Abstract
Experiments were carried out on cancerous HeLa cells and blood serum using a double integrating sphere and a He-Ne laser to investigate the optical properties and cellular effects due to photodynamic therapy (PDT). In the first experiment, HeLa cells were exposed to Photofrin at concentrations of 0, 10, 20, 30, 50 and 112.4 µg/ml at an irradiance of 0.2 W/cm2 using diode laser light. Using a confocal microscope, cell debris and morphological changes in HeLa cells were recorded at different Photofrin concentrations. The results showed cell debris in HeLa cells at the highest concentration of Photofrin. In a second experiment, photobleaching was observed in HeLa cells in the presence of various concentrations of 5-aminolaevulinic acid ranging from 0–50 µg/ml. There was progressive degradation of the 635 nm peak during continuous laser irradiation at an irradiance of 0.2 W/cm2.
Effects of KTP laser on oral soft tissues. An in vitro study
Tue, 2010-02-16 20:06 — Guest
Abstract
A biopsy is a surgical procedure performed to establish a clear diagnosis of a lesion in order to clarify a clinical diagnostic suspicion. During a biopsy procedure it is fundamental to maintain safe and readable cut margins in order to permit histological visualization of possible marginal infiltrations or malignant transformation of a lesion. The aim of this study was to evaluate the histological peripheral damage caused by application of a KTP (potassium titanium phosphate) laser during oral soft tissue biopsy procedures. A KTP laser (λ 532 nm) at different power settings and fluences was used to obtain 45 samples from pig cadaver tongues. The samples were then subdivided into five groups of nine samples each. A final specimen was taken by scalpel as a control. All samples were put into test tubes containing 10% buffered formalin solution, and were examined separately under an optical microscope by two pathologists to evaluate the peripheral thermal damage induced by the laser.
Activation of the extracellular signal-regulated kinase signal pathway by light emitting diode irradiation
Tue, 2010-02-16 20:06 — Guest
Abstract
Irradiation by light emitting diode (LED) promotes fibroblast proliferation and wound healing. However, its mechanism is still unknown. The purpose of this study was to clarify the mechanism of fibroblast proliferation by LED irradiation. Cultured NIH3T3 fibroblasts from normal mice were irradiated by LED with a center wavelength of 627 nm. LED irradiation was performed with an energy density of 4 J/cm2, at subculture and 24 h later. The expression of several growth factors and their receptors was analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR): platelet-derived growth factor (PDGF)-A, PDGF-B, and PDGF-C, transforming growth factor-beta (TGF-β), basic fibroblast growth factor (bFGF), PDGF-α receptor, and TGF-β receptor. Then, the activation of the extracellular signal-regulated kinase (ERK) pathway was examined by Western blotting with and without the PDGF receptor inhibitor. LED irradiation induced cell growth of NIH3T3 fibroblasts.
Microleakage of repaired class V silorane and nano-hybrid composite restorations after preparation with erbium:yttrium–aluminum–garnet laser and diamond bur
Tue, 2010-02-16 20:06 — Guest
Abstract
The aim of this in vitro study was to compare the microleakage of repaired class V resin composite restorations prepared either by Er:YAG laser or a diamond bur. Ninety-six intact human molar teeth were randomly distributed into eight groups. In the first four groups, class V cavities (3 × 3 × 3 mm) prepared on the buccal and lingual surfaces of the teeth using an erbium:yttrium-aluminum-garnet laser (VersaWave, HOYA ConBio, Japan). Similar class V cavities were prepared in the second four groups using a diamond bur (S-Class, Komet, UK). Teeth in groups 1, 2, and 5, 6 were restored with a nano-ceramic composite (Ceram.X duo, DENTSPLY), whereas a silorane material (Filtek Silorane, 3M ESPE) was used to restore cavities in groups 3, 4, and 7, 8. Two different adhesive systems (XP Bond, DENTSPLY, and Silorane System Adhesive, 3M ESPE) were also used. All specimens were aged for 7 days.
Comparing the reliability of a new fluorescence camera with conventional laser fluorescence devices in detecting caries lesions in occlusal and smooth surfaces of primary teeth
Mon, 2010-02-15 20:00 — Guest
Abstract The aims of this in vitro study were (1) to compare the reliability of a new fluorescence camera (FC; VistaProof) with that of two other laser fluorescence devices (DIAGNOdent and DIAGNOdent pen) in assessing smooth and occlusal caries lesions in primary teeth and (2) to determine the influence of the spacer, the protective cover and air drying on the FC readings. We selected 129 primary molars which were divided into two groups: smooth surfaces (n=68) and occlusal surfaces (n=61). Two trained examiners performed the evaluations using the FC and the other laser fluorescence devices separately. One examiner repeated all assessments after 1 week. Inter- and intraexaminer reproducibility was calculated from the absolute values derived from the devices using intraclass correlation coefficient (ICC) and Bland-Altman analysis. Pearson correlation was performed among the values obtained with the different devices. For aim 2, only teeth from the occlusal surface group were used.
Removal of orange eyebrow tattoo in a single session with the Q-switched Nd:YAG 532-nm laser
Sat, 2010-02-13 08:48 — GuestRemoval of orange eyebrow tattoo in a single session with the Q-switched Nd:YAG 532-nm laser
- Content Type Journal Article
- Category Letter to the editor
- DOI 10.1007/s10103-009-0748-2
- Authors
- Rita Guedes, Centro Hospitalar de Vila Nova de Gaia Dermatology Department Rua Conceição Fernandes 4430 Vila Nova de Gaia Portugal
- Luiz Leite, Clínica Laser de Belém Dermatology Department Calçada da Ajuda, 72B 1300 Lisbon Portugal
- Journal Lasers in Medical Science
- Online ISSN 1435-604X
- Print ISSN 0268-8921
Shear bond strength of bonding to enamel with different laser irradiation distances
Fri, 2010-02-12 09:09 — Guest
Abstract The aim of this study was to investigate the shear bond strength of bonding to enamel following laser etching with the Er:YAG or Er,Cr:YSGG laser using different irradiation distances. Of 99 extracted human premolar teeth, 90 were divided equally into nine groups. In the control group (group A) the teeth were etched with 38% phosphoric acid. In the laser groups (groups B–I) the enamel surface of the teeth was laser-irradiated, groups B–E with the Er:YAG laser and groups F–I with the Er,Cr:YSGG laser at distances of 1, 2, 4 and 6 mm, respectively. The shear bond strengths were tested using a universal testing machine. The shear bond strengths associated with the Er:YAG laser at 4 and 6 mm and the Er,Cr:YSGG laser at 2, 4 and 6 mm were significantly less than the strengths obtained with the other irradiation distances (p<0.001). The Er:YAG laser at 1 mm and the Er,Cr:YSGG laser at 1 mm etched enamel in the same manner (p>0.05). This finding was confirmed by scanning electron microscopy examination.
In vitro analysis of human tooth pulp chamber temperature after low-intensity laser therapy at different power outputs
Thu, 2010-02-11 13:48 — Guest
Abstract In vitro studies have provided conflicting evidence of temperature changes in the tooth pulp chamber after low-level laser irradiation of the tooth surface. The present study was an in vitro evaluation of temperature increases in the human tooth pulp chamber after diode laser irradiation (GaAlAs, λ = 808 nm) using different power densities. Twelve human teeth (three incisors, three canines, three premolars and three molars) were sectioned in the cervical third of the root and enlarged for the introduction of a thermocouple into the pulp chamber. The teeth were irradiated with 417 mW, 207 mW and 78 mW power outputs for 30 s on the vestibular surface approximately 2 mm from the cervical line of the crown. The highest average increase in temperature (5.6°C) was observed in incisors irradiated with 417 mW. None of the teeth (incisors, canines, premolars or molars) irradiated with 207 mW showed temperature increases higher than 5.5°C that could potentially be harmful to pulp tissue.
Carbonized blood deposited on fibres during 810, 940 and 1,470 nm endovenous laser ablation: thickness and absorption by optical coherence tomography
Wed, 2010-02-10 08:47 — Guest
Abstract Endovenous laser ablation (EVLA) is commonly used to treat saphenous varicosities. Very high temperatures at the laser fibre tip have been reported during EVLA. We hypothesized that the laser irradiation deposits a layer of strongly absorbing carbonized blood of very high temperature on the fibre tip. We sought to prove the existence of these layers and study their properties by optical transmission, optical coherence tomography (OCT) and microscopy. We analysed 23 EVLA fibres, 8 used at 810 nm, 7 at 940 nm and 8 at 1,470 nm. We measured the transmission of these fibres in two wavelength bands (450–950 nm; 950–1,650 nm). We used 1,310 nm OCT to assess the thickness of the layers and the attenuation as a function of depth to determine the absorption coefficient. Microscopy was used to view the tip surface. All fibres showed a slightly increasing transmission with wavelength in the 450–950 nm band, and a virtually wavelength-independent transmission in the 950–1,650 nm band.
Depth sensitivity analysis of functional near-infrared spectroscopy measurement using three-dimensional Monte Carlo modelling-based magnetic resonance imaging
Mon, 2010-02-08 19:30 — Guest
Abstract Theoretical analysis of spatial distribution of near-infrared light propagation in head tissues is very important in brain function measurement, since it is impossible to measure the effective optical path length of the detected signal or the effect of optical fibre arrangement on the regions of measurement or its sensitivity. In this study a realistic head model generated from structure data from magnetic resonance imaging (MRI) was introduced into a three-dimensional Monte Carlo code and the sensitivity of functional near-infrared measurement was analysed. The effects of the distance between source and detector, and of the optical properties of the probed tissues, on the sensitivity of the optical measurement to deep layers of the adult head were investigated. The spatial sensitivity profiles of photons in the head, the so-called banana shape, and the partial mean optical path lengths in the skin-scalp and brain tissues were calculated, so that the contribution of different parts of the head to near-infrared spectroscopy signals could be examined.
