Journal of clinical laser medicine & surgery最新文献

Objective: The aim of this study was to evaluate the effectiveness of the clinical use of the gallium-aluminum-arsenium (GaAlAs) laser at the maximum and minimum energies recommended by the manufacturer for the treatment of dentine hypersensitivity.

Background data: Dentine hypersensitivity (DH) is a response to a stimulus that would not usually cause pain in a healthy tooth. It is characterized by sharp pain of short duration from the denuded dentin. Its etiology is unknown. The dentin only begins to show sensitivity when exposed to the buccal environment. This exposure can result after removal of the enamel and/or dental cement, or after root denudation. Different treatments are proposed for this disorder.

Materials and methods: In this study, 25 patients, with a total number of 106 cases of DH, were treated with GaAlAs low-level laser therapy (LLLT). 65% of the teeth were premolars; 14% were incisors and molars; 6.6% were canines. The teeth were irradiated with 3 and 5 J/cm2 for up to six sessions, with an interval of 72 h between each application, and they were evaluated initially, after each application, and at 15 and 60 days follow-up post-treatment.

Results: The treatment was effective in 86.53% and 88.88% of the irradiated teeth, respectively, with the minimum and maximum energy recommended by the manufacturer. There was a statistically significant difference between DH and after a follow-up of 60 days for both groups. The difference among the energy maximum and minimum was not significant.

Conclusion: The GaAlAs low-level laser was effective in reducing initial DH. A significant difference was found between initial values of hypersensitivity and after 60 days follow-up post-treatment. No significant difference was found between minimum (3 J/cm2) and maximum (5 J/cm2) applied energy.

Objective: The objective of this paper is to review 51 consecutive contact Nd:YAG laser parotidectomies to determine perioperative outcomes and complications related to the facial nerve and the use of the laser tips.

Background data: Parotid surgery is mostly performed with scalpel or scissors, techniques that may put the facial nerve at risk for injury due to brisk bleeding and imprecise dissection. Even though previous experiences with Nd:YAG lasers in surgery had raised concerns of energy dispersion, the contact sapphire tips used in this series allowed accurate precise dissection and hemostasis, limiting complications.

Materials and methods: Close facial nerve dissection was done at 8-12 watts, for an average total of 8,000-12,000 joules per case.

Results: No significant or permanent facial nerve complications resulted from the use of the laser tips, except for expected transient and reversible postoperative ipsilateral marginal mandibular nerve paresis observed in 43% of the patients-less than the generally quoted 50% expected after uneventful lateral lobe parotidectomy.

Conclusion: This review concludes that the contact Nd:YAG laser may offer significant technical and safety advantages, and no direct associated complications in the dissection and preservation of the facial nerve in parotidectomy.

Objective: The aim of this study was to histologically assess the effect of low-level laser therapy (LLLT) (lambda830 nm) on the repair of standardized bone defects of the femur of Wistar albinus rats grafted with inorganic bovine bone and associated (or not) with decalcified bovine cortical bone membrane.

Background data: Bone loss may be a result of pathology, trauma, or surgical procedure. Extensive studies on the process of bone repair have been undertaken, and several techniques for the correction of bone defects have been proposed. Amongst them is the use of several types of grafts, the use of membranes, and the combination of both techniques. There is evidence in the literature of the positive effect of LLLT on the healing of soft tissue wounds. However, its effect on bone healing is not completely understood.

Materials and methods: Five randomized groups were studied: group I (control); group IIA (Gen-ox); group IIB (Gen-ox + LLLT); group IIIA (Gen-ox + Gen-derm); and group IIIB (Gen-ox + Gen-derm + LLLT). Bone defects were created at the femur and were treated according to the group. The animals of irradiated groups were irradiated every 48 h for 15 days; the first irradiation was performed immediately after the procedure. The animals were irradiated transcutaneuosly at four points around the defect. At each point, a dose of 4 J/cm2 was given (phi approximately equal to 0.6 mm, 40 mW), and the total dose per session was 16 J/cm2. The animals were humanely killed at 15, 21, and 30 days after surgery. The specimens were routinely processed to wax, serially cut, stained with H&E and Picrosirius stains, and analyzed under light microscopy.

Results: The results showed more advanced repair of the irradiated groups when compared to the non-irradiated ones. The repair of the irradiated group was characterized by both increased bone formation and on the amount of collagen fibers around the graft within the cavity, as early as the 15th day after surgery, considering the osteoconductive capacity of the Gen-ox and the increment of the cortical repair in specimens with Gen-derm membrane.

Conclusion: It is concluded that LLLT had a positive effect on the repair of bone defect by graft associated or not with the use of biological membrane.

Objective: The present study aimed to compare carious dentin removal by air turbine, Carisolv and erbium,chromium:yttrium,scandium,gallium,garnet (Er,Cr:YSGG) laser, and examine morphological changes before and after these caries removal techniques under light microscopy and scanning electron microscopy (SEM).

Background data: Although there have been numerous studies on removing caries by Er,Cr:YSGG laser, none has compared Er,Cr:YSGG laser and Carisolv, or reported on the usage of DIAGNOdent as a diagnostic tool particularly for advanced caries in in vitro experiments.

Materials and methods: Sixty extracted human teeth diagnosed as advanced caries were divided into three groups based on the treatment received, namely air turbine, Carisolv, and Er,Cr:YSGG laser groups. Each group was sub-divided into two in order to examine the results with or without finishing using nylon brush, 15% ethylene diamine tetraacetic acid (EDTA) or low-power laser, respectively. After evaluation by DIAGNOdent, specimens were observed under light microscopy or SEM.

Results: Light microscopic observations varied considerably in the three treatment groups. SEM revealed that the surfaces treated by air turbine were very smooth, but with substantial debris. The Carisolv group exhibited a very rough surface with a thick smear layer, while the Er,Cr:YSGG group demonstrated smooth undulations with little smear layer and debris. Among the finishing techniques, the laser group demonstrated the best efficiency. DIAGNOdent scores supported the results of light microscopy.

Conclusion: These results suggest that caries removal by Er,Cr:YSGG laser is very effective even without finishing and DIAGNOdent is useful for diagnosing advanced caries in in vitro experiments.

Objective: The aim of this study was to investigate the irradiance-dependency of low-level laser therapy (LLLT) effects on bacterial growth.

Background: LLLT is applied to open wounds to improve healing; however, its effect on wound bacteria is not well understood.

Materials and methods: Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus were irradiated using a wavelength of 810 nm at irradiances of 0.015 W/cm2 (0-50 J/cm2) and 0.03 W/cm2 (0-80 J/cm2). Bacteria were counted after 20 h of incubation.

Results: LLLT effects varied significantly with species. P.aeruginosa growth decreased overall dependent on an interaction of irradiance and radiant exposure; greatest inhibition was produced using high irradiance delivering radiant exposures in the range of 1-20 J/cm2 (p = 0.001-0.04). In contrast, E. coli growth increased overall (p = 0.01), regardless of irradiance; greatest effects were produced using low radiant exposures (1-20 J/cm2). There was a main effect for irradiance (p = 0.03) on S. aureus growth; however, growth was not different compared with controls. Additional analysis showed that there were differences in growth of P.aeruginosa when comparing samples that were matched by exposure times (66, 329, 658, 1316, 1974, and 2632 sec) rather than radiant exposure; this suggests that irradiance rather than exposure time was the significant factor in P. aeruginosa inhibition.

Conclusion: These findings have immediate relevancy in the use of LLLT for infected wounds. Exposure to 810-nm irradiation (0.03 W/cm2) could potentially benefit wounds infected with P. aeruginosa. However, increased E. coli growth could further delay recovery.

Objective: The purpose of this preliminary study is to evaluate the effect of various wavelengths of light on nanobacteria (NB).

Background data: NB and mitochondria use light for biological processes. NB have been described as multifunctional primordial nanovesicles with the potential to utilize solar energy for replication. NB produce slime, a process common to living bacteria. Slime release is an evolutionary important stress-dependent phenomenon increasing the survival chance of individual bacteria in a colony. In the cardiovascular system, stress-induced bacterial colony formation may lead to a deposition of plaque.

Methods: Cultured NB were irradiated with NASA-LEDs at different wavelengths of light: 670, 728 and 880 nm. Light intensities were about 500k Wm(-2), and energy density was 1 x 10(4) J m(-2).

Results: Monochromatic light clearly affected replication of NB. Maximum replication was achieved at 670 nm.

Conclusions: The results indicate that suitable wavelengths of light could be instrumental in elevating the vitality level of NB, preventing the production of NB-mediated slime, and simultaneously increasing the vitality level of mitochondria. The finding could stimulate the design of cooperative therapy concepts that could reduce death caused by myocardial infarcts.

Objective: The current study focuses on any influence that depletion of endogenous glutathione in CHO K1 cells may have on the photodynamic action of zinc phthalocyanine (ZnPc).

Materials and methods: Two lasers--a HeNe laser, 632.5 nm, maximum power output 3.5 mW, and a Toshiba semiconducting laser, 670 nm, maximum power of 7 mW--were used. Chinese Hamster Ovary cells (CHO K1) were exposed to light, 2-10 J. Cellular reduced glutathione levels [GSH] were depressed prior to exposure to ZnPc and laser light, using buthionine sulphoximine, a potent inhibitor of gamma-glutamylcysteine synthetase. The influence of hypoxic intracellular conditions was studied by reduction of oxygen content of cells by 80% following purging of cell cultures with nitrogen.

Results: In well-aerated cells, doubling times are reduced by the photodynamic action of ZnPc by 29 +/- 6%, fig 2 (p = 0.01). Cells with lowered [GSH] do not show this effect (p = 0.1). When hypoxic cells are studied at normal [GSH], no photodynamic effect is observed (p = 0.1). When cell viability is studied, using the 670-nm laser, a photodynamic effect is observed, (80% fall from controls, p < 0.001), irrespective of the cellular [GSH] level for a single dose of 6 J. This effect is observed in cells with normal [GSH], for varied doses of 2 J and higher (63% fall at 2 J, p < 0.001).

Conclusions: Lowered [GSH] was observed to depress the photodynamic effect of ZnPc when cell-doubling times were the endpoint. The photostimulating effect of ZnPc was similarly suppressed by hypoxic conditions. When cell viability was the endpoint, then a photodynamic effect of ZnPc was observed irrespective of the endogenous [GSH] values.

Objective: The aim of this work was to study the effect of low-power laser radiation on guinea pig salivary glands.

Background data: Low-power laser radiation changes some cellular functions. The effect on salivary glands has not been sufficiently studied.

Materials and methods: One hundred and forty-four male guinea pigs (150 +/- 30 g body weight) were used. The animals were divided into two groups: control group (fed animals and those undergoing 2, 4, 8, 10, and 12 h of fasting) and experimental group (irradiated). Both the right and left submandibular glands were later irradiated with helium-neon laser at 7-mW power, with a 0.75-mm spot, under continuous pulse for 2 min in a one-session exposure; a 11.2 J/cm(2) energy density was applied. Then, the irradiated animals were fed, or underwent 2, 4, 8, 10 and 12 h of fasting. Samples of submandibular glands were taken with a punch (5 mm diameter) and were used for optic and transmission electron microscopy studies.

Results: The structural observations showed that the irradiation effect was progressive; and showed a trophic stimulant effect at 2 h following irradiation, with vasodilatation, vascular congestion, perivascular infiltrate, and a necrotic picture of glandular parenchyma at longer times. The ultrastructural observations showed alterations of rough endoplasmic reticulum.

Conclusion: We propose that low-power laser radiation with the doses applied in this study disturbs protein synthesis and secretion of guinea pig submandibulary glands.

Objective: The objective of this study was to evaluate the effect of Er:YAG laser on the formation of CaF(2), after the application of acidulated phosphate fluoride (APF), and its influence on the anti-cariogenic action in human dental enamel.

Background data: Er:YAG laser was designed to promote ablation of the enamel. However, the possibility of using this energy to increase the enamel's resistance to caries has hardly been explored, and neither has its interaction with the use of fluorides.

Materials and methods: One hundred and twenty blocks of enamel were allocated to four groups of 30 blocks each: (1) C, control group; (2) Er:YAG, laser; (3) APF; and (4) Er:YAG+APF. Of these, 80 blocks were submitted to pH cycling for 14 days. In the other 40 blocks, fluoride (CaF(2)) was measured before cycling. After pH cycling, surface microhardness (SMH), microhardness in cross-section (converted to mineral contents % vol. min.), and fluoride after cycling (40 blocks) were also determined.

Results: SMH decreased in all groups. The control group showed the highest decrease, and Er:YAG+APF showed the lowest decrease (p < 0.05). Groups APF and Er:YAG showed the same results (p > 0.05). Mineral content at depths 10, 20, and 40 microm was lower in the control and Er:YAG groups, and higher in groups APF and Er:YAG+APF. CaF(2) (microgF/cm(2)) deposited before pH cycling was higher in the APF group when compared to the Er:YAG+APF group. Control and Er:YAG groups showed the lowest values (p > 0.05).

Conclusion: It was concluded that Er:YAG laser influenced the deposition of CaF(2) on the enamel and showed a superficial anti-cariogenic action, but not in depth.