Optical clearing agents based on metallic and dielectric nanoparticles for caries diagnostic by optical coherence tomography.

OBJECTIVE: This study aimed to assess the effect of titanium dioxide (TiO2) and silver (Ag) nanoparticles dispersed in glycerol or water, serving as optical clearing agents nanocolloids (OCAs-NC), for improving optical coherence tomography (OCT) images and highlighting incipient lesions in ex vivo human teeth. MATERIALS AND METHODS: Twelve human teeth with incipient lesions were divided into seven groups according to the OCA-NC; they were subjected to G1 (air), G2 (glycerol), G3 (TiO2 0.1%), G4 (TiO2 0.01%), G5 (TiO2 0.001%), G6 (AgNO3 10%), and G7 (AgNO3 100%). The OCA-NC was applied to the occlusal surface, and two-dimensional images of the specimens were analyzed using OCT (930 nm central wavelength; 100 nm bandwidth; 5 mW output power; axial resolution of 7/5.3 µm in water and air, respectively; lateral resolution of 8 µm; and light penetration depth of 1.6 mm inside the sample). RESULTS: The findings demonstrated that the utilization of OCAs-NC containing metallic or dielectric nanoparticles (AgNO3 and TiO2) led to improved differentiation between sound and demineralized enamel on occlusal surfaces. Additionally, it enhanced the depth of image penetration when analyzing this hard tissue with OCT. CLINICAL RELEVANCE: In the current context of minimally invasive dentistry, the use of OCAs-NC in conjunction with OCT can provide clinicians with early diagnosis, allowing for the determination of less/more invasive therapies and consequently halting the disease before cavitation of dental tissues occurs.

Evaluation of the Antimicrobial Effect of Photodynamic Therapy and Er:YAG Laser Irradiation on Root Canals Infected with Enterococcus faecalis.

Objective: To carry out a histological and morphometric analysis of the antimicrobial effect of Er:YAG laser irradiation combined with photodynamic therapy (PDT) on root canals infected with Enterococcus faecalis. Background: PDT and Er:YAG laser irradiation may be alternatives for effective endodontic disinfection but there are no data on the combination of these therapies. Materials and methods: Forty single-rooted bovine teeth had their roots contaminated with E. faecalis for 72 h. The teeth were randomly divided into four groups (n = 10): group 1, irrigation with 2.5% sodium hypochlorite (NaOCl); group 2, Er:YAG laser (λ2940 nm, 15 Hz, 100 mJ); group 3, PDT with 0.07% methylene blue as photosensitizer and laser irradiation (λ660 nm, power 40 mW, 5 min); and group 4, Er:YAG laser + PDT. After treatment, the teeth were examined by confocal laser scanning microscopy to verify bacterial viability, and morphometric analysis of the images was performed. Results: The PDT and Er:YAG + PDT treatments promoted the greatest reduction in bacteria among the proposed therapies, whereas 2.5% NaOCl was the least effective in bacterial elimination. A statistically significant difference (p < 0.05) was observed among the groups studied, except between the group combining Er:YAG and PDT and the group treated with PDT alone. Conclusions: PDT combined or not with Er:YAG laser was found to be more effective in root canal disinfection when compared with the other groups.

Photobiomodulation Therapy in the Proliferation and Differentiation of Human Umbilical Cord Mesenchymal Stem Cells: An In Vitro Study.

Introduction: Since photobiomodulation therapy (PBMT) favors in vitro mesenchymal stem cell (MSC) preconditioning before MSC transplantation, increasing the proliferation of these cells without molecular injuries by conserving their characteristics, in the present in vitro study we analyzed the effect of PBMT on the proliferation and osteogenic differentiation of human umbilical cord mesenchymal stem cells (hUCMSCs). Methods: Irradiation with an InGaAIP Laser (660 nm, 10 mW, 2.5 J/cm2 , 0.08 cm2 spot size, and 10 s) was carried out. The cells were divided into four groups: CONTROL [cells grown in Dulbecco's Modified Eagle Medium (DMEM)], OSTEO (cells grown in an osteogenic medium); PBMT (cells grown in DMEM+PBMT), and OSTEO+PBMT (cells grown in an osteogenic medium plus PBMT). The cell proliferation curve was obtained over periods of 24, 48 and 72 hours using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Osteogenic differentiation was analyzed by the formation of calcium nodules over periods of 7, 14 and 21 days. Morphometric analysis was performed to quantify the total area of nodular calcification. Results: The highest cell proliferation and cell differentiation occurred in the OSTEO+PBMT group, followed by the PBMT, OSTEO and CONTROL groups respectively, at the observed times (P <0.05). Conclusion: PBMT enhanced the osteogenic proliferation and the differentiation of hUCMSCs during the periods tested, without causing damage to the cells and preserving their specific characteristics, a fact that may represent an innovative pretreatment in the application of stem cells.

Photobiomodulation Therapy in Bone Repair Associated with Bone Morphogenetic Proteins and Guided Bone Regeneration: A Histomorphometric Study.

OBJECTIVE: To evaluate the efficacy of photobiomodulation for bone repair of critical surgical wounds with implants of bone morphogenetic proteins (BMPs) and bovine biological membranes, using histological and histomorphometric analysis. BACKGROUND: Tissue engineering has been developing rapidly through the use of various biomaterials for the treatment of bone defects, such as mechanical barriers consisting of biological membranes and implants of biomaterials for bone supply. MATERIALS AND METHODS: Thirty-two male rats were divided into four groups (n = 8): group I-C: control; group II-PT: photobiomodulation therapy; group III-PM: Gen-Pro® BMPs+Gen-Derm® membrane; and group IV-PMPT: Gen-Pro® BMPs+Gen-Derm® membrane+photobiomodulation therapy. A 3 mm bone cavity was performed in the upper third of the lateral surface of the right rat femur to obtain a bone defect considered to be critical. The irradiated groups received seven applications of AlGaAs diode laser 830 nm, P = 40 mW, continuous wave (CW) emission mode, f ∼ 0.6 mm, 4 J/cm2 per point (north, south, east, and west) at 48 h intervals, for a total of 16 J/cm2 per session (final dose: 112 J/cm2). Bone repair was evaluated at sacrifice 15 and 30 days after the procedure. The specimens were embedded in paraffin and stained with hematoxylin and eosin and Picrosirius for analysis by light microscopy and by the Leica interactive measurement module software. Statistical analysis was performed (p < 0.05%). RESULTS: Histological analysis confirmed the histomorphometric results, with the experimental groups showing bone neoformation of significantly higher quality and quantity at the end of 30 days compared with the control group. CONCLUSIONS: Photobiomodulation therapy was effective for bone repair mainly when associated with BMPs and a biological membrane. The results of this study are promising and stimulate further scientific and clinical research.

Detection of vertical root fractures in endodontically treated teeth in the absence and in the presence of metal post by cone-beam computed tomography.

BACKGROUND: Aim of this study was to investigate the influence of gutta-percha and metallic posts on the efficiency of Cone Beam Computed Tomography (CBCT) in diagnosing Vertical Root Fracture (VRF). METHODS: Forty-eight teeth were divided into 3 experimental and 3 control groups. The teeth of the first experimental group and the first control group received neither gutta-percha nor metal posts. The teeth of the second experimental group and the second control group were filled with gutta-percha, and the teeth of the third experimental group and the third control group were filled with the metal posts. The teeth of the experimental groups were artificially fractured. The teeth were evaluated through images taken by a Prexion scanner with a 0.1 mm resolution. Fisher's exact test was used to measure the following values: sensitivity, false negative, specificity, false positive and accuracy for the VRF detection through the scanner. Three observers calibrated and blinded to the protocol evaluated the images. RESULTS: The inter-observer Kappa coefficient was 0.83. The presence of posts and gutta-percha reduced the sensitivity and the accuracy in detecting the VRF. Regarding to the sensitivity (p = 0.837, p = 0.304, p = 0.837 for evaluator 1, 2 and 3, respectively) and specificity (p = 0.162, p = 0.056, p = 0.062 for evaluator 1, 2 and 3, respectively), Fisher's exact test showed no statistically significant difference among the evaluated groups. However, a significant difference was observed in relation to the accuracy in the results of evaluator 2 (p = 0.03), which showed a much lower accuracy for the post group (50 %) than for the Nonfilled group (93.8 %). CONCLUSIONS: The Prexion tomograph was precise in detecting vertical root fractures and the CBCT diagnostic ability was not influenced by the presence of posts or gutta-percha.