experimental tests on new titanium alloy interbody cervical cages

Abstract Degenerative diseases of the spine, when not solvable with clinical treatments or with suitable stabilization systems, can be cured by means of the technique of arthrodesis through the interbody fusion of two or more vertebrae. The paper deals with the tests carried out on commercial and innovative cervical cages, used in the primary stabilization of the vertebrae, able to maintain the right distance and to assure the interbody fusion. Additive manufacturing (AM) is a powerful new tool offering the necessary competitiveness to the biomedical manufacturing companies, having the possibility to create materials with controlled porosity combined with solid parts, providing to the workpiece excellent capacity in the subsequent phases of osseointegration. Based on the knowledge developed either in the biomechanics of the spine or in the properties of biocompatibility and osseointegration of titanium alloys, MT Ortho has developed some models of cervical cage made from modern additive printing techniques with titanium alloy. Three different cervical cage made of different materials were subjected to static compression test: a commercial cervical intervertebral cage in PEEK and two cervical intervertebral cages in Ti alloy produced by the EBM process by MT Ortho. Tests on the innovative cage produced by EBM have shown encouraging results. From this first preliminary analysis its showed that the mechanical and functional failure of the innovative devices made in melted Ti alloy by EBM is achieved by load values greater than physiological ones of the cervical spine

design of a new intervertebral disc prosthesis a numerical approach

Abstract In the degenerative disc disease, an alternative treatment to the traditional arthrodesis, consisting in the fusion of the two adjacent vertebral bodies, is the artificial intervertebral disc. The advantage of an artificial intervertebral disc is that the d.o.f. of the vertebral segment can be saved and the mobility of the spine could be almost restored. Many solutions were proposed in the last decades, most of them consisting in metallic rigid joints able to assure the mobility and to maintain the correct distance between the vertebrae but subject to corrosion, wear and interface problems due to the different stiffness with the biological tissues. Purpose of this paper is the design of a prosthetic device substituting the disc to be placed in the intervertebral zone. Different types of artificial prostheses have been proposed by the authors, based on similarity with physiological discs, then with a central part (nucleus) made of hyperelastic material and an outer containment frame (annulus) consisting of a plastic material with a stiffness high enough to assure the reaction force and to avoid large radial displacements. In our solutions, the external parts (annulus and plates) were modeled by HDPE and the inner part (nucleus) by silicone and hydrogel. All the materials are highly biocompatible. The intention of the authors, moreover, is to permit an easier surgical technique. The prosthesis, in fact, could be mounted void of the nucleus, allowing an easier placement, and filled only after the frame insertion, by injecting the silicone through a syringe. The nucleus was modeled by the Mooney-Rivlin parameters related to elastomers, being the disc subject to large deformations that the materials have to be able to withstand in elastic conditions. The discs are subjected to compressive loads either in the mounting phase or, after the silicone filling, due to the physiological loads

fatigue limit assessment by energetic analyses in static and cyclic tensile tests

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Cyclic fatigue resistance, torsional resistance, and metallurgical characteristics of M3 Rotary and M3 Pro Gold NiTi files

Objectives: To evaluate the mechanical properties and metallurgical characteristics of the M3 Rotary and M3 Pro Gold files (United Dental). Materials and Methods: One hundred and sixty new M3 Rotary and M3 Pro Gold files (sizes 20/0.04 and 25/0.04) were used. Torque and angle of rotation at failure (n = 20) were measured according to ISO 3630-1. Cyclic fatigue resistance was tested by measuring the number of cycles to failure in an artificial stainless steel canal (60° angle of curvature and a 5-mm radius). The metallurgical characteristics were investigated by differential scanning calorimetry. Data were analyzed using analysis of variance and the Student-Newman-Keuls test. Results: Comparing the same size of the 2 different instruments, cyclic fatigue resistance was significantly higher in the M3 Pro Gold files than in the M3 Rotary files (p < 0.001). No significant difference was observed between the files in the maximum torque load, while a significantly higher angular rotation to fracture was observed for M3 Pro Gold (p < 0.05). In the DSC analysis, the M3 Pro Gold files showed one prominent peak on the heating curve and 2 prominent peaks on the cooling curve. In contrast, the M3 Rotary files showed 1 small peak on the heating curve and 1 small peak on the cooling curve. Conclusions: The M3 Pro Gold files showed greater flexibility and angular rotation than the M3 Rotary files, without decrement of their torque resistance. The superior flexibility of M3 Pro Gold files can be attributed to their martensite phase

Proposta di utilizzo di metodologie termografiche per il controllo di qualità di componenti meccanici

In base all’esperienza maturata in anni di sperimentazione sull’analisi delle caratteristichemeccaniche dei materiali mediante indagine termografica, nel presente lavoro è proposta una procedura per ilcontrollo di qualità di componenti meccanici in linea di produzione, che è già stata argomento di brevetto.Lo sviluppo di questo lavoro si colloca nell’ambito del progetto FIRB “Sistemi di produzione intelligenti,flessibili e riconfigurabili”. L’attività svolta dal DIIM riguarda il controllo avanzato dell’affidabilità dicomponenti meccanici per l’industria automobilistica. Viene proposta, quindi, la realizzazione di una cella dicontrollo in linea di produzione capace di valutare la presenza di eventuali componenti difettosi attraversol’analisi termica degli stessi, sollecitati secondo un modello predefinito.L’attività, svolta in questa prima fase in laboratorio, è facilmente trasferibile in linea di produzione,considerando la possibilità di realizzare celle di prova in ambiente controllato, con condizioni praticamenteidentiche a quelle di laboratorio, eliminando gli effetti di disturbo che possono influenzare la rispostadell’indagine termografica in ambiente non strutturato

low cycle fatigue hysteresis by thermographic and digital image correlation methodologies a first approach

Abstract The energetic behaviour of the material under low-cycle fatigue (LCF) can be controlled by the hysteresis cycle in order to define the variation of the mechanical characteristics and to forecast the fatigue and the failure response. The traditional analysis is performed using the force-displacement signals derived by the testing machine that can be coupled with other measuring methodologies. In the present paper, the authors have used the Digital Image Correlation (D.I.C.) to better define the specimen displacement, avoiding many errors of the displacement measurement chain. The thermographic analysis (T.A.), able to follow quickly and with great accuracy the energetic variations, was combined with the stress-strain measurements, allowing to calculate the damping energy. The results pointed out a similar behaviour between the hysteresis areas defined basing on the D.I.C. displacements and those found by the testing machine outputs, but substantial differences in terms of values. The thermal variations and the areas of the hysteresis loops, both linked to the plastic energy, were compared, showing a reliable agreement

Late Complication after Superficial Femoral Artery (SFA) Aneurysm: Stent-graft Expulsion Outside the Skin

A 78-year-old man presented with a 7-cm aneurysm in the left superficial femoral artery, which was considered unfit and anatomically unsuitable for conven- tional open surgery for multiple comorbidities. The patient was treated with stent-graft [Viabhan stent-graft (WL Gore and Associates, Flagstaff, AZ)]. Two years from stent-graft implantation, the patient presented a purulent secretion and a spontaneous external expulsion through a fistulous channel. No claudication symptoms or hemorrhagic signs were present. The pus and device cultures were positive for Staphylococcus aureus sensitive to piperacillin/tazobac- tam. Patient management consisted of fistula drainage, systemic antibiotic therapy, and daily wound dressing. At 1-month follow-up, the wound was closed. To our knowl- edge, this is the first case of this type of stent-graft com- plication presenting with external expulsion

Proposta di utilizzo di metodologie termografiche per il controllo di qualità di componenti meccanici

In base all’esperienza maturata in anni di sperimentazione sull’analisi delle caratteristichemeccaniche dei materiali mediante indagine termografica, nel presente lavoro è proposta una procedura per ilcontrollo di qualità di componenti meccanici in linea di produzione, che è già stata argomento di brevetto.Lo sviluppo di questo lavoro si colloca nell’ambito del progetto FIRB “Sistemi di produzione intelligenti,flessibili e riconfigurabili”. L’attività svolta dal DIIM riguarda il controllo avanzato dell’affidabilità dicomponenti meccanici per l’industria automobilistica. Viene proposta, quindi, la realizzazione di una cella dicontrollo in linea di produzione capace di valutare la presenza di eventuali componenti difettosi attraversol’analisi termica degli stessi, sollecitati secondo un modello predefinito.L’attività, svolta in questa prima fase in laboratorio, è facilmente trasferibile in linea di produzione,considerando la possibilità di realizzare celle di prova in ambiente controllato, con condizioni praticamenteidentiche a quelle di laboratorio, eliminando gli effetti di disturbo che possono influenzare la rispostadell’indagine termografica in ambiente non strutturato

Proposta di utilizzo di metodologie termografiche per il controllo di qualità di componenti meccanici

In base all'esperienza maturata in anni di sperimentazione sull'analisi delle caratteristiche meccaniche dei materiali mediante indagine termografica, nel presente lavoro è proposta una procedura per il controllo di qualità di componenti meccanici in linea di produzione, che è già stata argomento di brevetto. Lo sviluppo di questo lavoro si colloca nell'ambito del progetto FIRB Smart Reflex "Sistemi di produzione intelligenti, flessibili e riconfigurabili". L'attività svolta dal DIIM riguarda il controllo avanzato dell'affidabilità di componenti meccanici per l'industria automobilistica. Viene proposta, quindi, la realizzazione di una cella di controllo in linea di produzione capace di valutare la presenza di eventuali componenti difettosi attraverso l'analisi termica degli stessi, sollecitati secondo un modello predefinito. L'attività, svolta in questa prima fase in laboratorio, è facilmente trasferibile in linea di produzione, considerando la possibilità di realizzare celle di prova in ambiente controllato, con condizioni praticamente identiche a quelle di laboratorio, eliminando gli effetti di disturbo che possono influenzare la risposta dell'indagine termografica in ambiente non strutturato

Effect of cyclic torsional preloading on cyclic fatigue resistance of ProTaper Next and Mtwo nickel–titanium instruments

Aim: To evaluate the influence of different torsional preloads on cyclic fatigue resistance of endodontic rotary instruments made by conventional nickel–titanium (NiTi) or M-Wire. Methods: Eighty new Mtwo (#25/0.06) (Sweden & Martina, Due Carrare, Padova, Italy) and ProTaper Next X2 (Dentsply Maillefer, Ballaigues, Switzerland) were used. The Torque and distortion angles at failure of new instruments (n = 10) were measured and 0% (n = 10), 25%, 50%, and 75% (n = 20) of the mean ultimate torsional strength as preloading condition were applied according to ISO 3630-1 for each brand. The twenty files tested for every extent of preload were subjected to 25 or 50 torsional cycles (n = 10). After torsional preloading, the number of cycles to failure was evaluated in a simulated canal with 60° angle of curvature and 5 mm of radius of curvature. Data were analyzed using 2-way analysis of variance. Scanning electron microscope (SEM) was performed to evaluate the fracture surface of each fragment. Results: ProTaper Next X2 reduced their cyclic fatigue after 25 or 50 cycles of every torsional preloading (25%, 50%, and 75%) (P < 0.01). Cyclic fatigue of Mtwo was reduced by 50 cycles of every torsional preloading and only after the 75% of preload for 25 cycles (P < 0.01). Conclusions: Torsional preloads reduced the cyclic fatigue resistance of M-wire and conventional (as ProTaper Next and Mtwo) NiTi rotary instruments except for Mtwo with 25% or 50% of torsional preloading