Catalysis-based approaches with biopolymers and violet LED to improve in-office dental bleaching.

This in vitro experimental investigation aimed to evaluate the impact of the combined application of a nanofiber scaffold (NS), a polymeric catalyst primer (PCP) containing 10 mg/mL of heme peroxidase enzyme, and violet LED (LEDv) on the esthetic efficacy (EE), trans-amelodentinal cytotoxicity (TC), and procedural duration of conventional in-office bleaching therapy. To achieve this, 96 standardized enamel/dentin discs were individually placed in artificial pulp chambers. A 35% hydrogen peroxide (H2O2) bleaching gel was administered for 45, 30, or 15 min to the enamel, either previously coated with NS + PCP or left uncoated, followed by irradiation with LEDv for 15 min or no irradiation. The established groups were as follows: G1, negative control (no treatment); G2, 35% H2O2/45 min; G3, NS + PCP + LEDv; G4, NS + PCP + 35%H2O2/45 min + LEDv; G5, NS + PCP + 35%H2O2/30 min + LEDv; and G6, NS + PCP + 35%H2O2/15 min + LEDv. Extracts (culture medium + gel components diffused through the discs) were collected and applied to odontoblast-like MDPC-23 cells. EE (ΔE00 and ΔWI) and TC were assessed using ANOVA/Tukey analysis (p < 0.05). The EE analysis revealed no statistical differences between G6 and G2 (p > 0.05). Cells in G6 exhibited higher viability and lower oxidative stress compared to other bleached groups (p < 0.05). In conclusion, employing NS + PCP + LEDv to catalyze a 35%H2O2 bleaching gel applied for 15 min to the enamel resulted in successful esthetic improvements and reduced the cytotoxicity commonly linked with traditional in-office bleaching procedures.

A new approach for professional dental bleaching using a polymeric catalyst primer.

OBJECTIVE: Evaluate the influence of a polymeric catalyst primer (PCP) on esthetic efficacy (EE), degradation kinetics of hydrogen peroxide (H2 O2 ), and trans-amelodentinal cytotoxicity (TC) of bleaching gels. MATERIALS AND METHODS: The following groups were established: G1: No treatment (NC, negative control); G2: PCP; G3: 10% H2 O2 ; G4: PCP + 10% H2 O2 ; G5: 20% H2 O2 ; G6: PCP + 20% H2 O2 ; G7: 35% H2 O2 (positive control); G8: PCP + 35% H2 O2 . To determine EE, enamel/dentin discs (E/DDs) were stained and subjected or not to bleaching protocols for 45 min. To assess TC, the E/DDs were adapted to artificial pulp chambers. The extracts (culture medium + gel components diffused through E/DDs) were applied to odontoblast-like MDPC-23 cells. The viability (VB), oxidative stress (OxS), morphology (SEM), amount of H2 O2 diffused and the production of hydroxyl radical (OH• ) were assessed (two-way ANOVA/Tukey/paired Student t-test; p < 0.05). RESULTS: The highest EE was found in G8 (p < 0.05), and G4, G6, and G7 did not differ statistically (p > 0.05). In G4, the limited H2 O2 diffusion reduced OxS and increased cell VB (p < 0.05). CONCLUSIONS: Coating the enamel with PCP containing 10 mg/ml of manganese oxide before applying the 10% H2 O2 bleaching gel maintains the EE of conventional in-office bleaching and minimizes the toxic effects of this esthetic therapy. CLINICAL SIGNIFICANCE: Coating the enamel with a PCP before applying the bleaching gel may potentiate the EE of the conventional in-office tooth bleaching and reduce the toxicity of this professional therapy to the dental pulp.

Improved esthetic efficacy and reduced cytotoxicity are achieved with a violet LED irradiation of manganese oxide-enriched bleaching gels.

Gels with high concentrations of hydrogen peroxide (H2O2) have been associated with cytotoxicity and consequent post-bleaching tooth sensitivity. This study assessed the bleaching efficacy (BE) and cytotoxicity (CT) of bleaching gels with low concentrations of H2O2 containing manganese oxide (MnO2) and photocatalyzed with violet LED (LEDv). The following groups were established: G1: no treatment (negative control, NC); G2: 35% H2O2 (positive control, PC); G3: LEDv; G4: 10% H2O2; G5: 6% H2O2; G6: 10% H2O2 + MnO2 + LEDv; G7: 6% H2O2 + MnO2 + LEDv. To analyze BE, standardized enamel/dentin discs (E/DDs) were subjected to the bleaching procedures for 45 min (1 session). The color change was determined before and after performing the bleaching protocols (ΔE00; ΔWI). To analyze CT, the E/DDs were adapted to artificial pulp chambers, and the extracts (culture medium + diffused gel components) were applied to cultured odontoblast-like MDPC-23 cells. Then, the cells were assessed concerning their viability (VB), oxidative stress (OxS), and Live/Dead. The amount of H2O2 diffused was also determined (ANOVA/Tukey; p < 0.05). Cell viability decreased in all bleached groups compared to G1 (NC; p < 0.05). The cells in G6 and G7 presented higher viability than in G2, G4, and G5 (p < 0.05). The BE in G7 was similar to G2 (PC; p < 0.05). The lowest OxS and H2O2 diffusion values were found in G6 and G7, compared to the other bleached groups (G2, G4, and G5; p < 0.05). The 6% H2O2 bleaching gel (G7) submitted to both methods of catalysis (MnO2 + LEDv) caused only a mild cytotoxicity and maintained the excellent esthetic outcome promoted by in-office conventional tooth bleaching.

Innovative strategy for in-office tooth bleaching using violet LED and biopolymers as H2O2 catalysts.

OBJECTIVE: To assess the influence of coating the enamel with a nanofiber scaffold (NS) and a polymeric catalyst primer (PCP) on the esthetic efficacy, degradation kinetics of hydrogen peroxide (H2O2), and trans-amelodentinal cytotoxicity of bleaching gels subjected or not to violet-LED irradiation. METHODOLOGY: The following groups were established (n = 8): G1- No treatment (negative control); G2- NS+PCP; G3- LED; G4- NS+PCP+LED; G5- 35% H2O2 (positive control); G6- NS+PCP+35% H2O2+LED; G7- 20% H2O2; G8- NS+PCP+20% H2O2+LED; G9- 10% H2O2; G10- NS+PCP+10% H2O2+LED. For esthetic efficacy analysis, enamel/dentin discs were stained and exposed for 45 min to the bleaching protocols. To assess the cytotoxicity, the stained enamel/dentin discs were adapted to artificial pulp chambers, and the extracts (culture medium + components diffused through the discs) were collected and applied to MDPC-23 cells, which had their viability, oxidative stress, and morphology (SEM) evaluated. The amount of H2O2 diffused and hydroxyl radical (OH•) production were also determined (two-way ANOVA/Tukey/paired Student t-test; p < 0.05). RESULTS: G6 had the highest esthetic efficacy compared to the other groups (p < 0.05). Besides the esthetic efficacy similar to conventional in-office bleaching (G5; p > 0.05), G10 also showed the lowest toxic effect and oxidative stress to MDPC-23 cells compared to all bleached groups (p < 0.05). CONCLUSION: Coating the enamel with a nanofiber scaffold and a polymeric catalyst primer, followed by the application of 10%, 20%, or 35% H2O2 bleaching gels irradiated with a violet LED, stimulates H2O2 degradation, increasing esthetic efficacy and reducing the trans-amelodentinal toxicity of the treatment.

Hypoxia and proangiogenic proteins in human ameloblastoma.

Ameloblastomas are epithelial odontogenic tumours that, although benign, are locally invasive and may exhibit aggressive behaviour. In the tumour microenvironment, the concentration of oxygen is reduced, which leads to intratumoral hypoxia. Under hypoxia, the crosstalk between the HIF-1α, MMP-2, VEGF, and VEGFR-2 proteins has been associated with hypoxia-induced angiogenesis, leading to tumour progression and increased invasiveness. This work showcases 24 ameloblastoma cases, 10 calcifying odontogenic cysts, and 9 dental follicles, used to investigate the expression of these proteins by immunohistochemistry. The anti-HIF-1α, anti-MMP-2, anti-VEGF, and anti-VEGFR-2 primary antibodies are used in this work. The results have been expressed by the mean grey value after immunostaining in images acquired with an objective of 40×. The ameloblastoma samples showed higher immunoexpression of HIF-1α, MMP-2, VEGF, and VEGFR-2 when compared to the dental follicles and calcifying odontogenic cysts. Ameloblastomas show a higher degree of expression of proteins associated with intratumoral hypoxia and proangiogenic proteins, which indicates the possible role of these proteins in the biological behaviour of this tumour.

Is nutritional intervention an improvement factor in the management of periodontitis? A systematic review.

AIMS: This systematic review aimed to evaluate the effect of nutritional intervention in the management of periodontitis. METHODS: This study was registered on the Prospective International Registry of Systematic Reviews-PROSPERO, under the registration number CRD42017076674. The database searching was performed on: Pubmed, Scopus, Web of Science, Clinical Trials and Lilacs. The OpenGrey and Google Scholar were also assessed for searching the grey literature. The PICO framework was carried out, in which the participants (P) were humans with periodontitis receiving conventional periodontal therapy simultaneously with dietary supplements (I), compared (C) with those managed with conventional therapy only, having as an outcome (O) the influence-or not influence-of nutritional intervention in the management of periodontitis. After the searching, duplicates were removed and articles were first assessed by title and abstract, following the inclusion and exclusion criteria; then, the full text of the remaining articles were reviewed. All steps within the review process were performed independently by two reviewers and checked by a third-party disagreement evaluator. For quality/risk of bias assessment of the study selection, The Cochrane Collaboration's tool for randomized studies and Robins-TOOL for non-randomized studies (ROBINS-I) were performed. The Grading of recommendations, assessment, development and evaluation (GRADE) was used for assessing the level of evidence. RESULTS: A total of 2574 citations were recorded, but only four were considered eligible. The included studies reported different nutritional interventions such as fruit concentrate, vegetables and fruit juice powders, multivitamins, fish oil, and a customized dietary advice. The three studies using nutritional supplements showed improvements in at least one clinical parameter of periodontitis -reduction of probing depths, attachment gain, crevicular fluid decreased, reduced bleeding values on probing-after 2-6 months. Although, only two articles presented a moderate risk of bias, a very low level of evidence was found among the four studies taken together. CONCLUSIONS: Despite the results suggested that nutritional intervention is beneficial for periodontal therapy, the evidence in general, is inconsistent and imprecise. More interventional studies with longer periods of follow-up and the assessment of a specific nutritional intervention must be conducted.