At present, new acrylic plastic technologies are being developed in dentistry. Although this kind of material has been used for dental prostheses for over 80 years, it has been produced in the form of disks with the computer-aided design/computer-aided manufacturing (CAD/CAM) technology for over 15 years. The purpose of the article was to collect information from the literature on acrylic materials processed through the milling technology (CAD/CAM). The publicly available databases PubMed, Google Scholar and Scopus were searched using the key word "acrylic resins, CAD/CAM". All articles describing the application and testing of CAD/CAM disks were selected. Duplicate articles were removed. More than 100 articles that described the use of materials machined using the milling equipment were found. These included works comparing the mechanical properties, biocompatibility and clinical use of the materials. After the initial selection, 36 papers on this subject were included in this review. The number of studies on the processing of acrylic materials with the use of the CAD/CAM technology has been increasing worldwide. Since such materials have better mechanical properties, no polymerization shrinkage occurs during processing, the amount of residual monomer material is very low and they have better color stability than self-curing materials.
- Klíčová slova
- CAD/CAM, acrylic resin, flexural strength, residual monomer, surface,
- MeSH
- akrylové pryskyřice * MeSH
- design s pomocí počítače MeSH
- lidé MeSH
- polymethylmethakrylát MeSH
- testování materiálů MeSH
- zubní materiály * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
- systematický přehled MeSH
- Názvy látek
- akrylové pryskyřice * MeSH
- polymethylmethakrylát MeSH
- zubní materiály * MeSH
OBJECTIVE: To evaluate the influence of different types of modifications with resin on fatigue resistance and failure behavior of CAD-CAM resin nano ceramic (RNC) restorations for maxillary first premolars. METHODS: Sixty standardized resin composite root dies received CAD-CAM RNC endocrowns (n=30) and crowns (n=30) (Lava Ultimate, 3M Espe). Restorations were divided into six groups: full anatomic endocrowns (group A) and crowns (group D), buccal resin veneered endocrowns (group B) and crowns (group E) and buccal resin veneered endocrowns (group C) and crowns (group F) with a central groove resin filling. A nano-hybrid resin composite was used to veneer the restorations (Filtek Supreme, 3M Espe). All specimens were first submitted to thermo-mechanical cyclic loading (1.7Hz, 49N, 600000 cycles, 1500 thermo-cycles) and then submitted to cyclic isometric stepwise loading (5Hz) until completion of 105000 cycles or failure after 5000 cycles at 200N, followed by 20000 cycles at 400N, 600N, 800N, 1000N and 1200N. In case of fracture, fragments were analyzed using SEM and modes of failure were determined. Results were statistically analyzed by Kaplan-Meier life survival analysis and log rank test (p=0.05). RESULTS: The differences in survival between groups were not statistically significant, except between groups D and F (p=0.039). Endocrowns fractured predominantly with a mesio-distal wedge-opening fracture (82%). Partial cusp fractures were observed above all in crowns (70%). Analysis of the fractured specimens revealed that the origin of the fracture was mainly at the occlusal contact points of the stepwise loading. SIGNIFICANCE: Veneering of CAD-CAM RNC restorations has no influence on their fatigue resistance except when monolithic crowns are modified on their occlusal central groove.
- Klíčová slova
- CAD/CAM, Endocrown, Endodontically treated teeth, Fatigue, Fractography, Lava Ultimate, Veenering,
- MeSH
- analýza zatížení zubů MeSH
- design s pomocí počítače * MeSH
- složené pryskyřice MeSH
- zubní korunky * MeSH
- zubní porcelán * MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- složené pryskyřice MeSH
- zubní porcelán * MeSH
BACKGROUND: The master cast is the gold standard for the control and eventual adjustment of restorations produced by conventional procedures. Some digital workflow bypasses the master cast and relies completely on the precision of the CAD/CAM restoration. AIM: To examine the reproducibility of the margins of CAD/CAM restorations generated from a single digital scan. Also, to check the readiness of these restorations for delivery directly after fabrication without adjustment on a master cast and thereby eliminate the need for the master cast. METHODS: A total of 18 metal substructures made from cobalt chrome alloy were fabricated utilizing a single STL file. The circumference was divided into eight zones. The vertical marginal discrepancy (VMD) was measured at each zone of each metal substructure, with optical microscopy at ×200 magnification. RESULTS: Measurements of vertical marginal discrepancy were in a range of (-94: 300) with a mean of 62 ± 60 μm. A one-way ANOVA test revealed that the mean VMD is significantly different among the 18 substructures (F17, 1,134 = 63.948, p < 0.001). CONCLUSION: Although all the received substructures were fabricated from the same scan file, they were not identical and varied widely, and they were going outside the acceptable range in some zones. Within the limitations of this study, the marginal fit can be improved by extraoral adjustments on the master cast. Thus, skipping the master cast deprives the dentist of delivering a restoration of higher quality.
- Klíčová slova
- CAD/CAM, Digital impression, Digital workflow, Digitalization, Marginal adaptation, Marginal discrepancy, Marginal gap, Master cast, Metal coping, Metal substructures,
- MeSH
- analýza rozptylu MeSH
- design s pomocí počítače * MeSH
- mikroskopie * MeSH
- reprodukovatelnost výsledků MeSH
- slitiny chromu MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- slitiny chromu MeSH
This study aimed to compare the vertical marginal gap of teeth restored with lithium disilicate crowns fabricated using CAD/CAM or by pressed ceramic approach. Twenty mandibular third molar teeth were collected after surgical extractions and prepared to receive full veneer crowns. Teeth were optically scanned and lithium disilicate blocks were used to fabricate crowns using CAD/CAM technique. Polyvinyl siloxane impressions of the prepared teeth were made and monolithic pressed lithium disilicate crowns were fabricated. The marginal gap was measured using optical microscope at 200× magnification (Keyence VHX-5000, Japan). Statistical analysis was performed using Wilcoxon test. The lithium disilicate pressed crowns had significantly smaller (p = 0.006) marginal gaps (38 ± 12 μm) than the lithium disilicate CAD/CAM crowns (45 ± 12 μm). This research indicates that lithium disilicate crowns fabricated with the press technique have measurably smaller marginal gaps compared with those fabricated with CAD/CAM technique within in vitro environments. The marginal gaps achieved by the crowns across all groups were within a clinically acceptable range.
- MeSH
- design s pomocí počítače * MeSH
- lidé MeSH
- materiály pro zubní otisky MeSH
- neparametrická statistika MeSH
- referenční hodnoty MeSH
- referenční standardy MeSH
- reprodukovatelnost výsledků MeSH
- testování materiálů MeSH
- zubní korunky normy MeSH
- zubní marginální adaptace normy MeSH
- zubní porcelán chemie MeSH
- zubní protéza - design MeSH
- zubní technika otisková * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- srovnávací studie MeSH
- Názvy látek
- lithia disilicate MeSH Prohlížeč
- materiály pro zubní otisky MeSH
- zubní porcelán MeSH
Transient receptor potential (TRPs) channels are crucial downstream targets of calcium signalling cascades. They can be modulated either by calcium itself and/or by calcium-binding proteins (CBPs). Intracellular messengers usually interact with binding domains present at the most variable TRP regions-N- and C-cytoplasmic termini. Calmodulin (CaM) is a calcium-dependent cytosolic protein serving as a modulator of most transmembrane receptors. Although CaM-binding domains are widespread within intracellular parts of TRPs, no such binding domain has been characterised at the TRP melastatin member-the transient receptor potential melastatin 6 (TRPM6) channel. Another CBP, the S100 calcium-binding protein A1 (S100A1), is also known for its modulatory activities towards receptors. S100A1 commonly shares a CaM-binding domain. Here, we present the first identified CaM and S100A1 binding sites at the N-terminal of TRPM6. We have confirmed the L520-R535 N-terminal TRPM6 domain as a shared binding site for CaM and S100A1 using biophysical and molecular modelling methods. A specific domain of basic amino acid residues (R526/R531/K532/R535) present at this TRPM6 domain has been identified as crucial to maintain non-covalent interactions with the ligands. Our data unambiguously confirm that CaM and S100A1 share the same binding domain at the TRPM6 N-terminus although the ligand-binding mechanism is different.
- Klíčová slova
- CaM and S100A1, TRPM6, binding domain, calmodulin binding motif, fluorescence anisotropy, molecular modelling,
- MeSH
- kalmodulin chemie MeSH
- kationtové kanály TRPM chemie MeSH
- lidé MeSH
- molekulární modely * MeSH
- proteinové domény MeSH
- proteiny S100 chemie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- kalmodulin MeSH
- kationtové kanály TRPM MeSH
- proteiny S100 MeSH
- S100A1 protein MeSH Prohlížeč
- TRPM6 protein, human MeSH Prohlížeč
The spring-loaded camming device (SLCD), also known as "friend", is a simple mechanism used to ensure the safety of the climber through fall prevention. SLCD consists of two pairs of opposing cams rotating separately, with one (single-axle SLCD) or two (dual-axle SLCD) pins connecting the opposing cams, a stem, connected to the pins, providing the attachment of the climbing rope, springs, which simultaneously push cams to a fully expanded position, and an operating element controlling the cam position. The expansion of cams is thus adaptable to allow insertion or removal of the device into/from a rock crack. While the pins, stem, operating element, and springs can be considered optimal, the (especially internal) shape of the cam allows space for improvement, especially where the weight is concerned. This paper focuses on optimizing the internal shape of the dual-axle SLCD cam from the perspective of the weight/stiffness trade-off. For this purpose, two computational models are designed and multi-step topology optimization (TOP) are performed. From the computational models' point of view, SLCD is considered symmetric and only one cam is optimized and smoothened using parametric curves. Finally, the load-bearing capacity of the new cam design is analyzed. This work is based on practical industry requirements, and the obtained results will be reflected in a new commercial design of SLCD.
OBJECTIVES: During the physiological ageing process atrophy of the alveolar bone appears in vertical direction. This bone resorption causes pushing the limits of the maxillary sinus at the expense of a degraded bone. The sinus volume increases due to the facial development in children and adolescents or during the ageing process due to the loss of teeth and bone mass. The main aim of this study is to determine the sinus shape and sinus floor morphology related to age. MATERIALS AND METHODS: Human adult male and female cadaveric heads (aged 37 to 83 years) with different dental status were used. The three-dimensional CAD/CAM software was used to scan the solid impressions of the maxillary sinus to visualize the real sinus shape and sinus floor. Subsequently, other findings are shown in tables and evaluated graphically. RESULTS: The maxillary sinus morphology, its relationship to the nasal cavity, the sub sinus alveolar bone height, displacement of the lowest and highest points of sinus, and the sinus relationship to the roots of the upper teeth were studied and evaluated. Some septa, crests, and the prominent infraorbital canal were also found in the area of the sinus floor. CONCLUSIONS: This paper provides a unique view on the maxillary sinus and its changes during the ageing process with preserved topographical relations in a representative sample of the Slovak population. The visualization of the maxillary sinus anatomy is necessary in the diagnosis and treatment plans for dental implants and during current surgical procedures.
- Klíčová slova
- 3D imaging, 3D scanning, Ageing process, Alveolar recess, Maxillary sinus, Morphology,
- MeSH
- design s pomocí počítače * MeSH
- dospělí MeSH
- kosti a kostní tkáň anatomie a histologie MeSH
- lidé středního věku MeSH
- lidé MeSH
- modely anatomické MeSH
- mrtvola MeSH
- nosní dutina anatomie a histologie růst a vývoj MeSH
- počítačové zpracování obrazu MeSH
- processus alveolaris anatomie a histologie MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- sinus maxillaris anatomie a histologie růst a vývoj MeSH
- stárnutí fyziologie MeSH
- zobrazování trojrozměrné metody MeSH
- zuby anatomie a histologie růst a vývoj MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Slovenská republika MeSH
OBJECTIVES: To explore fatigue limits of ceramic endocrowns for premolars. METHODS: Forty-eight devitalized premolars were cut at the CEJ. They were restored with standardized CAD-CAM lithium disilicate reinforced ceramic restorations (IPS e.max CAD, Ivoclar-Vivadent) and divided into four Groups (n=12): overlays (Group A, no endo-core, negative control), endocrowns with an endo-core of 2mm (Group B), 4mm (GroupC) and crowns with post and core (Group D, positive control). All specimens were first submitted to thermo-mechanical cyclic loading (TCML)(1.7Hz, 49N, 600000 cycles, 1500 thermo-cycles). Margins were analysed before and after the loading. Survived specimens were then submitted to cyclic isometric stepwise loading (5Hz, 200N to 1200N) until completion of 105000 cycles or failure. In case of fracture, fragments were analysed using SEM and failure mode was determined. Results of stepwise loading were statistically analysed by Kaplan-Meier life survival analysis and log rank test (p=0.05). RESULTS: All the specimens survived the TCML test except four specimens of Group A (early restorations' debonding). No difference in percentages of closed margins was found between endocrowns (Groups B, C) and crowns (Group D). After the stepwise test, differences in survival within the groups were not statistically significant. Most of restorations experienced non-reparable fracture. CONCLUSIONS: Endocrowns with both 2-mm and 4-mm long endo-cores displayed outcomes after fatigue equivalent to classical crowns. Results of this study discourage the use of flat overlays with only adhesive retention. CLINICAL SIGNIFICANCE: When restoring extremely destroyed devitalized premolars, adhesive strategies should be coupled to a macro-mechanical retention in the root.
- Klíčová slova
- CAD-CAM, Endo-core, Endocrown, Endodontically treated, Fatigue, Lithium disilicate, Marginal integrity,
- MeSH
- analýza přežití MeSH
- analýza zatížení zubů MeSH
- cementování MeSH
- design s pomocí počítače * MeSH
- keramika MeSH
- lidé MeSH
- mechanický stres MeSH
- pevnost v tlaku MeSH
- premolár * MeSH
- testování materiálů MeSH
- trvalá zubní náhrada MeSH
- výsledek terapie MeSH
- zubní korunky * MeSH
- zubní krček MeSH
- zubní marginální adaptace MeSH
- zubní materiály * MeSH
- zubní porcelán chemie MeSH
- zubní protéza - design * MeSH
- zuby neživé * MeSH
- zuby-sanace - selhání MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- IPS e.max CAD LT MeSH Prohlížeč
- lithia disilicate MeSH Prohlížeč
- zubní materiály * MeSH
- zubní porcelán MeSH
Transient receptor potential melastatin 7 (TRPM7) represents melastatin TRP channel with two significant functions, cation permeability and kinase activity. TRPM7 is widely expressed among tissues and is therefore involved in a variety of cellular functions representing mainly Mg2+ homeostasis, cellular Ca2+ flickering, and the regulation of DNA transcription by a cleaved kinase domain translocated to the nucleus. TRPM7 participates in several important biological processes in the nervous and cardiovascular systems. Together with the necessary function of the TRPM7 in these tissues and its recently analyzed overall structure, this channel requires further studies leading to the development of potential therapeutic targets. Here we present the first study investigating the N-termini of TRPM7 with binding regions for important intracellular modulators calmodulin (CaM) and calcium-binding protein S1 (S100A1) using in vitro and in silico approaches. Molecular simulations of the discovered complexes reveal their potential binding interfaces with common interaction patterns and the important role of basic residues present in the N-terminal binding region of TRPM.
- Klíčová slova
- Binding region, CaM, Calcium, Fluorescence anisotropy, S100A1, TRPM7,
- Publikační typ
- časopisecké články MeSH
The main regulatory mechanism of smooth muscle contraction involves Ca2+/calmodulin (CaM)-dependent phosphorylation of myosin (CDPM), by myosin light chain kinase (MLCK). It is also known that the increase in intracellular Ca2+ and phosphorylation of myosin occurs within a short time under physiological conditions, but the muscle tension may persist for a longer period of time. However, the mechanism of this phenomenon is still not clear. We hypothesize that MLCK also phosphorylates myosin in a Ca2+/CaM-independent manner (CIPM). The difference between CIPM and CDPM are as follows. Firstly, the extent of CIPM by MLCK was temperature-independent, whereas CDPM by MLCK was apparently decreasing with increasing temperature. Secondly, in contrast to the decreased extent of CDPM, the prolongation of incubation time did not decrease the extent of CIPM. Thirdly, a high concentration of K+ influences CIPM less than CDPM. Furthermore, the MLCK inhibitor ML-9 significantly inhibited CDPM by MLCK but not CIPM by MLCK. Lastly, arachidonic acid selectively increased CIPM by MLCK but not CDPM by MLCK. Finally, the activity of Mg2+-ATPase of myosin followed the sequence as this: CDPM>CIPM>unphosphorylated myosin. Our results revealed some primary features of CIPM by MLCK.
- MeSH
- azepiny farmakologie MeSH
- časové faktory MeSH
- chlorid draselný MeSH
- fosforylace MeSH
- inhibitory enzymů farmakologie MeSH
- kalmodulin metabolismus MeSH
- kinasa lehkého řetězce myosinu antagonisté a inhibitory metabolismus MeSH
- kur domácí MeSH
- kyselina arachidonová farmakologie MeSH
- lehké řetězce myosinu chemie metabolismus MeSH
- myosiny metabolismus MeSH
- osmolární koncentrace MeSH
- teplota MeSH
- vápník metabolismus MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
- Názvy látek
- azepiny MeSH
- chlorid draselný MeSH
- inhibitory enzymů MeSH
- kalmodulin MeSH
- kinasa lehkého řetězce myosinu MeSH
- kyselina arachidonová MeSH
- lehké řetězce myosinu MeSH
- ML 9 MeSH Prohlížeč
- myosiny MeSH
- vápník MeSH
