Journal of clinical laser medicine & surgery最新文献

Objective: The objective of this study was to evaluate a new optical method - photon undulatory non-linear conversion (PNC)--for use in different stages of caries detection.

Background data: Caries should be considered an infectious disease managed by risk assessment, early detection, and preventive therapies, rather than simply "drilling and filling."

Material and methods: Fluorescence emission spectroscopy was performed in vitro on 90 extracted teeth, with intact occlusal surfaces. This system differs from the basic Diagnodent unit in its ability to distinguish between different tissue components with respect to their spectrums. Histological analysis served as the gold standard for verification. The teeth sections correspond to the specific point with the highest reading of the detector. The system was compared to visual inspection, probing, and x-ray methods. The system tested (helium-neon [He-Ne], lambda = 633 nm) has a fiber optic device that delivers radiation to the tooth and a spectrophotometer device that detects bacterial porphyrins fluorescence, allowing detection of caries, fillings, and calculus by simultaneous measurement of backscattering and fluorescence intensity.

Results: The system tested provides quantitatively reproducible measurements and detection even through sound enamel of more than 1 mm in thickness.

Conclusion: The PNC method detects different stages of caries lesions in real time, and it exceeds x-rays in sensitivity, without any ionizing radiation. Preliminary results showed a high potential of using the PNC method in clinical practice (98% accuracy) in comparison to the other methods.

Objective: In this study, near-infrared Raman spectroscopy (NIRS) was used for evaluation of human atherosclerotic lesions using a simple algorithm based on discriminant analysis. The Mahalanobis distance was used to classify the clustered spectral features extracted from NIRS of a total of 111 arterial fragments of human coronary arteries.

Background data: Raman spectroscopy has been used for diagnosis of a variety of diseases. For real-time applications, it is important to have a simple algorithm that could perform fast data acquisition and analysis. The ultimate goal is to obtain a feasible diagnosis, which discriminates various atherosclerotic lesions with high sensitivities and specificities.

Materials and methods: Non-atherosclerotic (NA) arteries, atherosclerotic plaques without calcification (NC), and atherosclerotic plaques with classification (C) were obtained and scanned with an NIR Raman spectrometer with 830-nm laser excitation. An algorithm based on the discriminant analysis using the Mahalanobis distance of the clustered spectral features was used for tissue classification into three categories: Na, NC, and C.

Results: Human coronary arteries exhibit different spectral signatures depending on different bio-chemicals present in each tissue type such as collagen, cholesterol, and calcium hydroxyapatite, respectively. It is shown that our algorithm has a maximum sensitivity and specificity of 85% and 89%, respectively, for the diagnosis of the NA tissue type, 85% and 89% for the NC tissue type, and 100% and 100% for the C tissue type.

Conclusion: An algorithm (with a minimum of mathematical and computational requirements) based on the discriminant analysis of spectral features has been developed to classify atherosclerotic lesions with high sensitivities and specificities.

Objective: The purpose of this research was to evaluate the influence of the Nd:YAG laser on microleakage of class V composite restorations.

Background data: There has been very little research that concerns microleakage resulting from the use of lasers and restorative materials.

Materials and methods: Thirty-six cavities were prepared and divided into three groups (n = 12) as follows: Group 1, control; Group 2, Nd:YAG laser irradiation before adhesive technique; Group 3, Nd:YAG laser irradiation after adhesive technique. Nd:YAG laser parameters were 320 micro m of fiberoptics; energy/pulse of 40 mJ of energy/pulse; repetition rate of 15 Hz; power of 0.6 W; pulsed and non-contact, 1 mm from the surface; 30 sec in scanning mode; energy density was 49,76 J/cm(2). Cavities were restored with microhybrid composite. After polishing, thermocycling and impermeabilization procedures were performed and specimens were submitted to a microleakage test, with complete immersion in aqueous solution of 50% silver nitrate for 8 h, in the total absence of light. After washing and drying, teeth were embedded to facilitate buccal-lingual vertical sectioning. Microleakage was revealed by light.

Results: We used the Kruskal-Wallis test at a 5% level of confidence and observed no statistically significant difference among the tested groups.

Conclusion: It was possible to conclude that Nd:YAG laser does not influence marginal microleakage on composite restorations, independent of the moment the laser had been used.

Objective: The present study investigated the effects of low-level laser therapy (LLLT) on the mitochondria, nucleus, and cytoskeleton of CHO K-1 cells by the use of specific fluorescent probes.

Background data: The use of LLLT has been recommended by several authors for acceleration of the healing process. The literature on the effects of LLLT in this process is highly contradictory because of difficulties in identifying its effects on cells.

Materials and methods: CHO K-1 cells were cultivated using MEM containing 5% FBS and were irradiated or not with a semiconductor laser (lambda = 830 nm; phi approximately 0.8 mm; 10 mW; 2 J/cm2). The cells were incubated with specific fluorescent probes--0.1 microM for 30 min with 5,5', 6,6'-tetrachloro-1, 1',3,3'-tetraethyl-benzimidazol-carbocyanine iodide (JC-1) for the mitochondria; 5 mM for 5 min of 4',6'-diamidino, 2'-phenylindole (DAPI)for the nucleus, and 0.1 M of 1:100 PHEM of rhodamine-phalloidin during 1 h for the cytoskeleton--and were analyzed by epifluorescence.

Results: Positive biomodulatory effects were observed on irradiated cells compared to their controls as seen on JC-1, DAPI, and rhodamine-phalloidin labeling. Irradiated cells showed an increased level of cellular division, as evidenced by analyzing the intermediary filaments of the cytoskeleton and the chromosomes. Another important observation was that cells maintained under the condition of nutritional deficiency had both membrane and genetic material that was more preserved in comparison to the controls, in which the presence of an apoptotic nucleus could be observed in some cells.

Conclusion: The results of the present study demonstrate that LLLT, in addition to providing positive biomodulation, acts in the re-establishment of cellular homeostasis when the cells are maintained under the condition of nutritional stress; it also prevents apoptosis in CHO K-1 cells.

Objective: We describe a simple technique in which the prominent surface of the cyst is vaporized by a carbon dioxide (CO(2)) laser, thus avoiding linear scarring and reducing postoperative complications.

Background data: Epidermal cysts are commonly excised in outpatient clinics under local anaesthesia. The procedure usually entails an elliptical skin incision to include the puncture of the cyst. This may lead to infection, scarring or recurrence.

Materials and methods: The cyst is marsupilized using a scanning CO(2 )laser under local anaesthetic.

Results: Surgical results assessed by pre- and postoperative photographic records confirmed smaller scars the absence of linear scars.

Conclusion: In cosmetically sensitive areas, laser marsipulization of epidermal cysts represents a viable alternative to conventional dissection.

Objective: The aim of this study was to examine the effects of low-level laser therapy (LLLT) on production of reactive oxygen (ROS) species by human neutrophils.

Background data: LLLT is an effective therapeutic modality for inflammatory conditions.

Materials and methods: The laser device used was the infrared diode laser (GaAlAs), 830-nm continuous wave (150 mW/cm(2)). After irradiation, ROS production by neutrophils was measured using luminol-dependent chemiluminescence (LmCL) and expression of CD11b and CD16 on neutrophil surface was measured by flow cytometry.

Results: The LmCL response of neutrophils was reduced by laser irradiation at 60 min prior to the stimulation with opsonized zymosan and calcium ionophore. The attenuating effect of LLLT was larger in neutrophils of smokers than non-smokers, while the amount of produced ROS was larger in neutrophils of smokers. Expression of CD11b and CD16 on neutrophil surface was not affected by LLLT.

Conclusion: Attenuation of ROS production by neutrophils may play a role in the effects of LLLT in the treatment of inflammatory tissues. There is a possible usage of LLLT to improve wound healing in smokers.

Objective: The purpose of this study was to describe the long-term effect of image-guided percutaneous laser disk decompression (PLDD).

Background data: PLDD has been reported to be an alternative method to treat herniated lumbar disks. It has proved to be effective on a short-term basis. Although the procedure has been used for several years, few articles report on the long-term effect of the intervention.

Materials and methods: Two hundred patients, who were treated with image-guided PLDD for herniated lumbar disks, were observed over a period of 4 +/- 1.3 years. Treatments were carried out under CT/fluoroscopy guidance with local anesthesia on an outpatient basis with an Nd:YAG laser of 1064 nm.

Results: At follow-up, back pain was eliminated or reduced in 73% of the patients. Regarding sensorimotor impairment, PLDD did have a positive effect on 74% of the patients. In the majority of patients, the number of sick days and consumption of pain medication was reduced. In one patient, diskitis occurred as a complication of PLDD; 74% of the patients said they were satisfied with the outcome of the therapy; and 81.5% of the patients would have required another PLDD in cases of disk herniation.

Conclusion: From our clinical results, we conclude that image-guided PLDD is an effective and secure method to treat contained herniated lumbar disks. Advantages of the procedure include the minimally invasive approach on an out-patient basis and the low complication rate.

Objective: The aim of this study was to investigate the effect of water on dental hard tissue ablation using Er:YAG laser as it relates to energy and pulse repetition rate, and determine the water flow rate that produces the most effective ablation at a given irradiation condition.

Background data: Er:YAG laser application leads to volumetric expansion and micro-explosions that result in hard tissue ablation. Ablation efficiency is improved when combined with fine water spray.

Materials and methods: Extracted, healthy human molars were sectioned into two pieces and categorized into small groups related to water flow rate (1.69, 6.75, and 13.5 mL/min), pulse energy (250 and 400 mJ), and pulse repetition rate (5, 10, and 20 Hz). Within the combination of irradiation parameters, a laser beam was applied over enamel and dentin surfaces of the specimens, and the ablation amount was determined by differences in weight before and after irradiation.

Results: At a pulse energy of 250 mJ, the most effective ablation resulted from a water flow rate of 1.69 mL/min in both enamel and dentin. With 400 mJ/pulse, dentin removal was most effective at the water flow rate of 1.69 mL/min, whereas the efficiency of enamel ablation was the highest at 6.75 mL/min. Dental hard tissue ablated better as energy and pulse repetition rate increased.

Conclusion: Effective ablation of dental hard tissue using Er:YAG laser requires that the appropriate water flow rate correspond properly to irradiation conditions. The results of this study suggest the following parameters; a water flow rate of 1.69 mL/min for enamel and dentin ablation at a pulse energy of 250 mJ and for dentin ablation at 400 mJ/pulse, and a water flow rate of 6.75 mL/min for enamel ablation at a pulse energy of 400 mJ, regardless of pulse repetition rate of 5, 10, and 20 Hz.