This study evaluated the influence of the irradiation with a short-pulse Er:YAG laser on the adhesion of composite resin to sound and eroded dentin (SD and ED). Forty-six samples of occlusal dentine, obtained from human molars, had half of their surface protected, while the other half was submitted to erosive cycles. Afterward, 23 samples were irradiated with Er:YAG laser, resulting in four experimental groups: SD, sound irradiated dentine (SID—Er:YAG, 50 μs, 2 Hz, 80 mJ, and 12.6 J/cm2), ED, and eroded irradiated dentin (EID—erosion + Er:YAG laser). A self-etching adhesive system was used, and then cylinders of composite resin were prepared. A microshear bond strength test was performed after 24 h storage (n=20). The morphology of SD and ED, with or without Er:YAG laser irradiation, was evaluated under scanning electron microscopy (n=3). Bond strength values (MPa) were subjected to analysis of variance followed by Tukey’s test. Statistically significant differences were found among the experimental groups: SD (9.76±3.39 B), SID (12.77±5.09 A), ED (5.12±1.72 D), and EID (7.62±3.39 C). Even though erosion reduces the adhesion to dentin, the surface irradiation with a short-pulse Er:YAG laser increases adhesion to both ED and SD.
The immediate dental implant placement in the molars region is critical, because of the high amount of bone loss and the discrepancy between the alveolar crest thickness and the dental implant platform. Laser phototherapy (LPT) improves bone repair thus could accelerate the implant placement. Twenty patients were selected for the study. Ten patients were submitted to LPT with GaAlAs diode laser (808nm) during molar extraction, immediately after, 24h, 48h, 72h, 96h and 7 days. The irradiations were applied in contact and punctual mode (100mW, 0.04cm2, 0.75J/cm2, 30s per point, 3J per point). The control group (n=10) received the same treatment; however with the power of the laser off. Forty days later samples of the tissue formed inside the sockets were obtained for further microtomography (microCTs) and histomorphometry analyses. Data were compared by the Student t test, whereas those from the different microCT parameters were compared by the Pearson correlation test (p<0.05). The relative bone volume, as well as area was significantly higher (p<0.001) in the lased than the control group. In the control group there were negative correlations between number and thickness, and between number and separation of trabecula (p<0.01). Between thickness and separation of trabecula the correlation was positive (p<0.01). The laser group showed significant negative correlation between the number and the thickness of trabecula (p<0.01). LPT accelerated bone repair. By the Pearson correlation test it was possible to infer that the lased group presented a more homogeneous trabecular configuration, which would allow earlier dental implant placement.
This research analyzed the quality of resin-based sealer adaptation after intracanal laser irradiation. Extracted teeth (n=168) were root canal treated and divided into four groups, according to dentin surface treatment: no laser; Nd:YAG laser (1.5 W, 100 mJ, 15 Hz); diode laser (2.5 W in CW), and Er:YAG laser (1 W, 100 mJ, 10 Hz). The teeth were divided into four subgroups according to the sealer used: AH Plus, EndoREZ, Epiphany, and EpiphanySE. For testing the sealing after root canal obturation, the penetration of silver nitrate solution was measured, whereas to evaluate the adaptation and penetration of the sealer into the dentin, environmental scanning electron microscopy (ESEM) was used. The ESEM images were analyzed using a four-grade criteria score by three evaluators. The inter-examiner agreement was confirmed by Kappa test and the scores statistically compared by the Kruskal-Wallis’ test (p<0.05). Both adaptation and sealer penetration in root canals were not affected by the laser irradiation. Nd:YAG and diode laser decreased the tracer penetration for AH Plus, whereas EndoREZ and EpiphanySE performances were affected by Nd:YAG irradiation (p<0.05). It can be concluded that intracanal laser irradiation can be used as an adjunct in endodontic treatment; however, the use of hydrophilic resin sealers should be avoided when root canals were irradiated with Nd:YAG laser.
Oral lichen planus (OLP) is a relatively common chronic mucocutaneous inflammatory disease and a search for novel therapeutic options has been performed. We sought to compare the efficacy of laser phototherapy (LPT) to topical clobetasol propionate 0.05% for the treatment of atrophic and erosive OLP. Forty-two patients with atrophic/erosive OLP were randomly allocated to two groups: clobetasol group (n=21): application of topical clobetasol propionate gel (0.05%) three times a day; LPT group (n=21): application of laser irradiation using InGaAlP diode laser three times a week. Evaluations were performed once a week during treatment (Days 7, 14, 21, and 30) and in four weeks (Day 60) and eight weeks (Day 90) after treatment. At the end of treatment (Day 30), significant reductions in all variables were found in both groups. The LPT group had a higher percentage of complete lesion resolution. At follow-up periods (Days 60 and 90), the LPT group maintained the clinical pattern seen at Day 30, with no recurrence of the lesions, whereas the clobetasol group exhibited worsening for all variables analyzed. These findings suggest that the LPT proved more effective than topical clobetasol 0.05% for the treatment of OLP.
Keratinocytes play a central role in wound healing by responding to tissue injury through the activation of cellular proliferation and migration. Current clinical evidence suggests that the laser phototherapy (LPT) accelerates wound healing in a variety of oral diseases; however, the molecular mechanisms involved in response to LPT are not fully understood. Oral keratinocytes (NOK-SI) maintained under nutritional-deficit culture medium (2% fetal bovine serum) were irradiated with InGaAlP laser (660 nm; 40 mW; 0.04 cm 2 spot size) in punctual and contact modes. The energy densities used were 4 and 20 J/cm 2 corresponding to 4 and 20 s of exposure times and 0.16 and 0.8 J of energy per point, respectively. Three sessions of irradiations were applied with 6-h intervals. Further, the impact of LPT over cellular migration, proliferation, and activation of the mammalian target of rapamycin (mTOR) pathway, known to play a major role in epithelial migration and wound healing, was analyzed. Compared with control cells, the LPT-treated cells showed accelerated cellular migration without any changes in proliferation. Furthermore, LPT resulted in an increase in the phospho-S6 ribosomal protein, indicating activation of the mTOR signaling pathway. Collectively, these findings suggest that the LPT activates mTOR signaling pathway, promotes epithelial cell migration, and accelerates healing of oral mucosa.
The aim of the present prospective study was to evaluate the impact of laser phototherapy (LPT) on the healing of oral ulcers. Different power densities were used on oral wounds in Wistar rats (n=72 ) randomly divided into three groups: control (0 J/cm 2 ), 4 J/cm 2 laser, and 20 J/cm 2 laser. Ulcers (3 mm in diameter) were made on the dorsum of the tongue with a punch. Irradiation with an indium-gallium-aluminum-phosphide laser (660 nm; output power: 40 mW; spot size: 0.04 cm 2 ) was performed once a day in close contact with the ulcer for 14 consecutive days. A statistically significant acceleration in healing time was found with wounds treated with 4 J/cm 2 LPT. Moreover, striking differences were found in the ulcer area, healing percentage, degree of reepithelialization, and collagen deposition. The most significant changes occurred after 5 days of irradiation. Based on the conditions employed in the present study, LPT is capable of accelerating the oral mucosa wound-healing process. Moreover, faster and more organized reepithelialization and tissue healing of the oral mucosa were achieved with an energy density of 4 J/cm 2 in comparison to 20 J/cm 2 .
Endotoxins released in the dental root by Gram-negative microorganisms can be neutralized by calcium hydroxide, when this medication is applied inside the root canal for at least seven days. However, several clinical situations demand faster root canal decontamination. Thus, for faster endotoxin neutralization, endodontists are seeking additional treatments. The in vitro study tested whether or not intracanal Nd:YAG laser irradiation would be able to neutralize endotoxin within the human dental root canal in a single session. Twenty-four human teeth with one root were mounted between two chambers. After conventional endodontic treatment, root canals were contaminated with Escherichia coli endotoxin. Then they were irradiated or not (controls) in contact mode with an Nd:YAG laser (1.5 W, 15 Hz, 100 mJ and pulse fluency of 124 J/cm2). The endotoxin activity was measured using the limulus lysate technique and data were statistically compared (p≤0.05). The concentration of active endotoxin measured in the negative control group was significantly lower than that of the positive control group (p=0.04). The concentrations of endotoxin in both irradiated groups were significantly lower than that of the positive control group (p=0.027) and similar to that of negative control group (p=0.20). A single session of intracanal Nd:YAG laser irradiation is able to neutralize endotoxin in the dental root tissues.
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 effects of phototherapy on herpes lesions have been clinically demonstrated by either preventing the lesion
formation or speeding their repair. The aim of this in vitro study was analyze the effect of phototherapy on epithelial
cells and HSV-1 in culture. Cultures of HSV-1 and epithelial cells (Vero cell line) were used. The irradiations were done
using a GaAlAs laser (660 e 780 nm, 4.0 mm2). One, two and three irradiations with 6 h-intervals were done. The
experimental groups were: Control: non-irradiated; 660 nm and 3 J/cm2 (2.8 sec); 660 nm and 5 J/cm2 (3.8 sec); 780 nm
and 3 J/cm2 (1.9 sec), and 780 nm and 5 J/cm2 (2.5 sec). The HSV-1 cytopatic effect and the cell viability of irradiated
cultures and controls were analyzed in four different conditions: irradiation of non-infected epithelial cells; epithelial
cells irradiated prior infection; virus irradiated prior infection; irradiation of HSV infected cells. The mitochondrial
activity and cytopathic effects were assessed. The number of irradiations influenced the cell growth positively and
proportionally, except for the 660 nm/ 3 J/cm2 group. Any variation in cytopathic effects was observed amongst the
experimental groups. The viability of infected cells prior irradiation was significantly higher than that of non-irradiated
cultures when 2 irradiations were done. Under the experimental conditions of this study we concluded that phototherapy
is capable of enhancing epithelial cell growth and prolonging cell viability of HSV-1 infected cells. Positive benefits of
phototherapy could be resultant from prolongation of infected cells viability, corroborating with host defenses.
The present study aimed to compare root caries removal by air turbine and Er,Cr:YSGG laser, and examine
morphological changes after these caries removal techniques under scanning electron microscopy (SEM). Seventy two
extracted human carious-free third molars were used in this study. After the in vitro root caries induction using S.
mutans, the carious lesions were removed by the conventional technique, using burs (control), and by the Er,Cr:YSGG
laser, using 13 different parameters, between 1 and 4,0 W. During caries removal, preparation time was recorded for all
groups. The results appointed out that the conventional method was the fastest one. When only laser treatment was
evaluated, the higher parameters seemed to remove caries faster then the lower ones. SEM revealed that the surfaces
treated by air turbine were smooth, but with debris. The laser groups demonstrated smooth undulations, with little or
absence of smear layer, and no signs of carbonization. These results suggest that caries removal by Er,Cr:YSGG laser
was effective. Therefore, this equipment requires training on cavity preparation, in order to avoid damages in dental hard
tissues.
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.
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