130 resultados para Confocal scanning laser ophthalmoscopy (HRT3)


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This study evaluated the effect of Er,Cr:YSGG laser irradiation on the external adaptation of composite resin restorations in caries-affected cavities. Mixed class V cavity preparations were performed in 36 intact human third molars, in half of which caries was artificially induced. Both healthy and carious dentin were etched with 35% phosphoric acid (Ultradent Products Inc., South Jordan, Utah, USA), and the teeth were divided into three groups, i.e., (a) untreated etched dentin, (b) application of the Er, Cr:YSGG laser and (c) use of chlorhexidine as an adjunct in the bonding process. Restorations were fabricated with Z350 XT FiltekTM composite resin (3M ESPE) and subsequently the specimens were subjected to thermocycling to simulate artificial ageing. Quantitative analysis of external adaptation was performed by scanning electron microscopy in both healthy and affected dentin using epoxy resin replicas. It was concluded that the application of laser and chlorhexidine did not affect the percentages of marginal adaptation of class V restorations. Furthermore, thermocycling may influence adaptation values.

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

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

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

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

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Objectives: This study evaluated the durability of bond strength to enamel using total-etch (Single Bond/SB) and self-etch (Clearfil SE Bond/CSEB) adhesives associated with neody-mium: yttrium-aluminu- garnet (Nd:YAG) laser irradiation through the uncured adhesives.Methods: Bovine incisors were worn to expose an area of enamel and were divided into four groups: group 1 (control) SB + polymerization; group 2 (control) CSEB + polymerization; group 3 (laser) - B + Nd:YAG laser (174.16 J/cm(2)) + polymerization; and group 4 (laser) CSEB + Nd:YAG (174.16 J/cm(2)) + polymerization. Blocks of composite were fabricated and stored for 24 hours or 12 months, sectioned into beams, and submitted to microtensile tests. Results were analyzed by three-way analysis of variance (ANOVA) (adhesive, technique, and storage time) and Tukey tests.Results: ANOVA revealed significant differences for adhesive 3 technique and technique 3 storage time (p<0.05). The mean values (MPa) for interaction adhesive x technique (standard deviation) were as follows: SB/control = 35.78 (6.04)a; SB/laser = 26.40 (7.25)b, CSEB/control = 26.32 (5.71)b, CSEB/laser = 23.90 (7.49)b. For interaction technique x storage time the mean values were as follows: control/24 hours = 32.58 (6.49)a; control/12 months = 29.52 (8.38)a; laser/24 hours = 29.37 (5.71)a; laser/12 months = 20.92 (6.5)b. Groups with the same letters showed no statistically significant differences.Conclusion: Scanning electron microscope analysis showed evident areas of micromorphological alterations in lased samples after 12 months of water storage. Nd: YAG laser irradiation of enamel through unpolymerized totaletch adhesive significantly reduced bond strength compared with the control. Bond strength decreased when enamel samples irradiated with Nd: YAG laser through unpolymerized adhesives were stored in water for 12 months.

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In this paper, a method is proposed to refine the LASER 3D roofs geometrically by using a high-resolution aerial image and Markov Random Field (MRF) models. In order to do so, a MRF description for grouping straight lines is developed, assuming that each projected side contour and ridge is topologically correct and that it is only necessary to improve its accuracy. Although the combination of laser data with data from image is most justified for refining roof contour, the structure of ridges can give greater robustness in the topological description of the roof structure. The MRF model is formulated based on relationships (length, proximity, and orientation) between the straight lines extracted from the image and projected polygon and also on retangularity and corner injunctions. The energy function associated with MRF is minimized by the genetic algorithm optimization method, resulting in the grouping of straight lines for each roof object. Finally, each grouping of straight lines is topologically reconstructed based on the topology of the corresponding LASER scanning polygon projected onto the image-space. The results obtained were satisfactory. This method was able to provide polygons roof refined buildings in which most of its contour sides and ridges were geometrically improved.

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Objective: A morphological and ultra-structural study of copper vapor laser (λ = 510.6 nm) effects on enamel and dentine was performed to show the effects of this radiation. Methods: A total of 15 human molars were cut in half; 15 pieces were separated for irradiation on enamel and 15 for dentine. These two groups were further divided into five experimental groups, including a control group, comprised of three half-sections each, irradiated by a CVL laser with a power of 7 W, a repetition rate of 15,000 pulses/sec and exposed at 500, 600, and 800 msec and 1 sec irradiation times with a 5-sec interval between irradiations. Results: In an ultra-structural SEM exam, we observed that on the enamel surfaces irradiated for 1 sec there was morphological alteration that consisted of catering, flaking, and melting on the surfaces. There was no alteration for the other exposure times. On the dentine teeth irradiated for 1 sec, we observed an evident ultra-structural alteration of melted tissue and loss of morphological characteristics. In the dentine group irradiated by 800 msec, we observed ablation and a partial loss of morphological characteristics. In the dentine groups irradiated by 500 and 600 msec, no alteration was observed. Conclusions: The results showed that irradiation with CVL promoted morphologic changes in the enamel as well as in the dentine and demonstrated a need for future studies in order to establish a safe protocol for further use in the odontological practice.

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Neste trabalho investigou-se a modificação de superfície do titânio pela irradiação com feixe de Laser Nd:YAG. Os parâmetros do laser como a potência, o comprimento de onda, a frequência, a velocidade de varredura e a área de exposição foram mantidos constantes, exceto o espaçamento da matriz, o qual foi de 0,01 e 0,02 mm. A caracterização da superfície foi realizada por Microscopia Eletrônica de Varredura (MEV) e Difração de Raios X (DRX), sendo que os espectros foram refinados pelo método Rietveld. Pela análise de MEV, observou-se uma mudança na topografia, obtendo uma superfície rugosa produzida pelo fenômeno de ablação. As análises por Rietveld dos espectros de difração de raios X detectaram TiN, Ti2N, TiO2 (anatásio e rutilo), sendo que a amostra com espaçamento 0,01 mm apresentou uma maior quantidade de óxidos e nitretos. Isso pode ser devido à sobreposição do feixe, induzindo à formação de uma superfície com maior estabilidade termodinâmica. Os óxidos e nitretos obtidos são de grande importância, pois são responsáveis por produzir uma maior interação entre o osso-implante.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)