Microtensile Bond Strength Test And Failure Analysis To Assess Bonding Characteristics Of Different Adhesion Approaches To Ground Versus Unground Enamel

This study evaluated the bonding characteristics to ground and unground enamel obtained with different strategies. For this purpose, 24 sound third-molars were bisected mesiodistally to obtain tooth halves. A flat enamel area was delimited in the tooth sections, which were randomly distributed into 8 groups (n=6), according to the enamel condition (ground and unground) and adhesive system (Adper Single Bond 2 - SB2; Adper Prompt L-Pop - PLP; Adper Prompt - AD; Clearfil SE Bond - SE). Each system was applied according manufacturers' instructions and a 6-mm-high resin composite "crown" was incrementally built up on bonded surfaces. Hourglass-shaped specimens with 0.8 mm2 cross-section were produced. Microtensile bond strength (μTBS) was recorded and the failure patterns were classified. Results were analyzed by two-way ANOVA and Tukey's test (α=0.05). There were no statistically significant differences among the μTBS values of SB2, PLP and AD (p>0.05). SE values were significantly lower (p0.05). There was prevalence of cohesive failure within enamel, adhesive system and resin composite for SB2. The self-etch systems produced higher incidence of cohesive failures in the adhesive system. Enamel condition did not determine significant differences on bonding characteristics for the same bonding system. In conclusion, the bonding systems evaluated in this study resulted in specific μTBS and failure patterns due to the particular interaction with enamel.222122128Goes, M.F., Sinhoreti, M.A., Consani, S., Silva, M.A., Morphological effect of the type, concentration and etching time of acid solutions on enamel and dentin surfaces (1998) Braz Dent J, 9, pp. 3-10Swift Jr., E.J., Perdigão, J., Heymann, H.O., Bonding to enamel and dentin: A brief history and state of the art, 1995 (1995) Quintessence Int, 26, pp. 95-110van Meerbeek, B., Yoshihara, K., Yoshida, Y., de Mine, A.J.M.K.L.V.L., State of the art of self-etch adhesives (2011) Dent Mater, 27, pp. 17-28Mine, A., de Munck, J., Vivan Cardoso, M., van Landuyt, K.L., Poitevin, A., Kuboki, T., Enamel-smear compromises bonding by mild self-etch adhesives (2010) J Dent Res, 89, pp. 1505-1509Kanemura, N., Sano, H., Tagami, J., Tensile bond strength to and SEM evaluation of ground and intact enamel surfaces (1999) J Dent, 27, pp. 523-530Pivetta, M.R., Moura, S.K., Barroso, L.P., Lascala, A.C., Reis, A., Loguercio, A.D., Bond strength and etching pattern of adhesive systems to enamel: Effects of conditioning time and enamel preparation (2008) J Esthet Restor Dent, 20, pp. 322-335Pashley, D.H., Tay, F.R., Aggressiveness of contemporary self-etching adhesives. Part II: Etching effects on unground enamel (2001) Dent Mater, 17, pp. 430-444Di Hipólito, V., de Goes, M.F., Carrilho, M.R., Chan, D.C., Daronch, M., Sinhoreti, M.A., SEM evaluation of contemporary self-etching primers applied to ground and unground enamel (2005) J Adhes Dent, 7, pp. 203-211Mjor, I.A., Moorhead, J.E., Dahl, J.E., Reasons for replacement of restorations in permanent teeth in general dental practice (2000) Int Dent J, 50, pp. 361-366Burrow, M.F., Tyas, M.J., 1-year clinical evaluation of one-step in non-carious cervical lesions (1999) Am J Dent, 12, pp. 283-285Opdam, N.J., Roeters, F.J., Feilzer, A.J., Verdonschot, E.H., Marginal integrity and postoperative sensitivity in Class 2 resin composite restorations in vivo (1998) J Dent, 26, pp. 555-562Perdigão, J., Lambrechtes, P., van Meerbee, K.B., Vanherle, G., Lopes, A.L., Filed emission SEM comparison of four postfixation drying techniques for human dentin (1995) J Biomed Mater Res, 290, pp. 1111-1120Sano, H., Shono, T., Sonoda, H., Takatsu, T., Ciucchi, B., Carvalho, R., Relationship between surface area for adhesion and tensile bond strength. Evaluation of a micro-tensile bond test (1994) Dent Mater, 10, pp. 236-240Shinchi, M.J., Soma, K., Nakabayashi, N., The effect of phosphoric acid concentration on resin tag length and bond strength of a photo-cured resin to acid-etched enamel (2000) Dent Mater, 16, pp. 324-329Yoshida, Y., Nagakane, K., Fukuda, R., Nakayama, Y., Okazaki, M., Shintani, H., Comparative study on adhesive performance of functional monomers (2004) J Dent Res, 83, pp. 454-458Takahashi, A., Sato, Y., Uno, S., Pereira, P.N.R., Sano, H., Effects of mechanical properties of adhesive resins on bond strength to dentin (2002) Dent Mater, 18, pp. 263-268Salz, U., Zimmermann, J., Zeuner, F., Moszner, N., Hydrolytic stability of self-etching adhesive systems (2005) J Adhes Dent, 7, pp. 107-116Cehreli, Z.C., Altay, N., Effects of a nonrinse conditioner and 17% ethylenediaminetetraacetic acid on the etch pattern of intact human permanent enamel (2000) Angle Orthod, 70, pp. 22-27Camps, J., Pashley, D.H., Buffering action of human dentin in vitro (2000) J Adhes Dent, 2, pp. 39-50Ripa, L.W., Gwinnett, A.J., Buonocore, M.G., The "prismless" outer layer of deciduous and permanent enamel (1966) Arch Oral Biol, 11, pp. 41-4

Quantificação de neurofilamentos de hipocampo de ratos submetidos à isquemia cerebral transitória

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Nutrient extraction and exportation by common bean cultivars under different fertilization levels: I - macronutrients

The use of cultivars with a higher yield potential and the adoption of new technology have achieved high grain yields in common bean, which probably changed the demand for nutrients in this crop. However, there is almost no information about the periods of the cycle in which nutrients are most demanded at which quantities by the main cultivars. The objective of this study was to evaluate the macronutrient extraction and exportation by the common bean cultivars Pérola and IAC Alvorada, under different levels of NPK fertilization, on a dystroferric Red Nitosol, in Botucatu, São Paulo State, Brazil. The experiment was arranged in a randomized complete block (split plot) design with four replications. The plots consisted of six treatments based on a 2 x 3 factorial model, represented by two cultivars and three NPK levels (PD0 - 'Pérola' without fertilization, PD1 - 'Pérola' with 50 % of recommended fertilization, PD2 - 'Pérola' with 100 % of recommended fertilization, AD0 - 'IAC Alvorada' without fertilization, AD1 - 'IAC Alvorada' with 50 % of recommended fertilization, and AD2 - 'IAC Alvorada' with 100 % of recommended fertilization) and subplots sampled seven times during the cycle. At higher levels of NPK fertilization, the grain yield and macronutrient extraction and exportation of both cultivars were higher, but without statistical differences. Macronutrient absorption was higher in the treatments with 100 % of recommended NPK fertilization (average amounts per hectare: 140 kg N, 16.5 kg P, 120 kg K, 69 kg Ca, 17.9 kg Mg, and 16.3 kg S). Regardless of the treatment, the demand for N, P, K, Ca, and Mg was highest from 45 to 55 days after emergence (DAE), i.e., in the R7 stage (pod formation), while the highest S absorption rates were concentrated between 55 and 65 DAE. More than 70 % of P, between 58 and 69 % of N, 40 and 52 % of S, 40 and 48 % of K, and 35 and 45 % of Mg absorbed during the cycle was exported with grains, whereas less than 15 % of Ca was exported.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Department of Crop Science College of Agricultural Sciences São Paulo State University - FCA/UNESP, P.O. Box 37, CEP 18610-307 Botucatu SPFCA/UNESPDepartment of Crop Science College of Agricultural Sciences São Paulo State University - FCA/UNESP, P.O. Box 37, CEP 18610-307 Botucatu SPFCA/UNESPFAPESP: 10/18602-