Cytotoxicity, biocompatibility and osteoinductive profile of an MTA-hydrogel-based cement: An in vitro and animal study.

AIM: This study aimed to evaluate the cytotoxicity, biocompatibility and osteoinductive profile of a mineral trioxide aggregate (MTA)-hydrogel-based material (MTA Flow) in comparison with MTA Angelus. METHODOLOGY: Cell viability was evaluated in human periodontal ligament stem cells (hPDLSCs) using the methyl-thiazol-tetrazolium (MTT) colourimetric assay. Polyethylene tubes containing the tested materials and empty polyethylene tubes (control) were implanted in the subcutaneous tissue of Wistar rats. Cellular (lymphocyte infiltration) and extracellular events (ECM; collagen fibres) were analysed in histological sections. Immunohistochemical (collagen I, osteopontin, bone sialoprotein, bone morphogenetic protein4) analyses were also performed. RESULTS: At 24, 48 and 72 h, all tested groups showed cell viability similar to control (p > .05). Regarding biocompatibility, all groups showed similar cellular events represented by a slight inflammatory reaction characterized by hyperaemia and a mild lymphocytic inflammatory infiltrate. The analysis of lymphocytes during the time showed a decrease in these cells in the control group and a significant interaction between MTA Angelus and control (p < .001), with MTA Angelus showing a more extensive inflammatory infiltrate. Regarding fibres, an increase in content was observed in all groups during the experimental time (7, 30 and 60 days), however, no difference was detected among the experimental groups (p = .063). After 60 days, the immunoexpression of bone matrix proteins in the MTA Flow group was similar to or higher than that observed in the MTA Angelus and in the control group. CONCLUSIONS: MTA Flow showed a non-cytotoxic behaviour, biocompatibility and ability to stimulate tissue mineralization.

Antibacterial effect, cytotoxicity, and bond strength of a modified dental adhesive containing silver nanoparticles.

This study aimed to evaluate the antibacterial effect, cytotoxicity, and microtensile bond strength of an adhesive system containing silver nanoparticles (NAg). NAg was synthesized and incorporated (500 and 1000 ppm) into Scotchbond Multi-Purpose (SBMP) primer and bond. A microtensile bond test (µTBS) was performed after 24 h and 1 year. The adhesive interface was characterized using a confocal Raman microscope. The antibacterial activity was assessed using agar diffusion and biofilm inhibition assays (S. mutans). MTT assay was used to assess the cytotoxicity of NAg-conditioned culture media on human dental pulp stem cells (hDPSCs). The results were statistically analyzed using analysis of variance and Tukey's tests (α = .01). Incorporating 500 and 1000 ppm of NAg in the SBMP did not affect the µTBS after 24 h (p > 0.05). However, in the 1 year evaluation, 500 ppm presented the highest µTBS values (p < 0.05). The addition of NAg at 500 and 1000 ppm in the primer and bond led to larger inhibition halos and colony-forming units than the control (p < 0.05). For the unpolymerized and polymerized groups, the combination of primer and bond presented the highest cytotoxic effects on hDPSCs (p < 0.05). In conclusion, incorporating 500 or 1000 ppm of NAg into an etch-and-rinse adhesive system led to an antibacterial effect without altering the cytotoxicity. SBMP at 500 ppm presented a higher µTBS at 1 year.

Photobiomodulation as an adjunctive therapy for alveolar socket preservation: a preliminary study in humans.

Bone remodeling results in loss of alveolar bone height and thickness. Photobiomodulation (PBM) based on photochemical stimulation by low-intensity lasers emerges as an adjunctive therapy for alveolar socket preservation. Our study aimed to evaluate the effects of PBM therapy on alveolar bone repair. Twenty healthy patients in need of bilateral extraction of lower molars were enrolled in this split-mouth randomized and blind clinical trial. The extraction sites were randomly selected to receive either the PBM therapy with a CW GaAIAs diode laser (808 nm; 0.028 mm2; 0.1 W; 3.6 W/cm2; 89 J/cm2; 2.5 J/point) or no treatment (Control). Bone biopsies were harvested 45 days after the dental extraction and evaluated using micro-computerized tomography (µCT), morphometric, and histological analysis. Data were compared using the paired t test, and the level of significance was set at 5%. Bone surface (p = 0.029), bone surface/total volume (p = 0.028), trabecular number (p = 0.025), and connectivity density (p = 0.029) were higher at the PBM group compared with Control. The histological observations confirmed the µCT findings. PBM samples exhibited higher number of organized and connected bone trabeculae along with higher density of blood vessels than Control. Control samples displayed a dense and highly cellular connective tissue at the central area accompanied by the presence of immature bone trabeculae at the periphery. Our results indicated that the PBM therapy improved the newly bone trabeculae formation and their connectivity which increased bone surface, indicating the positive effect of the laser on alveolar human socket repair.

Short-term evaluation of photobiomodulation therapy on the proliferation and undifferentiated status of dental pulp stem cells.

The aim of this in vitro study was to analyze the effect of photobiomodulation therapy (PBMT) on the proliferation and undifferentiating status of stem cell from human exfoliated deciduous teeth (SHEDs). PBMT was carried out with an aluminum gallium indium phosphide (InGaAlP) diode laser in contact and punctual mode (continuous wave, 660 nm, 20 mW, 0.028 cm2, and average energy densities of 1 (1 s), 3 (4 s), 5 (7 s), 10 (14 s), 15 (21 s), or 20 (28 s) J/cm2 per point). The immunoprofile of the SHEDs was analyzed using flow cytometry. Cell proliferation was assessed by the MTT reduction assay. Gene expressions of mesenchymal stem cell markers (OCT4, Nestin, CD90, and CD105) were assessed by RT-qPCR 48 h after PBMT. Data were compared by analysis of variance (ANOVA) and Tukey's test (p ≤ 0.05). Cells cultured under nutritional deficit and treated with PBMT at 5 J/cm2 presented similar cell growth than those of positive control group. Cell growth was significantly higher than those of other groups. Mesenchymal stem cell gene markers were still expressed after PBMT at 5 J/cm2. In a short-term analysis, PBMT increases the number of stem cells with no interference in the undifferentiated state of the irradiated cells, which opens wide possibilities for application in tissue regeneration.

Cell sheets of human dental pulp stem cells for future application in bone replacement.

OBJECTIVES: To analyze the potential of human dental pulp stem cells (hDPSCs) for maintaining their undifferentiated status and osteogenic differentiation capacity when arranged in cell sheets (CSs) for future application in bone replacement. MATERIALS AND METHODS: CSs were formed after being induced for 10-15 days by clonogenic medium containing additional vitamin C (20 µg/ml). The cell viability of hDPSC4s in the CSs was followed until 96 h using the Live/Dead® assay. The cells of the CSs were enzymatically dissociated and then compared with the original hDPSC4s. The two cell types were characterized immunophenotypically by flow cytometry using specific mesenchymal stem cell-associated markers (CD105, CD146, CD44, STRO-1, and OCT3/4) and non-associated markers (CD34, CD45, and CD14). Osteogenic differentiation was analyzed with the Alizarin red assay. RESULTS: Living cells were observed until 96 h in the CSs. Both cell types exhibited osteogenic differentiation and expressed the specific undifferentiated MSC-associated markers. Cells spontaneously detached from the CSs attached and proliferated at the bottom of the culture dishes. CONCLUSIONS: Cells in the hDPSC4s cell sheets survived for at least 96 h. Moreover, the cells in the cell sheets retained their stemness and their osteogenic differentiation potential. CLINICAL RELEVANCE: Cell sheets of hDPSCs could be employed as natural tri-dimensional structures for treating bone loss. This technique would be useful particularly for critical bone defects or any type of bone defects in patients carrying diseases that impair bone regeneration, such as diabetes mellitus, medication-related osteonecrosis of the jaw (MRONJ), and osteoporosis.

Relationship between toothpastes properties and patient-reported discomfort: crossover study.

OBJECTIVES: This study aims to correlate patient-reported reactions with in vitro analyses of the pH, abrasive quality, and cytotoxicity of four toothpastes. MATERIALS AND METHODS: One hundred twenty-one patients received non-identified samples of toothpaste to be used for 6 days and answered a questionnaire about their sensations. In vitro analysis: the pH of toothpastes was measured with a pH meter. The abrasivity of toothpastes was evaluated against composite resin specimens (n = 10). A toothbrushing machine was used to simulate wear, which was indirectly measured by mass loss using a scale. Cell culture media conditioned with toothpaste were used to assess the cytotoxicity. Confluent cells were kept in contact with the conditioned media or control for 24 h. The cell viability was measured using the 3-(bromide, 4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium (MTT)-reduction assay. The obtained data on the pH, weight loss, and cell viability were compared by ANOVA/Tukey's tests (p < 0.05). RESULTS: With the exception of the bleaching effect paste, the Oral B® paste produced the highest frequencies of irritation reports, tooth sensitivity, taste discomfort, and texture discomfort in the clinical study; patients also reported rougher teeth, soft tissue peeling, dry mouth, thrush, tingling, and taste changes in response to this paste. The in vitro analysis demonstrated that Oral B® had the lowest pH, the highest abrasivity, and produced the lowest cell viability (p < 0.01). CONCLUSION: Results suggest that low pH toothpastes that are highly abrasive and cytotoxic may cause undesirable reactions in patients. CLINICAL RELEVANCE: Toothpaste's properties should be well known for indication to patient therefore minimizing discomfort reports.

Evaluation of pain, jaw movements, and psychosocial factors in elderly individuals with temporomandibular disorder under laser phototherapy.

Few studies have been carried out on the application of laser phototherapy (LPT) for treating painful temporomandibular disorder (TMD) in elderly population that is growing worldwide. The aim of the present study was to evaluate the pain, jaw movements, and psychosocial factors in ten elderly patients with painful TMD before and after LPT. All patients were evaluated before and after LPT by using the Research Diagnostic Criteria for temporomandibular disorders (RDC/TMD) axes I and II. For pain assessment, a visual analogue scale (VAS) was used. The LPT was carried out with an GaAlAs diode laser (780 nm; spot size 0.04 cm(2)) in punctual and contact mode. Two settings of irradiations were applied as follows: in patients presenting myofascial pain, 10 mW, 5 J/cm(2), 20 s, 0.2 J per application point; and in patients with joint TMD, 70 mW, 105 J/cm(2), 60 s on five points, 4.2 J per point. Two sessions of LPT were carried out per week over four consecutive weeks, in the total of eight sessions. Data was statistically analyzed (p < 0.05). Significant pain reduction was found in all patients. There were increase in maximum mouth opening without pain and reduction in muscle pain during right and left lateral excursion. A significant reduction in chronic pain severity (p = 0.02) and significant improvements in depression (p = 0.038) and nonspecific physical symptoms with pain (p = 0.0167) were observed. The present findings indicate that LPT is able to promote pain relief and improvement of jaw movements in elderly patients with TMD, with a positive effect on psychosocial aspects.

Influence of CO2 (10.6 µm) and Nd:YAG laser irradiation on the prevention of enamel caries around orthodontic brackets.

One possible undesirable consequence of orthodontic therapy is the development of incipient caries lesions of enamel around brackets. The aim of this study was to compare the effects of CO2 (λ = 10.6 µm) and Nd:YAG (λ = 1,064 nm) lasers associated or not with topical fluoride application on the prevention of caries lesions around brackets. Brackets were bonded to the enamel of 65 premolars. The experimental groups (n = 13) were: G1--application of 1.23% acidulated fluoride phosphate gel (AFP, control); G2--Nd:YAG laser irradiation (0.6 W, 84.9 J/cm(2), 10 Hz, 110 µs, contact mode); G3--Nd:YAG laser irradiation associated with AFP; G4--CO2 laser irradiation (0.5 W, 28.6 J/cm(2), 50 Hz, 5 µs, and 10 mm focal distance); and G5--CO2 laser irradiation associated with AFP. Quantitative light-induced fluorescence was used to assess enamel demineralization. The data were statistically compared (α = 5%). The highest demineralization occurred in the Nd:YAG laser group (G2, 26.15% ± 1.94). The demineralization of all other groups was similar to that of the control group. In conclusion, CO2 laser alone was able to control enamel demineralization around brackets at the same level as that obtained with topical fluoride application.

Laser phototherapy enhances mesenchymal stem cells survival in response to the dental adhesives.

BACKGROUND: We investigated the influence of laser phototherapy (LPT) on the survival of human mesenchymal stem cells (MSCs) submitted to substances leached from dental adhesives. METHOD: MSCs were isolated and characterized. Oral mucosa fibroblasts and osteoblast-like cells were used as comparative controls. Cultured medium conditioned with two adhesive systems was applied to the cultures. Cell monolayers were exposed or not to LPT. Laser irradiations were performed using a red laser (GaAlAs, 780 nm, 0.04 cm(2), 40 mW, 1 W/cm(2), 0.4 J, 10 seconds, 1 point, 10 J/cm(2)). After 24 h, cell viability was assessed by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide reduction assay. Data were statistically compared by ANOVA followed by Tukey's test (P < 0.05). RESULTS: Different cell types showed different viabilities in response to the same materials. Substances leached from adhesives were less cytotoxic to MSCs than to other cell types. Substances leached from Clearfil SE Bond were highly cytotoxic to all cell types tested, except to the MSCs when applied polymerized and in association with LPT. LPT was unable to significantly increase the cell viability of fibroblasts and osteoblast-like cells submitted to the dental adhesives. CONCLUSION: LPT enhances mesenchymal stem cells survival in response to substances leached from dental adhesives.

Role of rhBMP-2 and rhBMP-7 in the metabolism and differentiation of osteoblast-like cells cultured on chemically modified titanium surfaces.

This study analyzed the role of recombinant human bone morphogenetic protein 2 (rhBMP-2) and recombinant human bone morphogenetic protein 7 (rhBMP-7) in the adhesion and differentiation of rat osteoblast-like (osteo-1) cells cultured on chemically modified titanium surfaces. Osteo-1 cells were cultured on chemically modified (modified sandblasted and acid-etched) titanium surfaces in 3 different types of medium: control, medium supplemented with 20 ng/mL rhBMP-2, and medium supplemented with 20 ng/mL rhBMP-7. The following parameters were evaluated: cell adhesion after 24 hours; total protein content; collagen content and alkaline phosphatase (AP) activity after 7, 14, and 21 days; and calcified nodule formation after 21 days. The addition of rhBMP-2 or rhBMP-7 did not influence cell adhesion (P = .1175). Cell differentiation was influenced by rhBMP-2, as demonstrated by a significant increase in collagen content after 7 days of culture (P < .0001) and a significant decrease in AP activity after 21 days (P < .0001). The addition of rhBMP-7 only influenced AP activity, and a significant increase was observed after 21 days (P < .0001). Within the limitations of the study, we conclude that the presence of rhBMP-2 or rhBMP-7 did not influence cell adhesion to chemically modified titanium surfaces but provided an additional stimulus during the differentiation of rat osteo-1 cells cultured on this type of surface.

New uses for rehabilitation protocol for oral sinus communications in ARONJ patients.

This report presents a new use for rehabilitation protocol for oral sinus communications in patients with antiresorptive agent-induced osteonecrosis of the jaw. The treatment plan consisted of constructing an atraumatic complete denture with rounded edges, made with nontoxic resin, to prevent any injury to the mucosa and recurrence of the disease. The patient was followed up for 4 years, without any complications, and was socially reintegrated by resuming the normal life he experienced before tooth loss.

Osteoradionecrosis in a Torus Mandibularis Treated by Antimicrobial Photodynamic Therapy: A Case Report.

Background: Osteoradionecrosis (ORN) of the jaws is a late complication after radiotherapy to head and neck cancer. Objective: To describe a rare case of ORN of the torus mandibularis that was successfully managed exclusively with antimicrobial photodynamic therapy (aPDT). Case report: A 72-year-old man presented an exposed necrotic bone observed in the torus mandibularis, extending to the lingual alveolar ridge with no edema nor suppuration. The treatment provided a noninvasive treatment leading to spontaneous sequestrectomy of the torus in 2 weeks with complete mucosal repair in 5 weeks and absence of lesion signs and/or symptoms even after 6 months of follow-up. Conclusions: The aPDT indicated to be a satisfactory treatment for ORN affecting torus mandibularis, a region with surgical limitations, avoiding surgery.

Tricalcium phosphate-loaded injectable hydrogel as a promising osteogenic and bactericidal teicoplanin-delivery system for osteomyelitis treatment: An in vitro and in vivo investigation.

Osteomyelitis is an inflammation of bone tissue usually caused by pyogenic bacteria. The most recurrent clinical approach consists of bone debridement followed by parenteral administration of antibiotics. However, systemic antibiotic treatment has limitations regarding absorption rate and bioavailability over time. The main challenge of osteomyelitis treatment consists of coupling the persistent infection treatment with the regeneration of the bone debrided. In this work, we developed an injectable drug delivery system based on poloxamer 407 hydrogel containing undoped Mg, Zn-doped tricalcium phosphate (ß-TCP), and teicoplanin, a broad-spectrum antibiotic. We evaluated how the addition of teicoplanin and ß-TCP affected the micellization, gelation, particle size, and surface charge of the hydrogel. Later, we studied the hydrogel degradation and drug delivery kinetics. Finally, the bactericidal, biocompatibility, and osteogenic properties were evaluated through in vitro studies and confirmed by in vivo Wistar rat models. Teicoplanin was found to be encapsulated in the corona portions of the hydrogel micelles, yielding a bigger hydrodynamics radius. The encapsulated teicoplanin showed a sustained release over the evaluated period, enough to trigger antibacterial properties against Gram-positive bacteria. Besides, the formulations were biocompatible and showed bone healing ability and osteogenic properties. Finally, in vivo studies confirmed that the proposed locally injected formulations yielded osteomyelitis treatment with superior outcomes than parenteral administration while promoting bone regeneration. In conclusion, the presented formulations are promising drug delivery systems for osteomyelitis treatment and deserve further technological improvements.

Tooth bleaching induces changes in the vascular permeability of rat incisor pulps.

PURPOSE: To evaluate the inflammatory response in dental pulps of rat incisors subjected to tooth bleaching protocols with different HP concentrations and application times. METHODS: 42 incisors from Wistar rats were submitted to tooth bleaching using concentrations of 25% or 35% HP for treatment times of 15, 30 or 45 minutes. Four non-bleached teeth were used as controls. The animals received an intravenous injection of India ink immediately after the bleaching procedure and were sacrificed 1 hour later. Six bleached teeth from each group and three controls were made transparent, and one sample from each group was processed for histological analysis. The data were statistically analyzed using Kruskal Wallis and Dunn's tests (P < 0.05). RESULTS: The amount of dental pulp ink content was significantly higher in the samples that were bleached with 35% HP for 30 minutes and with both HP concentrations (25 and 35%) for 45 minutes than in the controls. For the samples bleached with the same HP concentration, the ink content was higher in samples that were bleached for 45 minutes. These results indicate that HP tooth bleaching can induce an increase in vascular permeability in rat incisors. Importantly, this increase is more dependent on the length of the bleaching procedure than on the concentration of the bleaching agent.

Bactericidal effects of two parameters of Er:YAG laser intracanal irradiation: ex-vivo study.

The success of endodontic treatment depends on the complete elimination of microorganisms from the root canal system, thus the search for new procedures to eliminate them is justified. The aim of this study was to assess bacterial reduction after intracanal irradiation with the Er:YAG laser. The canals of 70 extracted human maxillary canines were prepared up to file #40 using 1% NaOCl, irrigated with 17% EDTA, and then washed with physiological solution activated by ultrasound. The roots were sterilized by autoclaving, inoculated with 10 µl of a suspension containing 1.5 × 10(8) CFU/ml of Enterococcus faecalis ATCC 29212 and incubated at 37°C for 72 h. The canals were irradiated with the Er:YAG laser using two energy settings: 60 mJ and 15 Hz, and 100 mJ and 10 Hz. The remaining bacteria were counted immediately and 48 h after laser irradiation. The results showed a high bacterial reduction at both time points. With 60 mJ and 15 Hz there was an immediate reduction of 99.73% and the reduction was 77.02% after 48 h, and with 100 mJ and 10 Hz there was an immediate reduction of 99.95% and the reduction was 84.52% after 48 h. Although the best results were observed with 100 mJ of energy, the difference between the two settings was not statistically significant. The count performed 48 h after irradiation showed that E. faecalis were able to survive, and can grow even from small numbers.

Cytotoxicity evaluation of Curcuma zedoaria (Christm.) Roscoe fluid extract used in oral hygiene products.

OBJECTIVE: This in vitro study evaluated the cytotoxic effects of the Curcuma zedoaria (Christm.) Roscoe (popular name: zedoary) fluid extract, as used in preparations for oral hygiene, mostly for anti-septic purposes. MATERIALS AND METHODS: The cell viability and cell growth were assessed by Trypan blue dye exclusion assay using the LMF cell line derived from oral mucosa. Cell viability (short-term assay) was measured 0, 6, 12 and 24 h after contact with the fluid extract. Cell growth (long-term assay) was analyzed in 1, 3, 5 and 7 days. The experimental groups were those testing the fluid extract obtained from the zedoary rhizome and the extractor liquid (ethanol 70° GL) in the concentrations of 0.01-0.0001% v/v. Fresh DMEM were used in the control cultures. RESULTS: Short-term assay-all studied cultures maintained stable cell viability; Long-term assay-there was progressive cell growth in all studied cultures. CONCLUSION: According to the results, the zedoary fluid extract presents low cytotoxicity and probably can be used in the oral hygiene products.

A 58S bioactive glass for dentin hypersensitivity and erosive tooth wear: An in vitro study.

OBJECTIVES: To assess the effect of an experimental 58S bioactive glass on dentin permeability (dP) and erosive tooth wear (dentin surface loss - dSL). METHODS: 58S bioactive glass was synthetized using a sol-gel methodology, following by lyophilization and calcination, then mixed with phosphoric acid to obtain a paste (BGP). Forty-eight dentin disks (1 mm-thick) were used for dP, and 48 dentin slabs (3 mm × 3 mm) for dSL, which were assessed at three time intervals: post-EDTA (5 min in 17% EDTA solution); post-treatment (C: distilled water; BGP: experimental bioactive glass paste; NP: Nupro prophylaxis paste; CXT: Clinpro XT varnish); and post-erosive/abrasive cycling. Data were statistically analyzed (α=0.05). RESULTS: For dP and dSL, Groups did not differ significantly post-EDTA (p>0.05). Post-treatment, all groups showed lower dP than C (p<0.05), without differing significantly among them. For the dSL analysis, Groups C, BGP and NP did not differ significantly, showing lower values than CXT (p<0.05). Post-cycling, C continued to show the highest dP (p<0.05). Specimens from Group CXT had the lowest dP and did not differ from NP (p=0.86) which did not differ from BGP (p=0.193). For C and BGP, dP value was higher post-cycling than post-treatment (p<0.05). For NP and CXT, these experimental times did not differ (p>0.05). Post-cycling, dSL for C, BGP and NP did not differ significantly; values were higher than those for CXT (p<0.05). CONCLUSIONS: BGP reduced dP after application, with a reduced effect after cycling. Nonetheless, it was not able to protect dentin against erosive tooth wear. CLINICAL SIGNIFICANCE: Minimizing dentin hypersensitivity is a challenge in the field of dentistry. The development of alternative products with potential to obliterate dentinal tubules and provide resistance to chemical/mechanical stimuli is, thus, highly desirable. We have proposed a material able to reduce dentin permeability, which has emerged as a promising alternative for this purpose.

Effect of Low-Level Er: YAG (2940 nm) laser irradiation on the photobiomodulation of mitogen-activated protein kinase cellular signaling pathway of rodent cementoblasts.

BACKGROUNDS: Dental avulsion due to trauma, especially in young patients, is a worldwide problem, requiring tooth replacement. Delayed replantation could cause tooth loss when the cementum is severely damaged. A small number of studies has reported that photobiomodulation (PBM) therapy using Er: YAG laser irradiation activates cellular signaling responses in different cell types, resulting in a variety of favorable biological effects. The aim of this in vitro study was to evaluate the potential biostimulatory effect of low-level Er: YAG laser irradiation on the biological responses of cultured mouse cementoblasts (OCCM-30), including the mitogen-activated protein kinases (MAPKs). METHODS: OCCM-30 cells were exposed to 2940 nm Er: YAG laser irradiation for 15 s at 0.34 W (pulse duration of 100 or 1000 µs, 17 mJ/pulse) at energy densities of 1 or 2 J/cm2. Irradiated and non-irradiated OCCM-30 cells were tested for migration (Scratch assay), proliferation (MTS assay) and functional differentiation (Alizarin Red S assay). Lumican (Lum) and Fibromodulin (Fmod) gene expression, and activation of MAPKs, were assessed by RT-PCR and Western blotting, respectively. RESULTS: Low-level Er: YAG laser irradiation at 2 J/cm2 and pulse duration of 1000 µs resulted in the highest migration rate and proliferation. Moreover, the pulse duration irradiation of 100 µs increased Lum expression. Fmod expression was increased after 1000 µs pulse duration laser stimulation. Low-level Er: YAG laser irradiation increased the mineralization of OCCM-30 cells after 7 days and activated ERK1/2, P38 and JNK signaling. CONCLUSIONS: Low-level Er: YAG laser irradiation induces OCCM-30 cell migration, proliferation and differentiation, and activates the MAPK signaling pathway.

Violet led dental whitening: Effectiveness and biological safety: An in vitro study.

INTRODUCTION: The light-emitting diode (Led) in the violet spectrum associated or not with hydrogen peroxide (HP) has been suggested as a promising technique for dental bleaching. Violet led has a wavelength of 405-410 nm, which is very close to that of ultraviolet (UV) radiation, and this has raised biological safety concerns. AIM: To investigate the effectiveness of the violet led dental bleaching technique by evaluating color parameters, enamel surface microhardness, and biological safety analysis. METHODS: One hundred bovine dental blocks were divided into groups according to the bleaching technique (G1 - only HP; G2 - HP associated with blue led; G3 - only blue led; G4 - HP associated with a violet led; and G5 - only violet led). The color analysis (ΔE, ΔL, and WID) and enamel surface microhardness were assessed before and after bleaching (immediately, 5, 14, and 30 days). The biological safety of the violet led irradiation was assessed by measuring the number of micronuclei formed in human cells in culture in response to irradiation. Data analysis included Kruskal-Wallis test, Friedman test, and Mann-Whitney test. RESULTS: In groups G4 and G5 there was the formation of precipitates on the enamel surface. At the time of 14 days, it was observed that the G2 group had lower values of microhardness than G5. ΔL and ΔE showed differences between groups in experimental times. Mean percentages of micronuclei occurrence were similar in the control group and the violet led group. CONCLUSION: The violet led irradiation can be applied for dental bleaching because this approach produces significant color changes preserving tooth enamel integrity and causes no genotoxic effects on vital cells.

Genotoxicity and Cytotoxicity Comparison of Calcium Silicate-Based and Resin-Based Sealers on Human Periodontal Ligament Stem Cells.

OBJECTIVE: This study aimed to assess the genotoxicity and cytotoxicity of Sealer Plus BC (SBC), AH Plus (AHP) and MTA Fillapex (MTF). METHODS: Human periodontal ligament dental stem cells (hPDLSCs) from third molars were isolated and cultured in a clonogenic medium. Cells were maintained in an incubator, and cell growth was monitored daily. hPDLSCs were characterised under flow cytometry and stem cell surface markers. The tested groups were a control group, SBC, AHP and MTF. Each sealer was prepared according to the manufacturer's instructions and placed in a clonogenic medium to produce a conditioned media. Conditioned media were then diluted to 10% to be placed in contact with culture cells in cell viability assay afterwards. The cells were harvested and plated into 96 wells culture plates. Genotoxicity was assessed by evaluation of micronucleus formation and cytotoxicity by MTT-based assay. All experiments were performed in triplicate. Data normality was verified by the Kolmogorov-Smirnov test. Statistical analysis for genotoxicity was performed with Kruskal-Wallis and Dunn's tests and two-way ANOVA for cytotoxicity, both with a significance level of 5%. RESULTS: Cells expressed typical levels of mesenchymal stem cell surface markers. No differences in the number of micronuclei were observed among all groups (P>0.05). In all periods analysed (24, 48, and 72 h), the sealers presented statistically different results for cell viability (P<0.05), with SBC presenting the lowest cytotoxicity, followed by the control group, MTF, and AHP. CONCLUSION: All sealers presented low genotoxicity, and Sealer Plus BC presented the lowest cytotoxicity.