Ricardo Scarparo Navarro

Er:YAG Laser Effects on Enamel Occlusal Fissures: An in Vitro Study

This study evaluated by scanning electron microscopy (SEM) the morphological changes in occlusal fissure enamel, of permanent models, irradiated by Er:YAG laser using contact and noncontact fiberoptics in vitro. Previous studies have demonstrated the efficacy of Er:YAG laser for dental hard tissue removal and cavity preparation. The treatment of occlusal fissures in noncarious permanent human molars (n = 9) was carried out with Er:YAG laser (KEY Laser II) using handpiece no. 2051, noncontact, focused (12 mm), water spray-cooled, pulse energy 200 mJ, and frequency 2 Hz (group 1), and handpiece no. 2055 with a quartz fiberoptic 50/10, in contact, air cooled, pulse energy setting of 350 mJ and frequency 2 Hz (group 2) and 400 mJ/2 Hz (group 3). The specimens were sectioned, dehydrated in a graded series of aqueous ethanol, dried, and sputtering with gold. Morphological change analysis on occlusal fissures was performed by SEM. Group 1 showed removal of fissure debris and predominantly enamel etching-like patterns, and groups 2 and 3 showed irregular edges, melting, and recrystallization of fissure enamel, with a lava-like structure and bubble-like voids. The results of this in vitro study suggest that the irradiation of fissures by Er:YAG laser using a fiberoptics (contact and air cooled) produced melting and recrystallization of fissures enamel. Further studies are required with different energy parameters and water cooling to evaluate the thermal effects on teeth.

Effect of a Single Application of TiF4 and NaF Varnishes and Solutions Combined with Nd:YAG Laser Irradiation on Enamel Erosion in Vitro

OBJECTIVE This in vitro study aimed to analyze the influence of neodymium-doped yttrium aluminum garnet (Nd:YAG) laser irradiation on the efficacy of titanium tetrafluoride (TiF(4)) and sodium fluoride (NaF) varnishes and solutions to protect enamel against erosion. BACKGROUND DATA The effect of Nd:YAG laser irradiation on NaF and AmF was analyzed; however, there is no available data on the interaction between Nd:YAG laser irradiation and TiF(4). METHODS Bovine enamel specimens were pre-treated with NaF varnish, TiF(4) varnish, NaF solution, TiF(4) solution, placebo varnish, Nd:YAG (84.9 J/cm(2)), Nd:YAG prior to or through NaF varnish, Nd:YAG prior to or through TiF(4) varnish, Nd:YAG prior to or through NaF solution, Nd:YAG prior to or through TiF(4) solution, and Nd:YAG prior to or through placebo varnish. Controls remained untreated. Ten specimens in each group were then subjected to an erosive demineralization (Sprite Zero, 4 × 90 s/day) and remineralization (artificial saliva, between the erosive cycles) cycling for 5 days. Enamel loss was measured profilometrically (μm). Additionally, treated but non-eroded specimens were additionally analyzed by scanning electron microscope (SEM) (each group n = 2). The data were statistically analyzed by ANOVA and Tukeys post-hoc test (p < 0.05). RESULTS Only TiF(4) varnish (1.8 ± 0.6 μm), laser prior to TiF(4) varnish (1.7 ± 0.3 μm) and laser prior to TiF(4) solution (1.4 ± 0.3 μm) significantly reduced enamel erosion compared to the control (4.1 ± 0.6 μm). SEM pictures showed that specimens treated with TiF(4) varnish presented a surface coating. CONCLUSIONS Nd:YAG laser irradiation was not effective against enamel erosion and it did not have any influence on the efficacy of F, except for TiF(4) solution. On the other hand, TiF(4) varnish protected against enamel erosion, without the influence of laser irradiation.

CO2 laser and/or fluoride enamel treatment against in situ/ex vivo erosive challenge.

ABSTRACT Objective This in situ/ex vivo study investigated the effect of CO2 laser irradiation and acidulated phosphate fluoride gel (APF) application, separately and in combination, on enamel resistance to erosion. Material and Methods During 2 experimental 5-day crossover phases, 8 volunteers wore intraoral appliances containing bovine enamel blocks which were submitted to four groups: 1st phase - control, untreated and CO2 laser irradiation, 2nd phase - fluoride application and fluoride application before CO2 laser irradiation. Laser irradiation was performed at 10.6 µm wavelength, 5 µs pulse duration and 50 Hz frequency, with average power input and output of 2.3 W and 2.0 W, respectively (28.6 J/cm2). APF gel (1.23%F, pH 3.5) was applied on enamel surface with a microbrush and left on for 4 minutes. Then, the enamel blocks were fixed at the intraoral appliance level. The erosion was performed extraorally 4 times daily for 5 min in 150 mL of cola drink. Enamel loss was measured profilometrically after treatment and after the in situ phase. The data were tested using one-way Repeated Measures Anova and Tukeys test (p<0.05). Results CO2 laser alone (2.00±0.39 µm) did not show any significantly preventive effect against enamel erosion when compared with the control group (2.41±1.20 µm). Fluoride treated enamel, associated (1.50±0.30 µm) or not (1.47±0.63 µm) with laser irradiation, significantly differed from the control. Conclusion The APF application decreased enamel wear; however, CO2 laser irradiation did not enhance fluoride ability to reduce enamel wear.

Effects of Er:YAG Laser Irradiation on the Microtensile Bond Strength to Bleached Enamel

OBJECTIVE The objective of this study was to evaluate the influence of different Er:YAG laser (λ = 2.94  μm) energy parameters on the microtensile bond strength (μTBS) and superficial morphology of bovine enamel bleached with 16% carbamide peroxide. BACKGROUND Laser irradiation could improve adhesion to bleached enamel surfaces. METHODS Sixty bovine enamel blocks (7 × 3 × 3  mm(3)) were randomly assigned to six groups according to enamel preparation procedures (n = 10): G1-bleaching and Er:YAG laser irradiation with 25.52  J/cm(2) (laser A, LA); G2-bleaching and Er:YAG laser irradiation with 4.42 J/cm(2) (laser B, LB); G3-bleaching; G4-Er:YAG laser irradiation with 25.52  J/cm(2); G5-Er:YAG laser irradiation with 4.42 J/cm(2); G6-control, no treatment. G1 to G3 were bleached for 6  h during 21 days. Afterwards, enamel surfaces in all groups were slightly abraded with 600-grit SiC papers and G1, G2, G4 and G5 were irradiated according to each protocol. Enamel blocks were then restored with an etch-and-rinse adhesive system and a 4-mm thick composite buildup was made in two increments (n = 9). After 24  h, restored blocks were serially sectioned with a cross-section area of ∼1  mm(2) at the bonded interface and tested in tension in a universal testing machine (1  mm/min). Failure mode was determined at a magnification of x100 using a stereomicroscope. One treated block of each group was selected for scanning electron microscopy (SEM) analysis. μTBS data were analyzed by two-way ANOVA and no statistical differences were observed among groups. RESULTS Mean bond strengths (SD) in MPa were: G1-30.4(6.2); G2-27.9(8.5); G3-32.3(3.9); G4-23.7(5.8); G5-29.3(6.0); G6-29.1(6.1). A large number of adhesive failures was recorded for bleached and irradiated enamel surfaces. CONCLUSIONS Bleached enamel surfaces μTBS values were not significantly different from those of unbleached enamel. Even though Er:YAG laser irradiation with both parameters had no influence on μTBS for bleached and unbleached enamel, SEM analysis revealed that Er:YAG laser irradiation with 25.52  J/cm(2) should not be recommended, as enamel ablation was observed, whereas irradiation with 4.42 J/cm(2) did not promote any remarkable changes on enamel surface.

Experimental full-thickness burns induced by CO2 laser

Many studies have been conducted on the treatment of burns because they are important in morbidity and mortality. These studies are mainly focused on improving care and quality of life of patients. The aim of this study is the induction of standardized full-thickness burns of the skin of rats using the CO2 laser. The results show that non-contact technique using the CO2 laser is effective to induce such standardization of burning and is an important step in determining the efficiency of different therapies used in treating burns.

Could near-infrared Raman spectroscopy be correlated with the METAVIR scores in liver lesions induced by hepatitis C virus?

The liver is responsible for several basic functions in human body how the syntheses of the most main proteins and degradation process of toxins, drugs and alcohols. In present days, the viral hepatitis C is one of the highest causes of chronic hepatic illness worldwide, affecting around 3% of the world population. The liver biopsy is considered the gold standard for diagnosing hepatic fibrosis; however, the biopsies may be questioned because of potential sampling error, morbidity, possible mortality and relatively high costs. Spectroscopy techniques such as Raman spectroscopy have been used for diagnosis of human tissues, with favorable results. Raman spectroscopy has been employed to distinguish normal from hepatic lesions through spectral features mainly of proteins, nucleic acids and lipids. In this study, eleven patients with diagnoses of chronic hepatitis C underwent hepatic biopsies having two hepatic fragments collected: one was scored through METAVIR system and the other one was submitted to near-infrared Raman spectroscopy using a dispersive spectrometer (830 nm wavelength, 300 mW laser power and 20 s exposure time). Five spectra were collected in each fragment and submitted to Principal Components Analysis (PCA). Results showed a good correlation between the Raman spectroscopy features and the stage of hepatic fibrosis and inflammation. PCA showed that samples with higher degree of fibrosis presented higher amount of protein features (collagen), whereas samples of higher degree of inflammation presented higher features of hemoglobin, in accordance to the expected evolution of the chronic hepatitis. It has been found an important biomarker for the beginning of hepatic lesion (quinone) with a spectral feature at 1595 cm-1.

Er:YAG‐laser and sodium hypochlorite influence on bond to dentin

The aim of this in vitro study was to verify the interference of previous application of sodium hypochlorite in the bond strength to dentin irradiated with Er:YAG laser (80 mJ, 2 Hz, 25 J/cm2), using two adhesive systems with different solvents (Adper Single Bond2 – 3M ESPE [SB] and Prime&Bond 2.1 – Dentsply [PB].

Pre-exercise LED phototherapy (638 nm) prevents grip strength loss in elderly women: A double-blind randomized controlled trial

BACKGROUND: LED phototherapy can attenuate muscle fatigue and accelerate muscle recovery in young persons, but little is known about photobiomodulation effects on muscle strength in the elderly. OBJECTIVE: To assess the effects of LED phototherapy on the grip strength and muscle fatigue of wrist flexors in elderly women. METHODS: Twenty-nine women were recruited and allocated to Placebo Group (PG) (n = 14) and LED Group (LG) (n = 15). Grip strength, number of resisted wrist flexion repetitions, and serum creatine kinase (CK) were measured. The subjects were irradiated with one diode (638 nm, 150 mW, 11.7 J/cm 2 , 4.5 J/point) at four points on the wrist flexor muscles, and fatigue was induced by exercise using 75% of one maximum repetition (1MR). When muscle fatigue was reached, grip strength and CK were reassessed. RESULTS: In the LG, there was no intra-group difference for grip strength (N), 217.7 ± 34.3 to 209.9 ± 35.3 (p = 0.063) whereas in the PG, there was decrease in strength from 203.0 ± 22.5 to 181.4 ± 21.6 ( p< 0.001). LED increased the number of repetitions by 22.0%. An increase in CK (U/L) was observed in PG in all post-fatigue periods (p = 0.003) but no difference was found in the LG (p = 0.972). CONCLUSIONS: A single application of LED before muscle fatigue induction may effectively maintain grip strength and reduce muscle fatigue and damage.

Morphological analysis of cavities prepared by different parameters of Er:YAG laser

The purpose of this study was to evaluate the morphological changes in cavities made by Er:YAG laser (2.94μm)(KaVo KEY 3)(LELO-FOUSP) and high-speed drill. Cavities were made on the buccal and lingual surfaces of 27 human molars (Banco de Dentes-FOUSP), using different laser parameters (n=3): G1-15Hz/160mJ enamel/ 6Hz/200mJ dentin; G2-15Hz/180mJ enamel/ 6Hz/200mJ dentin; G3-15Hz/160mJ enamel/ 6Hz/250mJ dentin; G4-15Hz/180mJ enamel/ 6Hz/250mJ dentin; G5-15Hz/180mJ enamel/ 10Hz/180mJ dentin; G6-15Hz/160mJ enamel/ 10Hz/180mJ dentin; G7-15Hz/160mJ enamel/ 10Hz/160mJ dentin; G8-15Hz/180mJ enamel/ 10Hz/160mJ dentin and G9-high-speed drill. Samples were fixed (2.5% glutaraldhyde, 12h, 4°C), dehydrated (25-100% ethanol), dried to a critical point and sputter-coated with gold for analysis under SEM. All laser parameters used showed no evidence of thermal damage and signs of burning and melting, Er:YAG laser ablated dental hard tissues, showing enamel prisms, like scales, dentin surface without smear layer and opened dentinal tubules. It was concluded that Er:YAG laser parameters were effective for ablation of hard tissues, promoting morphological changes in irradiated tissues, creating an irregular and microretentive morphological pattern.

Effects of the Photodynamic Therapy on microbial reduction of diabetic ulcers in humans

Diabetes Mellitus is a chronic disease that can lead to lower-limb ulceration. The photodynamic therapy (PDT) is based on light interaction with a photosensitizer capable to promote bacterial death and tissue repair acceleration. This study analyzed the effects of PDT in the repair of human diabetic ulcers, by means of microbiological assessment. The clinical study was composed of 12 patients of both sexes with diabetic ulcers in lower limbs that were divided into two groups, control group (n=6) and PDT group (n=6). All patients were treated with collagenase/chloramphenicol during the experimental period, in which 6 of them have received PDT with methylene blue dye (0.01%) associated with laser therapy (660 nm), dose of 6 J/cm2¨ and 30 mW laser power. PDT group received ten treatment sessions. Wounds were evaluated for micro-organisms analysis. It was found a reduction in the occurrence of Staphylococcus aureus in both groups, being that reduction more pronounced in the PDT group. Microbial count was performed on PDT group, showing a statistical difference reduction (p<0.05) when compared before and after the treatment. It is concluded that PDT seems to be effective in microbial reduction of human diabetic wounds, promoting acceleration and improvement of tissue repair quality.ty.