The development of dental adhesive resins with long-lasting antibacterial properties is a possible solution to overcome the problem of secondary caries in modern adhesive dentistry. Objectives: Synthesis and characterization of nitrogen-doped titanium dioxide nanoparticles (N_TiO2), (ii) topographical, compositional and wettability characterization of thin-films (unaltered and experimental) and, (iii) antibacterial efficacy of N_TiO2-containing dental adhesives against Streptococcus mutans biofilms. Materials and methods: Nanoparticles were synthesized and characterized using different techniques. Specimens (diameter= 12 mm, thickness ≅ 15 μm) of OptiBond Solo Plus (Kerr Corp., USA) and experimental adhesives [50, 67 and 80% (v/v)] were fabricated, photopolymerized (1000 mW/cm2, 1 min) and UV-sterilized (254 nm, 800,000 μJ/cm2) for microscopy, spectroscopy, wettability and antibacterial testing. Wettability was assessed with a contact angle goniometer by dispensing water droplets (2 μL) onto four random locations of each specimen (16 drops/group). Drop profiles were recorded (1 min, 25 frames/sec, 37°C) and contact angles were calculated at time=0s (θINITIAL) and time=59s (θFINAL). Antibacterial testing was performed by growing S. mutans (UA159-ldh, JM10) biofilms for either 3 or 24 hours (anaerobic conditions, 37°C) with or without continuous light irradiation (410 ± 10 nm, 3h= 38.75 J/cm2, 24h= 310.07 J/cm2) against the surfaces of sterile specimens. Results: N_TiO2 was successfully prepared using solvothermal methods. Doped-nanoparticles displayed higher light absorption levels when compared to undoped titania. Experimental adhesives demonstrated superior antibacterial efficacy in dark conditions. Conclusions: The findings presented herein suggest that N_TiO2 is a feasible antibacterial agent against cariogenic biofilms.

BackgroundNovel multifunctional biomaterials were recently designed to allow for an optimized tissue regeneration process.PurposeTo comprehensively assess (photographic, radiographic and histological) the in vivo functionality of demineralized bovine bone matrix (DBM) associated with an experimental marine organic extract (MOE) from nacre in a sheep ectopic grafting model.Materials and methodsSynthesis of MOE was based on mixing powdered nacre (0.05 g, particles average size <0.1 mm) with acetic acid (5 mL, pH 7) under constant stirring for 72 hours (25 °C). Polyethylene tubes (3/animal, n = 4, diameter: 5.0 mm × length: 10.0 mm) from the control (empty) or experimental groups (DBM or DBM + MOE) were then intramuscularly implanted into the lumbar regions of sheep (n = 8, 2-years old, ≈45 kg). Animals were euthanized at 3 and 6 months to allow for the collection of tissue samples. Tissue samples were fixed in formalin 10% (buffered, 7 days) in preparation for photographic, radiographic and histological assessments. Acquired images were then analyzed using digital image analysis software to quantify the amount of neoformed tissues, whereas radiographic and histological analyses were performed to determine radiopacity and classification of tissues deposited inside of the tubes.ResultsPhotographic and radiographic analyses have shown that both pure (unaltered) and MOE-modified DBM were capable of depositing neoformed tissues (at 3 and 6 months), where higher levels of deposition and radiopacity were observed on groups treated with experimental materials. Histological results, however, demonstrated that tissues formed from both unaltered and MOE-modified DBM were only fibrous connective in origin.ConclusionsAs an ectopic grafting in sheep, the experimental organo-biomaterial association applied did not reveal any osteoinductive property but led to a fibrous tissue repair only.

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Objective. The present work shows the optimization of a high-throughput bioluminescence assay to assess the metabolism of intact Streptococcus mutans biofilms and its utility as a screening method for nanofilled antibacterial dental materials. Methods. The assay was optimized by monitoring changes in bioluminescence mediated by variation of the experimental parameters investigated (growth media and sucrose concentration, inoculum:D-Luciferin ratio, dilution factor, inoculum volume, luminescence wavelength, replicate and luciferase metabolic activity). Confocal microscopy was then used to demonstrate the impact of biofilm growth conditions on the 3-D distribution of extracellular polymeric substance (EPS) within Streptococcus mutans biofilms and its implications as confounding factors in high-throughput studies (HTS). Results. Relative Luminescence Unit (RLU) values from the HTS optimization were analyzed by multivariate ANOVA ( α = 0.05) and coefficients of variation, whereas data from 3-D structural parameters and RLU values of biofilms grown on experimental antibacterial dental adhesive resins were analyzed using General Linear Models and Student–Newman–Keuls post hoc tests ( α = 0.05). Confocal microscopy demonstrated that biofilm growth conditions significantly influenced the quantity and distribution of EPS within the 3-D structures of the biofilms. An optimized HTS bioluminescence assay was developed and its applicability as a screening method in dentistry was demonstrated using nanofilled experimental antibacterial dental adhesive resins. Significance. The present study is anticipated to positively impact the direction of future biofilm research in dentistry, because it offers fundamental information for the design of metabolic-based assays, increases the current levels of standardization and reproducibility while offering a tool to decrease intra-study variability.

Meta-analysis Implantodontology Enéias Carpejani ROSA (a) Tatiana Miranda DELIBERADOR (a) Tuanny Carvalho de Lima do NASCIMENTO (a) Cibele Cândida de Almeida KINTOPP (a) Juliana Shaia Rocha ORSI (a) Letícia Maíra WAMBIER (a)