The aim of this study was to investigate the role of nickel in orthodontic treatment-induced gingival hyperplasia. The nickel concentration in gingival tissues with and without overgrowth, histopathology of gingival overgrowth, and epithelial cell proliferation response to different nickel concentrations were analysed. Ten patients receiving orthodontic therapy (eight females and two males, mean age 15.4 years) were included in the study. Hyperplastic and healthy gingiva samples were collected from the same patients. The amount of nickel in the gingival tissue samples was analysed using the atomic absorption spectrometry technique. The tissues removed from hyperplastic areas during gingivectomy were also used for histological analysis. To analyse the effect of nickel on epithelial cell proliferation, four different nickel concentrations (0.5, 2, 5, and 10 microg) were incubated with keratinocyte cells for 11 days. Mann-Whitney U-test, analysis of variance, and Tukey's test were used in the statistical analyses. The results did not show any difference in nickel concentration between the study and control gingiva tissue samples, but histological analysis demonstrated an increase in epithelial thickness and a significant increase (P = 0.031, 0.02, 0.02) in epithelial cell proliferation in response to low-dose nickel concentrations, with a toxic response to a higher dose. In the limitations of this study, it is plausible that the effect of a continuing low-dose nickel release to epithelium is the initiating factor of gingival overgrowth induced by orthodontic treatment.
The aim of this study was to evaluate the elemental release from a Ni-Cr dental casting alloy subjected to 10% hydrogen peroxide (HP) or 10% carbamide peroxide (CP) solutions and to determine the composition of surface oxide layer formed on alloy samples. Cylinder-shaped 15 specimens were cast from a Ni-Cr alloy and divided into three groups (n = 5). Samples were exposed either to phosphate-buffer solution, HP, or CP for 30 days, and total mass and individual elements (Ni, Cr, Mo) released into solutions were measured by means of atomic absorption spectrometry. Before and after elemental release measurements, a scanning electron microscope (SEM) accompanied by energy dispersive spectroscopy (EDS) (SEM/EDS) was used to analyze the surface morphology, and surface characterization of passive film formed on alloy samples was also performed by using X-ray photoelectron spectroscopy (XPS). The presence of bleaching agents induced the mass released compared to control group (4.9 μg/cm(2)); this effect was recorded in both HP (171.2 μg/cm(2)) and CP (59.7 μg/cm(2)). XPS data showed that Cr and Ni levels in oxide layers formed on HP group were higher, Mo level was lower than those of CP group.
ObjectivesThe biocompatibility of dental casting alloys is a critical issue because these alloys are in long-term intimate contact with oral tissues. Since the biocompatibility of alloys is not completely known; the release of elements from the alloys has been studied. The aim of this study was to compare the elemental release from dental casting alloy during exposure to artificial saliva and cell-culture medium.Materials and MethodsTwenty specimens made from Ni-Cr alloy were provided in the form of 5 mm diameter discs, 2 mm in thickness with a 7 mm stem attached to one face to facilitate handling. Ten of twenty samples were polished separately using a conventional technique. The remaining ten samples were left sandblasted with 50 μm Al203. Ten samples (5 polished, 5 sandblasted) were separately placed into cell-culture wells with Dulbecco’s Modified Eagle’s Medium. The other ten samples were placed separately into cell-culture wells with artificial saliva. The samples were subjected in contact with these medium for 30 days. These medium were collected every 7 days. The cell-culture medium and artificial saliva without alloy samples were subjected to elemental analyses as a control. At the end of the exposure time, Atomic Absorption Spectrometry (AAS) was used to determine the release of elements from the alloys into all collected medium. Statistical analyses were assessed with two-way ANOVA.ResultsIn general, the elemental release occurred with in all medium. The elemental releases of sandblasted alloys were higher than polished alloys. Artificial saliva was found to cause more release from the samples. In both media, Ni released from polished and sandblasted alloys were higher than Cr and Mo.ConlusionsThe results suggest that the release of elements from the alloys might have correlated with the environments and the surface of dental alloy.
The aim of the study was to determine the pharmacokinetics of a new hydroxyapatite-Eudragit RS100 diffusion-controlled fluoride-releasing system designed for intraoral use with a 0.15 mg F–/day release for a 1-month period. Matrix tablets, each containing 18 mg of sodium fluoride, were bonded to the buccal surface of the first maxillary molar teeth of 20 subjects (age 20–23 years). Morning and evening salivary and urinary samples were collected 5 days before the study and every day for the 1st week, then once a week for 1 month. Fluoride ion measurements were done using the microdiffusion method. The salivary and urinary fluoride concentrations were significantly raised during the treatment period (p < 0.05). Morning salivary fluoride levels were higher than evening salivary fluoride levels (p < 0.05) whereas evening urinary fluoride levels were higher than morning urinary fluoride levels (p < 0.05). The statistically significant increase in salivary fluoride levels indicates a caries-preventive role for this device.
Although the availability of thyroid cyst fluid is easy by fine-needle aspiration, less is known about the biochemical composition of thyroid cyst fluid. The authors have, therefore, determined the biochemical composition of 18 benign thyroid cyst fluid specimens. They found that the activities of aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and the concentrations of total protein, total bilirubin, and uric acid were highly increased in thyroid cyst fluid specimens when compared with normal human serum specimens. The concentrations of glucose, cholesterol, and triglycerides in cyst fluid were within normal serum limits. Selenium (Se) concentrations in most cyst fluids were low. Moreover, there was no correlation between Se and other biochemical parameters. Protein electrophoresis of cyst fluid specimens yielded high concentrations of alpha 1 and especially alpha 2 globulin fractions indicating an inflammation. The concentrations or activities of biochemical analytes were not significantly different in pure and mixed cysts. Those parameters were also not significantly different between cyst fluids of different colors. The gross appearance of the fluid and the presence of certain biochemical analytes were consistent with a hemorrhagic origin of most of the cyst fluid specimens. However, some biochemical markers indicate that autolysis or necrosis of thyroid tissue may also contribute the composition of thyroid cyst fluid. The reason for lower Se concentration in the thyroid cyst fluid may be the lower Se concentration in the Turkish population. These results also suggest that the fluid color or nature of cyst, e.g., pure or mixed cyst, is not a main determinant of biochemical composition of benign thyroid cyst fluid.
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