Toxicity and efficiency study of plant extracts-based bleaching agents.

OBJECTIVES: Tooth bleaching is one of the most required dental esthetic treatments. However, it can generate side effects like oral irritation, enamel alteration, tooth sensitivity, especially caused by hydrogen peroxide, the main bleaching component of the commercial products. Therefore, development of new tooth bleaching agents, based on natural products, with comparable esthetic results and lower side effects is needed. The aim of this study was to evaluate the biological effects and bleaching efficacy of four experimental bleaching agents, derived from fruit juices, against the commercially available Opalescence (Ultradent, USA). MATERIALS AND METHODS: Organic acid composition of the gels was characterized by HPLC. Bleaching efficiency was tested by spectrophotometry on composite restorative materials. Biological testing was done in vitro, on human fibroblasts. Cells were exposed to dilutions of the bleaching gel-conditioned medium. Viability was measured by MTS, apoptosis by FACS-AnnexinV FITC/Propidium iodide, NF-kB activation by western blot, malondyaldehide, and superoxide dismutase activity by spectrophotometry. RESULTS: All gels exhibited physical stability and dental bleaching capabilities. Experimental gels induced significantly better viability and apoptosis rates, lower lipid peroxidation, and increased antioxidant defense, compared to Opalescence. CONCLUSIONS: The studied experimental gel formulations exhibited a good safety profile in vitro, as well as bleaching efficiency on restorative composite materials. CLINICAL RELEVANCE: These data open new possibilities for the use of new natural products in dental bleaching treatments that can insure significant esthetic results and lower side effects.

Cytotoxicity assessment of graphene-based nanomaterials on human dental follicle stem cells.

Graphene-oxide (GO) and its most encountered derivatives, thermally reduced graphene oxide (TRGO) and nitrogen-doped graphene (N-Gr), were synthesized and structurally characterized by spectroscopic techniques, like Raman and (13)C MAS solid state NMR. Several biological effects (cytotoxicity, oxidative stress induction, and cellular and mithocondrial membrane alterations) induced by such graphene-based materials on human dental follicle stem cells were investigated. Graphene oxide shows the lowest cytotoxic effect, followed by the nitrogen-doped graphene, while thermally reduced graphene oxide exhibits high cytotoxic effects. Graphene oxide induces oxidative stress without causing cell membrane damage. Nitrogen-doped graphene shows a slight antioxidant activity; however, at high doses (20 and 40 µg/ml) it causes membrane damage. Both graphene oxide and nitrogen-doped graphene seem to be valuable candidates for usage in dental nanocomposites.

Fractal analysis of ibuprofen effect on experimental dog peri-implantitis.

INTRODUCTION: The aim of this study was to assess the correlation between the fractal analysis of gingival changes and systemic nitro-oxidative stress in a short-term low-dose ibuprofen (IBU) treatment at experimental peri-implantitis (PI). MATERIALS AND METHODS: Six adult male mixed-breed dogs with PI were randomly treated for 2 weeks, 3 with IBU (5 mg/kg b.w.) and 3 with placebo. Clinical and radiological evaluation were performed. Gingival biopsies were assessed by light microscopy, transmission electron microscopy, and fractal analysis. Blood was collected to assay nitric oxide (NOx), total oxidative status (TOS), total antioxidant response (TAR), and oxidative stress index (OSI). RESULTS: Specific gingival ultrastructural alterations, bone loss, and systemic nitro-oxidative stress were evident in PI-placebo animals. IBU caused significant clinical, microscopic, fractal dimensions (P < 0.01), NOx, TOS, and OSI improvements. IBU caused no important bone and TAR changes. CONCLUSION: This study confirms that fractal analysis was a good method to assess the complex morphological changes and correlations with the nitro-oxidative stress in PI. Short-term low-dose IBU treatment consistently improved gingival status and reduced systemic nitro-oxidative stress.

Effect of Cimetidine on Nitro-Oxidative Stress in a Rat Model of Periodontitis.

BACKGROUND AND AIMS: Periodontitis is a chronic inflammation that involves nitro-oxidative stress with damaging periodontal structural effects. We aimed to evaluate the consequences of low-dose cimetidine on nitro-oxidative stress in periodontitis. METHODS: A rat model of ligature-induced periodontitis was used. After two weeks, the periodontitis groups were treated with cimetidine, aminoguanidine, N-nitro-L-arginine methyl ester and trolox for one week. On day 21, blood was drawn and the serum analyzed for measurement of total nitrites and nitrates, total oxidative status, total antioxidant response, and oxidative stress index. RESULTS: Cimetidine had an inhibitory effect on the synthesis of nitric oxide (p=0.001), total oxidative status (p=0.01) and oxidative stress index (p=0.01). Total antioxidant reactivity was increased by cimetidine (p=0.01). The effects of cimetidine were almost like those of aminoguanidine, NG-nitro-L-arginine methyl ester, and trolox. CONCLUSIONS: Low-dose cimetidine can be used as adjunctive host modulatory therapy in chronic periodontitis because it reduces nitro-oxidative stress.

Patients' perspective on dental aesthetics in a South-Eastern European community.

OBJECTIVES: To assess the importance attributed to dental aesthetics by subjects from a Romanian community. In addition, the role played by dental color, the group-distributions based on the self-evaluation of dental color and the previous experience regarding whitening treatments are analysed. METHODS: A multiple-choice questionnaire was administered to 540 patients in dental offices in Cluj-Napoca, Romania; the subjects were also asked to self-evaluate their dental shade, using a set of images as a comparison. Answers to the questionnaires were statistically analysed using Microsoft Excel and SPSS 13.00 (Pearson's chi-square test, Fisher's exact test, Kendall's tau b). RESULTS: From the participants, 17.96% were motivated by aesthetic reasons to ask for treatment; most of the patients evaluated their smile as "acceptable" (38.51%) or "having some defects" (29.44%) and were self-included in groups of medium and dark shades (33.7% and 33.89%, respectively). Whilst 22.40% of the subjects considered the dental color as being the most evident defect of their dentition, 39.07% indicated a self-perception of "an abnormal dental shade". A strong correlation between darker self-assessed tooth color-groups and the self-perception of an abnormal tooth color was found (Chi square p≪0.001, Kendall's tau-c=0.44, with p≪0.001). Previous whitening treatments were reported by 8.88% of the subjects. CONCLUSIONS: Among patients who wanted to improve one of their oral functions, the majority requested changes in aesthetics. Dental shade is one of the aspects recognized as problematic by the participants, but nonetheless the percentage of patients who had previously benefited by whitening treatments was moderate.

In vitro testing of an experimental dental composite resin and adhesive system.

UNLABELLED: In vitro testing of new experimental materials has been introduced for many years as a method to evaluate them in simulated conditions, before the clinical trials. Our study has investigated a new experimental composite resin C1 and adhesive system Ad1 by scanning electron microscope (SEM) studies and microleakage tests. MATERIALS AND METHODS: Both in vitro test were performed on extracted human teeth, that were prepared for standardized class II and V restorations and restored with three composite resins (experimental C1, TetricCeram TC and Solitaire2 S2) and their total-etch adhesive systems (Ad1, Excite EX and GlumaOneBond GB). Teeth were sectioned and investigated under the SEM microscope for the interfaces created and under the optical microscope for dye penetration and microleakage. RESULTS: The Romanian experimental composite C1 has shown lower alpha "ideal" interfaces than TC and S2, with no significant difference between the latter. Microleakage was significantly lower at the enamel margin and significantly higher at the gingival margin placed below the CEJ for all three compared composites. C1 presented similar dye penetration scores with the commercial available systems. DISCUSSION: The differences in SEM analysis can be attributed to higher viscosity and handling properties in the experimental adhesive Adl and to technique sensitivity. CONCLUSIONS: Further investigation is required to obtain better working properties for the experimental adhesive and higher "ideal" scores at the interfaces. Also the SEM investigation is more sensitive than the optical microscope analysis.