Brushing Effect Of Abrasive Dentifrices During At-home Bleaching With 10% Carbamide Peroxide On Enamel Surface Roughness

During tooth bleaching abrasive dentifrices might change the outer superficial enamel. The aim of this in vitro study was to evaluate the roughness of human enamel exposed to a 10% carbamide peroxide bleaching agent at different times and submitted to different superficial cleaning treatments. The study consisted of 60 sound human enamel slabs, randomly assigned to different treatment groups: G1 - not brushed; G2 - brushed with a fluoride abrasive dentifrice; G3 - brushed with a non-fluoride abrasive dentifrice; and G4 - brushed without a dentifrice. There were 15 enamel slabs per group. Slabs of molar teeth were obtained and sequentially polished with sandpaper and abrasive pastes. A perfilometer was used to obtain the mean of Ra value on the surface of each specimen to initial and experimental times. Bleaching was performed on the enamel surface for six hours daily. After that, each slab received a cleaning surface treatment and was stored in artificial saliva. Analysis of variance (ANOVA) and Tukey's HSD hoc analysis (α =0.05) revealed significant differences in roughness values over time for enamel bleached and treated with different superficial cleaning methods. G1 and G4 showed no significant differences in roughness over time, G2 and G3 showed a significant increase in the surface roughness values. This in vitro investigation showed the sole use of 10% carbamide peroxide did not alter the enamel surface roughness, but the cleaning treatments that employed the use of brushing with abrasive dentifrices resulted in a significant increase of enamel surface roughness.712534Leonard, R.H., Sharma, A., Haywood, V.B., Use of different concentrations of carbamide peroxide for bleaching teeth: An in vitro study (1998) Quintessence Int, 29, pp. 503-507. , AugBasting, R.T., Rodrigues Jr., A.L., Serra, M.C., The effect of 10% carbamide peroxide bleaching material on microhardness of sound and demineralized enamel and dentin in Situ (2001) Oper Dent, 26, pp. 531-539. , Nov-DezBitter, N.C., A scanning electron microscopy study of the effect of bleaching agents on enamel: A preliminary report (1992) J Prost Dent, 67, pp. 852-855. , JunGultz, J., Kaim, J., Scherer, W., Two in-office bleaching systems: A scanning electron microscope study (1999) Compend Contin Educ Dent, 20, pp. 965-968. , OctMcGuckin, R.S., Babin, J.F., Meyer, B.J., Alterations in human enamel surface morphology following vital bleaching (1992) J Prosthet Dent, 68, pp. 754-760. , NovSmidt, A., Weller, D., Roman, I., Effect of bleaching agents on microhardness and surface morphology of tooth enamel (1998) Am J Dent, 11, pp. 83-85Attin, T., Kielbassa, A.M., Schwanenberg, M., Effect of fluoride treatment on remineralization of bleached enamel (1997) J Oral Rehab, 24, pp. 282-286. , AprHachiya, Y., Takatsu, T., Hosoda, H., A Varnish to prevent etching unrestored enamel (1985) J Prosthet Dent, 53, pp. 46-50. , JanRodrigues, J.A., Basting, R.T., Serra, M.C., Effects of 10% carbamide peroxide bleaching materials on enamel microhardness (2001) Am J Dent, 14, pp. 67-71. , AprFreitas, P.M., Basting, R.T., Rodrigues Jr., A.I., Effects of two 10% peroxide carbamide bleaching agents on dentin microhardness at different time intervals (2002) Quintessence Int, 33, pp. 370-375. , MayErnest, C.P., Marroquin, B.B., Willershausen- Zönnchen, B., Effects of hydrogen peroxide-containing bleaching agents on the morphology of human enamel (1996) Quintssence Int, 27, pp. 53-56Hegedüs, C., Bistey, T., Flóra-Nagy, An anatomic force microscopy study on the effect of bleaching agents on enamel surface (1999) J Dent, 27, pp. 509-515McCracken, M., Haywood, V.B., Demineralization effects of 10 percent carbamide peroxide (1996) J Dent, 24, pp. 395-398. , NovKuroiwa, M., Kodaka, T., Kuroiwa, M., Microstructural changes of human enamel surfaces by brushing with and without dentifrice containing abrasive (1993) Caries Res, 27, pp. 1-8White, D.J., Development of an improved whitening dentifrice based upon "stain specific soft silica" technology (2001) J Clin Dent, 12, pp. 25-29Isaacs, R.L., Bartizek, R.D., Owens, T.S., Maintenance of tooth color after prophylaxis: Comparison of three dentifrices (2000) J. Clinic Dent, 112, pp. 51-55Gerlach, R.W., Barker, M.L., Hyde, J.D., Effects of a tartar control whitening dentifrice on tooth shade in a population with long-standing natural stain (2001) J Clin Dent, 12, pp. 47-50Silverstone, L.M., Remineralization Phenomena (1977) Caries Res, 11 (1 SUPPL.), pp. 59-84Featherstone, J.D.B., O'Really, M.M., Shariati, M., Enhancement of remineralization in vitro and in vivo (1986) Factors Relating to Demineralization and Remineralization of the Teeth, pp. 23-34. , Leach AS. Oxford: IRLSerra, M.C., Cury, J.A., The in vitro effect of glass-ionomer cement restoration on enamel subjected to a demineralization and remineralization model (1992) Quintessence Int, 24, pp. 39-44. , FebWorschech, C.C., Rodrigues, J.A., Martins, L.R.M., "In vitro" evaluation of human dental enamel surface roughness bleached with 35% carbamide peroxide and submitted to abrasive dentifrice brushing (2003) Pesqui Odontol Bras, 17 (4), pp. 342-348. , Oct-De

Avaliação da interação biológica entre compósito de quitosana, colágeno e hidroxiapatita e tecido ósseo ovino

RESUMO As lesões em membros de grandes animais são um desafio para médicos veterinários, uma vez que somente a osteossíntese não garante resultados satisfatórios. Muitos pesquisadores vêm se dedicando ao desenvolvimento e estudo de substitutos ósseos produzidos de materiais naturais, como quitosana, colágeno e hidroxiapatita, que auxiliam na regeneração óssea. Seis ovinos fêmeas da raça Santa Inês foram submetidos a ostectomias unicorticais de sete milímetros de diâmetro na região proximal da superfície dorsomedial dos III/IV metacarpianos. Foi implantado compósito de quitosana, colágeno e hidroxiapatita em um membro torácico para avaliação da biocompatibilidade do material ao tecido ósseo ovino, e no membro contralateral foi reproduzida a mesma técnica, porém foi mantido sem preenchimento, como controle. Após 60 dias do procedimento cirúrgico, realizou-se biópsia óssea na área de interface entre biomaterial/osso (membro com compósito) e tecido neoformado/osso (membro controle), para realização de avaliação histológica do material não descalcificado, por meio de microscopia de luz e microscopia eletrônica de varredura. Na análise histomorfométrica, mediante microscopia de luz, foi possível identificar maior porcentagem de tecido neoformado em membro controle, quando comparado ao membro com compósito (80% e 63,5%, respectivamente; P<0,05). Por meio da microscopia eletrônica de varredura, observou-se invasão da estrutura interna do compósito por tecido ósseo neoformado. Não houve formação de tecido cicatricial, reação de corpo estranho ou resposta inflamatória crônica nas amostras analisadas. Conclui-se que o compósito de quitosana, colágeno e hidroxiapatita, quando implantado em tecido ósseo ovino, apresenta biocompatibilidade e perfil osteocondutor

Draft genome sequence of Bradyrhizobium elkanii TnphoA 33, a producer of polyhydroxyalkanoates

The genus Bradyrhizobium comprises bacteria with the ability to form nitrogen-fixing symbioses with legumes. They are of great interest in agriculture, as well as for the production of biopolymers such as polyhydroxyalkanoates. Here, we report the draft genome assembly of Bradyrhizobium elkanii TnphoA 33 comprising 9 Mb, 1,124 contigs, and 9,418 open reading frames