regeneration is also related to the degree of the peripheral nerve lesion, and not only to the lesion duration. LLLT resulted in neurosensory functional improvement in both immediate and late treatments of hypoesthesia.

Inexpensive laser diodes and fiber-optic technology have revived optical transillumination as a promising diagnostic method for the early detection of dental caries. The principal factor limiting transillumination through dental hard tissue is light scattering in the normal enamel and dentin. Previous studies have shown that the scattering coefficient decreases with increasing wavelength. Therefore, the near-IR region is likely to be well suited for fiber optic transillumination. The objective of this study was to measure the optical attenuation of near-IR light through dental enamel at 1310-nm and 1550-nm. These laser wavelengths are readily available due to their suitability for application to fiber optic communication. In this study the collimated transmission of laser light through polished thin sections of dental enamel for various thickness from 0.1 to 2.5 mm was measured in cuvettes of index matching fluid with n= 1.63. Beer-Lambert plots show that the attenuation coefficients are 3.1+/- 0.17cm^-1 and 3.8+/- 0.17cm^-1 for 1310-nm and 1550-nm, respectively. This study indicates that near-IR laser wavelengths are well-suited for the transillumination of dental enamel for caries detection since the attenuation through normal tissue is an order of magnitude less than in the visible.

Carbon dioxide laser irradiation induces chemical changes in dental hard tissues including, dehydration, decomposition, disproportionation, and vaporization. Such changes can lead to either an increase or decrease in susceptibility to acid dissolution and adversely affect the bond strength to restorative materials. The objective of this study was to measure the evolved molecular species produced during laser irradiation. Samples of bovine enamel were irradiated by a 9.6 micrometers TEA CO₂ laser in a vacuum chamber connected to a quadruple mass spectrometer. At irradiation intensities above 0.37 J/cm² an increase in evolved CO₂ and H₂O were detected indicative of thermal decomposition of the mineral phase. The respective ion yields changed markedly with increasing number of laser pulses suggesting that the decomposition was complete after less than ten laser pulses at irradiation intensities from 0.4 to 0.8 J/cm². Above irradiation intensities of 1.0 J/cm² there is continual emission after 50 laser pulses indicative of vaporization and material removal. At higher ablative fluence, higher mass species were detected due to the ejection of hydroxyapatite. This study demonstrates that mass spectroscopy can be used to directly probe laser induced physical and chemical changes in dental hard tissue during laser ablation.

Optical Coherence Tomography (OCT) has been used to produce longitudinal images of dental tissues. We investigated the influence on OCT system, of factors that could limit detection and quantitative monitoring of incipient caries. The effect of such factors as saliva, dental plaque, lesion staining, ambient lighting, and Dacron gauze (used to encourage plaque growth in in situ caries studies) on OCT imaging and analysis were determined during demineralization to produce early caries. The system can collect A-scans, B- scans (longitudinal images) and C-scans (en-face images). Caries lesions were shown as volumes of reduced reflectivity. A-scan, which showed the levels of reflectivity versus the depth of penetration into the tooth tissue, was used for the quantitative analysis of the reflectivity loss. The reflectivity of the tooth tissue decreased with demineralization. The percentage change in reflectivity of the tissue was quantified as a measure of the change in mineral status of the tissue following demineralization. Neither the presence of saliva, plaque, Dacron gauze, plaque/Dacron gauze, nor lesion staining nor the level of ambient lighting significantly affected OCT detection and analysis of an incipient caries.

The aim of this study was to evaluate the effect of Er:YAG and Nd:YAG laser on radicular dentine permeability when using distilled and deionized water and 1% sodium hypochlorite as irrigating solutions. Thirty human maxillary canines obtained from laboratory stock and conserved in 0.1% thymol until use were divided randomly into six groups of five teeth each. The root canals were instrumented with K files and the step-back technique. The surgical diameter was achieved 4 files above the original anatomical diameter. Group I, the teeth were irrigated with distilled and deionized water; Group II, the teeth were irrigated with 1% sodium hypochlorite, Group II the teeth were irrigated with distilled and deionized water and then Er:YAG laser was applied with 140mJ, 15Hz, 300 pulses and 42J; group 4 the teeth were irrigated with 1% sodium hypochlorite and Er:YAG laser was applied in the same parameters as Group III, Group V, the teeth received irrigation with distilled and deionized water and Nd:YAG laser application with 150mJ, 15Hz, 2,25W and Group VI the teeth were irrigated with 1% sodium hypochlorite and Nd:YAG laser was applied with the same parameters as Group V. During laser application the teeth were always filled with irrigating solution. The fiber optic tip was introduced until the apex and the laser was activated. The tip was withdrawn gently with helicoidally movement from the apex until the pulp chamber. After preparation the teeth were immersed in 10% copper sulfate for 30 minutes, in vacuum for the first 5 minutes. The teeth were then placed in a 1% rubianic acid alcohol solution for the same periodsin solution and in vacuum as above. Upon completion of this reaction the teeth were sectioned transversally, in 150micrometers slices, and sanded, washed, dehydrated, cleared and mounted on glass slides for microscopic examination. The quantification of the penetration of copper ions was done by morphmetric analysis with a 400-point grid. The data was submitted to statistical analysis and shoed normality and hemocedacity of the sample, parametric analysis was applied. The Tukey test showed that the cervical and middle thirds were statistically similar (p>0.05) and greater than the apical third (p<0.05). The Scheffe test showed greater dentine permeability in root canals where water and Er:YAG laser were used and significant different from the other treatments (p<0.05). The use of 1% sodium hypochlorite with Nd:YAG laser, distilled and deionized water with Nd:YAG laser and the use of water, were statistically similar (p<0.05) and increased less dentine permeability when compared to other groups. The use of 1% sodium hypochlorite with and without Er:YAG laser application presented statistically similar permeability values (p>0.05) and positioned in an intermediate among the treatments.

We present data supporting the efficacy of the procedure, laser sulcular debridement (laser curettage), as an important component in the treatment of inflammatory periodontal disease. Laser Assisted New Attachment Procedure (LANAP) is a detailed protocol for the private practice treatment of gum disease that incorporates use of the PerioLase pulsed Nd:YAG Dental Laser for laser curettage. Laser curettage is the removal of diseased or inflamed soft tissue from the periodontal pocket with a surgical dental laser. The clinical trial conducted at The University of Texas HSC at San Antonio, Texas, evaluated laser curettage as an adjunct to scaling and root planing. They measured traditional periodontal clinical indices and used a questionnaire to evaluate patient comfort and acceptance. The Texas data (N=10 patients) are compared with pocket depth changes following LANAP. LANAP data were obtained from a retrospective review of patient records at three private practices (N=65). No significant differences in post treatment probe depth changes were found among the four centers indicating that the procedure produced consistent, favorable outcomes, and that results from controlled scientific clinical trials can be replicated in private practices. Reduction in pocket depths following laser treatment compare well with results obtained with scalpel surgery. The use of the laser offers additional benefits. We also present quantitative evidence from digitized radiographs of increased bone density in affected areas following LANAP.