Effect of silver diamine fluoride on adhesion and microleakage of a pit and fissure sealant to tooth enamel: in vitro trial.

AIM: To identify the effect of silver diamine fluoride in adhesion and microleakage of a pit and fissure sealant to tooth enamel. METHODS: An in vitro study including 120 human molars without caries, and caries grade 1 was performed. Molars were randomly divided into four groups. Occlusal surfaces of groups 2 and 4 were sealed. In groups 1 and 3 silver diamine fluoride (SDF) was placed in the occlusal surface and then molars were sealed according to manufacturer's instructions. Afterwards, all groups were submitted to the adhesion test. Groups 1 and 2 were placed in a forming cylinder and their roots were submerged in polymethyl methacrylate after that they were stored in deionised water (37 °C ± 1). Subsequently, they were tested by applying a tractional load (Instron machine, speed cross of 1 mm/min). Sealant adhesion was evaluated through: Resistance to the detachment (MPa), residues of sealant area (mm2) and adhesive remaining index (ARI) (0-3 interval). Microleakage test: Groups 3 and 4 were placed in a plastic container and subjected to 2000 cycles at different temperatures one at 6 °C ± 1 and the other at 60 °C ± 1. Later the occlusal surface was immersed for 24 h in 1% toluidine blue. Microleakage was observed by optical microscopy (10×) and was interpreted in micrometres. RESULTS: Of the samples without SDF 18.1 and 23.0% of the sealant remaining and of the samples with SDF present 100% of sealant remaining on enamel. Samples with SDF obtained an average in the test of detachment of 6.89 ± 3.09 MPa, whereas in the group without SDF the average obtained was 6.42 ± 3.35 MPa. Differences were not statistically significant (p = 0.579). Most of the samples not treated with SDF (81.6%) showed microleakage than those treated with SDF in which 47% presented microleakage. CONCLUSIONS: There is an improvement in the retention properties of a fissure sealant applied after treatment with silver diamine fluoride. The application of fissure sealant to improve the aesthetics of teeth treated with SDF is recommended.

Multiresistant extended-spectrum beta-lactamase-producing Klebsiella pneumoniae causing an outbreak of nosocomial bloodstream infection.

This article describes an outbreak of bloodstream infection due to clonal dissemination of multiresistant Klebsiella pneumoniae in a neonatal area, during August 1999, in Mexico City General Hospital. The intestinal tract was the likely reservoir, and intensification of Contact Precaution measures contained the outbreak.

Outbreak of nosocomial sepsis and pneumonia in a newborn intensive care unit by multiresistant extended-spectrum beta-lactamase-producing Klebsiella pneumoniae: high impact on mortality.

We describe a case-control study of a small outbreak of nosocomial sepsis and pneumonia with high mortality due to clonal dissemination of a multiresistant Klebsiella pneumoniae in the neonatal intensive care unit of a Mexican institution. Our study helped to change nosocomial infection control policy in this hospital.

[Detection of TEM-beta-lactamase in strains of Haemophilus influenzae resistant to ampicillin using the polymerase chain reaction (PCR)]. / Detección de betalactamasa tipo TEM en cepas de Haemophilus influenzae resistentes a ampicilina utilizando la reacción de polimerasa en cadena (PCR).

With the purpose of determining the type of beta-lactamases that mediate ampicillin resistance to in Haemophilus influenzae strains in the Hospital Infantil de México "Federico Gómez", we determined the minimum inhibitory concentration of 180 strains, isolated from different sources, to ampicillin, amoxicillin-clavulanic acid and ampicillin-sulbactam. All ampicillin resistant strains (29) were beta-lactamase positive as determined by nitrocephin hydrolysis. Using PCR with the primers from pBR322, we detected the presence of the gene for the TEM-beta-lactamase in 100% of the ampicillin resistant strains.