Co-doped titanium dioxide nanoparticles decrease the cytotoxicity of experimental hydrogen peroxide gels for in-office tooth bleaching.

OBJECTIVE: To evaluate the efficacy and cytotoxicity of experimental 6% and 35% hydrogen peroxide gels (HP6 or HP35) incorporated with titanium dioxide nanoparticles (NP) co-doped with nitrogen and fluorine and irradiated with a violet LED light (LT). METHODS: Bovine enamel-dentin disks adapted to artificial pulp chambers were randomly assigned to bleaching (n = 8/group): NC (negative control), NP, HP6, HP6 + LT, HP6 + NP, HP6 + NP + LT, HP35, HP35 + LT, HP35 + NP, HP35 + NP + LT, and commercial HP35 (COM). Color (ΔE00) and whiteness index (ΔWID) changes were measured before and 14 days after bleaching. The extracts (culture medium + diffused gel components) collected after the first session were applied to odontoblast-like MDPC-23 cells, which were assessed concerning their viability, oxidative stress, and morphology. The amount of HP diffused through the disks was determined. Data were analyzed by generalized linear models or Kruskal Wallis Tests (α = 5%).  RESULTS: HP6 + NP + LT exhibited ΔE00 and ΔWID higher than HP6 (p < 0.05) and similar to all HP35 groups. HP6 + NP + LT showed the lowest HP diffusion, and the highest cell viability (%) among bleached groups, preserving cell morphology and number of living cells similar to NC and NP. HP6 + LT, HP6 + NP, and HP6 + NP + LT exhibited the lowest cell oxidative stress among bleached groups (p < 0.05). HP35, HP35 + LT, and HP35 (COM) displayed the lowest cell viability. CONCLUSION: HP6 achieved significantly higher color and whiteness index changes when incorporated with nanoparticles and light-irradiated and caused lower cytotoxicity than HP35 gels. The nanoparticles significantly increased cell viability and reduced the hydrogen peroxide diffusion and oxidative stress, regardless of HP concentration. CLINICAL SIGNIFICANCE: Incorporation of co-doped titanium dioxide nanoparticles combined with violet irradiation within the HP6 gel could promote a higher perceivable and acceptable efficacy than HP6 alone, potentially reaching the optimal esthetic outcomes rendered by HP35. This approach also holds the promise of reducing cytotoxic damages and, consequently, tooth sensitivity.

Effects of black tea tooth staining previously to 35% hydrogen peroxide bleaching

Aim: To determine if the artificial staining with black tea (BT) influences the enamel microhardness before in-office bleaching and if BT staining is necessary to evaluate the efficacy of bleaching with 35% hydrogen peroxide Methods: Enamel/dentin blocks were randomized into groups according to the staining protocol (n=5/group): (CO) control ­ maintained in artificial saliva solution (AS); (BT4) immersed in black tea solution for 4 h; (BT24) immersed in black tea solution for 24 h. After the staining protocols, all specimens were kept in AS for one week, followed by bleaching (three sessions of HP application for 40 min). Knoop surface microhardness (kgF/mm2) was determined at baseline (T0), after staining (T1), after 7 days of storage in AS (T2), and after bleaching (T3). The color (∆E00) and coordinate changes (∆L, ∆a, ∆b) were measured using a digital spectrophotometer at T0 and T3. Data were submitted to one-way (∆E00, ∆L, ∆a, ∆b) or two-way ANOVA repeated measures (kgF/mm2) and Tukey's test (a=5%). Results: The staining protocols (BT4 and BT24) promoted significantly lower microhardness (T1 and T2, p<0.05) than CO, whereas CO was the only group to maintain microhardness values over time. Bleaching promoted perceptible ∆E00 without a significant difference among the groups regardless of the staining protocol (p=0.122). CO and BT4 showed no differences in terms of ∆L and ∆a (p>0.05), but BT4 displayed a higher ∆b than CO. Conclusion:The artificial staining with BT negatively affected the enamel surface microhardness and was not essential to evaluate the efficacy of 35% hydrogen peroxide bleaching

Characterization of Experimental Nanoparticulated Dental Adhesive Resins with Long-Term Antibacterial Properties.

Experimental adhesives with functional nitrogen-doped titanium dioxide nanoparticles (N_TiO2) have been shown to display improved properties. However, these materials have not been characterized regarding their degree of conversion (DC), biaxial flexure strength (BFS), surface roughness (SR), elastic modulus (EM), and long-term antibacterial functionalities. Experimental adhesives were synthesized by dispersing N_TiO2 (10%, 20%, or 30%, v/v%) into OptiBond Solo Plus (OPTB, Kerr Corp., USA). Unpolymerized adhesives (volume = 50 µL/drop, n = 3/group) were individually placed onto a heated (37 °C) attenuated total reflectance (ATR) monolithic diamond crystal (Golden Gate, Specac). The spectra of composites were obtained with a Fourier-transform infrared (FTIR) spectrometer (Nicolet IS50; 500-4500 cm-1; resolution = 4 cm-1, 10 internal scans/spectrum) before and after polymerization. Disk-shaped specimens (diameter = 6.0 mm, thickness = 0.5 mm) for BFS (n = 12/group), SR and EM (n = 3/group), and for antibacterial testing (n = 18/group/time-point) were fabricated and photopolymerized (1 min each; 385-515 nm, 1000 mW/cm2; VALO). DC values (%) were calculated from pre- and post-polymerization spectra using the two-frequency method and tangent-baseline technique. BFS was assessed using a universal testing machine (Instron 68TM-5, crosshead speed = 1.27 mm/min, 25 °C). SR and EM were investigated using an atomic force microscope (Multimode 8) with aluminum-coated silicon probes (8 nm pyramidal tip, spring constant 40 N/m, Bruker). Antibacterial testing was performed by growing Streptococcus mutans biofilms (UA159-ldh, 37 °C, microaerophilic) on the surfaces of specimens for 24 h and then measuring the relative luminescence units (RLU) with a Biotek Synergy HT multi-well plate reader. Results demonstrate that experimental materials containing 10%, 20%, and 30% of N_TiO2 displayed higher levels of DC, had better mechanical properties, and were able to exert strong and durable antibacterial properties without visible light irradiation and after extended periods of simulated shelf-life and aging in PBS. The reported experimental materials are expected to increase the service lives of polymer-based bonded restorations by decreasing the incidence of secondary caries.

Antibacterial efficacy of non-thermal atmospheric plasma against Streptococcus mutans biofilm grown on the surfaces of restorative resin composites.

The aim of this study was to evaluate the antimicrobial efficacy of non-thermal atmospheric plasma (NTAP) against Streptococcus mutans biofilms. Resin discs were fabricated, wet-polished, UV sterilized, and immersed in water for monomer extraction (37 °C, 24 h). Biofilms of bioluminescent S. mutans strain JM10 was grown on resin discs in anaerobic conditions for (37 °C, 24 h). Discs were divided into seven groups: control (CON), 2% chlorhexidine (CHX), only argon gas 150 s (ARG) and four NTAP treatments (30 s, 90 s, 120 s, 150 s). NTAP was applied using a plasma jet device. After treatment, biofilms were analyzed through the counting of viable colonies (CFU), bioluminescence assay (BL), scanning electron microscopy (SEM), and polymerase chain reaction (PCR). All NTAP-treated biofilm yielded a significant CFU reduction when compared to ARG and CON. BL values showed that NTAP treatment for 90 s, 120 s or 150 s resulted in statistically significantly lower metabolic activity when compared to the other groups. CHX displayed the lowest means of CFU and BL. SEM showed significant morphological changes in NTAP-treated biofilm. PCR indicated damage to the DNA structure after NTAP treatment. NTAP treatment was effective in lowering the viability and metabolism of S. mutans in a time-dependent manner, suggesting its use as an intraoral surface-decontamination strategy.

The Applicability of a Drop Penetration Method to Measure Contact Angles on TiO2 and ZnO Nanoparticles.

In this study, six solvents (water, diiodomethane, bromonaphthalene, formamide, ethanol and ethylene glycol) were examined for three nanoparticle substrates, zinc oxide and titanium dioxide (21 nm and 100 nm), with the goal of assessing the suitability of a modified drop penetration method (DPM) for orders of magnitude smaller particles. Nanoparticles were compressed into flat discs and the solvent dropped on the surface while the image with time was recorded. Contact angles were in reasonable agreement with literature over the range of 20-80°, but failed to provide acceptable results for surface energy components. It was necessary to eliminate certain solvents and substrates not meeting the selection criteria.

Immediate Implant Placement and Provisionalization Using the Patient's Extracted Crown: 12-Month Follow-Up.

STATEMENT OF PROBLEM: Immediate placement and provisionalization of implants in fresh sockets has been previously demonstrated to be a predictable treatment in the restoration of non-recoverable teeth in the anterior regions of the maxilla. PURPOSE: This article reports a clinical case in which an immediate implant placement protocol was used in combination with two distinct and sequential grafts (bovine bone and connective tissue, respectively) followed by immediate implant provisionalization using the patient's crown of an extracted tooth. CLINICAL REPORT: Physical, clinical, and image examinations of the patient (female, 23 years old) revealed a maxillary central incisor (tooth No. 8) with slight mobility due the presence of extensive cervical resorption. The treatment proposed was the atraumatic extraction of the tooth followed by immediate implant placement and provisionalization. Two grafts (bovine bone and connective tissue) were used due to the presence of a very thin maxillary bone plate associated with a thin gingival biotype. RESULTS: The use of the extracted crown as a temporary crown after immediate implant placement resulted in immediate attainment of an esthetically pleasing outcome and long-term favorable results. CONCLUSION: The treatment protocol proposed can be efficiently used to immediately restore the patient's esthetics and function while maintaining the health, volume, and contours of gingival tissues over a 12-month follow-up period. CLINICAL IMPLICATIONS: Anterior teeth extractions typically require the execution of single-unit prostheses using dental materials of synthetic origin (such as polymers), which often are incapable of achieving the esthetic and physiological results patients expect. The use of the patient's own crown was demonstrated, which allowed good clinical results to be achieved and the natural shape and function of tissues to be maintained.

ScanWhite: método objetivo para avaliação do nível de clareamento dentário / ScanWhite: Objective method for dental bleaching level evaluation

Introdução: o clareamento dentários pode ser avaliado por meio de técnicas comparativas subjetivas (visual) ou objetivas (instrumental). Essa última tem se mostrado mais adequado para tal tipo de avaliação. Métodos: a avaliação do sistema foi realizado em laboratório, utilizando-se uma câmara digital, escala de cores Vita Classical e tres diferentes tipos de iluminação. No total, foram realizadas 480 imagens. Em seguida, o software foi avaliado quanto à sua eficiência clínica. Para tal, foi selecionado um caso de microabrasão complementado com clareamento dentário fotoacelerado. Resultados: os testes laboratoriais com diferentes iluminantes apresentaram resultados similares. Clinicamente, foram obsaervados diferentes níveis de clareamento em cada uma das sessões clínicas realizadas. Discussão: os vários métodos objetivos disponíveis atualmente apresentam diferentes graus de imitação na análise da cor de corpos semitranslúcidos (por exemplo, dentes e materiais dentários). Essas estão relacionadas ao posicionamento e ao sistema de cor utilizado (por exemplo, RGB, CYM) por cada equipamento. Portanto, o método proposto apresenta algumas vantagens em relação aos sistemas objetivos, como a ausência da necessidade de manutenção do posicionamento da amostra ou do paciente, algoritmo calibrador e a geração de gráficos e laudos. Conclusões: as comprovações geradas pelo sistema proposto geram maior conforto e segurança durante o tratamento

Introduction: The dental bleaching outcome can be evaluated using subjective (visual) and objective (instrumental) comparative techniques. The latter has demonstrated more suitable results to that kind of evaluation. Methods: The assessment of the proposed system was realized in th laboratory using Vita Classical color pallets, digital camera and three different illuminations. In total, 480 images were acquired. Next, the software was evaluated to check its clinical efficiency.For this, a case of micro-abrasion complemented with photoacelerated dental bleaching was chosen. Results: The laboratorial tests with different illuminants showed similar results. Clinically different levels of dental bleaching were observed in each one of the clinical appointments realized. Discussion: The several objective methods available nowadays present different limitation levels when analysing semitranslucid samples (e.g. teeth and dental materials). These limitations are related with the samples's position and with the color space used by each system (e.g. RGB, CYM). Therefore, the proposed method shows some advantages when compared with the traditional objective methods, such as the absence of position maintenance of the sample or of the patient, calibration algorithm and generation of graphs and reports. Conclusions: The outcomes generated by the proposed system can provide more security both to patient and professional during the treatment