18 research outputs found
Desempenho de cordeiros em confinamento alimentados com dieta exclusiva de concentrado com diferentes porcentagens de proteína
Fatores que influenciam os parâmetros das curvas de lactação em cabras no Distrito Federal
Georeferenced database generation with the purpose of hydrologic molding in reservoirs of the hydrographic basin of Jaguaribe river in the state of Ceará, Brazil
Associação de SNPs nos genes para κ-caseína e β-lactoglobulina com curvas de lactação em cabras leiteiras
Eficiência da escarificação mecânica e biológica na melhoria dos atributos físicos de um latossolo muito argiloso e no incremento do rendimento de soja
Analysis Of The Effects Of Thermal Cycling On The Microtensile Shear Bond Strength Of A Self-etching And A Conventional Pit And Fissure Sealants To Dental Enamel
Objective: To analyze the effects of thermal cycling on the microtensile shear bond strength of a self-etching and a conventional pit and fissure sealants to dental enamel. Material and Method: Twenty-four healthy human molars extracted for orthodontic reasons, were sectioned in the mesio-distal direction and divided into two groups (n=24) according to the sealant to be applied: GI - conventional sealant Climpro (3M/ESPE) and GII - self-etching sealant Enamel Loc (Premier Dental). The sealants were applied on flattened enamel in matrixes 1 mm in diameter, in accordance with the manufacturers' recommendations. The specimens were stored in distilled water at 37°C for 24 hours. After this, half the samples of both groups were submitted to 500 thermal cycles in 30s baths at temperatures between 5 and 55°C. Forty-eight hours after the samples were made, the microtensile shear test was performed in an Instron 4411 test machine, with a stainless steel wire with a cylindrical cross section of 0.2mm in diameter at a constant speed of 0.5mm/s. The bond strength values were submitted to ANOVA for 2 factors and the fracture patterns were examined under an optical microscope at 65X magnification. Results: Thermal cycling did not influence the bond strength of the two sealants. The conventional sealant Climpro presented a statistically higher microtensile shear bond strength (11.72MPa, 11.34MPa with and without cycling, respectively) than the self-etching sealant Enamel Loc (5.92MPa, 5.02MPa with and without cycling, respectively). Fracture pattern analysis showed the occurrence of 100% of adhesive failures for Enamel Loc, while the conventional sealant Climpro presented 95% of adhesive failures and 5% of mixed failures. Conclusion: The conventional sealant presented higher microtensile shear bond strength to dental enamel in comparison with the self-etching sealant. Thermal cycling did not affect the bond strength of the sealants used in this study. © 2011 Nova Science Publishers, Inc.41110Sundfeld, R.H., Mauro, S.J., Briso, A.L.F., Clinical/photographic evaluation of a single application of two sealants after eleven years (2004) Bull Tokyo Dent Coll, 45 (2), pp. 67-75Sundfeld, R.H., Croll, T.P., Mauro, S.J., Longitudinal photographic observation of the occurrence of bubbles in pit and fissure sealants (2006) J. Appl. Oral Sci, 14 (1), pp. 27-32Sundfeld, R.H., Briso, A.L.F., Mauro, S.J., Twenty years experience with pit and fissure sealants (2009) Int. J. Clin. Dent., , in printBuonocore, M.G., A simple method of increasing the adhesion of acrylic filling materials to enamel surfaces (1955) J. Dent. Res., 34 (6), pp. 849-853Croll, T.P., Sundfeld, R.H., Berg, J.H., A pit-and-fissure clinical protocol (2005) Compend Contin. Educ. Dent., 26 (12), pp. 862-868Simonsen, R.L., Retention and effectiveness of dental sealant after 15 years (1991) J. Am. Dent. Assoc., 122 (10), pp. 34-42Feigal, R.J., Quelhas, I., Clinical trial of a self-etching adhesive for sealant application: Success at 24 months with Prompt L-Pop (2003) Am. J. Dent., 16 (4), pp. 249-251Gillet, D., Nancy, J., Dupuis, V., Microleakage and penetration depth of three types of materials in fissure sealant: Self-etching primer vs etching: An in vitro study (2002) J. Clin. Pediatr. Dent, 26 (2), pp. 175-178Tay, F.R., Frankenberger, R., Carvalho, R.M., Pit and fissure sealing. Bonding of bulk-cured, low-filled, light-curing resins to bacteria-contaminated uncut enamel in high c-factor cavities (2005) Am. J. Dent., 18 (1), pp. 28-36Peutzfeldt, A., Nielsen, L.A., Bond strength of a sealant to primary and permanent enamel: Phosphoric acid versus self-etching adhesive (2004) Pediatr. Dent., 26 (3), pp. 240-244Venker, D.J., Kuthy, R.A., Qian, F., Twelve-month sealant retention in a school-based program using a self-etching primer/adhesive (2004) J. Public Health Dent, 64 (4), pp. 191-197Papacchini, F., Goracci, C., Sadek, F.T., Microtensile bond strength to ground enamel by glass-ionomers, resin-modified glass-ionomers, and resin composites used as pit and fissure sealants (2005) J. Dent., 33 (6), pp. 459-467Perdig, J., Fundingsland, J.W., Duarte Jr., S., Microtensile adhesion of sealants to intact enamel (2005) Int. J. Paediatr Dent., 15 (5), pp. 342-348Al-Sarheed, M., Bond strength of 4 sealants using conventional etch and a self-etching primer (2006) J. Dent. Child (Chic)., 73 (1), pp. 37-41Retief, D.H., Effect of conditioning the enamel surface with phosphoric acid (1973) J. Dent. Res., 52 (2), pp. 333-341dos Santos, K.T., Sundfeld, R.H., Garbin, C.A., Length of resin tags in pit-and-fissure sealants: All-in-one self-etching adhesive vs phosphoric acid etching (2008) Compend Contin. Educ. Dent., 29 (3), pp. 186-192van Meerbeek, B., de Munck, J., Yoshida, Y., Buonocore memorial lecture. Adhesion to enamel and dentin: Current status and future challenges (2003) Oper. Dent., 28 (3), pp. 215-235Al-Sarheed, M.A., Evaluation of shear bond strength and SEM observation of all-in-one self-etching primer used for bonding of fissure sealants (2006) J. Contemp. Dent. Pract., 7 (2), pp. 9-16Sundfeld, R.H., de Oliveira, C.H., da Silva, A.M., Resin tag length of one-step and self-etching adhesives bonded to unground enamel (2005) Bull Tokyo Dent Coll., 46 (3), pp. 43-49Sundfeld, R.H., da Silva, A.M., Croll, T.P., The effect of temperature on self-etching adhesive penetration (2006) Compend. Contin. Educ. Dent., 27 (10), pp. 552-556. , quiz 7, 81Tay, F.R., Pashley, D.H., Water treeing--a potential mechanism for degradation of dentin adhesives (2003) Am. J. Dent., 16 (1), pp. 6-12Fujita, K., Nishiyama, N., 13C NMR analysis of the etching efficacy of acidic monomers in self-etching primers (2006) J. Dent., 34 (2), pp. 123-133Tay, F.R., Pashley, D.H., Suh, B.I., Single-step adhesives are permeable membranes (2002) J. Dent., 30 (7-8), pp. 371-382Tay, F.R., Pashley, D.H., Suh, B.I., Hiraishi, N., Yiu, C.K., Water treeing in simplified dentin adhesives--deja vu? (2005) Oper. Dent., 30 (5), pp. 561-579Asselin, M.E., Fortin, D., Sitbon, Y., Marginal microleakage of a sealant applied to permanent enamel: Evaluation of 3 application protocols (2008) Pediatr Dent., 30 (1), pp. 29-33Carvalho, R.M., Carrilho, M.R.O., Pereira, L.C.G., Sistemas adesivos: Fundamentos para aplicação clínica (2004) Biodonto, 2, pp. 1-85El-Araby, A.M., Talic, Y.F., The effect of thermocycling on the adhesion of self-etching adhesives on dental enamel and dentin (2007) J. Contemp. Dent Pract., 8 (2), pp. 17-24Titley, K., Caldwell, R., Kulkarni, G., Factors that affect the shear bond strength of multiple component and single bottle adhesives to dentin (2003) Am. J. Dent., 16 (2), pp. 120-124Tay, F.R., Pashley, D.H., Suh, B.I., Single-step adhesives are permeable membranes (2002) J. Dent., 30 (7-8), p.
Comparação de alguns modelos matemáticos para o ajuste às curvas de lactação individuais de vacas da raça Caracu Comparison of some mathematical models for the adjustment of individual lactation curves of Caracu cows
Foram ajustadas 7239 curvas de lactação de vacas Caracu, controladas semanalmente entre os anos de 1978 a 1988, pertencentes à Fazenda Chiqueirão, Poços de Caldas, MG. As funções utilizadas foram a linear hiperbólica (FLH), a quadrática logarítmica (FQL), a gama incompleta (FGI) e a polinomial inversa (FPI). Os parâmetros foram estimados por meio de regressões não lineares, usando-se processos iterativos. A verificação da qualidade do ajuste baseou-se no coeficiente de determinação ajustado (R²A), no teste de Durbin-Watson (DW) e nas médias e desvios-padrão estimados para os parâmetros e funções dos parâmetros dos modelos. Para a curva média, os R²A foram superiores a 0,90 para todas as funções. Bons ajustes, baseados nos R²A>0,80 foram obtidos, respectivamente, por 25,2%, 39,1%, 31,1% e 28,4% das lactações ajustadas pelas funções FLH, FQL, FGI e FPI. De acordo com o teste de DW, bons ajustes foram proporcionados para 29,4% das lactações ajustadas pela FLH, 54,9% pela FQL, 34,9% pela FGI e 29,6% pela FPI. Para ambos os critérios, a FQL foi superior às demais funções, indicando grande variação nas formas das curvas de lactação geradas pelos ajustes individuais. Curvas atípicas foram estimadas pelas funções, com picos ocorrendo antes do parto e algumas vezes após o término da lactação. Todas as funções apresentaram problemas quando ajustaram dados individuais.<br>The present study was carried out to test the goodness of fit of different lactation curve functions for 7239 Caracu cows, belonging to Chiqueirão farm, Poços de Caldas - MG, weekly recorded from 1978 to 1988. The functions used to describe the lactation curves were: linear hyperbolic function (LHF); logarithmic quadratic function (LQF); incomplete gamma function (IGF) and inverse polynomial function (IPF). Parameters were estimated by iterative methods. The criteria used to compare the models were the adjusted coefficient of determination (R²A), Durbin-Watson statistic (DW) and the estimated means and standard deviations estimated for the parameters and function of parameters. All R²A were higher than 0.90 for the average curves. When fitted to individual lactation, the functions showed lack of fit. Goodness of fit, according to R²A>0.80 were observed for 25.2%; 39.1%; 31.1% and 28.4% of LHF, LQF, IGF and IPF functions, respectively. Durbin-Watson statistics estimated goodness of fit for 29.4%; 54.9%; 34.9% and 29.6% of LHF, LQF, IGF and IPF functions, respectively. All models showed high CV for the parameters and function of parameters. The results indicated a wide variation in the shape of individual lactation curves. There was a great number of atypical curves with observed peaks before calving or after the end of lactation