1. Rapid radiation sintering of additively manufactured large-sized alumina tetrahedronsAljaž Iveković, Miha Križaj, Andraž Kocjan, 2026, izvirni znanstveni članek Povzetek: Rapid radiation techniques, such as pressureless spark plasma sintering (pSPS) and ultra-fast high-temperature sintering (UHS), have proven effective in achieving rapid densification of ceramics, including additively manufactured components. However, sintered component sizes tend to be small, disk-shaped or having thin-strutted geometries. Here, fused filament fabrication (FFF) of a commercial filament was used for manufacturing complex-shaped and large-sized alumina tetrahedra with edge thickness of 5 mm, varying the edge size (15‒40 mm). The aim was to investigate the effect of heating rate (33‒300°C/min) and tetrahedron size on the pSPS outcome. The pSPS reductive environment discoloured the tetrahedra, but were all successfully rapidly sintered to full density irrespective of their size and heating rate employed. The evolved thermal gradient contributed to differential, anisotropic densification related shrinkage, microstructure and mechanical properties specific to tetrahedra` edge position, i.e., core versus shell and base versus lateral, also triggering cracking of the largest tetrahedra.
Ključne besede: additive manufacturing, fused filament fabrication, pressureless spark plasma sintering
Objavljeno v DiRROS: 15.06.2026; Ogledov: 106; Prenosov: 77
 Celotno besedilo (7,97 MB)
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2. Additive manufacturing of polymer-derived SiOC(Fe) ceramic composites as a catalyst support exhibiting magnetic heating capabilityMilan Vukšić, Thomas Konegger, Martin Schwentenwein, Sašo Gyergyek, Anja Sedminek, Sandra Drev, Marijan Nečemer, Andraž Kocjan, Aljaž Iveković, 2026, izvirni znanstveni članek Povzetek: Additive manufacturing (AM) of advanced functional ceramics using preceramic polymers (PCPs) is gaining attention due to its processability and tailorable properties. A photosensitive resin with iron-modified polysiloxanes was developed for vat photopolymerization (VPP) to create porous SiOC(Fe) catalytic supports with magnetic heating capability. Ferric acetylacetonate and ferrocene were examined as iron precursors, leading to the formation of Fe-based magnetic particles (α-Fe, Fe3C, FexSiy) within the silicon oxycarbide (SiOC) ceramic matrix after pyrolysis at 800 to 1500 °C. Depending on the Fe-based precursor used and the applied pyrolysis temperature, the obtained monoliths exhibited magnetic nanoparticle (MNP) contents ranging from 0.9 to 7.9 wt%, with particle sizes from 17 to 96 nm. The monolithic catalyst supports fabricated from ferric acetylacetonate modified PCP-based resin formulations, pyrolyzed at 900 °C, exhibited the highest specific absorption rate and resulted in magnetic heating up to 200 °C at an applied external magnetic field of 60 kA·m−1. While catalyst supports fabricated from ferrocene modified PCP-based resin formulations had lower heating capabilities, they offered better printability and higher ceramic yield. In situ formed MNPs impart magnetic properties advantageous for catalyst support heating, highlighting AM’s design flexibility and PCPs’ role in creating tailored, lightweight structures with controlled porosity.
Ključne besede: preceramic polymers, magnetic nanoparticles, ceramic nanocomposite, induction/magnetic heating, advanced functional ceramics
Objavljeno v DiRROS: 20.05.2026; Ogledov: 129; Prenosov: 125
Celotno besedilo (13,76 MB)
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3. Effects of airborne-particle abrasion and zirconia composition on porcelain–zirconia bond strengthMaja Antanasova, Tine Malgaj, Sandra Drev, Milan Vukšić, Peter Jevnikar, Andraž Kocjan, 2026, izvirni znanstveni članek Povzetek: Porcelain chipping in zirconia-based dental restorations remains a major clinical complication. This study evaluated the effects of airborne-particle abrasion (APA) and yttria content in zirconia on porcelain–zirconia bond strength. Six groups were tested: low-translucency (3Y-TZP) and high-translucency zirconia (4Y-TZP), each with or without APA, and APA-treated Co–Cr and Ti–6Al–4V alloys as metal–ceramic references. Bond strength was assessed using the Schwickerath test. Interfacial structure and mechanical properties were analyzed by scanning and transmission electron microscopy and nanoindentation. APA significantly increased zirconia surface roughness but did not improve bond strength. Zirconia composition had no effect on porcelain bonding. Bond strength values for porcelain-zirconia (34.0–40.6 MPa) were comparable to those of metal–ceramic systems, lower than Co–Cr (45.5 MPa) but similar to Ti–6Al–4V (37.3 MPa). Microscopy and nanoindentation revealed sharp zirconia–porcelain interfaces with pronounced mechanical mismatch and yttrium segregation at grain boundaries.
Ključne besede: airborne-particle abrasion, Yttria-stabilized zirconia (Y-TZP), zirconia-based ceramics
Objavljeno v DiRROS: 19.05.2026; Ogledov: 140; Prenosov: 118
Celotno besedilo (12,45 MB)
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4. Eight-year clinical performance of cantilevered zirconia resin-bonded fixed dental prostheses : a randomized controlled trial evaluating the effect of nanostructured alumina coatingTine Malgaj, Andraž Kocjan, Mutlu Özcan, Peter Jevnikar, 2026, izvirni znanstveni članek Povzetek: Objective. To evaluate the clinical performance of cantilevered zirconia resin-bonded fixed dental prostheses (RBFDPs) pretreated with nanostructured alumina coating (NAC) as a non-invasive surface modification alternative to airborne-particle abrasion (APA). Materials and Methods. In this prospective, randomized, controlled clinical trial, 57 patients requiring replacement of a maxillary or mandibular incisor received 64 zirconia RBFDPs, randomly assigned to APA (n = 32) or NAC (n = 32) groups. APA surfaces were air-abraded with 50-μm alumina, whereas NAC surfaces were coated with NAC. Restorations were further classified by pontic position. Retention and survival rates were analyzed using Kaplan–Meier and log-rank tests; patient-specific factors were assessed with Mann–Whitney U and Fisher's exact tests (α = 0.05). Debonded surfaces were examined under scanning electron microscopy. Results. Over a mean observation period of 61.4 ± 22.1 months (range, 8.3–97.4 months), six debondings occurred, corresponding to an overall survival rate of 100% and retention rates of 88.4% for NAC and 89.1% for APA (p = 0.99), with no significant differences among pontic groups (p = 0.18). Failures were predominantly adhesive, characterized by partial coating delamination at the NAC–zirconia interface. Conclusions. NAC-pretreated zirconia RBFDPs achieved mid- to long-term retention comparable to APA and represent a minimally invasive, clinically reliable pretreatment alternative. Clinical Significance. NAC provides a minimally invasive zirconia pretreatment, particularly for RBFDPs fabricated from damage-prone translucent zirconia, mitigating mechanical failures while maintaining long-term retention comparable to APA.
Ključne besede: nanostructured alumina coating
Objavljeno v DiRROS: 12.03.2026; Ogledov: 275; Prenosov: 228
Celotno besedilo (1,11 MB)
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5. In vitro effects of different biomaterials on canine dental pulp stem cellsRobert Marx, Ana Nemec, Andraž Kocjan, Metka Voga, 2026, izvirni znanstveni članek Povzetek: Objective: Regenerative endodontic treatments are being developed in veterinary dentistry. The aim of this study was to evaluate the biocompatibility and odontogenic potential of three biomaterials, ProRoot® MTA (MTA), RS + ™ (RS+), and CellFoam™ (CF), on canine dental pulp stem cells (cDPSCs) under conditions simulating early and clinically relevant exposures.Methods: cDPSCs were isolated from three healthy dog teeth extracted for clinical reasons and characterized by flow cytometry (CD44+/CD90+/CD29+/CD34−) and multilineage differentiation. Cells were cultured with material suspensions (acute cytotoxic effect) or conditioned medium (physiologically relevant effect). Metabolic activity and cell viability were assessed by MTT and live/dead assays. Osteogenic/odontogenic differentiation was evaluated by Alizarin Red S staining and RT–qPCR for RUNX2, ALPL, and MMP13 expression.Results: In suspension cultures, compared with MTA and RS+, CF maintained significantly higher metabolic activity and cell viability across several dilutions, indicating lower acute cytotoxicity. Under conditioned exposure, no significant differences among materials were observed, reflecting the dilution and buffering effects that mitigate early reactivity. All the materials supported Alizarin Red S-positive mineral deposition, with a significant difference at D3, when ARS staining of cDPSCs was greater in cells conditioned with MTA than in those conditioned with CF. Gene expression analysis revealed lower RUNX2 and ALPL expression in MTA-conditioned cells, suggesting, together with ARS staining, progression toward a more advanced osteogenic or odontogenic differentiation stage. MMP13 expression remained comparable across materials.Conclusion: MTA, RS+, and CF demonstrated overall biocompatibility with cDPSCs and supported odontogenic differentiation under clinically relevant conditions. CF exhibited the lowest acute cytotoxicity, indicating its potential as a carrier for DPSC-based regenerative endodontic applications. These findings support the translational importance of in vitro cDPSC models for evaluating biomaterial performance in veterinary regenerative endodontics.
Objavljeno v DiRROS: 18.02.2026; Ogledov: 500; Prenosov: 225
Celotno besedilo (2,83 MB)
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7. Tuning the rheological properties of paraffin-wax ceramic feedstocks for deposition with thermoplastic 3D printingIpeknaz Özden, Milan Vukšić, Matevž Dular, Aljaž Iveković, Andraž Kocjan, 2024, izvirni znanstveni članek Povzetek: Droplet deposition with material-jetting methods such as thermoplastic 3D printing (T3DP) depends greatly on the rheological properties of the feedstocks. This study investigated the effect of particle interactions and the degree of weak flocculation on the shear thinning behaviour, the yield stress and the storage/loss moduli of paraffin-wax-based feedstocks containing 40 vol% of zirconia (3Y-TZP) micron-sized powder. Steric stabilization of the feedstocks was provided by varying the ratios of the surfactants with different chain lengths, i.e., stearic acid (2.4 nm) and Solsperse 3000® (10 nm), which in turn affected the dynamics of the droplet formation and the quality of the layers when jetting non-Newtonian, thermoplastic ceramic feedstocks. The results of the study extend the guidelines for the processing of printable feedstocks used in T3DP additive manufacturing.
Ključne besede: additive manufacturing, material jetting, colloidal processing
Objavljeno v DiRROS: 19.12.2025; Ogledov: 903; Prenosov: 342
Celotno besedilo (6,86 MB)
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