Several studies indicate that low level laser therapy (LLLT) accelerates the healing process, however, for a determined
pathology, dosimetry remains difficult to be established. To understand the tissue optical properties under different
conditions is extremely relevant since the dose delivered to the target tissue is known to be critical. The skin
pigmentation influence on the laser attenuation is not yet well established on different mice lineages or human ethnical
groups, making the dose problematic. Along the same line, inflammatory processes may cause similar problems since the
tissues in this condition change their optical properties due to inflammatory cell accumulation. This work evaluated the
attenuation pattern of a HeNe laser (λ=632.8 nm) using ex vivo skin samples from Balb/C and C57BL/6 mice under
inflammatory stages induced in their paw by local carrageenan inoculation. The samples were placed between two
microscope slides, and a CCD camera was placed orthogonal to the beam path. The intensity distribution of the scattered
light was photographed in grayscale and analyzed by ImageJ software. Our findings suggest that even slight differences
of the epithelial pigmentation could result in a relevant dose loss delivered to the deeper tissues. The increase of the
inflammatory cell density in the connective tissue indicated a highly scattering area also resulting in a dose loss for the
deeper tissues when compared to control group.
Introduction: New technologies in dental practice, such as laser, have enabled new strategies to be established in dental
education. The aim of this study was to analyze the difficulties that dental students encountered with performing surgical
incisions using Er:YAG laser (LE), and the morphology of these incisions. Material and Methods: Sixteen undergraduate
dental students and ten dental professionals (DP) enrolled at The Master of Science Program in Laser Dentistry were
asked to perform 15 incisions using an LE and 15 with a conventional scalpel. The incisions were compared, based on
the shape factor (relation between area and perimeter), which was obtained by a digital image system and by a
morphometry software. Data was submitted to statistical analysis of variance (p 0.05). Results: Considering the incisions
performed by scalpel, DP showed statistically significant differences (p < 0.01) in relation to control group (CG).
Considering the LE, all groups showed significant differences (p<0.0001) in relation to CG, especially the DP group. The
main laser technical failures were performing an incision that was not in a straight line, without defined borders, using an
inconstant cutting speed, and absence of suction and water jet appliances. None of the groups performed adequate
incisions using LE. Conclusion: Greater emphasis is required in relating laser therapy practice to the physical properties
of laser, particularly for dental professionals that specialize in laser.
Laser phototherapy has proven to improve treatment of several pathologies in dentistry. The aim of the
present study was to analyze the low power laser phototherapy effects comparing multiple irradiations with
the same total energy at once. This in vitro study focuses on the biostimulation of cellular growth of pulp
fibroblasts (FP5 cell lineage). The cells were grown in Dulbecco's Modified Eagle's (DME) medium with
either 5% (nutritional deficit) or 10% fetal bovine serum (FBS). Laser irradiation was carried out with
diode lasers with the following parameters: 685 nm, 40 mW, spot size 0.019 cm2. The groups were:
G1(6.3J/cm2, 3 s, 0.12J), G2 (12.6J/cm2, 6 s, 0.24J), G3 (18.9J/cm2, 9 s, 0.36J), G4 (2 irradiations of
6.3J/cm2, 0.24J), G5 (3 irradiations of 6.3J/cm2, 0.36J), G6 (5% SFB, negative control, without irradiation),
and G7 (10% SFB, positive control, without irradiation). On groups G4 and G5 the irradiation was
performed with 6h-intervals. For growth analysis, the MTT test was used 24 hours after the last irradiation.
The data from spectrophotometer were analyzed by ANOVA followed by the Tukey's test. The groups
submitted to multiple irradiations presented significantly higher cell growth than the groups with single
irradiation. This cell growth was similar to that of positive control group. The laser phototherapy with
multiple irradiations is more effective on cellular growth.
The aim of this study was to analyze the effects of phototherapy with low intensity laser on the inflammatory reaction after rat brain injury. Cryogenic injury was performed at the brain of 16 male Wistar rats (250-300g) using a cooper probe at -80º C. Immediately, 24 h and 48 h later, the rats received laser irradiation using a GaAlAs laser (830 nm, 100 mW). The samples were randomly divided into four groups (n= 4 per group): A: control (non- irradiated); B: energy density of 14.28 J/cm2; C: 28.57 J/cm2; D: 42.85 J/cm2. Three days later, the cerebral vascular permeability and the inflammatory cells at the trauma site were evaluated. For vascular permeability analysis, 2 h prior sacrifice an intra vascular injection of Evans blue stain was done in the rats. For inflammatory cells counting, frozen samples were sectioned and the histological slides were stained with Giemsa. The data were compared by either ANOVA or Kruskall-Wallis complemented by the Dunn's test. The irradiated groups presented higher cerebral vascular permeability than controls (A: 2.6 ± 0.8; B:12.0 ± 2.0; C: 13.1 ± 4.1, and D: 12.4 ± 1.8; p=0.016). The inflammatory cell numbers of irradiated samples were similar to controls (A: 65 ± 6; B:85 ± 9; C: 84 ±14, and D: 83 ± 3; p=0.443). The data showed that phototherapy with low intensity laser modulates the inflammatory reaction in the brain by increasing the cerebral vascular permeability after a cryogenic trauma.