The structural safety qualification of medical devices such as trans-tibial prosthetic foot for regulatory compliance is performed in vitro as per international standards. This study attempts application of in silico analysis-driven approach for prosthetic foot design verification before attempting pilot production and in vitro qualification tests as per regulatory requirements. This procedure reduces the time and cost involved in developing and qualifying a batch of trans-tibial prosthetic feet prototypes. This paper presents the structural performance assessment of the FUPRO Grace Foot, a trans-tibial prosthetic foot, which is now commercialized in India by M/s FUPRO Innovation Pvt Limited. The study starts with a modal analysis of the device to determine the mode shapes and frequencies. Subsequently, the study reports static structural analysis of the device for forefoot and heel configurations. Finally, the study verifies the finite element model by in vitro tests of a batch of the Grace Foot as per the international standard, ISO 22675. The in silico modelling approach was verified by custom made fixtures, test systems and standard experimental protocols. The in silico results show a close correlation with in vitro results, which implies that the modelling approach can be used for the analysis-driven design of safe and effective trans-tibial prosthetic devices. Also, the FUPRO grace foot qualified for the in vitro cyclic endurance test, which implies the device is structurally safe.
Category: Articles
The study aimed to compare the canal transportation and centring ability of M two R (Mt), Neoniti (Nn) and WaveOne Gold (Wg) systems during retreatment procedure using Cone Beam Computed Tomography. Forty freshly extracted single-rooted mandibular premolars were selected. Teeth were decoronated and were standardized to a length of 15mm from the root apex. The root canals were instrumented using Protaper rotary files. All the teeth were embedded in soft putty blocks, and post-instrumentation Cone Beam Computed Tomography (CBCT) imaging was done at 3, 6 and 9 mm levels. Root canals of all the specimens were obturated with gutta-percha using AH Plus sealer. Samples were randomly divided into four groups (n = 10), and retreatment in each group was performed as follows: Group I – using Hand instrumentation (Hi), Group II- using Mtwo R (Mt), Group III – using Neoniti (Nn), Group IV- using WaveOne Gold (Wg). CBCT imaging of all the teeth was repeated after the completion of retreatment procedures at the same position. The centring ability and canal transportation were calculated at 3, 6, and 9 mm from the apex in mesiodistal and buccolingual directions. Statistical analysis was performed using ANOVA and Post Hoc Tukey tests. Results have shown a significant difference for canal transportation mesiodistally at 9 mm from the apex (P< 0.05), where Hi removed more dentin in one direction compared to Wg. A significant difference in centring ability was observed buccolingually at 9 mm from the apex (P< 0.05), where Hi was less centred in the canal compared with Nn and Wg. Among the tested file systems Mt, Nn, Wg, there was no significant difference in canal transportation and centring ability during retreatment at 3, 6, and 9mm from the apex in both dimensions.
Soybean oil (SBO) incorporated in situ polymerizable bioactive inorganic-organic hybrid resin containing alkoxide of zinc with polymerizable dimethacrylate groups (ZnSBOR) and soy protein concentrate (SPC)as filler along with surface treated quartz powder are used for the preparation of photopolymerized composite. ZnSBOR was synthesized using a modified sol-gel method. Soy flour without the oil was used as the SPC filler. Resin along with diluents, photoinitiator, activator/stabilizers and the filler components are mixed well in an agate mortar to get the uniform paste which upon exposure to visible light undergoes in situ polymerization to get cured composite. The photocured composite was evaluated in terms of linear polymerization shrinkage (LPS), depth of cure (DoC) and diametral tensile strength (DTS). The biocomposites (100QZNSBO) prepared using ZnSBOR showed significantly lower polymerization shrinkage and comparable diametral tensile strength (DTS) compared to composite prepared (100QZN) using ZnR. Good biological properties such as bioactivity and antimicrobial property of soybean merged with good physical properties will make the new Soybean oil (SBO) and soy protein concentrate (SPC) incorporated biocomposites as a suitable candidate material for biomedical applications.
The use of medical devices has facilitated the management of serious illnesses. However, the insertion of foreign material into the body creates a favorable niche for bacterial adhesion and biofilm formation. Biofilm formations on medical devices have contributed significantly to increased patient morbidity and mortality. Biofilm infections are often chronic and recalcitrant to antibiotic therapy. Biofilms of bacteria are composed of polysaccharides, proteins, and extracellular DNA (eDNA). eDNA is an integral part of the biofilm and plays a vital role in maintaining the 3D architecture of the biofilm. We investigated the effect of ceftazidime (3rd generation cephalosporin), gentamicin (aminoglycoside) and norfloxacin (fluoroquinolone) antibiotics on biofilm formation and eDNA release in ATCC 27853 strain and clinical isolates of Pseudomonas. We observed that all clinical isolates were resistant to ceftazidime. Our study showed that ceftazidime, gentamicin and norfloxacin at sub-inhibitory concentrations induced biofilm formation. Half MIC concentrations increased biofilm formation by both ATCC 27853 strain and clinical isolates. On the other hand, an increase in eDNA release was observed only at sub-inhibitory concentrations of gentamicin and norfloxacin, observation of clinical relevance, as bacteria are continuously exposed to sub-lethal concentrations of antibiotics. An increase in biofilm formation and eDNA release at sub-inhibitory concentrations of antibiotics suggest a protective mechanism by bacteria to resist antibiotics and persist within the host and indwelling medical devices.