Effects of resveratrol on the proliferation and osteogenic differentiation of deciduous dental pulp stem cells from neurofibromatosis type 1 patient.

PURPOSE: We aimed at verifying whether resveratrol can decrease cell proliferation and change osteogenic differentiation of cells obtained from patients with type 1 neurofibromatosis (NF1). METHODS: Deciduous dental pulp derived stem cells were isolated from NF1 patient and healthy volunteer. These cells were subjected to increasing concentrations of resveratrol and evaluated for proliferation and mineralization of osteogenic differentiation. RESULTS: The results showed that resveratrol reduced the difference in proliferation between CNT and NF1 cells in a dose-dependent manner and this property was more prominent in affected cells than in healthy cells. Resveratrol showed no statistically significant changes in mineralization in osteogenic differentiation of NF1 cells, at low doses tested. CONCLUSIONS: In conclusion, in a dose-dependent manner, resveratrol displays interesting properties that could be applied in a possible treatment aimed at decreasing cellular proliferation in neurofibromatosis. Furthermore, it is selective concerning healthy cells and not affecting cell differentiation. Further research to cell selectivity, differentiation to other tissue types, and cell cytotoxicity are needed.

Proposing the use of dental pulp stem cells as a suitable biological model of neurofibromatosis type 1.

PURPOSE: This study aims to propose the dental pulp stem cells (DPSCs) as a model for studying two features related to neurofibromatosis type 1 (NF1), i.e. augmented proliferative capacity and altered osteogenic differentiation. METHODS: We isolated a DPSC from the pulp of deciduous teeth of a 6-year-old NF1 patient and two other healthy children of similar age. Cell proliferation was assayed by counting with a haemocytometer after successive cell re-plating. In order to compare osteogenic differentiation, we used osteoblast-differentiating medium and quantified alizarin stain, which relates to degree of calcification, and evaluated the expression of osteoblastic markers by reverse transcription polymerase chain reaction (RT-PCR). RESULTS: The DPSCs isolated from the NF1 patient displayed a greater rate of proliferation when compared to the control cells. Osteogenic differentiation occurred as expected for both NF1 and control, which concerned cell morphology and expression of osteoblast marker genes ALP, BMP2, BMP4, OCN and SPP1. However, alizarin staining denoted a markedly lower calcification level in the cells from the NF1-diagnosed child, considering that less calcium deposits were visualized under light microscopy and a smaller amount of alizarin could be quantified by spectrophotometry after extraction from the stained cells. CONCLUSION: DPSCs seem to be useful as a model for studying NF1 and predicting prognosis of patients, since their in vitro behaviour seems to mimic at least two features of this disorder: higher tendency to develop bone abnormalities and neoplastic cell proliferation.

Corrosion resistance assessment of nickel-titanium endodontic files with and without heat treatment.

OBJECTIVES: The aim of this study was to evaluate the corrosion resistance of heat-treated (Reciproc and WaveOne) and non-heat-treated (ProTaper and Mtwo) superelastic nickel-titanium endodontic files when immersed in a 5.25% sodium hypochlorite solution. MATERIALS AND METHODS: Anodic polarization curves were obtained with potential sweeps that began at the open circuit potential or corrosion potential (Ecorr). The pitting potential (Epit) was identified on the anodic polarization curve as the potential at which a sudden increase in current was observed. The micromorphology of the 28 tested files was analyzed before and after the electrochemical assay using scanning electron microscope (SEM). The data were analyzed using 1-way analysis of variance with the post hoc Bonferroni test (for Ecorr) and the Student t-test for independent samples (for Epit). RESULTS: The mean Ecorr values were 0.506 V for ProTaper, 0.348 V for Mtwo, 0.542 V for Reciproc, and 0.321 V for WaveOne files. Only WaveOne and Protaper files exhibited pitting corrosion, with Epit values of 0.879 V and 0.904 V, respectively. On the SEM images of the ProTaper and WaveOne files, cavities suggestive of pitting corrosion were detected. CONCLUSIONS: Signs of corrosion were observed in both heat-treated and non-heat-treated files. Of the evaluated files, WaveOne (a heat-treated file) and ProTaper (a non-heat-treated file) exhibited the lowest corrosion resistance.

Detection of vertical root fractures in the presence of intracanal metallic post: a comparison between periapical radiography and cone-beam computed tomography.

INTRODUCTION: This in vitro study compared cone-beam computed tomography (CBCT) exam with different voxel sizes with digital periapical radiography in the detection of vertical root fractures in teeth with and without intracanal metallic posts. METHODS: Eighteen single-rooted human teeth were endodontically treated, prepared for cast metal posts, and artificially fractured. After positioning the teeth in dry mandibular sockets, the samples were subjected twice (with and without posts) to digital periapical radiography at 3 different angles and to CBCT examinations with 2 voxel sizes, 0.125 and 0.25 mm. The images were evaluated by 3 oral radiologists. Indices of sensitivity, specificity, and positive and negative predictive values, in addition to the areas under the receiver operating characteristic curves (accuracy), were calculated. Comparison of the accuracy of the imaging methods was assessed by using the χ(2) test. Comparison of the accuracy between teeth with and without posts was determined by using the Fisher exact test. RESULTS: The accuracy of the imaging methods showed no significant differences (P = .08). The comparison between teeth with and without posts in each examination revealed significant differences for CBCT with a voxel of 0.125 mm (P = .04) and for periapical radiography (P = .04). CONCLUSIONS: No significant differences were observed between CBCT and periapical radiography in the detection of vertical root fractures, except for teeth with metallic posts in images from CBCT with a voxel of 0.125 mm and in digital periapical radiography. Furthermore, voxel size did not significantly influence the diagnosis of vertical root fractures.