Estudo da viabilidade do sistema LZAS para uso como selante de PaCOS

Cells the solid oxide fuel are systems capable to directly convert energy of a chemical reaction into electric energy in clean, quiet way and if its components in the solid state differentiate of excessively the techniques for having all. Its more common geometric configurations are: the tubular one and to glide. Geometry to glide beyond the usual components (anode, cathode and electrolyte) needs interconnect and sealant. E the search for materials adjusted for these components is currently the biggest challenge found for the production of the cells. The sealants need to present chemical stability in high temperatures, to provoke electric isolation, to have coefficient of compatible thermal expansion with the excessively component ones. For presenting these characteristics the glass-ceramics materials are recommended for the application. In this work the study of the partial substitution of the ZrO2 for the Al2O3 in system LZS became it aiming at the formation of system LZAS, this with the addition of natural spodumene with 10, 20 and 30% in mass. The compositions had been casting to a temperature of 1500°C and later quickly cooled with the objective to continue amorphous. Each composition was worn out for attainment of a dust with average diameter of approximately 3μm and characterized by the techniques of DRX, FRX, MEV, dilatometric analysis and particle size analysis. Later the samples had been conformed and treated thermally with temperatures in the interval between 700-1000 °C, with platform of 10 minutes and 1 hour. The analyses for the treated samples had been: dilatometric analysis, DRX, FRX, electrical conductivity and tack. The results point with respect to the viability of the use of system LZAS for use as sealant a time that had presented good results as isolating electric, they had adhered to a material with similar α of the components of a SOFC and had presented steady crystalline phases

Avaliação da eficácia de selante ionomérico modificado por resina e escovação dentária na preservação de cárie oclusal

The purpose of this study was to evaluate the effectiveness during a twelve-month period, of resin-modified glass ionomer (Vitremer@) used as fissure sealants compared to supervised teeth brushing in the prevention of oclusal caries in permarient molars of pubIlc school children from 5 to 7 years of age. A total of 91 children participated in the study, being randomly divided up into three groups of investigation: group with sealant (n=31), group of supervised brushing (m=30), and control gorup (n=30). After 12 months, a total of 28.5% of tosses in the sample of 26 children was registered, and although there wasn t a significant diference between these losses and the groups studles (p = 0.6355), there was a considerable reduction in the sample. The results showed that none of the independentIy studied variables (present caries experience, biofilm, bleeding, sealant retention, position of the tooth in the arch, and sex) interfered in the final results, and that there was no significant difference between applying the sealant in question, perfornling supervised dental brushing, or not intervening at alI (p=0.542). These results could have been a consequence of the limitations found alI through the study, especially relating to the losses occurred because of school evasion, transfer, or because of the accident in the Marise Paiva Municipal School, Keeping students away for approximately one semester, so tht a new reseach had to be developed sos as to better clarify the effects among the treatments done there

Eficácia do cimento de ionômero de vidro como selante oclusal sobre a paralisação de lesões cariosas em dentina

Dental caries consists in a multifactorial and dynamic process. The knowledge of the ionic interactions among dental tissues and dental biofilm make possible its understanding as a process that can be stopped. Recently, the use of sealants have lost its function as preventive agent and passed to be argued as a possible therapeutical agent. This happens by hindering the substratum flow to the lesion inner and, therefore, controls the advance of the process. This study aimed to evaluate glass ionomer cement as a not invasive technique of treatment in occlusal caries without clinical cavitation, but with dentinal involvement. The research was accomplished using a controlled clinical trial with two groups (experimental and control) in 38 subjects (8-18 years) with 51 molars. The teeth of the experimental group were sealed with glass ionomer cement (Vidrion-R, S.S.White, Juiz de Fora, Brazil) and the molars control did not suffer intervention. The experimental group was followed by a year and the control by 8 months due the progression of the carious injury. Both groups were reevaluated to each 4 months with the use of clinical, radiographic and laser fluorescence (DIAGNOdent®) examination. The analysis of the clinical evaluation did not observe a significant difference between experimental and control groups. However, analysis with radiographic and laser fluorescence (DIAGNOdent®) examination observed a significant difference (p> 0,05) between groups, demonstrating a wors condition to the group without intervention. The results suggest that glass ionomer cement as sealant can be efficient to paralyze dentinal caries without clinical cavitation

Influência do pré-aquecimento na adaptação marginal de dois materiais seladores de fóssulas e fissuras, analisada através de tomografia de coerência ótica

Among the non-invasive techniques employed in the prevention of caries highlights the sealing pits and fissures which is a conservative maneuver, in order to obliterate them to protect them from attack acid bacteria. Influenced by the studies of pre-heating composite resin, which has experienced great improvement in some of their physical properties, this study aimed to evaluate in vitro the superficial and internal marginal adaptation of different materials and sealants in pre-heating or not. A total of 40 extracted human third molars (n=10) that had their occlusal surfaces prepared to receive sealant. We tested two types of sealing materials: resin sealant (Fluoroshield) and low-viscosity resin (Permaflo), where 50% of previously received heated material and the other half received sealant material at room temperature. All samples were subjected to thermal cycling and pH, simulating a cariogenic oral environment, and later were analyzed appliance OCT (optical coherence tomography). The images obtained alterations were recorded and analyzed statistically. Change was considered as the emergence of bubbles, gaps and cracks in the sealant. Comparisons of the same material, assessing the fact that it is not sealed or preheated material, as well as comparisons between different materials subjected to the same temperature were carried out. The nonparametric Tukey test was used (p < 0,05). The results showed that there was statistically significant difference between both the materials analyzed, as between the situations in which the sealant material was submitted (preheated or not). On the issue of marginal adaptation and internal surface, seen through Optical coherence tomography, may suggest that there is a difference between the use of one type or another of the sealing material analyzed, with superiority attributed to resin Permaflo compared to sealant Fluroshield, telling is the same for the different techniques used

Effect of Artificial Aging on the Roughness and Microhardness of Sealed Composites

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of fluid resins on the surface roughness and topography of resin composite restorations analyzed by atomic force microscope

The aim of the study was to verify the influence of surface sealants on the surface roughness of resin composite restorations before and after mechanical toothbrushing, and evaluate the superficial topography using atomic force microscope. Five surface sealers were used: Single Bond, Opti Bond Solo Plus, Fortify, Fortify Plus and control, without any sealer agent. The lowest values of surface roughness were obtained for control, Single Bond and Fortify groups before toothbrushing. Fortify and Fortify Plus were the sealer agents that support the abrasive action caused by the toothbrushing although Fortify Plus group remained with high values of surface roughness. The application of specific surface sealants could be a useful clinical procedure to maintain the quality of resin-based composite restorations. (C) 2010 Elsevier Ltd. All rights reserved.

Comparison of visual inspection, radiographic examination, laser fluorescence and their combinations on treatment decisions for occlusal surfaces

Purpose: To compare visual inspection (VI), radiographic examination (RX) and the laser fluorescence device DIAGNOdent (L), as well as their combinations in vitro regarding treatment decisions for occlusal surfaces. Methods: 72 extracted human permanent teeth (molars and premolars) were used. Treatment decisions were recorded by three calibrated examiners, and the options available were fissure sealant and conservative restoration. For validation of treatment decisions, the teeth were sectioned and examined in a stereomicroscope. Thereafter, dental slices were scanned and the images were edited to facilitate classification of existing carious lesions. Intra and inter-examiner reproducibility for the determination of treatment plans were calculated using Cohen's kappa test (95%-CI). Sensitivity, specificity, positive and negative predictive values, and the area under the ROC curve were also calculated. Results: VI and L provided on average the greatest intra- and inter-examiner reproducibility, respectively. Although the combination of diagnostic methods may decrease both intra- and inter examiners reproducibility, combination of VI, L and RX resulted in the greatest sensitivity, being statistically superior to RX and L. There was more inter-examiner agreement for the option of restorative treatment, while the use of sealants as a treatment option yielded the lowest values. Negative predictive values were numerically inferior to positive predictive values, indicating that the examiners preferred not to restore a carious tooth than to proceed operatively in an intact tooth. The combination of the three methods studied showed the best results in determining treatment plans for occlusal surfaces, when compared to the other types of exams. on the other hand, radiographic examination and laser fluorescence were less efficient when used alone.

Relationship between DIAGNOdent values and sealant penetration depth on occlusal fissures

The aim of this in vitro study was to evaluate the relationship between laser fluorescence values and sealant penetration depth on occlusal fissures. One hundred and sixty-six permanent molars were selected and divided into four groups, which were each treated using a different sealant (two clear and two opaque). The teeth were independently measured twice by two experienced dentists using two laser fluorescence devices-DIAGNOdent (LF and LFpen)-before and after sealing, and then thermoclycled. After measuring, the teeth were histologically prepared and assessed for caries extension. Digital photographs of the cut sealed sites were assessed, and the sealant penetration depth was measured. All 166 sites were measured by one of the examiners taking as limits the outer and inner surface of the sealant into the fissure. For each device (LF and LFpen) and each group, the difference between the values at baseline and after sealing was plotted against the sealant penetration depth and scatter plots were provided. It could be observed that most of the points were concentrated around the zero line, for both LF and LFpen in the four groups. In conclusion, there is no relation between changes in DIAGNOdent values and increasing of depth sealant penetration within the occlusal fissures.

Bond strength and morphology of resin materials applied to the occlusal surface of primary molars

International Journal of Paediatric Dentistry 2012; 22: 435441 Background. Hydrophilic adhesives may be used as pit and fissure sealants (sealants), but there is concern about the ability of self-etching adhesives to bond sealants to enamel. Aim. To study the bond strength (BS) and morphology of adhesive systems used as sealants. Design. OptiBond FL, OptiBond All-in-One, combined OptiBond All-in-One + OptiBond FL adhesive, and Fluroshield were applied to the occlusal surfaces of 16 primary molars (n = 4). Teeth were stored in distilled water (24 h at 37 degrees C) and sectioned through the interface to obtain sticks (0.8 mm2) tested under a tensile load (0.5 mm/min). Failure modes were observed. Data were analysed by ANOVA and Tukeys tests (a = 5%). The morphology of 12 primary molars was examined in terms of the etching pattern and resin reproduction. Results. Differences in the BS were found (P = 0.001), with OptiBond FL showing the highest (36.84 +/- 5.7 MPa), Fluroshield (24.26 +/- 2.13 MPa) and OptiBond All-in-One (17.12 +/- 4.97 MPa) similar, and OptiBond All-in-One + OptiBond FL adhesive the lowest (9.8 +/- 2.94 MPA). OptiBond FL showed the best results in terms of morphology. Conclusion. Under the conditions of this study, OptiBond FL was the best material to be used for sealing.

Avaliação clínica de vinte e quatro meses do Fluroshield e do Vitremer utilizados como selante de fossas e fissuras

Avaliou-se o desempenho de dois materiais utilizados como selante oclusal (Fluroshield e Vitremer). Foram selados 46 pré-molares, superiores e/ou inferiores, sem sinais clínicos de lesões de cárie, sendo que 23 dentes foram selados com Vitremer e 23 com Fluroshield. Após seis, doze e vinte e quatro meses de acompanhamento, observou-se que o Vitremer apresentou uma retenção total de 91,30%, 91,30% e 82,60%, enquanto o Fluroshield apresentou 100% de retenção total nos três intervalos de tempo. Ambos os materiais impediram o desenvolvimento de lesões de cárie, independente de sua retenção e períodos avaliados.

Penetration of a light-cured glass ionomer and a resin sealant into occlusal fissures and etched enamel.

PURPOSE: To evaluate the penetration of a light-cured glass ionomer and a resin sealant into occlusal fissures and etched enamel. MATERIALS AND METHODS: Forty-eight maxillary and mandibular caries-free premolars scheduled for extraction for orthodontic reasons were isolated, the occlusal surfaces subjected to prophylaxis and acid-etched with orthophosphoric acid prior to the application of the VariGlass VLC glass ionomer and Concise resin sealants. The teeth were extracted, two longitudinal median sectiors from each tooth were ground to a thickness of 80-100 microns, and the sealant penetration into the fissures evaluated. The sections were placed in nitric acid to dissolve the enamel so the lengths of the tags which had penetrated into the etched enamel could be measured at different sites on the walls of the fissures. RESULTS: Both sealants adapted well to the fissures but penetrated deeper into shallow, open fissures than into deep, constricted fissures. The VariGlass VLC tags into etched enamel were generally longer than the Concise projections.

pH changes at the surface of root dentin when using root canal sealers containing calcium hydroxide

The purpose of this study was to investigate long-term pH changes in cavities prepared in root surface dentin of extracted teeth after obturation of the root canal with gutta-percha and a variety of sealers containing calcium hydroxide. After cleaning and shaping, root canals in 50 recently extracted, human single-rooted teeth were divided into five groups. Each of four groups was obturated with gutta-percha and either Sealapex, Sealer 26, Apexit, or CRCS, all of which contain calcium hydroxide. The remaining group served as the control and was not obturated with gutta-percha or sealer. Cavities were prepared in the facial surface of the roots in the cervical and middle regions. The pH was measured in these dentinal cavities at the initiation of the experiment, and 3, 7, 14, 21, 28, 45, 60, 90, and 120 days after obturation. Results indicate that the pH at the surface of the root does not become alkaline when calcium hydroxide cements are used as root canal sealers. Regardless of the sealer used, the observed pattern of pH change was not different from that seen in the control group of roots that were not treated with sealer. It is concluded that calcium hydroxide-containing cements, although suitable for use as root canal sealants, do not produce an alkaline pH at the root surface. If such a pH change is related to treatment of root resorption, these sealants do not contribute to this treatment. Copyright © 1996 by The American Association of Endodontists.

Use of one-bottle adhesive as an intermediate bonding layer to reduce sealant microleakage on saliva-contaminated enamel

Purpose: To evaluate the influence of three different adhesives, each used as an intermediary layer, on microleakage of sealants applied under condition of salivary contamination. Materials and Methods: Six different experimental conditions were compared, 3 with adhesives and 3 without. After prophylaxis and acid etching of enamel, salivary contamination was placed for 10 s. In Group SC the sealant was applied after saliva without bonding agent and then light-cured. In Group SCA, after saliva, the surface was air dried, and then the sealant was applied and cured. In Groups ScB, SB and PB, a bonding agent (Scotchbond Dual Cure/3M, Single Bond/3M and Prime & Bond 2.1/Dentsply, respectively) was applied after the saliva and prior to the sealant application and curing. After storage in distilled water at 37°C for 24 hrs, the teeth were submitted to 500 thermal cycles (5°C and 55°C), and silver nitrate was used as a leakage tracer. Leakage data were collected on cross sections as percentage of total enamel-sealant interface length. Representative samples were evaluated under SEM. Results: Sealants placed on contaminated enamel with no bonding agent showed extensive microleakage (94.27% in SC; 42.65% in SCA). The SEM revealed gaps as wide as 20 μm in areas where silver nitrate leakage could be visualized. In contrast, all bonding agent groups showed leakage less than 6.9%. Placement of sealant with a dentin-bonding agent on contaminated enamel significantly reduced microleakage (P< 0.0001). The use of a bonding agent as an intermediary layer between enamel and sealant significantly reduced saliva's effect on sealant microleakage.

Effect of 10% carbamide peroxide dental bleaching on microhardness of filled and unfilled sealant materials

Purpose: The purpose of this study was to quantitatively evaluate the effect of 10% carbamide peroxide on the microhardness of pit and fissure sealant materials. Methods: Fluroshield, Vitroseal Alfa, and one unfilled (Clinpro) sealants were placed in Teflon matrices (4 mm in diameter by 2 mm in height) and polymerized for 40 seconds. A total of 20 specimens were prepared for each material, in which half were assigned as the control group (stored in artificial saliva and no bleaching treatment). For the remaining half, Clarigel Gold bleaching agent (10% carbamide peroxide) was placed over the specimen surface for 4 hours/day during 4 weeks. When specimens were not under bleaching treatment, they were kept in artificial saliva. Afterwards, specimens were subjected to Knoop microhardness testing using a 25-g load for 5 seconds. Five measurements were made on the sealants' surfaces and then calculated in Knoop hardness values. The data were statistically analyzed by two-way analysis of variance and Tukey's tests with a 5% confidence level. Results: The results of this in vitro study showed that the application of a carbamide peroxide-based bleaching material significantly affected the microhardness values of filled sealant materials. The bleaching agent did not affect the microhardness of the unfilled sealant. CLINICAL SIGNIFICANCE: The results of this in vitro study suggest that the bleaching agents altered the surface hardness of filled sealant restorative materials. This could possibly lead to increased wear and surface roughness. © 2006, Copyright the authors.

Measurement of sealant surface area by clinical/computerized analysis: 11-year results.

OBJECTIVE: To analyze the clinical behavior of 2 pit and fissure sealants through clinical/computerized evaluation. METHOD AND MATERIALS: Occlusal sealants were placed on maxillary and mandibular first and second premolars according to a split-mouth design. All premolars were sealed with either Concise (3M Espe) or Prisma Shield (Caulk/Dentsply) sealant agents. A hematoxylin-based staining solution was applied on the occlusal surface 7 days, 18 months, 36 months, and 11 years after occlusal sealing to allow checking of the sealant material on the surface. At each analysis time all occlusal surfaces were photographed, and the photographs corresponding to each time period were analyzed with SigmaScan 4.0 Software. The alterations of the sealed area of each sealant were analyzed with the software and recorded. Next, the measurements of the areas were tabulated and analyzed according to each period. Analysis of variance (ANOVA), with parts subdivided into time, and the t test, with a significance level of 5%, were used. RESULTS: The greatest sealed area was maintained by the sealant Concise. However, over the course of 11 years, all sealants began to show the same level of alteration in sealed area. CONCLUSION: The sealing materials showed alteration in sealed area over time, but they were efficient in controlling caries lesion formation on premolar pits and fissures.