Biochemical changes on the repair of surgical bone defects grafted with biphasic synthetic micro-granular HA + ß-tricalcium phosphate induced by laser and LED phototherapies and assessed by Raman spectroscopy.

This work aimed the assessment of biochemical changes induced by laser or LED irradiation during mineralization of a bone defect in an animal model using a spectral model based on Raman spectroscopy. Six groups were studied: clot, laser (λ = 780 nm; 70 mW), LED (λ = 850 ± 10 nm; 150 mW), biomaterial (biphasic synthetic micro-granular hydroxyapatite (HA) + ß-tricalcium phosphate), biomaterial + laser, and biomaterial + LED. When indicated, defects were further irradiated at a 48-h interval during 2 weeks (20 J/cm2 per session). At the 15th and 30th days, femurs were dissected and spectra of the defects were collected. Raman spectra were submitted to a model to estimate the relative amount of collagen, phosphate HA, and carbonate HA by using the spectra of pure collagen and biomaterials composed of phosphate and carbonate HA, respectively. The use of the biomaterial associated to phototherapy did not change the collagen formation at both 15 and 30 days. The amount of carbonate HA was not different in all groups at the 15th day. However, at the 30th day, there was a significant difference (ANOVA, p = 0.01), with lower carbonate HA for the group biomaterial + LED compared to biomaterial (p < 0.05). The phosphate HA was higher in the groups that received biomaterial grafts at the 15th day compared to clot (significant for the biomaterial; p < 0.01). At the 30th day, the phosphate HA was higher for the group biomaterial + laser, while this was lower for all the other groups. These results indicated that the use of laser phototherapy improved the repair of bone defects grafted with the biomaterial by increasing the deposition of phosphate HA.

Effects of treatment for manipulation of teeth and Er:YAG laser irradiation on dentin: a Raman spectroscopy analysis.

OBJECTIVE: The main purpose of this study was to evaluate the utility of Raman spectroscopy analysis as a research tool to study the effects of Er:YAG laser etching on dentin mineral and organic components. A secondary aim was to study the effects of the decontamination process and the storage procedure on dentin components. BACKGROUND DATA: There are no spectroscopy reports relating the effects of Er:YAG laser irradiation as an alternative to acid etching and the manipulation process on the dentin structure. METHODS: Twelve non-carious human third molars were divided in two main groups: stored in thymol solution (group A, n = 6) or autoclaved (group B, n = 6). The specimens were either etched with 37% phosphoric acid (control subgroup) or irradiated with Er:YAG laser. Irradiated samples were divided into the following subgroups: I, II, and III (80 mJ, 3 Hz, 30 sec; 120 mJ, 3 Hz, 30 sec; and 180 mJ, 3 Hz, 30 sec, respectively). Samples were analyzed by Raman spectroscopy. RESULTS: The mineral and organic dentin contents were more affected in autoclaved teeth than in the specimens stored in thymol. Peak area reduction in group A specimens treated with phosphoric acid and pulse energy of 80 mJ were the most conservative surface treatments regarding changes in the peak area of organic and inorganic dentin components. CONCLUSION: The autoclaving process and pulse energies of 120 and 180 mJ produced greater reduction of organic and inorganic contents in dentin, associated with greater reduction in the areas of 968, 1077, 1460, and 1670 cm(1) Raman peaks.

Analysis of Human Tooth Pulp Chamber Temperature After 670 nm Laser Irradiation: In Vitro Study.

OBJECTIVE: One of the limiting factors of employing laser radiation on dental therapies is the potential of causing thermal injuries to pulp tissues. The purpose of this study was to evaluate intra-chamber temperature increase on extracted human teeth exposed to 670 nm wavelength InGaAlP laser diode radiation. MATERIALS AND METHODS: In vitro intra-chamber temperature measurements of 12 standardized human teeth (incisors, canines, premolars, and molars; n = 3) were taken both before and after laser radiation. A type-K thermocouple fast-response thermocouple wire with a 0.5 mm diameter probe was inserted into the tooth pulp chamber (ICEL-Manaus-brand). The laser device Lasotronic-brand InGaAlP laser diode was used to irradiate tooth enamel, perpendicularly to the external surface for 30 sec, with power of levels of 340, 272, 204, 136, and 68 mW. The measurements were taken at three time points: 0, 30 sec, and 3 min after the laser irradiation. Measurements were repeated 24 h after removal and reinsertion of the probe in the pulp chamber. The temperature gradient (ΔT in °C) was calculated (ΔT = final temperature-initial temperature) for each group. Data of ΔT were statistically analyzed by two-way analysis of variance (ANOVA) at the 95% confidence level and compared by Tukey post hoc test (α = 0.05). RESULTS: ANOVA showed statistically significant differences to the interaction of factors (p < 0.05). The highest ΔT values obtained were observed to incisors with 340 mW, 272 mW; 204 mW of power (respectively 4.7°C, 4.2°C, and 3.1°C); and canines presented the lowest ΔT (0.8°C-0.3°C) with no influence of power output. CONCLUSIONS: Since the thermal increase was observed in this study, especially in incisors, attention should be paid to avoid pulpal damage.

Molecular analysis of Er:YAG laser irradiation on dentin.

The aim of this study was to evaluate by dispersive Raman spectroscopy the mineral and organic components of human dentin before and after laser irradiation and acid etching. The occlusal enamel of six non-carious human third molars was removed providing 6 dentin discs, which were divided in four quadrants each of them receiving a different surface treatment: etching with a 37% phosphoric acid gel (control); irradiation by Er:YAG laser (KaVo Key Laser II) with 80 mJ, 3 Hz, 30 s (group I); 120 mJ, 3 Hz, 30 s (group II); and 180 mJ, 3 Hz, 30 s (group III). The Raman spectra of normal (untreated) and treated dentin were analyzed and the mineral and the organic component were evaluated. Results were submitted to statistical analysis by ANOVA and Tukey's test at 5% significance level. The minerals and organic content were less affected in the control group and group I (p>0.05). Group II presented more reduction in mineral content (p<0.01) whereas in group III the inorganic (p<0.05) and organic (p<0.01) content were more affected. Dispersive Raman spectroscopy provided valid information of dentin chemical constituents with non-chemical sampling preparation.

Molecular analysis of Er: YAG laser irradiation on dentin

O objetivo deste estudo foi avaliar por espectroscopia Raman, os componentes mineral e orgânico da dentina humana antes e após o condicionamento ácido e a irradiação com laser de Er:YAG. Seis discos de dentina foram obtidos de 6 terceiros molares humanos hígidos após remoção da superfície oclusal. Cada disco foi dividido em quatro regiões (quadrantes) de tratamento: condicionamento com ácido fosfórico a 37% (controle), irradiação com laser de Er:YAG (KaVo Key Laser II) com 80 mJ, 3 Hz, 30 s (grupo I); 120 mJ, 3 Hz, 30 s (grupo II) e 180 mJ, 3 Hz, 30 s (grupo III). Os espectros Raman da dentina normal e tratada foram analisados e os componentes mineral e orgânico foram avaliados. Os resultados foram submetidos a análise estatística pela ANOVA e teste de Tukey com intervalo de confiança de 95%. O conteúdo mineral e orgânico foi menos afetado nos grupos controle e I (p>0,05). O grupo II apresentou maior redução no conteúdo mineral (p<0,01) enquanto que a irradiação com laser Er:YAG 180 mJ (grupo III) reduziu mais o conteúdo inorgânico (p<0,05) e orgânico (p<0,01). A espectroscopia Raman forneceu informações dos conteúdos químicos da dentina sem preparação química dos espécimes.

Efeito da irradiação LED sobre a microinfiltração auricular em camundongo / Effect of LED irradiation on microcirculation of auricular mouse

A microcirculação pode ser considerada uma unidade funcional do sistema circulatório, sendo constituída pelos menores vasos distais. A radiação eletromagnética pode influenciar essa unidade agindo sobre esfíncteres pré-capilares. Essa influência pode gerar alterações na pressão hidrostática capilar, contribuindo na reabsorção de exsudato inflamatório e eliminando acúmulos de catabólitos intermediários. O efeito da radiação eletromagnética coerente na região do visível (vermelho) tem sido estudado principalmente no processo inflamatório, tendo sido encontrado aumento da permeabilidade capilar e vasodilatação. Contudo, poucos trabalhos foram realizados com o emprego de radiação eletromagnética não-coerente (LED) na região do visível. Dessa forma, o objetivo deste estudo foi observar o efeito do LED (640 :!: 20 nm, 100 m W, 1,77 cm2) sobre a microcirculação auricular em camundongos. Para tal, foram utilizados oito animais divididos em dois grupos (grupo placebo e grupo 3 J/cm2). A superfície auricular externa dos animais foi monitorada (durante 15 minutos) sob microscopia óptica (100x) e analisada com o auxílio do programa ImageJ. Observou-se uma diferença significativa no diâmetro dos vasos nos primeiros minutos após a irradiação, comprovando a existência de um efeito vasodilatador da radiação eletromagnética não-coerente, na região do vermelho, com os parâmetros testados. Esse resultado pode ser otimizado empregando-se maior fluência.

Microcirculation, considered a functional unit of the circulatory system, is composed of many smaller distal vessels. The electromagnetic radiation can influence this unit acting on the precapillary sphincters. This influence might generate alterations on the capillary hydrostatic pressure, contributing to the reabsortion of the inflammatory exudation and eliminating intermediate catabolite accumulation. The effect of coherent electromagnetic radiation on the visible region (red) has been studied mainly in the inflammatory process, and an increase in the capillary permeability and vasodilation was found. However few studies have been conducted on the use of noncoherent electromagnetic radiation (LED) in the visible region. Therefore, the aim of this study was to observe the effect of the LED (640:!: 20 nm, 100 mW, 1.77 cm2) on the auricular circulation of mice. To this end 8 animals were separated into 2 groups (placebo group and 3 J/cm2 group). The external auricular surface was monitored (15 minutes) under light microscopy (100X) and analysed with the help of IMAGEJ program. A significant difference was observed in the vessel diameter in the first minutes after the irradiation, proving the existence of a vasodilator effect of non coherent electromagnetic radiation in the red region of the tested parameters. This result can be optimized with the use of greater fluence.

Filtragem de sinais Raman de tecidos biológicos para reduçäo de ruído e background / Filter of Raman signals of biological tissue for background and noise reduction

A redução do tempo de aquisição do sinal e processamento de espectros Raman obtidos à partir de tecidos biológicos é um passo importante para se tornar os sistemas laboratoriais uma ferramenta clínica. Neste trabalho é apresentado a extração de fluorescência e ruído de um espectro Raman de uma coronária humana.