Technique for Darkening of Extracted Teeth Simulating Pulpal Necrosis Discoloration.

Background: The use of discolored teeth is required to test whitening products, and it is difficult to obtain them, given their scarcity. Objective: To present a technique for in vitro darkening of extracted teeth simulating pulpal necrosis discoloration. Materials and Methods: Hemolysates I and II from human blood were subjected or not to laser irradiation (442 nm) for 1 h. The concentration of oxyhemoglobin (O2Hb) was analyzed by ultraviolet/visible spectroscopy, and the conversion of O2Hb to methemoglobin (MetHb) by transmission spectroscopy was assessed immediately and after 3 and 40 days. For darkening evaluation, bovine incisors were divided into two groups (n = 25), and their pulp chambers were filled with hemolysate solution II (HSII) and hemolysate II solution + laser (HSII+L). After storage in artificial saliva for 40 days at 37°C, color changes were measured by a colorimeter and ΔE was compared with the NBS parameters. Data were analyzed using a mixed linear model (α=5%). Results: HSII+L presented the lowest O2Hb and higher MetHb. The conversion of O2Hb to MetHb in HSII+L was 42% higher than in HSII. Both groups were effective in darkening the teeth, according to the NBS. Darkening stabilized from day 35. HSII promoted a marked color difference. Conclusion: The proposed technique was effective in darkening the extracted teeth simulating necrosis discoloration for in vitro models.

Design of Nanostructured Lipid Carriers Containing Cymbopogon martinii (Palmarosa) Essential Oil against Aspergillus nomius.

Palmarosa essential oil (PEO) is an alternative to synthetic fungicides to control the contamination by food-deteriorating fungi, such as Aspergillus nomius. Nonetheless, the low long-term stability and volatility hamper its utilization. Thus, this study aimed to develop nanostructured lipid carriers (NLCs) containing PEO to improve its stability and consequently prolong the activity against A. nomius. A mixture design was applied to find the best preparation conditions for antifungal activity. The characterization analyses included size measurements, zeta potential (ζ-potential), entrapment efficiency (EE), and antifungal activity (by inhibition of mycelial growth (IMG) and/or in situ test (pre-contaminated Brazil nuts) tests). The nanocarriers presented particle sizes smaller than 300 nm, homogeneous size distribution, ζ-potential of -25.19 to -41.81 mV, and EE between 73.6 and 100%. The formulations F5 and F10 showed the highest IMG value (98.75%). Based on the regression model, three optimized formulations (OFs) were tested for antifungal activity (IMG and in situ test), which showed 100% of inhibition and prevented the deterioration of Brazil nuts by A. nomius. The preliminary stability test showed the maintenance of antifungal activity and physicochemical characteristics for 90 days. These results suggest a promising system as a biofungicide against A. nomius.

Studies of the early stages of the dynamic setting process of chemically activated restorative glass-ionomer cements.

OBJECTIVE: To evaluate the early stages of the setting process of chemically activated restorative glass-ionomer cements (GICs). MATERIAL AND METHODS: Five GICs were evaluated (n = 5): Equia Forte (GC), Equia Forte HT (GC), Ketac Universal (3M ESPE), Maxxion R (FGM) and Riva Self Cure (SDI) by Thermography, Fourier Transform Infrared Attenuated Total Reflectance Spectroscopy (FTIR-ATR) and Gillmore needle indentation mechanical testing. The FTIR-ATR spectra showed the formation of metal carboxylates within the cements and enabled the stabilization time (ST) to be determined and the thermographic camera measured the temperature field images in the sample. Data were statistically analyzed by ANOVA and Tukey-Kramer (α = 5%). RESULTS: The Gillmore needle test showed that the order of hardening was opposite to the order of ST values determined by FTIR. The results with the thermographic camera showed two stages of temperature variation, which coincided with the evolution of specific infrared bands. The exception was Maxxion R, which showed only a single step change in temperature. CONCLUSION: The early stages of the GIC setting reaction show temperature changes, both endothermic and exothermic, at specific times, confirming the occurrence of individual chemical reactions. The early setting involves reactions other than carboxylate formation.Significance: This study gives further detail of the early stages of the setting of GICs, and past research regarding the setting reaction of GIC.

DSC analysis and evaluation of forces released on deactivation of 0.40-mm (0.016") orthodontic thermo-activated NiTi wires: An in vitro study.

Background. This study evaluated the phase transformation of NiTi orthodontic wires and forces they release on deactivation. Methods. The structural phase transformations of the following five thermo-activated nickel-titanium (NiTi) wires were evaluated using differential scanning calorimetry (DSC): Flexy Thermal Sentalloy® (GAC International), NiTi (35ºC) (Eurodonto), Thermo-Plus® (Morelli), FlexyNiTi® Flexy Thermal (35ºC) (Orthometric) and Damon® CuNiTi (35ºC) (ORMCO Corp.). The wires had a cross-section of 0.40 mm (0.016"). In addition, the forces they released were investigated using the three-point bending test. Five arches of each wire were tested using DSC (-20/80ºC at 10ºC/min), and six arches from each wire were sectioned for bending tests. The data were analyzed with ANOVA and post hoc Tukey tests. Pearson's correlation test was performed between the results yielded by the DSC tests and those by three-point analyses (P=0.05). Results. The DSC analysis showed differences between the NiTi alloys from all the manufacturers, with no differences between the lots of the same brand. ORMCO and Orthometric wires exhibited similar TTR values in cooling (P=0.49), and statistically similar TTR values in heating (P=0.056). The three-point bending test showed different patterns in releasing forces. A correlation was found between the DSC analysis and the three-point bending test results. Conclusion. The higher the temperature transformation was, the larger was the variation of force. All the wires presented higher forces at 3-mm deflection from 155 (±12.3) to 168.1 (±8) cN. The DSC analysis and the three-point bending test showed differences between the NiTi alloys from all the manufacturers.

Study of the chemical interaction between a high-viscosity glass ionomer cement and dentin.

OBJECTIVE: To investigate the chemical interactions between a high-viscosity glass ionomer cement (GIC) (KetacTM Molar Easymix, 3M ESPE, Seefeld, Bavaria, Germany) and human dentin. It was also analyzed the dynamics of GIC setting mechanism based on the time intervals required for the GIC and the GIC mixed with dentin to achieve stability. MATERIAL AND METHODS: Each constituent of GIC - powder (P) and liquid (L) - and powdered dentin (D), as well as the associations P+L, D+L, and P+L+D in the concentrations of 29%, 50%, 65%, 78%, 82%, and 92% of GIC were analyzed with Fourier transform infrared (FTIR) and Raman spectroscopy. RESULTS: New optical absorption bands and/or Raman bands, which were not present in P, L, or D, were observed in the associations. The concentrations of 29% and 50% of GIC showed higher interaction, revealing that the amount of dentin influences the formation of new optical absorption or scattering bands. FTIR bands showed that the setting time to achieve bond stability was longer for the high-viscosity GIC (38±7 min) than for the sample with 29% of GIC (28±4 min). CONCLUSIONS: The analysis revealed the formation of new compounds or molecular rearrangements resulting from the chemical interactions between GIC and dentin. Moreover, this study provides an effective method to evaluate the dynamics of the setting mechanism of GICs.

Challenges in luting fibre posts: Adhesion to the post and to the dentine.

OBJECTIVE: To investigate the relationship between physicochemical interactions of resin luting cements with dentine and retention of fibre posts in root canals. METHODS: Retention of fibre posts (RelyX Fiber Post) was assessed by the pull-out method. The diffusion zone of the cements and their chemical interaction with dentine were estimated by micro-Raman spectroscopy. Resin luting cements employing etch-and-rinse (Rely X Ultimate and Variolink II), self-etch (Rely X Ultimate and Panavia F2.0), or self-adhesive (RelyX Unicem 2) modes were investigated. Data were analyzed by analysis of variance followed by Tukey HSD tests. RESULTS: The retention of the fibre posts decreased in the following order: RelyX Ultimate, etch-and-rinse mode>RelyX Unicem 2≥RelyX Ultimate, self-etch mode≥Panavia F2.0≥Variolink II (p<0.05). One of the etch-and-rinse mode cements presented the deepest diffusion zone, while the other, along with the self-adhesive cement, produced the shallowest zone. Cements used in the self-etch mode showed intermediary diffusion into dentine (p<0.05). All resin luting cements showed some degree of chemical interaction with dentine, the highest recorded for RelyX Ultimate used in the etch-and-rinse mode and the lowest for Panavia F2.0 (p<0.05). The retention of fibre posts in the root canal could be attributed neither to the mode of interaction of the luting cements with dentine nor to their ability to diffuse into dentine. SIGNIFICANCE: Chemical interaction between the resin luting cement and the dentine paired with adequate post pretreatment contribute positively to the retention of fibre posts.

Study of the chemical interaction between a high-viscosity glass ionomer cement and dentin

Abstract Objective To investigate the chemical interactions between a high-viscosity glass ionomer cement (GIC) (KetacTM Molar Easymix, 3M ESPE, Seefeld, Bavaria, Germany) and human dentin. It was also analyzed the dynamics of GIC setting mechanism based on the time intervals required for the GIC and the GIC mixed with dentin to achieve stability. Material and Methods Each constituent of GIC - powder (P) and liquid (L) - and powdered dentin (D), as well as the associations P+L, D+L, and P+L+D in the concentrations of 29%, 50%, 65%, 78%, 82%, and 92% of GIC were analyzed with Fourier transform infrared (FTIR) and Raman spectroscopy. Results New optical absorption bands and/or Raman bands, which were not present in P, L, or D, were observed in the associations. The concentrations of 29% and 50% of GIC showed higher interaction, revealing that the amount of dentin influences the formation of new optical absorption or scattering bands. FTIR bands showed that the setting time to achieve bond stability was longer for the high-viscosity GIC (38±7 min) than for the sample with 29% of GIC (28±4 min). Conclusions The analysis revealed the formation of new compounds or molecular rearrangements resulting from the chemical interactions between GIC and dentin. Moreover, this study provides an effective method to evaluate the dynamics of the setting mechanism of GICs.

Development of a technique for psyllium husk mucilage purification with simultaneous microencapsulation of curcumin.

This study focused on evaluating a technique for the psyllium husk mucilage (PHM) purification with simultaneous microencapsulation of curcumin. PHM was extracted with water and purified with ethanol. For the mucilage purification and simultaneous microencapsulation, an ethanolic solution of curcumin was used. After dehydration, the samples were analysed by instrumental techniques and evaluated for thermal stability. The presence of curcumin in the solution did not impair the yield of precipitated polysaccharide. Interactions of the dye and carbohydrates were confirmed by displacement of peaks in FT-IR and FT-Raman spectroscopy. The onset temperature of degradation of microcapsules was superior to that of curcumin. Thermal stability in solution at 90°C also improved. After 300 minutes of heating, the microcapsules had a remnant curcumin content exceeding 70%, while, in standard sample, the remaining curcumin content was 4.46%. Thus, the developed technique was successful on purification of PHM and microencapsulation of curcumin.

Correlation between histopathological and FT-Raman spectroscopy analysis of the liver of Swiss mice infected with Paracoccidioides brasiliensis.

Paracoccidioidomycosis is the most important systemic mycosis in Latin America. The main entrance of the fungus is the airway. It primarily occurs in the lung, but in its disseminated form may affect any organ. The liver is one of the organs afflicted by this disease and its homeostasis may be impaired. The aim of the present study was to evaluate the evolution of paracoccidioidomycosis in the liver of Swiss mice and correlate morphological factors with the expression of gp43 and with physicochemical analysis via FT-Raman of the infected organ. According to colony forming unit (CFU) and granuloma counting, the first and second weeks were the periods when infection was most severe. Tissue response was characterized by the development of organized granulomas and widespread infection, with yeasts located within the macrophages and isolated hepatocytes. The gp43 molecule was distributed throughout the hepatic parenchyma, and immunostaining was constant in all observed periods. The main physicochemical changes of the infected liver were observed in the spectral ranges between 1700-1530 cm(-1) and 1370-1290 cm(-1), a peak shifting center attributed to phenylalanine and area variation of -CH2 and -CH3 compounds associated to collagen, respectively. Over time, there was a direct proportional relationship between the number of CFUs, the number of granulomas and the physicochemical changes in the liver of mice infected with Paracoccidioides brasiliensis. The expression of gp43 was similar in all observed periods.

Microencapsulation by freeze-drying of potassium norbixinate and curcumin with maltodextrin: stability, solubility, and food application.

Stability of potassium norbixinate and curcumin by microencapsulation with maltodextrin DE20 and freeze-drying was evaluated as a function of exposition to light, air, different pH, water solubility, and in food applications. The best results were obtained with microencapsulated potassium norbixinate 1:20, which, when vacuum-packed and in the presence of natural light, showed color retention of 78%, while microencapsulated curcumin 1:20 showed color retention of 71%. Differential scanning calorimetry and thermogravimetry provided an indication of interaction between colorants and maltodextrin. Photoacoustic spectroscopy (PAS) showed that free and microencapsulated colorants exhibited high rates of absorption throughout the measured spectral region. This work evidenced that the freeze-drying process is favorable for microencapsulation of curcumin by maltodextrin, providing improved solubility to the microencapsulated colorant. Both microencapsulated colorants showed relevant results for use in a wide range of pH and food applications. The PAS technique was useful for the evaluation of the stability of free and microencapsulated colorants.

Use of photoacoustic spectroscopy in the characterization of inclusion complexes of benzophenone-3-hydroxypropyl-ß-cyclodextrin and ex vivo evaluation of the percutaneous penetration of sunscreen.

This work is aimed to evaluate the application of photoacoustic spectroscopy (PAS) in the characterization of inclusion complexes of benzophenone-3 (BZ-3) and hydroxypropyl-ß-cyclodextrin (HPCD) and to analyze the ex vivo percutaneous penetration of sunscreens and their reaction with the skin. The formation of inclusion complexes of BZ-3 and HPCD was performed by co-precipitation in stoichiometric ratios of 1:1 and 1:2. Thermal analysis and PAS characterized these inclusion complexes, and they indicated that the stoichiometric ratio of 1:2 was best. Sunscreen formulations were prepared and applied on the ears of rabbits. PAS suggested that the formulation with the complex resulted in lower penetration of BZ-3. Histological analysis demonstrated that the use of the formulation with BZ-3 was associated with an increase in the comedogenic effect and the presence of acanthosis, while no such effect was found in the formulation with the complex. The formulation with the BZ-3-HPCD complex is a promising strategy for improving the photoprotective effect of BZ-3. PAS can be used in the study of inclusion complexes with cyclodextrins and the evaluation of the percutaneous penetration of sunscreen formulations. Further tests are being conducted using PAS to monitor in vivo changes in the optical absorption spectra of formulations and to investigate their photostability.