RESUMO
The achievement of a strong and stable bond between composite resin and dentin remains a challenge in restorative dentistry. Over the past two decades, dental materials have been substantially improved, with better handling and bonding characteristics. However, little attention has been paid to the contribution of collagen structure/stability to bond strength. We hypothesized that the induction of cross-linking in dentin collagen improves dentin collagen stability and bond strength. This study investigated the effects of glutaraldehyde-and grape seed extract-induced cross-linking on the dentin bond strengths of sound and caries-affected dentin, and on the stability of dentin collagen. Our results demonstrated that the application of chemical cross-linking agents to etched dentin prior to bonding procedures significantly enhanced the dentin bond strengths of caries-affected and sound dentin. Glutaraldehyde and grape seed extract significantly increased dentin collagen stability in sound and caries-affected dentin, likely via distinct mechanisms.
Assuntos
Reagentes de Ligações Cruzadas/química , Colagem Dentária , Cárie Dentária/patologia , Materiais Dentários/química , Dentina/ultraestrutura , Condicionamento Ácido do Dente , Aminoácidos/análise , Bis-Fenol A-Glicidil Metacrilato/química , Colágeno/química , Colágeno/efeitos dos fármacos , Colágeno/ultraestrutura , Colagenases/farmacologia , Análise do Estresse Dentário/instrumentação , Dentina/efeitos dos fármacos , Adesivos Dentinários/química , Glutaral/química , Extrato de Sementes de Uva/química , Dureza , Humanos , Teste de Materiais , Metacrilatos/química , Microscopia Eletrônica de Varredura , Ácidos Fosfóricos/química , Cimentos de Resina/química , Estresse Mecânico , Resistência à Tração , Fatores de TempoRESUMO
Leptin is a hormone that affects the regulation of feed intake, energy balance and body composition in mammals. Several polymorphisms in the bovine leptin gene have been associated with phenotypic variance of these traits. We evaluated two known single nucleotide polymorphisms (SNPs) in the leptin gene of 253 grazing Brangus steers. Brangus is a 5/8 Angus-3/8 Brahman composite. Data were collected during two consecutive growth/fattening cycles from two farms in southeast Buenos Aires province, Argentina. One of the markers is in the promoter region of the gene (SNP1) and the other is a non-synonymous polymorphism in exon 2 (SNP2). The traits that we evaluated were live weight gain in the spring, gain in backfat thickness in the spring, final live weight, final ultrasound backfat thickness, final ultrasound rib eye area, carcass weight and length, carcass yield, kidney fat, kidney fat percentage, backfat thickness, rib eye area, and intramuscular fat percentage. Both markers affected some meat traits; though the only significant associations were of SNP1 with ultrasound rib eye area and of SNP2 with carcass yield and backfat thickness. Under the same conditions as in the present study, leptin markers could be of help only as part of a larger genotyping panel including other relevant genes.
