Stainless Steel Implants Research Articles

Comparative Evaluation of Biomechanical Performance of Titanium and Stainless Steel Mini Implants at Different Angulations in Maxilla: A Finite Element Analysis

Objective: To assess and compare the tensions and deformations (stresses and strains) generated after application of two types of forces (traction and torsion) in miniscrews of two different materials (titanium and stainless steel) placed at five different angulations. Materials and Methods: Three-dimensional models of the posterior maxillary area and the mini-implants were constructed using computer-aided design software program (CATIA P3 V5-6 R2015 B26 / 2016; Dassault Systèmes). Titanium and stainless steel materials were used for miniscrews. The area constructed was in between the maxillary second premolar and first molar. The models with mini-implants were inserted at five different angulations (30°, 45°, 60°, 75° and 90°). Torsional and tractional forces were applied on these implants, and the models were solved using ANSYS 10.0. Stress generated in implant and in the cortical and cancellous bones was evaluated and compared at all the five angulations. Results: Stress generated in stainless steel mini-implant during torsional and linear force application was less when compared with titanium mini-implant. Also, stress generated in implants of both materials increased as the angle increased from 30° to 90°. Difference in stress generated by stainless steel implant in the cortical bone for both linear and torsional forces was less when compared with titanium implant, whereas for cancellous bone, the difference was insignificant at all the angles. Conclusion: Irrespective of angles, difference in stress generated in stainless steel implants and titanium implants for both the forces was not significant, and hence, stainless steel implants can be used effectively in a clinical setting.

Hard Cr2O3 coatings on SS316L substrates prepared by reactive magnetron sputtering technique: a potential candidate for orthopedic implants.

316L stainless steel (SS) implants suffer from tribological and biocompatibility problems which limit their service lifetime. In order to improve the surface properties of 316L SS for orthopedic implant applications, hard chromium oxide coatings were applied on 316L SS substrates using a reactive magnetron sputtering technique. The morphological, structural, and phase compositional analyses were conducted on the deposited coatings by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. The Rockwell-C indentation tests were performed on the coated substrates to qualitatively evaluate the adhesion of coatings on the steel substrates. The surface characteristics of coatings were measured by using an optical profilometer. The mechanical properties of coatings were reported by measuring the Hardness and Young's modulus. The corrosion resistance of coated and uncoated SS substrates was compared using potentiodynamic polarization tests. An inductively coupled plasma optical emission spectrometry (ICP-OES) was employed to analyze the biocompatibility of the samples by measuring the amount of toxic Cr ions released after the immersion test. The results show that the coatings are adherent and composed of a single Cr2O3 phase with a hardness of 25 to 29GPa. The corrosion resistance of the SS has been improved by applying a chromium oxide coating. The coated SS samples have also demonstrated better wear resistance and lower friction coefficient compared to bare SS samples under a reciprocating sliding condition in saline solution. The biocompatibility of the SS has been enhanced by the Cr2O3 coating as much less Cr ions were released after immersion tests. These results indicate that the hard Cr2O3 coatings can be considered as a candidate for extending the lifetime of SS implants.

A Wearable Iron-Based Implant as an Intramedullary Nail in Tibial Shaft Fracture of Sheep.

A stable repaired fracture is the key factor responsible for the recovery of a damaged bone. The iron-based implant is one of the biodegradable metals that have been proven safe as a fracture fixation device. The objective of our experimental approach was to examine the potential of the iron-based implant as a biodegradable metal in tibia shaft fracture in sheep chronically. The samples used for this experiment were iron-based and stainless steel implants. Each had a diameter of 5 mm. These samples were analyzed through 3 phases which are material characterization, in vitro and in vivo examination. The samples were examined using a scanning electron microscope with energy dispersive spectrometer and X-ray diffraction. Based on the analysis carried out, the samples contained 90,02% and 60,81% Fe for iron-based implant and stainless implant, respectively. Both implants maintained high viability when being in contact with calf pulmonary artery endothelial cells, indicating that both implants had a minimum response to the cell in a hemocytometer and methyl tetrazolium (MTT) assay. The systemic effect of the implants was observed using hematology and blood chemistry examination. Data collection also shows that both implants also had a minimum response to the erythrocytes, leucocytes, blood chemistry, and blood mineral during the period of observation. Therefore, it could be concluded that the iron-based implant is tolerable for a period of 9 months. It also has the potential to be used as a biodegradable orthopedic implant.

3-dimensional visualization of implant-tissue interface with the polyethylene glycol associated solvent system tissue clearing method.

ObjectivesDental implants are major treatment options for restoring teeth loss. Biological processes at the implant‐tissue interface are critical for implant osseointegration. Superior mechanical properties of the implant constitute a major challenge for traditional histological techniques. It is imperative to develop new technique to investigate the implant‐tissue interface.Materials and methodsOur laboratory developed the polyethylene glycol (PEG)‐associated solvent system (PEGASOS) tissue clearing method. By immersing samples into various chemical substances, bones and teeth could be turned to transparent with intact internal structures and endogenous fluorescence being preserved. We combined the PEGASOS tissue clearing method with transgenic mouse line and other labelling technique to investigate the angiogenesis and osteogenesis processes occurring at the implant‐bone interface.ResultsClearing treatment turned tissue highly transparent and implant could be directly visualized without sectioning. Implant, soft/hard tissues and fluorescent labels were simultaneously imaged in decalcified or non‐decalcified mouse mandible samples without disturbing their interfaces. Multi‐channel 3‐dimensional image stacks at high resolution were acquired and quantified. The processes of angiogenesis and osteogenesis surrounding titanium or stainless steel implants were investigated.ConclusionsBoth titanium and stainless steel implants support angiogenesis at comparable levels. Successful osseointegration and calcium precipitation occurred only surrounding titanium, but not stainless steel implants. PEGASOS tissue clearing method provides a novel approach for investigating the interface between implants and hard tissue.

Evaluation of Healed Status in Tuberculosis of Spine by Fluorodeoxyglucose-positron Emission Tomography/Computed Tomography and Contrast Magnetic Resonance Imaging.

Background:The healed status (end-point of treatment) in tuberculosis (TB) spine is not defined; hence optimum antitubercular therapy (ATT) duration is unresolved. We, for the first time, prospectively evaluated the healed status in TB spine by fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) and contrast magnetic resonance imaging (MRI) with the objective to define end-point of treatment in TB spine.Materials and Methods:Thirty seven patients of TB spine diagnosed on clinicoradio imaging/cytology/histologically/molecular methods were enrolled, treated and were evaluated radiologically, by contrast MRI and FDG-PET/CT at 9 months. ATT was stopped on contrast MRI-based healing or absence of FDG uptake on PET-CT. ATT was continued in active/resolving lesion. Repeat evaluation was done at 12, 18, 24, and 30 months till healing is demonstrated. In this research work, we got contrast MRI and FDG-PET/CT done for the patients from government institution free of cost, so patients did not have to bear the burden of cost of these investigations.Results:Twenty-eight patients achieved healed status out of which 11 demonstrated healed status on contrast MRI and FDG-PET/CT both, 6 were MRI active (contrast enhancement) but FDG-PET/CT healed, 2 were MRI healed but FDG-PET/CT active (soft-tissue standardized uptake value <2.0), 9 patients were MRI incompatible due to stainless steel implants (n = 6), and in 3 patients MRI could not be done due to financial constraints and were declared healed on FDG-PET/CT. FDG-PET/CT showed healed bone lesion in 28/28 (100%) and on MRI 13/19 (68.42%), respectively. We had 6 patients whose spine was stabilized with stainless steel implants where MRI could not be performed, MRI was useful in 13/25 cases (52%) to demonstrate healed lesion. 7, 6, 6, 5, 1, 2, and 1 cases achieved healed status at 9, 12, 18, 24, 30, 36, and 48 months of ATT intake, respectively.Conclusions:FDG-PET/CT is more useful to demonstrate the healed status than MRI and is the only imaging to demonstrate healed status when MRI could not be performed due to metallic implants. All patients achieved healed status at variable length of ATT intake; hence TB spine should be treated by ATT till healed status (end-point of treatment) is demonstrated by FDG-PET/CT (absence of FDG uptake) or contrast MRI.

Biomechanical Analysis of Retrograde Flexible Intramedullary Nail Constructs in a Simulated Pediatric Femur Fracture Model

Various flexible intramedullary nail (FIMN) constructs for pediatric femur fractures are described; however, no biomechanical study has compared stability of medial-lateral entry versus all-lateral entry retrograde nailing. Our purpose is to compare the rotational and bending stiffness of 2 different FIMN constructs and 2 different materials in a simulated pediatric femur fracture model. Eighty adolescent-sized composite femurs were used to simulate transverse (40 femurs) and oblique (40 femurs) mid-diaphyseal fractures. Retrograde FIMN of the femurs was performed using either 3.5 mm titanium (Ti) or 3.5 mm stainless-steel (SS) flexible nails in 2 configurations: 2 "C"-shaped nails (CC) placed through medial and lateral entry sites or 1 "C"-shaped nail and 1 "S"-shaped nail (CS) placed through a single lateral entry site. Models were first tested in 10 cycles of axial rotation to ±1 N m of torque at a rate of 0.5 degrees/s under 36 kg of compression. Axial compression was performed and bending stiffness defined as the force required to achieve 10 degrees varus at the fracture site. No differences were noted in rotational stiffness comparing Ti and SS nails regardless of nail configuration or fracture pattern. Comparable rotational stability was found for CC and CS configurations with SS implants for both fracture patterns. The CS construct (0.60 N m/degree) was stiffer in rotation than the CC construct (0.41 N m/degree) with Ti implants in the transverse fracture model (P<0.005). SS nails provided greater bending stiffness than Ti nails in both oblique and transverse fracture patterns, regardless of nail construct. The all-lateral entry (CS) construct demonstrated statistically significant greater bending stiffness regardless of implant material or fracture pattern (P<0.03). An all-lateral entry (CS) FIMN construct demonstrated greater bending stiffness in both fracture patterns and materials. Ti and SS implants have comparable rotational stiffness in all fracture patterns and materials; however, SS nails were superior at resisting bending forces in both fracture patterns. CS nail configuration and SS implants demonstrated superior bending stiffness and rotational stiffness when compared with the more commonly used CC construct and Ti implants. NA (biomechanical study).

The relationship of surface roughness and wettability of 316L stainless steel implants with plastic deformation mechanisms

The wettability of the implant plays significant role in successful tissue-implant integration and shows strong dependence on the surface topography of the material. Recent studies showed that the plastic deformation mechanisms can improve cell response, and increase surface roughness and energy. In order to understand the effect of these mechanisms on wettability, 316L stainless steel samples were subjected to tensile test and deformed up to 15% to 35% of strain levels. Atomic force microscopy (AFM) presented approximately 22-fold greater average surface roughness on the 35% deformed sample compared to undeformed one. On the other hand, sessile drop test showed contact angle decrease from 82° to 52° as the deformation increased. This finding is significant since much higher contact angle value at similar surface roughness was presented in the literature. This demonstrates that the plastic deformation mechanisms can play significant role in enhancing the surface wettability without a need for a surface treatment technique. Hence, through the activation of these mechanisms, wettability and surface energy of the implant materials could be further increased which would result with enhanced cell response and lessened post-surgical complications

Applying environmental-friendly binder system for net shaped forming of 316L stainless steel implants

Abstract Over the years, Metal Injection Moulding (MIM) has thrived into an advanced near net shape forming of metallic components having intricate shapes and excellent properties. In the recent research work, the feedstock was prepared at a powder loading of 63 vol% using 316L stainless steel powder with particle size of 14.2 µm and environmental friendly binder system comprising of thermoplastic rice starch, palm stearin, polyethylene and stearic acid. The feedstock which possessed a pseudoplastic behaviour was injection-moulded into a tensile test part at a pressure of 400 bars and temperature of 170 °C. Following the injection moulding stage, the green part was debound using water at a temperature of 50 °C for 4 h. The part was then sintered in vacuum atmosphere at a temperature of 1380 °C. Approximately, 7.8 g/cm3 theoretical density, hardness of 216.18 HV and tensile strength of 81.68 MPa were achieved. The findings suggested that the physical and mechanical properties of sintered 316L stainless steel are in satisfactory agreement with the international benchmark.

Blood profile of implantation stainless steel 316L local implant material on rat femoral bone

&lt;p&gt;&lt;em&gt;&lt;strong&gt;&lt;/strong&gt;&lt;/em&gt;This study was aimed to obtain information regarding complete blood count (CBC) profile of post implantation of stainless steel (SS) 316L as an Indonesian local product of non-degradable metal implant. Thirty adult male rat, aged approximately 12 weeks were divided into 3 groups, i.e. control group without implantation, implant group with import SS316L and implant group with Indonesian national local SS316L that developed by Agency for the Assessment and Application of Technology (BPPT). The implant groups were given implants by inserting it between femoral bone and biceps femoris muscle. On the control group, defect was made on bone without inserting an implants material. Examination of the systemic response was done with CBC before and 30 days after implantation. The analysis of red blood cells amount, haemoglobin level, haematocrite value, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), total white blood cell and its differentiation from each group did not show significant differences. In conclusion, stainless steel 316L of import and national local product showed non-negative effects on blood profile.&lt;/p&gt;

Disadvantages of Stainless Steel Implant Compared to Carbon Fiber Reinforced Polymer for Vertebral Fracture

Disadvantages of Stainless Steel Implant Compared to Carbon Fiber Reinforced Polymer for Vertebral Fracture

Результаты спектрального анализа удаленных сломанных имплантов после остеосинтеза длинных костей конечностей

Introduction Along with expansion of the types of metal implants and indications to osteosynthesis with their application, contemporary operative traumatology continues to meet with such a complication as metal fixator breakage. The frequent cause of fixator failure is an incorrect osteosynthesis or an improperly chosen implant. Quite often, the cause of the complication remains unknown. The purpose of our study was to establish the need for spectral analysis in assessing the cases of metal fixator collapse after osteosynthesis of long bones as well as to determine the rate of the composition defects of the implants used for osteosynthesis of limb bones. Methods We performed a spectral analysis of 16 broken implants extracted from 15 patients operated on in Semashko Hospital, State Hospital No. 17 and State Hospital No. 68. The group included metal implants for both intra- and extramedullary osteosynthesis. Results Of the 16 implants studied, five (31.25 %) complied completely with the requirements of the standard, two stainless steel and three titanium metal implants among them; eleven implants (68.75 %) did not meet the international standards. Discussion In a number of cases (for example, with stainless steel implants) the deviations were significant; variability of the alloys was also noted in titanium implants. Because these deviations in composition may play a role in the destruction of metal fixators, we believe that such a study as spectrography should be recommended for the analysis of cases of implant breakage.

Sensitivity of Airport Metal Detectors to Orthopaedic Implants

* Patients frequently ask their orthopaedic surgeon if their implanted device will set off the metal detectors at the airport, but rarely get an evidence-based answer.* Total shoulder, hip, and knee arthroplasty implants composed of cobalt-chromium alloys or titanium are the most likely implants to be detected.* Stainless-steel implants in the foot and ankle, stainless-steel plates and screws in the upper extremity, and isolated stainless-steel nails, wires, and screws are the least likely implants to be detected.* Contrary to previous findings, body mass index does not seem to impact the rate of detection.* We recommend that surgeons provide their patients with medical documentation that can be presented to screeners and with evidence-based education based on the findings of this review and suggest that they avoid unnecessary alarm activation by non-orthopaedic metal (e.g. coins).

In vivo bone regeneration analysis of trilayer coated 316L stainless steel implant in rabbit model

Abstract

Angiotensin 1–7 Action in the Lateral Preoptic Area is Involved in Urinary Bladder Regulation in Female Wistar Rats.

BackgroundChemical lesions of the lateral preoptic area (LPA) enhance water intake induced by subcutaneous injection of hypertonic saline in rats. On the other hand, the LPA section abolishes the increase in intravesical pressure (IP) induced by olfactory tubercle stimulation in dogs. Immunohistochemical labeling has demonstrated the presence of Mas receptors for Angiotensin‐(1–7) in LPA. It is not known whether neurons with Mas receptors in LPA are involved in urinary bladder regulation.AimWe investigated the effects of activation or blockade of Mas receptors for angiotensin‐(1–7) in LPA on intravesical pressure in anesthetized female rats.Materials and methodsFemale Wistar rats (~240 g, N=6) underwent to a stereotaxic surgery for implantation of stainless steel guide cannulas into the LPA under ketamine and xylazin anesthesia. After 7 days, the animals were anesthetized and maintained with 2% isoflurane in 100% O2 and submitted to cannulation of the femoral artery and vein, placement of a miniaturized Doppler flow probe around the left renal artery to measure the renal blood flow and cannulation of the urinary bladder for IP measurements. After baseline IP and cardiovascular parameters recordings for 15 min, angiotensin‐(1–7) (5 nmol/ uL) or saline (1 uL) or A‐779 (Mas receptor antagonist, 50 nmol/uL) was injected into the LPA and the variables were measured for additional 60 min.ResultsUnilateral injection of angiotensin‐(1–7) into LPA evoked a significant increase in IP (187.5±37.2%) compared to saline (−2.1±1.9%). Unilateral injection of A‐779 into LPA decreased the IP (−15.9±2.8%) in comparison to saline (2.0±1.1%). Interestingly, the decrease in IP was enhanced after bilateral injection of A‐779 into LPA (−27.3±3.4%) compared to the unilateral injection of this drug and also in comparison to saline (−2.9±1.6%) bilaterally into LPA. No significant changes in cardiovascular parameters after angiotensin‐(1–7) or saline or A‐779 in APL were observed.ConclusionThe data suggest that LPA is an important part of the circuit that regulates the urinary bladder activity mediated by angiotensin‐(1–7).Support or Funding InformationFinancial support: FAPESP and NEPAS‐FMABCThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Does surface anodisation of titanium implants change osseointegration and make their extraction from bone any easier?

Titanium implants have a tendency for high bone-implant bonding, and, in comparison to stainless steel implants are more difficult to remove. The current study was carried out to evaluate, i) the release strength of three selected anodized titanium surfaces with increased nanohardness and low roughness, and ii) bone-implant bonding in vivo. These modified surfaces were intended to give improved anchorage while facilitating easier removal of temporary implants. The new surfaces were referenced to a stainless steel implant and a standard titanium implant surface (TiMAX). In a sheep limb model, healing period was 3 months. Bone-implant bonding was evaluated either biomechanically or histologically. The new surface anodized screws demonstrated similar or slightly higher bone-implant-contact (BIC) and torque release forces than the titanium reference. The BIC of the stainless steel implants was significant lower than two of the anodized surfaces (p = 0.04), but differences between stainless steel and all titanium implants in torque release forces were not significant (p = 0.06). The new anodized titanium surfaces showed good bone-implant bonding despite a smooth surface and increased nanohardness. However, they failed to facilitate implant removal at 3 months.

Development of computational Tibia model to investigate stress shielding effect at healing stages

A 3D CAD model of human Tibia is developed from scanned Computed Tomography (CT) images. Static analysis is carried out using finite element analysis (FEA) to study the maximum stresses, deformation and strain induced in tibia during normal gait cycle. A fracture of 1 mm is generated in the developed model and is bridged by a callus. Effect of growth of callus at various healing stages is analyzed with stainless steel (SS), Titanium-alloy and stiffness graded (SG) implant material coupled to the fractured bone. Result shows stress shielding effect is minimum in case of SG implants at every healed stage, compared to SS and Ti-alloy implants. At 1% healed stage, SG implant shows an increase of 16% and 19% in stresses as compared to SS and Ti-alloy implants.

Topographical and elemental changes of retrieved stainless steel and titanium mini-implants after orthodontic treatment

ObjectiveTo investigate the surface changes and elemental composition of retrieved titanium and stainless steel orthodontic mini-implants and to determine the type of bone at the mini-implant–alveolar bone interface. Materials and methodsSurface characteristics, such as dullness, cracks, craters, and blunting of retrieved stainless steel and titanium mini-implants placed for orthodontic anchorage were studied with scanning electron microscopy and the change in composition was assessed with energy dispersive X-ray spectroscopy analysis. Bone tissue samples adjacent to mini-implant surface were examined histologically to identify the bone type. ResultsThe mean scores showed that the surface defects were 26% in titanium mini-implant threads and 33.33% of stainless steel mini-implant threads at the tip portion which were not statistically significant on comparison (P = 0.75). Comparing mean net wt% of carbon, oxygen, and nitrogen elements adsorbed on the surface of retrieved and control groups of titanium mini-implants yielded statistically significant results (P = 0.001). The histological sections of bone particles from mini-implant surface showed lamellar bone. ConclusionsBlunting (of the tips and threads) of all retrieved mini-implants were evident on SEM images and craters were observed in body region of retrieved stainless steel mini-implant. The retrieved titanium implants showed oxygen, carbon, calcium, and nitrogen on the surface, whereas only carbon and oxygen elements were found on retrieved stainless steel implants. The elemental oxygen (22.67%) was higher in the titanium group and a higher carbon (7.43%) in the stainless steel group. Numerous lacunae, resting lines, and osteocytes were found in bone tissue from mini-implant surface.

Artifacts Quantification of Metal Implants in MRI

The presence of materials with different magnetic properties, such as metal implants, causes distortion of the magnetic field locally, resulting in signal voids and pile ups, i.e. susceptibility artifacts in MRI. Quantitative and unbiased measurement of the artifact is prerequisite for optimization of acquisition parameters. In this study an image gradient based segmentation method is proposed for susceptibility artifact quantification. The method captures abrupt signal alterations by calculation of the image gradient. Then the artifact is quantified in terms of its extent by an automated cross entropy thresholding method as image area percentage. The proposed method for artifact quantification was tested in phantoms containing two orthopedic implants with significantly different magnetic permeabilities. The method was compared against a method proposed in the literature, considered as a reference, demonstrating moderate to good correlation (Spearman’s rho = 0.62 and 0.802 in case of titanium and stainless steel implants). The automated character of the proposed quantification method seems promising towards MRI acquisition parameter optimization.

Peptide-functionalized poly[oligo(ethylene glycol) methacrylate] brushes on dopamine-coated stainless steel for controlled cell adhesion.

Stainless steel (SS) implants are widely used clinically for orthopaedic, spinal, dental and cardiovascular applications. However, non-specific adsorption of biomolecules onto implant surfaces results in sub-optimal integration with host tissue. To allow controlled cell-SS interactions, we have developed a strategy to grow non-fouling polymer brushes that prevent protein adsorption and cell adhesion and can be subsequently functionalized with adhesive peptides to direct cell adhesion and signaling. This approach has broad application to improve osseointegration onto stainless steel implants in bone repair.

Silver nanoparticle deposited implants to treat osteomyelitis.

In this study, electrolytically deposited strongly adherent silver nanoparticles on stainless-steel (SS) implants were used for in situ osteomyelitis treatment. Samples were heat treated to enhance adhesion of silver on 316 L SS. Ex vivo studies were performed to measure silver-release profiles from the 316 L SS screws inserted in equine cadaver bones. No change in the release profiles of silver ions were observed in vitro between the implanted screws and the control. In vivo studies were performed using osteomyelitic rabbit model with 3 mm diameter silver-deposited 316 L SS pins at two different doses of silver: high and low. Infection control ability of the pins for treating osteomyelitis in a rabbit model was measured using bacteriologic, radiographic, histological, and scanning electron microscopic studies. Silver-coated pins, especially high dose, offered a promising result to treat infection in animal osteomyelitis model without any toxicity to major organs. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1073-1083, 2018.