Determination of inner implant's volumes: a pilot study for microleakage quantification by stereomicroscopy and spectrophotometry.

AIM: Microleakage quantification of fluids and microorganisms through the connections of different implant parts seems to be sparse. Moreover, no data exist regarding the determination of the volumes of inner parts of dental implant systems. This study aims to determine the volumes of inner parts of three dental implant systems with the same interface and to evaluate the microleakage phenomenon. MATERIALS AND METHODS: Three implant system sets (Euro-teknika(®), Astra Tech(®) and Implantium(®)) were used in this study. Implants were inoculated with safranin, brain heart infusion and distilled water. After inoculation and assembly of the different parts, different inner volumes (V1, V2, V3, V4, V5 and V6) were measured and, the surfaces of the micro gaps were observed through a stereomicroscope. Implants containing safranin were immersed in vials containing distilled water. Samples then were taken to determine optical density using a spectrophotometer. RESULTS: Regardless the used substance, volumes of the 3-implant systems are different. Although volumes V1, V 2, V 3 and V5 appeared to be constant within the same system regardless the used substance, volumes V4 and V6 were not. CONCLUSION: The determination of the volumes and the evaluation of leaked substance using stereomicroscopic and spectrophotometric methods showed the accuracy of these methods and the importance of their use in the study of microleakage. CLINICAL SIGNIFICANCE: Leakage is an important factor for chronic inflammatory infiltration and marginal bone resorption. Studies have shown fluid and bacterial leakage into abutment- implant (A-I) assemblies of certain implants with 'closely locked' abutments and the creation of a constant bacterial reservoir in the empty space found between the implant and the abutment.

Purification of oligouronides using hollow-fiber membrane functionalised with L-histidine.

The pseudobioaffinity chromatography with L-histidines immobilized onto poly(ethylene-vinyl alcohol) hollow-fiber membranes was studied for a selective purification of anionic oligosaccharides. Oligoglucuronans with different degrees of polymerization and acetylation, prepared by an enzymatic degradation of bacterial polyglucuronic acid, were used as models. The adsorption and elution parameters were studied to optimise the selective adsorption. A better understanding of the physico-chemical phenomena governing this selectivity was attempted and a few hypotheses on the mechanism of selectivity are proposed.

Broadening the scope of Baeyer-Villiger monooxygenase activities toward α,ß-unsaturated ketones: a promising route to chiral enol-lactones and ene-lactones.

Three regiodivergent Baeyer-Villiger mono-oxygenases (enantioselectively) oxidized a series of cyclic α,ß-unsaturated ketones into (chiral) either enol-lactones or ene-lactones. An easy-to-use and efficient biocatalytic process based on a host-microorganism deprived of unwanted activities (knock-out mutant) was developed to enable the exclusive synthesis of unsaturated lactones.