RESUMEN
AIM: To assess the immediate influence of dentine bonding systems (DBS) associated with 2% chlorhexidine digluconate (CHX) on glass-fibre post-bond strength to root dentine, in terms of coronal, middle and apical thirds. METHODOLOGY: Sixty bovine roots were root filled and randomly assigned to 1 of 6 groups (n = 10): SBMP (3-step etch-and-rinse system, Scotchbond Multi-Purpose), SB (2-step etch-and-rinse system, Single Bond 2), SE (2-step self-etching system, Clearfil SE Bond) and SBMP-CHX, SB-CHX and SE-CHX, respectively, associated with CHX. For all groups, a glass-fibre post was luted with a dual-cure resin cement, RelyX ARC. After 7-day storage, specimens were subjected to the push-out test. Failure modes were analysed under optical microscopy (40x). Bond strength values were statistically analysed by two-way anova and Bonferroni tests (P < 0.05). RESULTS: The effect of DBS was significant (P < 0.05), and SE reached higher bond strength in comparison with the other DBS tested. CHX association did not show improvement with any DBS (P > 0.05); rather, it negatively affected SE, which was detected for all thirds. There was no difference between thirds (P > 0.05), except for the SE-CHX, which presented lower values for the apical third (P < 0.05). Adhesive cement/dentine adhesive failure was predominant for all groups. CHX did not influence the failure mode for any DBS (P > 0.05). CONCLUSIONS: The performance of the dentine bonding systems was material dependent. CHX did not improve immediate bond strength; however, CHX negatively affected the bond strength of the self-etching system, especially in the third apical.
Asunto(s)
Antiinfecciosos Locales/química , Clorhexidina/análogos & derivados , Recubrimiento Dental Adhesivo , Materiales Dentales/química , Cavidad Pulpar/ultraestructura , Dentina/ultraestructura , Vidrio/química , Técnica de Perno Muñón/instrumentación , Grabado Ácido Dental/métodos , Animales , Bisfenol A Glicidil Metacrilato/química , Bovinos , Clorhexidina/química , Cementos Dentales/química , Análisis del Estrés Dental/instrumentación , Recubrimientos Dentinarios/química , Polietilenglicoles/química , Ácidos Polimetacrílicos/química , Distribución Aleatoria , Cementos de Resina/química , Auto-Curación de Resinas Dentales , Estrés Mecánico , Factores de Tiempo , Ápice del Diente/ultraestructuraRESUMEN
Twenty isolates of group B streptococcus (GBS) were recovered from the milk of cows with bovine mastitis on three farms located in the south and south-east of Brazil between 1987 and 1988. These isolates were characterised by molecular methods and compared with a collection of 103 human GBS isolates from colonised and infected patients in the same region between 1980 and 2003. Some of the bovine isolates shared identical or similar pulsed-field gel electrophoresis (PFGE) patterns with a PFGE clone of human GBS type V. In addition, these bovine and human isolates also possessed the same ribotype. Multilocus sequence typing (MLST) of representative isolates confirmed the genetic relationship between the human and bovine GBS isolates with identical PFGE patterns, which clustered in the same ST-26 clonal complex. These data support the hypothesis that some bovine GBS strains are related closely to human isolates and may infect humans, or vice versa. Further comparative genomic analyses of GBS isolates from bovine and human origins are required to investigate this hypothesis further.