V práci byla hodnocena pevnost tablet v tahu ze suchého pojiva Prosolv SMCC 90 a vliv tří koncentrací mazadla stearanu horečnatého na pevnost tablet z této látky. Výsledky byly srovnávány se stejným hodnocením u Avicelu PH 102. Testované koncenti-ace stearanu byly 0,4; 0,8 a 1,2 %. Tablety byly lisovány třemi lisovacími silami (3; 3,5 a 4 kN). Na základě získaných výsledků lze konstatovat, že samotný Prosolv SMCC 90 poskytuje při stejných lisovacích silách pevnější výlisky než Avicel PH 102. Z hlediska snížení pevnosti výlisků přídavkem stearanu horečnatého je suché pojivo Prosolv SMCC 90 mnohem méně citiivé než Avicel PH 102. U Avicelu PH 102 je výrazné snížení pevnosti zaznamenáno přídavkem 0,4 % stearanu horečnatého, což u Prosolvu SMCC 90 zaznamenáno nebylo. Významnější snížení pevnosti výlisků vykazuje tato látka až u koncentrace stearanu 0,8 %. Nejvyšší použitá koncentrace stearanu 1,2 % snižuje pevnost tablet z Prosolvu SMCC 90 u lisovacích sil 3,5 a 4 kN dvakrát méně než pevnost výlisků z Avicelu PH 102.

The present paper evaluated the tensile strength of tablets made from the dry binder Prosolv SMCC 90 and the influence of three concentrations of the lubricant magnesium stearate on the tensile strength of tablets manufactured firom this material. The results were compared with the same evaluation in Avicel PH102. The tested concentrations of the stearate were 0.4,0.8 and 1.2 %. The tablets were compressed by three press powers (3, 3.5, and 4 kN). On the basis of obtained results it can be stated that under the same press powers Prosolv SMCC 90 alone yields stronger compacts than Avicel PH 102. From the viewpoint of decreased strength of compacts by adding magnesium stearate, the dry binder Prosolv SMCC 90 is much less sensitive than Avicel PH 102. In Avicel PH 102 a marked decrease in tensile strength was recorded with an addition of 0.4 %, which was not observed with Prosolv SMCC 90. Amore significant decrease in the strength of compacts was shown by the substance not until a stearate concentration of 0.8 %. The highest employed stearate concentration of 1.2 % decreases the tensile strength of tablets made from Prosolv SMCC 90 in the press powers of 3.5 and 4 kN two times less than the tensile strength of the compacts from Avicel PH 102.

• Klíčová slova
• PROSOLV SMCC 90, AVICEL PH 102,
• MeSH
• farmaceutické pomocné látky MeSH
• pevnost v tahu účinky léků   MeSH
• stearany farmakologie   MeSH
• tablety normy   terapeutické užití   MeSH
• techniky in vitro MeSH

In order to compare the strengths of various materials it is necessary to carry out a standard form of test to establish their relative properties. Th e tensile test, compression test, bending, shearing and torsion tests are used for examining mechanical properties of biological materials. Th e presented paper is a report which describes a specifi c and unique technical solution and upgrade of FM 1000 machine from the control and output processing point of view. Modern sensoric systems and I/O modules were used and custom soft ware was developed. Th e function and operation of the embedded system was tested by initial experimental measurements.

• MeSH
• automatizované zpracování dat metody   přístrojové vybavení   využití   MeSH
• biomechanika MeSH
• biomedicínské a zubní materiály klasifikace   MeSH
• financování organizované MeSH
• lidé MeSH
• pevnost v tahu MeSH
• polyestery klasifikace   MeSH
• řízení kvality MeSH
• statistika jako téma metody   MeSH
• testování materiálů metody   přístrojové vybavení   MeSH
• Check Tag
• lidé MeSH

• MeSH
• hodnocení léčiv MeSH
• pevnost v tahu MeSH
• tablety analýza   MeSH

OBJECTIVES: Ultra-high-speed (UHS) videography was used to visualize the fracture phenomena at the resin-dentin interface during micro-tensile bond strength (μTBS) test. We also investigated whether UHS videography is applicable for failure-mode analysis. METHODS: Ten human mid-coronal dentin surfaces were bonded using Clearfil SE Bond either in self-etching (SE) or etch-and-rinse (ER) mode. After 24-h water storage, the samples were cut into beams for μTBS test and tested at a cross-head speed of 1 mm/min. The fracture phenomena at the bonded interface were captured using a complementary metal-oxide-semiconductor digital UHS camera at 299,166 frames per second. The failure modes were classified using UHS videography, followed by scanning electron microscopy (SEM) analysis. The failure-mode distributions determined by UHS videography and SEM analysis were statistically analyzed using Fisher's exact test with Bonferroni correction. RESULTS: The crack-propagation speed exceeded 1,500 km/h. No significant difference was found between the SEM and UHS videography failure-mode distributions in the SE mode. A significant difference appeared between them in the ER mode. Significant differences in the incidence of cohesive failures within the adhesive and at the adhesive-composite interface between the SE and ER modes were identified by both SEM and UHS videography. SIGNIFICANCE: UHS videography enabled visualization of the fracture dynamics at the resin- dentin interfaces under tensile load. However, the resolution at such high frame rate was insufficient to classify the failure mode as precisely as that of SEM. Nevertheless, UHS videography can provide more detailed information about the fracture origin and propagation.

• MeSH
• dentin MeSH
• dentinová adheziva * MeSH
• lidé MeSH
• mechanický stres MeSH
• mikroskopie elektronová rastrovací MeSH
• pevnost v tahu MeSH
• povrchové vlastnosti MeSH
• pryskyřičné cementy MeSH
• složené pryskyřice MeSH
• testování materiálů MeSH
• vazba zubní * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The bonding performance of dental adhesives is most frequently evaluated using the micro-tensile bond strength (μTBS) test. Despite lacking evidence, peripheral specimens are often discarded to avoid regional variability. This study, therefore, examined whether μTBS to central and peripheral dentin differed. Dentin surfaces of extracted human molars were bonded with various self-etch adhesives, built up with a resin composite, cut into beams, and stressed in tension. Failure mode was classified as adhesive, cohesive in dentin, or other using scanning electron microscopy. Since cohesive failures in dentin were frequent and could confound μTBS results, the data from central/peripheral dentin were analyzed using a Weibull competing risk (CR) model distinguishing failure modes, and its outcomes were compared to a conventional failure mode non-distinguishing Weibull model. Based on the strength data of cohesively failed specimens, the CR model also estimated the strength of dentin. For comparison, the ultimate tensile strength (UTS) of dentin was measured in both regions. The conventional model suggested that peripheral μTBS was higher than central μTBS. Conversely, the CR model disclosed no significant difference in μTBS between the regions but indicated a higher strength of peripheral dentin. This finding was confirmed by UTS measurements, and further supported by the significantly higher incidence of cohesive failures in central dentin. Therefore, peripheral specimens can be used in the μTBS test as well as central ones, but a CR model should be used for statistical analysis if cohesive failures in dentin are frequent, as the strength of peripheral dentin is higher.

• MeSH
• dentin MeSH
• dentinová adheziva * MeSH
• lidé MeSH
• pevnost v tahu MeSH
• pryskyřičné cementy MeSH
• složené pryskyřice MeSH
• testování materiálů MeSH
• vazba zubní * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The effect of long-term water storage on the regional ultimate tensile strength (UTS), water sorption (Wsp) and water solubility (Wsl) of conventional and bulk-fill resin composites at various depths was investigated. Composite specimens light-cured from one side were sectioned into beams corresponding to different depths (1-5 mm) and stored in water for 24 h, 1 week, 1 month, 6 months or 1 year. UTS increased during the first week and then gradually decreased over time, especially in deeper regions. Bulk-fill composites initially exhibited similar UTS at all depths, whereas the UTS of conventional composites at 1 mm and 5 mm differed significantly at all time points. Wsp and Wsl increased with depth and storage time, markedly at 3-5 mm after 1 month for conventional composites and after 6 months for bulk-fill composites. The signs of degradation at depths beyond 3 mm suggested that even bulk-fill composites have suboptimal properties in layers more than 3 mm in thickness.

• MeSH
• pevnost v tahu MeSH
• polymerizace MeSH
• rozpustnost MeSH
• složené pryskyřice * MeSH
• testování materiálů MeSH
• voda * MeSH
• Publikační typ
• časopisecké články MeSH

Material properties of soft-tissue samples are often derived through uniaxial tensile testing. For engineering materials, testing parameters (e.g., sample geometries and clamping conditions) are described by international standards; for biological tissues, such standards do not exist. To investigate what testing parameters have been reported for tensile testing of human soft-tissue samples, a systematic review of the literature was performed using PRISMA guidelines. Soft tissues are described as anisotropic and/or hyperelastic. Thus, we explored how the retrieved parameters compared against standards for engineering materials of similar characteristics. All research articles published in English, with an Abstract, and before 1 January 2023 were retrieved from databases of PubMed, Web of Science, and BASE. After screening of articles based on search terms and exclusion criteria, a total 1,096 articles were assessed for eligibility, from which 361 studies were retrieved and included in this review. We found that a non-tapered shape is most common (209 of 361), followed by a tapered sample shape (92 of 361). However, clamping conditions varied and were underreported (156 of 361). As a preliminary attempt to explore how the retrieved parameters might influence the stress distribution under tensile loading, a pilot study was performed using finite element analysis (FEA) and constitutive modeling for a clamped sample of little or no fiber dispersion. The preliminary FE simulation results might suggest the hypothesis that different sample geometries could have a profound influence on the stress-distribution under tensile loading. However, no conclusions can be drawn from these simulations, and future studies should involve exploring different sample geometries under different computational models and sample parameters (such as fiber dispersion and clamping effects). Taken together, reporting and choice of testing parameters remain as challenges, and as such, recommendations towards standard reporting of uniaxial tensile testing parameters for human soft tissues are proposed.

• Publikační typ
• systematický přehled MeSH

• MeSH
• adheziva chemie   škodlivé účinky   MeSH
• ortodontické zámky MeSH
• pryskyřičné cementy chemie   škodlivé účinky   MeSH
• skloionomerní cementy chemie   MeSH
• techniky in vitro MeSH
• voda chemie   škodlivé účinky   MeSH

• Publikační typ
• abstrakty MeSH

Understanding the molecular and cellular processes in skin wound healing can pave the way for devising innovative concepts by turning the identified natural effectors into therapeutic tools. Based on the concept of broad‐scale engagement of members of the family of galactoside‐binding lectins (galectins) in pathophysiological processes, such as cancer or tissue repair/regeneration, the present study investigated the potential of galectins‐1 (Gal‐1) and ‐3 (Gal‐3) in wound healing. Human dermal fibroblasts, which are key cells involved in skin wound healing, responded to galectin exposure (Gal‐1 at 300 or Gal‐3 at 600 ng/ml) with selective changes in gene expression among a panel of 84 wound‐healing‐related genes, as well as remodeling of the extracellular matrix. In the case of Gal‐3, positive expression of Ki67 and cell number increased when using a decellularized matrix produced by Gal‐3‐treated fibroblasts as substrate for culture of interfollicular keratinocytes. In vivo wounds were topically treated with 20 ng/ml Gal‐1 or ‐3, and collagen score was found to be elevated in excisional wound repair in rats treated with Gal‐3. The tensile strength measured in incisions was significantly increased from 79.5±17.5 g/mm2 in controls to 103.1±21.4 g/mm2 after 21 days of healing. These data warrant further testing mixtures of galectins and other types of compounds, for example a combination of galectins and TGF‐β1.

• MeSH
• fibroblasty metabolismus   patologie   MeSH
• galektiny biosyntéza   MeSH
• kolagen biosyntéza   MeSH
• krevní proteiny biosyntéza   MeSH
• lidé MeSH
• pevnost v tahu * MeSH
• rány a poranění metabolismus   patologie   MeSH
• regulace genové exprese * MeSH
• škára metabolismus   patologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH