Fernando Luis Esteban Florez

Real-time assessment of Streptococcus mutans biofilm metabolism on resin composite

OBJECTIVE The release of unpolymerized monomers and by-products of resin composites influences biofilm growth and confounds the measurement of metabolic activity. Current assays to measure biofilm viability have critical limitations and are typically not performed on relevant substrates. The objective of the present study was to determine the utility of firefly luciferase assay for quantification of the viability of intact biofilms on a resin composite substrate, and correlate the results with a standard method (viable colony counts). METHODS Disk-shaped specimens of a dental resin composite were fabricated, wet-polished, UV-sterilized, and stored in water. Biofilms of Streptococcus mutans (strain UA159 modified by insertion of constitutively expressed firefly luc gene) were grown (1:500 dilution; anaerobic conditions, 24h, 37°C) in two media concentrations (0.35x and 0.65x THY medium supplemented with 0.1% sucrose; n=15/group). An additional group of specimens with biofilms grown in 0.65x+sucrose media was treated with chlorhexidine gluconate solution to serve as the control group. Bioluminescence measurements of non-disrupted biofilms were obtained after addition of d-Luciferin substrate. The adherent biofilms were removed by sonication, and bioluminescence of sonicated bacteria was then measured. Viable colony counts were performed after plating sonicated bacteria on THY agar plates supplemented with spectinomycin. Bioluminescence values and cell counts were correlated using Spearman correlation tests (α=0.05). RESULTS Strong positive correlations between viable colony counts and bioluminescence values, both before- and after-sonication, validated the utility of this assay. SIGNIFICANCE A novel non-disruptive, real-time bioluminescence assay is presented for quantification of intact S. mutans biofilms grown on a resin composite, and potentially on antibacterial materials and other types of dental biomaterials.

Optical Dental Whitening Efficacy of Blue Covarine Toothpaste in Teeth Stained by Different Colors.

OBJECTIVE Evaluate the immediate and cumulative optical whitening efficacy of a blue covarine toothpaste. MATERIALS AND METHODS 180 bovine tooth specimens with similar shade (ΔE < 3.5) were staining of different beverage: black tea(BT), green tea (GT), red wine (RW), orange soda (OS), and brazilian açai juice (AJ), and then submitted to tooth brushing with a blue covarine toothpaste (Op) or a control abrasive toothpaste (Ab). The whitening effect was evaluated at baseline (B), after staining (S), after 1 day (1D) and 7 days of cumulative use of toothpastes (7D). The color shade chances were assessment by Vita Easyshade reflectance spectroscope and the data of CIELab color coordinates (L*, a*, and b*), color difference (ΔE) and the whiteness index optimized (WIO), were analyzed by two-way mixed analysis of variance (ANOVA) for repeated measures and Bonferroni-corrected t-tests (α = 0.05). RESULTS The analysis showed statistically significant differences before and after staining by colored beverages (p < 0.05), but no differences were found due to the action of toothpaste (p > 0.05), in the CIELab coordinates, ΔE and WIO index. CONCLUSIONS The use of toothpastes (Op or Ab) reduced the dental staining caused by different colored beverage, but the whitening effect of blue covarine toothpaste could not be confirmed (p > 0.05).

Aged composite resins ablation under different parameters of Er:YAG laser: ablation rate and morphological aspects

This work presents a study to understand the interaction between Er:YAG laser and composite resin. The main purpose is the development of a new ultra-conservative clinical technique: differential ablation for composite resin restorations using Er:YAG laser. A hybrid composite resin (Z100, 3M, USA) formatted as tablets recently cured was used and after artificial aging method the teeth were irradiated with a Er:YAG laser and two different conditions were considered, energy level per pulse (100, 300 and 500mJ), frequencies (5, 10 and 15Hz) and different water fluxes. Diameter and depth of each resulted microcavity was measured and the material removed volumes were calculated. The resulted values were plotted and feted to allow a comparative observation of the material removed as a function of energy level per pulse. Frequencies of 5 and 10Hz were similar between them and seemed to allow the highest material ablated volume, however considering the energy per pulse parameter, 300mJ was more efficient than the others, mainly when water flux was around 0.1ml/s. The highest water flux showed lower ablation rate with the lowest fluency. Water fluxes presented an important factor considering composite ablation, even because it could modulate depth and surface regularity of the irradiated material.

Comparative assessment of the organization of the colors of the Vita Classical color pallet by digital images and visual analysis for dental bleaching

New formularizations, techniques and devices have become the dental whitening most safe and with better results. Although this, the verification of the levels whitening is being continued for visual comparison, that is an empirical, subjective method, subject to errors and dependent of the individual interpretation. Normally the result of the whitening is express for the amplitude of displacement between the initial and the final color, being take like reference the tonalities of a scale of color commanded of darkest for more clearly. Although to be the most used scale , the ordinance of the Vita Classical ® - Vita, according to recommendations of the manufacturer, reveals inadequate for the evaluation of the whitening. From digital images and of algorithm OER (ordinance of the reference scale), especially developed for the ScanWhite ©, the ordinance of the tonalities of the scale Vita Classical® was made. For such, the values of the canals of color R, G, and B of medium part average of the crowns was adopted as reference for evaluation. The images had been taken with the camera Sony Cybershoot DSC F828. The results of the computational ordinance had been compared with the sequence proposal for the manufacturer and with the earned one for the visual evaluation, carried through by 10 volunteers, under standardized conditions of illumination. It statistics analyzes demonstrated significant differences between the ordinances.

Quantification of the efficiency for Photo-bleached pigments using cellulose matrixes as substrate and digitalized gray scale

The bleaching process is been objective of many studies since the beginning of the XX century. Heat has been used to activate the hydrogen peroxide; the aesthetic results were satisfactory, but associated with this process high incidence of hypersensitivity as well as radical endodontic treatment was observed making this technique clinically hard to implemented. Nowadays the dental bleaching is one of the most wanted aesthetic procedures by the population at the dental office. With the utilization of new light sources as LASER and LED a technique to evaluate the efficiency of photo-bleaching of many pigments is necessary. This work demonstrates a new method to quantify the breakage of pigments on a cellulose matrix using a blue LED system with 1W/cm2. We employed a computational analysis and digital spectroscopy. These matrixes were used because of its inert physical-chemical properties. The obtained results are within the expectative, where the groups irradiated with light presents more broken pigments that the group with no light, it was also possible to observe on this experiment that light acts decreasing the free energy of the reaction and that way speeding up the rate of bleaching.

Antibacterial dental adhesive resins containing nitrogen-doped titanium dioxide nanoparticles

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 (i) 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/s, 37 °C) and contact angles were calculated at time = 0 s (θINITIAL) and time = 59 s (θFINAL). Antibacterial testing was performed by growing S. mutans (UA159-ldh, JM10) biofilms for either 3 or 24 h (anaerobic conditions, 37 °C) with or without continuous light irradiation (410 ± 10 nm, 3 h = 38.75 J/cm2, 24 h = 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.

In vivo regeneration functionalities of experimental organo-biomaterials containing water-soluble nacre extract

Background Novel multifunctional biomaterials were recently designed to allow for an optimized tissue regeneration process. Purpose To 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 methods Synthesis 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. Results Photographic 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. Conclusions As 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.

Flexural properties of rectangular nickel-titanium orthodontic wires when used as ribbon archwires.

OBJECTIVE: To compare the flexural properties of rectangular nickel-titanium (Ni-Ti) orthodontic wires in occlusoapical and faciolingual orientations using a standardized test method. MATERIALS AND METHODS: Twenty-two rectangular Ni-Ti wire groups were tested in occlusoapical (ribbon) orientation: eight conventional Ni-Ti products, five superelastic Ni-Ti products, and nine thermal Ni-Ti products (n = 10 per group). Six products of thermal Ni-Ti wire were tested in faciolingual (edgewise) orientation. A three-point bending test was performed to measure deactivation force at 3.0-, 2.0-, 1.0-, and 0.5-mm deflections of each rectangular wire at 37.0 ± 0.5°C. Analysis of variance and post hoc Student-Newman-Keuls tests were used to compare the mean values of the different groups (α = .05). RESULTS: The ranges of deactivation forces varied greatly with different kinds, sizes, products, and deflections of Ni-Ti wires. One product of conventional and superelastic Ni-Ti wires had steeper force-deflection curves. Four products had similarly shaped flat force-deflection curves, whereas the sixth product had a moderately steep force-deflection curve. Thermal Ni-Ti wires had smaller deactivation forces ranging from 0.773 N (78.8 g) to 2.475 N (252.4 g) between deflections of 1.0 and 0.5 mm, whereas wider ranges of force from 3.371 N (343.7 g) to 9.343 N (952.7 g) were predominantly found among conventional Ni-Ti wires between deflections of 3.0 and 2.0 mm. CONCLUSIONS: Clinicians should critically select archwires for use in the occlusoapical orientation not only based on Ni-Ti wire type, size (0.022 × 0.016-in or 0.025 × 0.017-in), and product but also with deactivation deflections from 0.5 and 1.0 mm to obtain light forces in the occlusoapical orientation.

Appraisal "In Vitro" of Antimicrobial Activity Photodynamic Therapy on Streptococcus Mutans over Dental Biofilm "In Situ"

The Photodynamic Antimicrobial Chemotherapy (PACT) has shown a promising alternative for oral disinfection. Thus, the purpose of this study was to investigate in situ the antimicrobial effect of photodynamic therapy over Streptococcus mutans biofilm by the use of different photosenstizers. Eighteen (n=18) pacients were randomly selected and used one removable palatine device that contained six enamel/dentine specimens of 5×5×2 mm. These patients used these devices during four days, after that the biofilm created over the specimens were treated using curcumine and Photogem® solutions associated with a light-emitting diode under energy density of 45J/cm 2. The effect of PACT treatments was evaluated by viability in colonyforming units per milliliter (CFU mL−1). Although, significant reductions in the bacterial count were observed for PACT with Photogem® photosensitizer (p=0.02), the results of this study suggests an antimicrobial effect of photodynamic therapy over biofilms by the use of curcumine (1.500µg/mL) and Photogem® (1.000µg/mL) solutions followed by LED system irradiation (λ=450± and 630±5nm).

Background interference on the color of dental composite materials with different thickness by digital contrast

In this work the color dependence of resin composites with the background color was evaluated. The objective was to measure since what thickness the color of the sample stops being influenced by the color of the background over which the resin is placed and the methodology used in experiment was based in analyzing the contrast of digital images of the sample over a black background. The results shown that since 0.8 mm the images contrast becomes almost constant; it prove that since this thickness the color of resin composite depends on the optical resin properties only. The experiment was repeated under three conditions of luminosity to evaluate the influence of it on the image contrast and the results obtained were identical.