Chitosan-Calcium-Simvastatin Scaffold as an Inductive Cell-Free Platform.

The development of biomaterials based on the combination of biopolymers with bioactive compounds to develop delivery systems capable of modulating dentin regeneration mediated by resident cells is the goal of current biology-based strategies for regenerative dentistry. In this article, the bioactive potential of a simvastatin (SV)-releasing chitosan-calcium-hydroxide (CH-Ca) scaffold was assessed. After the incorporation of SV into CH-Ca, characterization of the scaffold was performed. Dental pulp cells (DPCs) were seeded onto scaffolds for the assessment of cytocompatibility, and odontoblastic differentiation was evaluated in a microenvironment surrounded by dentin. Thereafter, the cell-free scaffold was adapted to dentin discs positioned in artificial pulp chambers in direct contact with a 3-dimensional (3D) culture of DPCs, and the system was sealed to simulate internal pressure at 20 cm/H2O. In vivo experiments with cell-free scaffolds were performed in rats' calvaria defects. Fourier-transform infrared spectroscopy spectra proved incorporation of Ca and SV into the scaffold structure. Ca and SV were released upon immersion in a neutral environment. Viable DPCs were able to spread and proliferate on the scaffold over 14 d. Odontoblastic differentiation occurred in the DPC/scaffold constructs in contact with dentin, in which SV supplementation promoted odontoblastic marker overexpression and enhanced mineralized matrix deposition. The chemoattractant potential of the CH-Ca scaffold was improved by SV, with numerous viable and dentin sialoprotein-positive cells from the 3D culture being observed on its surface. Cells at 3D culture featured increased gene expression of odontoblastic markers in contact with the SV-enriched CH-Ca scaffold. CH-Ca-SV led to intense mineralization in vivo, presenting mineralization foci inside its structure. In conclusion, the CH-Ca-SV scaffold induces differentiation of DPCs into a highly mineralizing phenotype in the presence of dentin, creating a microenvironment capable of attracting pulp cells to its surface and inducing the overexpression of odontoblastic markers in a cell-homing strategy.

In vivo analysis of the presence of heme oxygenase-1, transcription factor Jun-D and CD90+/CD73+/CD105+/CD45- cells in the pulp of bleached teeth.

AIM: To investigate hydrogen peroxide (H2 O2 )-induced responsiveness in pulp cells using heme oxygenase-1 (HO-1) immunolabelling, Jun-D immunolabelling to study the effects of H2 O2 on odontoblastic differentiation and CD90+/CD73+/CD105+/CD45- cell counting for in vivo identification of mesenchymal stem cells in the pulp. METHODOLOGY: The maxillary molars of 50 rats were treated with a bleaching gel (35% H2 O2 , 1 × 30 min) or placebo gel (control groups). At 2, 3, 7, 15 and 30 days after the treatment (n = 10), inflammation in pulp tissue was analysed by haematoxylin-eosin staining, HO-1- and Jun-D-immunolabelled cells were counted in each third of the pulp chamber, and the number of CD90+/CD73+/CD105+/CD45- cells was quantified by immunofluorescence. The results were assessed using the Paired t-test or Wilcoxon signed-rank test (P < 0.05). RESULTS: Significant H2 O2 -induced inflammation was noted at 2 and 3 days (P < 0.05), with tertiary dentine formation occurring from 7 days. The bleached specimens had greater HO-1 immunolabelling in the middle and cervical thirds of the coronal pulp at 2 and 3 days, in all thirds at 7 days, and in the occlusal third at 15 days (P < 0.05), and significant nuclear Jun-D immunolabelling in the cervical third at 2 and 3 days and in the occlusal and middle thirds at 7 days (P < 0.05). Bleached and control groups had low numbers of CD90+/CD73+/CD105+/CD45- cells in the pulp at all periods (P > 0.05). CONCLUSIONS: Pulp cells responded to oxidative stress by expressing HO-1 during the post-bleaching inflammation phase until the beginning of the repair phase. Jun-D expression occurred during the reduction of inflammation and the beginning of tertiary dentine production. The presence of oxidative stress did not influence the number of CD90+/CD73+/CD105+/CD45- cells identified in vivo in the dental pulp.

A New Approach for Dental Bleaching Using Violet Light With or Without the Use of Whitening Gel: Study of Bleaching Effectiveness.

The objective of this study was to evaluate the effectiveness of violet light-emitting diodes (LEDs) in dental bleaching treatment when used in conjunction with bleaching gels containing different concentrations of hydrogen peroxide (HP). Here, 90 bovine teeth (n=15) were randomly assigned to the following groups: GI, placebo without light; GII, 35% HP without light; GIII, 17.5% HP without light; GIV, placebo with violet LED; GV, 35% HP with violet LED; and GVI, 17.5% HP with violet LEDs. Three bleaching sessions of 45 minutes were conducted; 21 cycles involving one minute of irradiation by violet LEDs with 30-second intervals were performed during each session of bleaching (GIV, GV, and GVI). Color changes (ΔE, ΔL, Δa, and Δb) were analyzed using a visible ultraviolet light spectrophotometer 7 days after each bleaching session. The mean ΔE, ΔL, Δa, and Δb values were compared between groups by analysis of variance and Tukey tests, with a significance level of 5%. The groups treated with 35% HP had higher ΔE and ΔL and lower Δb values, regardless of whether violet light was used. The group that received only violet LED differed from the control group in terms of ΔE, and the group treated with 17.5% HP and violet LED presented higher ΔE values than the group treated with 17.5% HP only. Thus, violet light did not influence bleaching efficacy when using 35% HP, but when used in conjunction with 17.5% HP, it increased the bleaching efficacy. Moreover, use of the violet LED only also prompted a bleaching effect, although it was less marked.

An In Situ Study of the Influence of Staining Beverages on Color Alteration of Bleached Teeth.

The aim of this study was to evaluate overall color change in bovine tooth fragments submitted to dental bleaching treatment performed simultaneously with the ingestion of beverages containing dyes. For this purpose, tooth fragments assembled into intraoral devices were submitted to at-home dental bleaching using 10% carbamide peroxide (CP) for 14 days and to immersion in staining beverages for 10 minutes daily. The specimens were divided into the following study groups according to bleaching treatment and staining substance (n=12): G I (negative control): no bleaching + distilled water; G II (positive control): bleaching + distilled water; G III: bleaching + coffee; and G IV: bleaching + grape juice. Twelve volunteers used the device continually, except during meals, oral hygiene, dental bleaching, and pigment challenge. Color readings were performed using a spectrophotometer both before the bleaching treatment and after each treatment week. The results were submitted to the normality test. The data obtained were submitted to analysis of variance and the Tukey or Kruskal-Wallis and Dunn tests (α=0.05). All bleached groups showed similar ΔE results at the end of treatment. Staining beverages generated negative ΔL mean values, and the lowest result was obtained in the treatment with coffee after 14 days. The Δa values in the groups that received treatment with staining beverages were higher when compared to the control groups. Dental bleaching associated with the consumption of staining substances may not affect overall tooth color change by the end of the treatment, although the consumption of staining substances did influence the different color dimensions.

Transenamel and transdentinal penetration of hydrogen peroxide applied to cracked or microabrasioned enamel.

The present study evaluated transenamel and transdentinal penetration of hydrogen peroxide during tooth whitening recognized in altered enamel by the presence of cracks or microabrasion. We used 72 experimental units (n=20) obtained from bovine incisors: GI-sound enamel; GII-teeth showing visible enamel cracks (4 mm to 5.7 mm in length); and GIII-microabrasioned enamel. The 12 remaining specimens were used to analyze the enamel surface morphology using scanning electron microscopy. The specimens were cylindrical and 5.7 mm in diameter and 3.5 mm thick. A product based on 35% hydrogen peroxide was used for bleaching, following the manufacturer's recommendations for use. To quantify the H2O2 penetration, the specimens were placed in artificial pulp chambers containing an acetate buffer solution. After bleaching, the solution was collected and adequately proportioned with leucocrystal violet, peroxidase enzyme, and deionized water. The resulting solution was evaluated using ultraviolet visible reflectance spectrophotometer equipment. The data were analyzed by analysis of variance (ANOVA) and Fisher's PLSD at a significance level of 0.05, and significant differences in the penetration of peroxide in different substrate conditions were observed (p<0.0001). The penetration of hydrogen peroxide was more intense in cracked teeth. The group in which the enamel was microabraded showed intermediate values when compared to the control group. Microabrasion and the presence of cracks in the enamel make this substrate more susceptible to penetration of hydrogen peroxide during in-office whitening.