Papers by Author: Jan Ryszard Dąbrowski

Abstract: This work presents results of research on compressive strength, microhardness, polymerization shrinkage and water sorption of some specially developed composite materials for dental fillings. The investigated powder fillers were divided into two groups: fluorine-based fillers, such as fluoridated glass, strontium fluoride, ytterbium fluoride and additives of improved mechanical characteristics such as nanosilica and polyethylene. The influence of fluoride ion source on the properties of the composite materials was evaluated. Tests were performed just after the material polymerization and, additionally, after seven, thirty and sixty days. Some small differences between composites were observed.

Abstract: In the paper own prepared materials with addition fluorine sources were evaluated. The aim of the study was to assess the quality and quantity of fluoride source on fluoride ions release from composite materials. Antibacterial activity of analyzed materials in relation to four bacteria was investigated. Fluoride ions release was measured by direct potentiometry method with fluoride ion selective electrode. The measurements were carried out after 1, 4, 7, 14, 30, 60 days of storage in buffer at pH 6.8. The antibacterial activity of the materials was evaluated against standard bacterial strains using the agar diffusion test. Tests show that the highest level of fluoride ions emission was observed for composite with fluoridated glass (material A) on the seventh day of the study. Similar fluoride ions amount was released from material consisted of fluoridated glass and ytterbium fluoride (material C), but not until on the thirtieth day of the study. After 24 hours of composite bonding there was inhibition of bacterial growth by composite C, whereas composite A did not show similar activity. On the eighth day after polymerization, both materials were significantly more active towards two bacteria.

Abstract: The paper presents investigation results of the rheological and some physico-chemical properties of mixed and submandibular/sublingual saliva (both unstimulated). Samples were collected in accordance with a predetermined methodology in order to eliminate the influence of such factors as, for example, time elapsed since the last meal. The initial analysis of human saliva showed a considerable divergence of the studied physico-chemical and rheological parameters. It was found that the submandibular/sublingual saliva constitutes a better diagnostic basis than the mixed saliva.

Abstract: The surface of an endosseous implant has fundamental importance in forming mechanical and chemical connection with osseous tissue. One of the methods of enlarging area is using technology of powder metallurgy. The paper presents research regarding osteointegration of porous materials for implants made for Co-Cr-Mo and titanium with Bioglass type-S2. The research was made on the castrated goats averaging one year of age, from this oneself herds. Bone growth process on surfaces of implants made with additional bioglass was significantly intense. The amount of osseous tissue and the number of connection points are significantly increased. On surfaces of titanium implants few areas of stochastic callus formation were observed. In that case areas of preferential bone integration have uneven surface due to technological process. A significant difference appears in osseous tissue growth morphology on implant surface. In porous implants bone grows around the pores of an implant. The obtained results showed that porosity influences callus growth intensity beneficially on the implant structure. Use of bioglass increases bone growth intensity on implant surface.

Abstract: The aim of this study was to determine the influence of powder fillers on the tribological properties of composite materials used for dental fillings. The investigated composites contain a fluoridated filler (based on Ba-Sr-Al-P-Na-silicate glass fillers) as a fluoride source as well as different powder fillers (friction modifiers) e.g. silicon nitride (Si3N4), boron nitride (BN), polyethylene (PE), polytetrafluoroethylene (PTFE). Composite disks were photo-cured and tested for wear against harder stainless-steel counterface. Wear tests were carried out by means of special tribotester in the presence of phosphate buffer as a lubricant. Influence of the load and filler contents on the friction coefficients and wear were estimated. The interaction between the filler particles and organic matrix and its influence on the tribological behavior of prepared specimens were observed. Organic powder fillers (PE, PTFE) reduced the friction coefficient and the wear of tested composite materials for dental fillings. Inorganic friction modifiers (Si3N4, BN) did not exhibit this effect.