Morphological, Biochemical and Fluorescent Antibody Studies of Haemophilus Somnus

Haemophilus somnus was the tentative name given in 1969 to a fastidious gram negative pleomorphic coccobacillus which was consistently isolated from cattle affected with a clinical syndrome called thrombo embolic meningoencephalitis (TEME)(1). The organism was initially classidied as an Actinobacillus actinoides- like organism, but because of its demand for a blood base for primary isolationit was reclassified as Haemophilus-like. Bailie then designated the species name somnus, referring to the sleepiness commonly exhibited by TEME affected cattle(1). In this study, the biochemical reactions of 50 H. somnus isolants recovered from bovine specimens submitter to the South Dakota Animal Diseased Research and Diagnostics Laboratory over a period of 20 months were compared with two reference H. somnus strains plus 13 closely related organisms. A fluorescent antibody conjugate was prepared from the reference strain and used for rapid identification of H. somnus in pure culture as well as in tissues infected with the organism

Modelling studying as the tool of the identification forces of mandibular systems muscles

W pracy przedstawiono metodykę identyfikacji sił mięśni żwaczowych narządu żucia. W zaproponowanym podejściu przeprowadzono ocenę sił mięśniowych narządu żucia, z uwzględnieniem oddziaływania układu nerwowego. Taki sposób prowadzenia badań modelowych jest alternatywnym ujęciem problemu równowagi biostatycznej narządu żucia, w stosunku do dotychczas stosowanych metod obliczeniowych. Dodatkowo podczas przeprowadzonych obliczeń numerycznych uwzględniono ograniczenia, związane z maksymalną wydolnością poszczególnych mięśni żwaczowych. Wyniki obliczeń numerycznych przedstawiono w postaci przebiegów czasowych sił mięśni narządu żucia oraz charakterystyki odwzorowującej wpływ przyłożenia zewnętrznego obciążenia do łuku zębowego żuchwy.The paper presents a methodology to identify the forces of masticatory muscles. The proposed approach was evaluated masticatory muscle forces, including the impact of the nervous system. This method of research is an alternative model of the problem of balance of masticatory biostatic, with respect to existing methods of calculations. In addition, in carrying out numerical calculations take into account constraints related to the maximum capacity of the individual muscles. The results of numerical calculations are presented in the form of time histories of forces of masticatory muscles and the characteristics of mapping decisions and brokering the impact of application of external load to the arch of the mandible

Physicochemical Properties of Novel Copolymers of Quaternary Ammonium UDMA Analogues, Bis-GMA, and TEGDMA

This study aimed to elucidate the physicochemical properties of copolymers comprising 40 wt.% bisphenol A glycerolate dimethacrylate (Bis-GMA), 40 wt.% quaternary ammonium urethane-dimethacrylate analogues (QAUDMA-m, where m corresponds to the number of carbon atoms in the N-alkyl substituent), and 20 wt.% triethylene glycol dimethacrylate (TEGDMA) copolymers (BG:QAm:TEGs). The BG:QAm:TEG liquid monomer compositions and reference compositions (40 wt.% Bis-GMA, 40 wt.% urethane-dimethacrylate (UDMA), 20 wt.% TEGDMA (BG:UD:TEG) and 60 wt.% Bis-GMA, 40 wt.% TEGDMA (BG:TEG)) were characterized in terms of their refractive index (RI) and monomer glass transition temperature (Tgm) and then photocured. The resulting copolymers were characterized in terms of the polymer glass transition temperature (Tgp), experimental polymerization shrinkage (Se), water contact angle (WCA), water sorption (WS), and water solubility (SL). The prepared BG:QAm:TEG liquid monomer compositions had RI in the range 1.4997–1.5129, and Tgm in the range −52.22 to −42.12 °C. The BG:QAm:TEG copolymers had Tgp ranging from 42.21 to 50.81 °C, Se ranging from 5.08 to 6.40%, WCA ranging from 81.41 to 99.53°, WS ranging from 25.94 to 68.27 µg/mm3, and SL ranging from 5.15 to 5.58 µg/mm3. Almost all of the developed BG:QAm:TEGs fulfilled the requirements for dental materials (except BG:QA8:TEG and BG:QA10:TEG, whose WS values exceeded the 40 µg/mm3 limit)

Influence of silver-containing filler on antibacterial properties of experimental resin composites against Enterococcus faecalis

Purpose: The aim of the presented work was to investigate the impact of the S-P introduction into resin-based composites on their effectiveness against Enterococcus faecalis (E. faecalis). Design/methodology/approach: Seven experimental composites based on typical matrix were developed. Six of them contained a filler with antimicrobial properties (silver sodium hydrogen zirconium phosphate, S-P), while the control material contained only common reinforcement fillers. The materials were characterized in terms of the dispersion of the extender in the matrix and then subjected to microbiological tests. The efficiency in the reduction of E. faecalis in the microenvironment was tested. Findings: The composites show a satisfactory distribution of fillers and a high initial reduction of bacteria colonies for the tested strain of E. faecalis. The reduction in bacteria colonies achieved for S-P concentrations from 7% to 13% was similar (median value from 99.8 to 99.9%, when for control material and compound with 1% S-P the number of colonies increased compared to positive control. Research limitations/implications: Laboratory test results may differ from in vivo test performance. In addition, there are many models for conducting laboratory antimicrobial efficacy studies, the results of which are also varied. The cytotoxic tests, long-term investigations and in vivo experiments need to be performed in future experiments. Practical implications: E. faecalis is a Gram-positive bacterium that is commonly detected in persistent endodontic infections and may enter the root canal through the coronal part. Development of composites with antimicrobial properties against this bacterium is as important as obtaining efficacy against cariogenic bacteria. Originality/value: The antimicrobial effectiveness against E. faecalis of experimental composites with submicrometer-sized particles of S-P was not investigated until now

Characterization of the Mechanical Properties, Water Sorption, and Solubility of Antibacterial Copolymers of Quaternary Ammonium Urethane-Dimethacrylates and Triethylene Glycol Dimethacrylate

The use of dental composites based on dimethacrylates that have quaternary ammonium groups is a promising solution in the field of antibacterial restorative materials. This study aimed to investigate the mechanical properties and behaviors in aqueous environments of a series of six copolymers (QA:TEG) comprising 60 wt.% quaternary ammonium urethane-dimethacrylate (QAUDMA) and 40 wt.% triethylene glycol dimethacrylate (TEGDMA); these copolymers are analogous to a common dental copolymer (BG:TEG), which comprises 60 wt.% bisphenol A glycerolate dimethacrylate (Bis-GMA) and 40 wt.% TEGDMA. Hardness (HB), flexural strength (FS), flexural modulus (E), water sorption (WS), and water solubility (SL) were assessed for this purpose. The pilot study of these copolymers showed that they have high antibacterial activity and good physicochemical properties. This paper revealed that QA:TEGs cannot replace BG:TEG due to their insufficient mechanical properties and poor behavior in water. However, the results can help to explain how QAUDMA-based materials work, and how their composition should be manipulated to produce the best performance. It was found that the longer the N-alkyl chain, the lower the HB, WS, and SL. The FS and E increased with the lengthening of the N-alkyl chain from eight to ten carbon atoms. Its further extension, to eighteen carbon atoms, caused a decrease in those parameters

Influence of Chemical Composition on the Properties of Experimental Silicone-Based Soft Lining Composites

The paper analyses the influence of chemical composition of silicone-based composites on their properties in the aspect of using them as long-term soft denture lining materials. Different concentrations of filler and methylhydrosiloxane-dimethylsiloxane copolymer were used. The filler was introduced into the composite with mechanical mixing combined with ultrasonic homogenization. Scanning electron microscopy was used to investigate the quality of filler dispersion. Shore A hardness, tensile strength, sorption, solubility and tensile bond strength to poly(methyl methacrylate) were measured. Tests show satisfactory results for some experimental composites, which met all the requirements for such materials

Effects of Different Inorganic Fillers on Mechanical Properties and Degree of Conversion of Dental Resin Composites

The aim of the study was to evaluate the influence of different fillers on the chosen functional properties of experimental composites based on typical polymeric matrix, in order to understand the effect of different fillers on their properties and to develop a simple base composite for further investigations with experimental fillers, e.g. with antimicrobial properties. Previous experiments have been usually based on commercially available composites of unknown composition or compilation of monomers, without reinforcing fillers. Scanning electron microscopy was used to investigate the quality of fillers’ dispersion, which was satisfying. Results showed significant differences between materials’ diametral tensile strength (p = 0.0019), compressive strength (p < 0.0001), Vickers microhardness (p < 0.0001), flexural modules (p = 0.0018), and the degree of conversion (p < 0.0001), but flexural strength was not significantly different (p = 0.0583). Investigations indicated that no filler type had an especially positive impact on the mechanical properties, but reinforcement effect was achieved by proper compilation of silica nanofiller and variable glass fillers. Nanofiller decreased the degree of conversion