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Lasers Technology | Progress Report 27

mineralization by FTRaman spectroscopy. De- increase in energy density, which points out
mineralization promoted reduction in organic the importance of using the proper energy
contents; Nd:YAG laser irradiation promoted density in clinical procedures to avoid thermal
loss of carbonate and organic content, while or chemical damage to the tissue caused by
Er,Cr:YSGG did not produce significant chang- laser irradiation.
es in the relative band intensities of organic
and inorganic contents of the enamel. In lased Other Laser Health activities (activities) in-
samples, no effects caused by pH-cycling on clude Development of therapeutic processes
enamel were observed. Our group showed that of photobiomodulation and photodynamic
laser treatment and its association with fluo- inactivation which aims to explore innovative
ride can interfere with the demineralization light-based therapeutic processes through
dynamics, reducing its effects over the enamel. low power lasers and light-emitting diodes
(LEDs) to provide scientific background for cli-
Lasers cutting bone and nicians. Our major interests are to investigate
dental hard tissues the effects of photobiomodulation (PBM) and
photodynamic inactivation (PDI) therapies.
Infrared lasers can be useful in several appli- Other activities encompass tissue optics, nano-
cations, since they are strongly absorbed by materials, and tissue engineering.
water and hydroxyapatite, two of the main
components of the body mineralized tissues, Photobiomodulation
like enamel, dentine and bone. The Er,Cr:YSGG
laser (2780 nm) cuts bone by thermal ablation. Photobiomodulation (PBM) is a non-invasive
In this process, the water molecules of tissue therapeutic modality used in Health Sciences
absorb the laser energy, increasing its tem- for pain relief, wound healing, bone repair, al-
perature and the pressure inside the tissue, though mechanisms behind its effects are still
causing a micro-explosion that removes the not completely known. Our group develops
material. However, for an efficient and safe researches about the physical, chemical and
application, it is necessary to know the exact biological mechanisms of the non-thermal
effects that the laser irradiation promotes in effects of light on biological tissues. Studies are
tissue. Infrared Thermography and Atten- carried out in vitro and in vivo to investigate
uated Total Reflectance-Fourier Transform the influence of PBM on cell cultures, tumor
Infrared spectroscopy (ATR-FTIR) techniques cells, pain relief, bone repair, and chronic in-
were used to characterize natural and irradi- flammation in obesity. Our results show that
ated bone tissue showing that irradiation at PBM is able to trigger senescence in tumor
3 J/cm promotes an increased temperature cells, but proliferation in fibroblasts following
2
2
of approximately 100 °C, while 6 J/cm up to gamma-radiation, reduces abdominal adipose
215 °C; 8, 12, and 15 J/cm promoted increased tissue inflammatory infiltrate of diet-induced
2
temperature up to 300 °C. The compositional obese and hyperglycemic mice, stimulates
analysis revealed that laser irradiation pro- bone metabolism and inhibits root resorp-
motes changes in the carbonate content and tion during tooth movement in rodents, and
affects the intermolecular interaction within modulate serotonin levels and blood flow in
the mineral part of bone. Moreover, the pro- women with headache. Skin optics chang-
portion of organic components (amides) in the es, depending on mouse gender and strain
bone samples significantly decreased with the suggesting that absorption and scattering