Effect of ultrasonic and sonic instrumentation on shear bond strength of resin composite to enamel: An in vitro study.

PURPOSE: To assess and compare the effects of sonic and ultrasonic instrumentation on shear bond strength (SBS) and investigate the influence of adhesive system application modes (etch&rinse/self-etch) on SBS. METHODS: In this experimental study, 45 extracted sound human molars were selected. Mesial and distal surfaces of the teeth were abraded until 90 smooth enamel surfaces were obtained. Specimens were divided into two groups, with half (N= 45) conditioned in etch&rinse mode and the remaining (N= 45) in self-etch mode using Tetric N Bond Universal. Composite resin discs were produced on these surfaces by filling Teflon molds. All specimens were aged via thermocycling. Each group was further divided into three more groups (n= 15) according to the type of periodontal instrumentation (ultrasonic, sonic or none). SBS values were recorded and analyzed using two-way ANOVA. Fracture sites were examined under a stereomicroscope. RESULTS: The type of periodontal instrumentation had no significant effect on SBS values, whether sonic, ultrasonic or their absence (P= 0.945). The type of adhesive system mode had a significant influence on the shear bond strength values. Etch&rinse groups had significantly higher shear bond strength values than self-etch groups (P< 0.001). CLINICAL SIGNIFICANCE: This study reassures practitioners that sonic and ultrasonic instruments are safe for enamel bonding and highlights the importance of selecting adhesive techniques for optimal restorative outcomes.

A novel, high stringency selection system allows screening of few clones for high protein expression.

To obtain highly productive mammalian cell lines, often large numbers of clones need to be screened. This is largely due to low selection stringencies, creating many, but low protein producing clones. To remedy this problem, a novel, very stringent selection system was designed, to create few, but high protein producing clones. In essence, a selection marker with a startcodon that confers attenuated translation initiation frequency was placed upstream of the gene of interest with a startcodon that confers optimal translation initiation. From the transcribed bicistronic mRNA, the selection marker is translated at a low frequency, and the protein of interest at a high frequency. This selection system is so stringent that clones form only rarely. However, application of anti-repressor elements, which increase promoter activity, did induce the formation of clones that expressed proteins at high levels. When combined with anti-repressor elements, this novel selection system can be a valuable tool to rapidly create few, but highly productive mammalian cell lines.

CVD diamond-based semi-transparent beam-position monitors for synchrotron beamlines: preliminary studies and device developments at CEA/Saclay.

Polycrystalline diamond synthesized using the chemical vapour deposition (CVD) technique can be used to fabricate new types of photodetectors for the characterization of X-ray light in synchrotron beamlines. Since diamond exhibits a low absorption to low-energy photons, such devices allow beam-position monitoring with very little beam attenuation at photon energies as low as 2 keV up to 15-20 keV. Here it is shown how diamond-based devices can simply be processed as ionization chambers for advanced semi-transparent position monitoring with high position resolution (<2 microm). Other configurations using the same principle can also enable in-line field profiling. It is also shown what can be expected from these devices in terms of performances, signal-to-noise ratios and reliability, together with their inherent limitations caused by the presence of defects in polycrystalline materials. In particular, diamond devices with extremely low carrier lifetimes, owing to quenched transport properties, could also be of particular interest for the characterization of the temporal structure of synchrotron light. Interest in these devices lies in the permanent insertion into beamlines and withstanding high levels of radiation for continuous beam monitoring.

[Complications of punctum plug in the symptomatic treatment of dry eye]. / Complications des bouchons lacrymaux employés dans le traitement symptomatique des sécheresses oculaires.

76 patients with dry eyes were treated by mechanical obstruction of lacrymal puncta. The sex ratio is: 62 females and 14 males. The age average was 55, ranging from 12 to 88. The etiologies were: Sjögren's syndrome: 16 cases (21%); filamentous kerato-conjonctivitis sicca: 12 cases (15%); anxiolytical and anti-depressant treatments: 10 cases (13%); complicated viral kerato-conjonctivitis: 4 cases (5%); post radiotherapy dry syndrome: 3 cases (4%); idiopathic and various etiologies: 31 cases (40%). The 149 plugs are completely made of hydrophobic silicone; 20 had a barb inclined on the neck axis. Insertion was achieved after tropical anesthesia in 90% of the cases. 121 plugs (81%) did not lead to any anatomical complication (the average duration remaining on time interval of implantation per plug was of 5 months). Functional tolerance depends on the quality of plug-punctum adjustment. Plug protrusion is the main cause of intolerance and disappearance. The complications were: rupture of punctum during dilation: 1%; suppurative canaliculitis: 1.3%; disappearance: 16%; epiphora: 22%. No intra-canalicular migration was observed. We check canalicular permeability in 26 cases, after loss or removal: che was normal 23 times (average time-interval: 5 months). We had 3 cases of canalicular stenosis after 4 months, 5 months and 18 months of intubation.

[Thin soft hydrogel lenses of high and low water (author's transl)]. / Lentilles souples thérapeutiques de faible épaisseur et de forte teneur en eau: résultats et indications.

The authors relate the results obtained with very thin soft hydrogel lenses (0,10 mm thickness) of high and low water content: the Vergo-Softcon THX of 70% water-content and the Bauch and Lomb Plano-T of 38%. The most frequent indications encountered are bullous keratopathy, epithelial defects and keratitis sicca. The results are positive in 78,2% of cases with 70% w/c soft hydrogel lenses. Results are given for cases of direct fitting of thin lenses, as well as for cases of fitting after failures of classic soft hydrogel lenses and in cases of exchanges of 40% lenses for 70% lenses. The 70% water content lenses seem to give better results main in cases of epithelial defects and keratitis sicca.

On the mechanism of the "photo-geo" response in the mesocotyl of oat seedlings.

The photo-geo response comes about through the differential inhibition of cell growth on the two curved sides of the mesocotyl.