Effect of ibuprofen on proliferation, differentiation, antigenic expression, and phagocytic capacity of osteoblasts

Ibuprofen is a nonselective nonsteroidal antiinflammatory drug commonly prescribed for acute postsurgical and posttraumatic pain. However, little known is about the effect of this drug on osteoblasts. In this study, we aimed to investigate the effect of ibuprofen on cell proliferation, differentiation, antigenic profile, and phagocytic activity, in a human MG-63 osteosarcoma cell line, as a model of osteoblasts. Flow cytometry was used to study proliferation, antigenic profile, and phagocytic activity, and radioimmunoassay was used to determine osteocalcin synthesis as a cell differentiation marker. Our results showed that therapeutic doses of ibuprofen (5 and 25?μM) did not modify cell proliferation and osteocalcin synthesis in the MG-63 cellular line. However, treatment with a higher dose (25?μM) increased the expression of antigens CD21, CD44, CD80, CD86, and HLA-DR and decreased phagocytic activity. The results indicate that a therapeutic dose of ibuprofen has no adverse effects on growth of the osteoblast-like cells. Treatment with ibuprofen alone may produce some cell activation, which would explain the increase in expression of membrane markers and decrease in phagocytic capacity.     

Laser and light-emitting diode effects on pre-osteoblast growth and differentiation

The acceleration of bone regeneration by low-intensity laser irradiation may hold potential benefits in clinical therapy in orthopedics and dentistry. The purpose of this study is to compare the effects of light-emitting diode (LED) and laser on pre-osteoblast MC3T3 proliferation and differentiation. Cells were irradiated with red, infrared, and LED (3 and 5 J/cm²). Lasers had a power density of 1 W/cm² and irradiation time of 2 and 5 s. LED had a power density of 60 mW/cm² and irradiation time of 50 and 83 s. Control group did not receive irradiation. Cell growth was assessed by a colorimetric test (MTT) (24, 48, 72, and 96 h), and cell differentiation was evaluated by alkaline phosphatase (ALP) quantification after growth in osteogenic medium (72 and 96 h and 7 and 14 days). At 24 h, the cell growth was enhanced 3.6 times by LED (5 J/cm²), 6.8 times by red laser (3 J/cm²), and 10.1 times by red laser (5 J/cm²) in relation to control group (p?<?0.05). At the other periods, there was no influence of irradiation on cell growth (p?>?0.05). The production of ALP was not influenced by irradiation at any period of time (p?>?0.05). Low-intensity laser and LED have similar effects on stimulation of cell growth, but no effect on cell differentiation.     

Effects of Er:YAG laser on bacteria associated with titanium surfaces and cellular response in vitro

This in vitro study examined (a) the anti-bacterial efficacy of a pulsed erbium-doped yttrium aluminum garnet (Er:YAG) laser applied to Streptococcus sanguinis or Porphyromonas gingivalis adhered to either polished or microstructured titanium implant surfaces, (b) the response of osteoblast-like cells and (c) adhesion of oral bacteria to titanium surfaces after laser irradiation. Thereto, (a) bacteria adhered to titanium disks were irradiated with a pulsed Er:YAG laser (λ?=?2,940 nm) at two different power settings: a lower mode (12.74 J/cm² calculated energy density) and a higher mode (63.69 J/cm²). (b) After laser irradiation with both settings of sterile titanium, disks were seeded with 10⁴ MG-63 cells/cm². Adhesion and proliferation were determined after 1, 4, and 24 h by fluorescence microscopy and scanning electron microscopy. (c) Bacterial adhesion was also studied on irradiated (test) and non-irradiated (control) surfaces. Adhered P. gingivalis were effectively killed, even at the lower laser setting, independent of the material’s surface. S. sanguinis cells adhered were effectively killed only at the higher setting of 63.69 J/cm². Laser irradiation of titanium surfaces had no significant effects on (b) adhesion or proliferation of osteoblast-like MG-63 cells or (c) adhesion of both oral bacterial species in comparison to untreated surfaces. An effective decontamination of polished and rough titanium implant surfaces with a Er:YAG laser could only be achieved with a fluence of 63.69 J/cm². Even though this setting may lead to certain surface alterations, no significant adverse effect on subsequent colonization and proliferation of MG-63 cells or increased bacterial adhesion was found in comparison to untreated control surfaces.     

Effect of low-level laser therapy on odontoblast-like cells exposed to bleaching agent

The aim of the present study was to evaluate the effect of low-level laser therapy (LLLT) on odontoblast-like MDPC-23 cells exposed to carbamide peroxide (CP 0.01 %–2.21 μg/mL of H₂O₂). The cells were seeded in sterile 24-well plates for 72 h. Eight groups were established according to the exposure or not to the bleaching agents and the laser energy doses tested (0, 4, 10, and 15 J/cm²). After exposing the cells to 0.01 % CP for 1 h, this bleaching solution was replaced by fresh culture medium. The cells were then irradiated (three sections) with a near-infrared diode laser (InGaAsP—780?±?3 nm, 40 mW), with intervals of 24 h. The 0.01 % CP solution caused statistically significant reductions in cell metabolism and alkaline phosphate (ALP) activity when compared with those of the groups not exposed to the bleaching agent. The LLLT did not modulate cell metabolism; however, the dose of 4 J/cm² increased the ALP activity. It was concluded that 0.01 % CP reduces the MDPC-23 cell metabolism and ALP activity. The LLLT in the parameters tested did not influence the cell metabolism of the cultured cells; nevertheless, the laser dose of 4 J/cm² increases the ALP activity in groups both with and without exposure to the bleaching agent.     

Biostimulatory effect of low-level laser therapy on keratinocytes in vitro

Epithelial cells play an important role in reparative events. Therefore, therapies that can stimulate the proliferation and metabolism of these cells could accelerate the healing process. To evaluate the effects of low-level laser therapy (LLLT), human keratinocytes were irradiated with an InGaAsP diode laser prototype (LASERTable; 780?±?3 nm; 40 mW) using 0.5, 1.5, 3, 5, and 7 J/cm² energy doses. Irradiations were done every 24 h totaling three applications. Evaluation of cell metabolism (MTT assay) showed that LLLT with all energy doses promoted an increase of cell metabolism, being more effective for 0.5, 1.5, and 3 J/cm². The highest cell counts (Trypan blue assay) were observed with 0.5, 3, and 5 J/cm². No statistically significant difference for total protein (TP) production was observed and cell morphology analysis by scanning electron microscopy revealed that LLLT did not promote morphological alterations on the keratinocytes. Real-time polymerase chain reaction (qPCR) revealed that LLLT also promoted an increase of type I collagen (Col-I) and vascular endothelial growth factor (VEGF) gene expression, especially for 1.5 J/cm², but no change on fibroblast growth factor-2 (FGF-2) expression was observed. LLLT at energy doses ranging from 0.5 to 3 J/cm² promoted the most significant biostimulatory effects on cultured keratinocytes.     

Synthesis of dental matrix proteins and viability of odontoblast-like cells irradiated with blue LED

To evaluate the effect of irradiation with light-emitting diode (LED; 455 nm) on the viability and synthesis of dentin matrix proteins by odontoblast-like cells, MDPC-23 cells were cultivated (10⁴ cells/cm²) in 24-well culture plates. After 12 h incubation in Dulbecco’s modified Eagle’s medium (DMEM), the cells were submitted to nutritional restriction by means of reducing the concentration of fetal bovine serum (FBS) for an additional 12 h. Cells were irradiated one single time with one of the following energy densities (EDs): 0.5, 2, 4, 10, or 15 J/cm² and irradiance fixed at 20 mW/cm². Non-irradiated cells served as control. After 72 h, cells were evaluated with regard to viability (methylthiazol tetrazolium technique (MTT)), mineralization nodule (MN) formation, total protein (TP) production, alkaline phosphatase activity (ALP), and collagen synthesis (Sircol), n?=?8. The data were submitted to Kruskal–Wallis and Mann–Whitney tests (p?>?0.05). There was no statistical difference between the viability of cells irradiated or not (control), for all the EDs. However, an increase in TP was observed for all the EDs when compared with the control group. A reduced ALP activity was seen in all irradiated groups, except for the ED of 0.5 J/cm², which did not differ from the control. There was no difference between the irradiated groups and control regarding collagen synthesis, with the exception of the ED of 10 J/cm², which inhibited this cell function. Significant reduction in MN occurred only for the EDs of 0.5 and 2 J/cm². The single irradiation with blue LED (455 nm), irradiance of 20 mW/cm², and energy densities ranging from 0.5 to 15 J/cm² exerted no effective biostimulatory capacity on odontoblast-like cells.     

808-nm laser therapy with a flat-top handpiece photobiomodulates mitochondria activities of <Emphasis Type="Italic">Paramecium primaurelia</Emphasis> (Protozoa)

Photobiomodulation is proposed as a non-linear process, and only low-level laser therapy (LLLT) is assumed to stimulate exposed cells, whereas high powered laser and fluences can cause negative effects, exhausting the cell’s energy reserve as a consequence of excessive photon-based stimulation. In our work, we investigated and compared the effects of 808-nm diode laser (CW) with a new flat-top handpiece. To this purpose, we tested the photobiomodulation effects of 1 and 3 J/cm² fluence, both generated by 100 mW or 1 W of laser power and of 64 J/cm² of fluence generated by 100 mW, 1 W, 1.5 W or 2 W, as expressed through oxygen consumption and ATP synthesis of Paramecium. Data collected indicates the incremental consumption of oxygen through irradiation with 3 J/cm²–100 mW or 64 J/cm²–1 W correlates with an increase in Paramecium ATP synthesis. The Paramecium respiration was inhibited by fluences 64 J/cm²–100 mW or 64 J/cm²–2 W and was followed by a decrease in the endogenous ATP concentration. The 1 J/cm²–100 mW or 1 W and 3 J/cm²–1 W did not affect mitochondrial activity. The results show that the fluence of 64 J/cm²–1 W more than the 3 J/cm²–100 mW causes greater efficiency in Paramecium mitochondria respiratory chain activity. Our results suggest that thanks to flat-top handpiece we used, high fluences by high-powered laser have to be reconsidered as an effective and non-invasive therapy. Possible associated benefits of deeper tissue penetration would increase treatment effectiveness and reduced irradiation time.     

Effects of high-frequency near-infrared diode laser irradiation on the proliferation and migration of mouse calvarial osteoblasts

Laser irradiation activates a range of cellular processes and can promote tissue repair. Here, we examined the effects of high-frequency near-infrared (NIR) diode laser irradiation on the proliferation and migration of mouse calvarial osteoblastic cells (MC3T3-E1). MC3T3-E1 cells were cultured and exposed to high-frequency (30 kHz) 910-nm diode laser irradiation at a dose of 0, 1.42, 2.85, 5.7, or 17.1 J/cm². Cell proliferation was evaluated with BrdU and ATP concentration assays. Cell migration was analyzed by quantitative assessment of wound healing using the Incucyt^® ZOOM system. In addition, phosphorylation of mitogen-activated protein kinase (MAPK) family members including p38 mitogen-activated protein kinase (p38), stress-activated protein kinase/Jun-amino-terminal kinase (SAPK/JNK), and extracellular signal-regulated protein kinase (ERK)1/2) after laser irradiation was examined with western blotting. Compared to the control, cell proliferation was significantly increased by laser irradiation at a dose of 2.85, 5.7, or 17.1 J/cm². Laser irradiation at a dose of 2.85 J/cm² induced MC3T3-E1 cells to migrate more rapidly than non-irradiated control cells. Irradiation with the high-frequency 910-nm diode laser at a dose of 2.85 J/cm² induced phosphorylation of MAPK/ERK1/2 15 and 30 min later. However, phosphorylation of p38 MAPK and SAPK/JNK was not changed by NIR diode laser irradiation at a dose of 2.85 J/cm². Irradiation with a high-frequency NIR diode laser increased cell division and migration of MT3T3-E1 cells, possibly via MAPK/ERK signaling. These observations may be important for enhancing proliferation and migration of osteoblasts to improve regeneration of bone tissues.     

Combined effects of low-level laser therapy and human bone marrow mesenchymal stem cell conditioned medium on viability of human dermal fibroblasts cultured in a high-glucose medium

Low-level laser therapy (LLLT) exhibited biostimulatory effects on fibroblasts viability. Secretomes can be administered to culture mediums by using bone marrow mesenchymal stem cells conditioned medium (BM-MSCs CM). This study investigated the combined effects of LLLT and human bone marrow mesenchymal stem cell conditioned medium (hBM-MSCs CM) on the cellular viability of human dermal fibroblasts (HDFs), which was cultured in a high-glucose (HG) concentration medium. The HDFs were cultured either in a concentration of physiologic (normal) glucose (NG; 5.5 mM/l) or in HG media (15 mM/l) for 4 days. LLLT was performed with a continuous-wave helium-neon laser (632.8 nm, power density of 0.00185 W/cm² and energy densities of 0.5, 1, and 2 J/cm²). About 10 % of hBM-MSCs CM was added to the HG HDF culture medium. The viability of HDFs was evaluated using dimethylthiazol-diphenyltetrazolium bromide (MTT) assay. A significantly higher cell viability was observed when laser of either 0.5 or 1 J/cm² was used to treat HG HDFs, compared to the control groups. The cellular viability of HG-treated HDFs was significantly lower compared to the LLLT?+?HG HDFs, hBM-MSCs CM-treated HG HDFs, and LLLT?+?hBM-MSCs CM-treated HG HDFs. In conclusion, hBM-MSCs CM or LLLT alone increased the survival of HG HDFs cells. However, the combination of hBM-MSCs CM and LLLT improved these results in comparison to the conditioned medium.     

Low-level laser therapy promotes proliferation and invasion of oral squamous cell carcinoma cells

Low-level laser therapy (LLLT) has been shown to be effective in promoting cell proliferation. There is speculation that the biostimulatory effect of LLLT causes undesirable enhancement of tumor growth in neoplastic diseases since malignant cells are more susceptible to proliferative stimuli. This study evaluated the effects of LLLT on proliferation, invasion, and expression of cyclin D1, E-cadherin, β-catenin, and MMP-9 in a tongue squamous carcinoma cell line (SCC25). Cells were irradiated with a diode laser (660 nm) using two energy densities (0.5 and 1.0 J/cm²). The proliferative potential was assessed by cell growth curves and cell cycle analysis, whereas the invasion of cells was evaluated using a Matrigel cell invasion assay. Expression of cyclin D1, E-cadherin, β-catenin, and MMP-9 was analyzed by immunofluorescence and flow cytometry and associated with the biological activities studied. LLLT induced significantly the proliferation of SCC25 cells at 1.0 J/cm², which was accomplished by an increase in the expression of cyclin D1 and nuclear β-catenin. At 1.0 J/cm², LLLT significantly reduced E-cadherin and induced MMP-9 expression, promoting SCC25 invasion. The results of this study demonstrated that LLLT exerts a stimulatory effect on proliferation and invasion of SCC25 cells, which was associated with alterations on expression of proteins studied.     

Mesenchymal stromal cell and osteoblast responses to oxidized titanium surfaces pre-treated with <Emphasis Type="Italic">λ</Emphasis> = 808 nm GaAlAs diode laser or chlorhexidine: in vitro study

Preservation of implant biocompatibility following peri-implantitis treatments is a crucial issue in odontostomatological practice, being closely linked to implant re-osseointegration. Our aim was to assess the responses of osteoblast-like Saos2 cells and adult human bone marrow-mesenchymal stromal cells (MSCs) to oxidized titanium surfaces (TiUnite^®, TiU) pre-treated with a 808 ± 10 nm GaAlAs diode laser operating in non-contact mode, in continuous (2 W, 400 J/cm²; CW) or pulsed (20 kHz, 7 μs, 0.44 W, 88 J/cm²; PW) wave, previously demonstrated to have a strong bactericidal effect and proposed as optional treatment for peri-implantitis. The biocompatibility of TiU surfaces pre-treated with chlorhexidine digluconate (CHX) was also evaluated. In particular, in order to mimic the in vivo approach, TiU surfaces were pre-treated with CHX (0.2%, 5 min); CHX and rinse; and CHX, rinse and air drying. In some experiments, the cells were cultured on untreated TiU before being exposed to CHX. Cell viability (MTS assay), proliferation (EdU incorporation assay; Ki67 confocal immunofluorescence analysis), adhesion (morphological analysis of actin cytoskeleton organization), and osteogenic differentiation (osteopontin confocal immunofluorescence analysis; mineralized bone-like nodule formation) analyses were performed. CHX resulted cytotoxic in all experimental conditions. Diode laser irradiation preserved TiU surface biocompatibility. Notably, laser treatment appeared even to improve the known osteoconductive properties of TiU surfaces. Within the limitations of an in vitro experimentation, this study contributes to provide additional experimental basis to support the potential use of 808 ± 10 nm GaAlAs diode laser at the indicated irradiation setting, in the treatment of peri-implantitis and to discourage the use of CHX.     

Impact of low-level laser therapy on hyposalivation,salivary pH,and quality of life in head and neck cancer patients post-radiotherapy

Late effects of radiotherapy for head and neck cancer treatment have been increasingly investigated due to its impact on patients’ quality of life. The purpose of this study was to evaluate the effect of low-level laser therapy on hyposalivation, low salivary pH, and quality of life in head and neck cancer patients post-radiotherapy. Twenty-nine patients with radiation-induced xerostomia received laser sessions twice a week, during 3 months (24 sessions). For this, a continuous wave Indium-Gallium-Aluminium-Phosphorus diode laser device was used punctually on the major salivary glands (808 nm, 0.75 W/cm², 30 mW, illuminated area 0.04 cm², 7.5 J/cm², 10 s, 0.3 J). Six extraoral points were illuminated on each parotid gland and three on each submandibular gland, as well as two intraoral points on each sublingual gland. Stimulated and unstimulated salivary flow rate, pH (two scales with different gradations), and quality of life (University Of Washington Quality of Life Questionnaire for Patients with Head and Neck Cancer) were assessed at baseline and at the end of the treatment. There were significant increases in both mean salivary flow rates (unstimulated: p?=?0.0012; stimulated: p?<?0.0001), mean pH values (p?=?0.0002 and p?=?0.0004), and mean score from the quality of life questionnaire (p?<?0.0001). Low-level laser therapy seems to be effective to mitigate salivary hypofunction and increase salivary pH of patients submitted to radiotherapy for head and neck cancer, thereby leading to an improvement in quality of life.     

The effects of diode laser on <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> biofilm and <Emphasis Type="Italic">Escherichia coli</Emphasis> lipopolysaccharide adherent to titanium oxide surface of dental implants. An in vitro study

Effective decontamination of biofilm and bacterial toxins from the surface of dental implants is a yet unresolved issue. This in vitro study aims at providing the experimental basis for possible use of diode laser (λ 808 nm) in the treatment of peri-implantitis. Staphylococcus aureus biofilm was grown for 48 h on titanium discs with porous surface corresponding to the bone-implant interface and then irradiated with a diode laser (λ 808 nm) in noncontact mode with airflow cooling for 1 min using a Ø 600-μm fiber. Setting parameters were 2 W (400 J/cm²) for continuous wave mode; 22 μJ, 20 kHz, 7 μs (88 J/cm²) for pulsed wave mode. Bactericidal effect was evaluated using fluorescence microscopy and counting the residual colony-forming units. Biofilm and titanium surface morphology were analyzed by scanning electron microscopy (SEM). In parallel experiments, the titanium discs were coated with Escherichia coli lipopolysaccharide (LPS), laser-irradiated and seeded with RAW 264.7 macrophages to quantify LPS-driven inflammatory cell activation by measuring the enhanced generation of nitric oxide (NO). Diode laser irradiation in both continuous and pulsed modes induced a statistically significant reduction of viable bacteria and nitrite levels. These results indicate that in addition to its bactericidal effect laser irradiation can also inhibit LPS-induced macrophage activation and thus blunt the inflammatory response. The λ 808-nm diode laser emerges as a valuable tool for decontamination/detoxification of the titanium implant surface and may be used in the treatment of peri-implantitis.     

Effect of low-level laser irradiation and epidermal growth factor on adult human adipose-derived stem cells

The study investigated the effects of low-level laser radiation and epidermal growth factor (EGF) on adult adipose-derived stem cells (ADSCs) isolated from human adipose tissue. Isolated cells were cultured to semi-confluence, and the monolayers of ADSCs were exposed to low-level laser at 5 J/cm² using 636 nm diode laser. Cell viability and proliferation were monitored using adenosine triphosphate (ATP) luminescence and optical density at 0 h, 24 h and 48 h after irradiation. Application of low-level laser irradiation at 5 J/cm² on human ADSCs cultured with EGF increased the viability and proliferation of these cells. The results indicate that low-level laser irradiation in combination with EGF enhances the proliferation and maintenance of ADSCs in vitro.     

Effects of low-level laser irradiation on human blood lymphocytes in vitro

Low-level laser irradiation (LLLI) has various effects on cultured human lymphocytes in vitro, but little is known about such effects in whole blood. This study investigated whether LLLI affected lymphocyte count in human whole blood in vitro. A total number of 130 blood samples were collected from apparently healthy adult patients through venipuncture into tubes containing EDTA. Each sample was divided into two equal aliquots to be used as a non-irradiated control sample and an irradiated sample. The irradiated aliquot was subjected to laser wavelengths of 405, 589, and 780 nm with different fluences of 36, 54, 72, and 90 J/cm², at a fixed irradiance of 30 mW/cm². A paired student t test was used to compare between non-irradiated and irradiated samples. The lymphocyte counts were measured using a computerized hematology analyzer and showed a significant (P?<?0.02) maximum increase (1.6%) at a fluence of 72 J/cm² when compared with non-irradiated samples. This increase in lymphocyte count upon irradiation was confirmed by flow cytometry. At a wavelength of 589 nm and fluence of 72 J/cm², irradiation of whole blood samples showed a significant increase in CD45 lymphocytes and natural killer (NK) (CD16, CD56) cells, but no significant changes in CD3 T lymphocytes, T-suppressor (CD3, CD8) cells, T-helper (CD3, CD4) cells, and CD19 B lymphocytes when compared with their non-irradiated counterparts. Our results clearly demonstrate that NK cell count is altered by irradiation, which ultimately affects the whole lymphocyte count significantly.     

Effect of the laser and light-emitting diode (LED) phototherapy on midpalatal suture bone formation after rapid maxilla expansion: a Raman spectroscopy analysis

The aim of this study was to analyze the effect of laser or light-emitting diode (LED) phototherapy on the bone formation at the midpalatal suture after rapid maxilla expansion. Twenty young adult male rats were divided into four groups with 8 days of experimental time: group 1, no treatment; group 2, expansion; group 3, expansion and laser irradiation; and group 4, expansion and LED irradiation. In groups 3 and 4, light irradiation was in the first, third, and fifth experimental days. In all groups, the expansion was accomplished with a helicoid 0.020″ stainless steel orthodontic spring. A diode laser (λ780 nm, 70 mW, spot of 0.04 cm², t?=?257 s, spatial average energy fluence (SAEF) of 18 J/cm²) or a LED (λ850 nm, 150 mW?±?10 mW, spot of 0.5 cm², t?=?120 s, SAEF of 18 J/cm²) were used. The samples were analyzed by Raman spectroscopy carried out at midpalatal suture and at the cortical area close to the suture. Two Raman shifts were analyzed: ～960 (phosphate hydroxyapatite) and ～1,450 cm^?1 (lipids and protein). Data was submitted to statistical analysis. Significant statistical difference (p?≤?0.05) was found in the hydroxyapatite (CHA) peaks among the expansion group and the expansion and laser or LED groups. The LED group presented higher mean peak values of CHA. No statistical differences were found between the treated groups as for collagen deposition, although LED also presented higher mean peak values. The results of this study using Raman spectral analysis indicate that laser and LED light irradiation improves deposition of CHA in the midpalatal suture after orthopedic expansion.     

Effects of different treatments on chemical and morphological features of eroded dentin

To evaluate the treatment of eroded dentin (Sensodyne Repair & Protect?, Er:YAG laser and combinations). The occlusal surfaces of 25 third molars were sectioned 1.5 mm in thickness. After an erosion cycle (5 min in demineralizing solution + 3 h in remineralizing solution; six cycles a day for 8 days), the samples were divided into five groups (n?=?5): (E) erosion ? control; (ES) erosion + Sensodyne Repair & Protect (NovaMin); (EL) erosion + Er:YAG laser (40 mJ, 10 Hz, 0.4 W, 50 μs, 3.1 J/cm², 63 W/cm²); (ELS) erosion + Er:YAG laser + Sensodyne; and (ESL) erosion + Sensodyne + Er:YAG laser. Following storage in ultrapure water (37 °C/14 days), the Ca/P ratio was evaluated by EDXRF and the morphology surfaces examined in SEM. The percentage of exposed dentin tubules was calculated. One-way analysis of variance and Tukey’s test at 5% were used to treat the data. The Ca/P ratio was higher in E and ES groups. More exposed dentin tubules were found in E group and less exposed tubules were found in the ES group (p?<?0.0001). When the toothpaste and laser were combined, the number of occluded dentin tubules was higher when laser was performed first (ELS). A positive effect was found when the laser and toothpaste were combined.     

Influence of Er,Cr:YSGG laser irradiation on enamel caries prevention

The objective of this study was to evaluate the effects of chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser irradiation on the acid resistance of dental enamel. Forty human enamel samples were divided into four groups. They were manually irradiated with an Er,Cr:YSGG laser device (λ?=?2.78 µm, 20 Hz, 20 s), in a scanning mode, with and without water cooling, according to the following parameters: Group 1: 0.25 W, 62.5 J/cm², no water cooling; group 2: 0.25 W, 62.5 J/cm², 5.0 ml/min; group 3: 0.5 W, 125 J/cm², no water cooling; group 4: 0.5 W, 125 J/cm², 5.0 ml/min. No airflow was used. Afterwards, the samples were submitted to an acid challenge and assessed by cross-sectional Knoop microhardness at different depths (20, 40, 60, 80, and 100 µm) from the outer enamel surface. Average values were obtained for both irradiated and control areas in each sample and they were compared to obtain a percentage of microhardness increase. Data were analyzed by analysis of variance and Fisher’s exact test (α?=?5%). The percentage of microhardness increase observed in group 1 (+23.58%) was similar to group 3 (+19.12%), but higher than groups 2 (+3.61%) and 4 (10.9%) (p?<?0.05). The comparison of the depths showed that the Er,Cr:YSGG laser acted in the superficial layers of the dental enamel. The findings of the present study suggest that the energy densities of 62.5 and 125 J/cm² were capable of increasing the acid resistance of human enamel. The presence of water during irradiation makes it difficult to obtain an enamel surface more resistant to acids.     

Methylene blue mediated photobiomodulation on human osteoblast cells

Photobiomodulation (PBM) and photodynamic therapy (PDT) are two major methods, which use light in medicine and dentistry. PBM uses low-level laser light to induce cell proliferation and activity. In contrast, PDT use laser light combined with a photosensitizer (PS) to cause cell death. Due to similar, not fully understood mechanisms and biphasic response of light, unexpected and complex outcomes may be observed. In the present study, the effect of 635 nm laser light, with power density 50 mW/cm², at three different energy densities (0.5, 1, and 2 J/cm² which last 10, 20, and 40 s, respectively) mediated by methylene blue (MB) on the human osteoblast cell line (ATCC-CRL-11372, Rockville, MD, USA) was investigated. Cell viability (MTT assay and acridine orange/propidium iodide staining) and proliferation (Alamar Blue assay) were assessed at 24, 48, and 72 h post irradiation. Alkaline phosphatase (ALP) activity, mineralization (Alizarin Red staining) and gene expressions (RT-PCR analysis) were analyzed at 7th and 14th days after treatment. Five groups were formed as the control group (no MB, no irradiation), MB (only 0.05 μM MB), MB + 0.5 J/cm², MB + 1 J/cm², and MB + 2 J/cm². Cell viability was decreased at 72 h (ANOVA; p < 0.05) for MB + 0.5 J/cm², MB + 1 J/cm², and MB + 2 J/cm² groups. Although proliferation does not seem to be effected by MB-mediated laser application, osteo-anabolic activity is altered. ALP activity was significantly increased at day 7 (ANOVA; p < 0.05) for MB-combined laser groups; on the other hand, mineralization was significantly decreased (ANOVA; p < 0.05) in all treatment groups. Alkaline phosphatase and collagen-I expressions were upregulated in MB + 2 J/cm² group at 7th and 14th days, respectively. These results may contribute to the low-dose PDT researches and understanding PBM effects on osteoblast behavior but further studies are needed since inappropriate conditions may lead to undesirable results for both therapies.