https://onlinelibrary.wiley.com/doi/pdf/10.1002/jor.23075

Laser and electron-beam powder-bed additive manufacturing of metallic implants: A review on processes, materials and designs.

Glucocorticoid receptor signaling in health and disease.

https://www.journalofprosthodonticresearch.com/article/S1883-1958(15)00099-7/pdf

Applications of polyetheretherketone (PEEK) in oral implantology and prosthodontics

Background—Stent thrombosis is a lethal complication of endovascular intervention. Concern has been raised about the inherent risk associated with specific stent designs and drug-eluting coatings, yet clinical and animal support is equivocal. Methods and Results—We examined whether drug-eluting coatings are inherently thrombogenic and if the response to these materials was determined to a greater degree by stent design and deployment with custom-built stents. Drug/polymer coatings uniformly reduce rather than increase thrombogenicity relative to matched bare metal counterparts (0.65-fold; P=0.011). Thick-strutted (162 μm) stents were 1.5-fold more thrombogenic than otherwise identical thin-strutted (81 μm) devices in ex vivo flow loops (P<0.001), commensurate with 1.6-fold greater thrombus coverage 3 days after implantation in porcine coronary arteries (P=0.004). When bare metal stents were deployed in malapposed or overlapping configurations, thrombogenicity increased compared with apposed, length-matche...

Stent Thrombogenicity Early in High Risk Interventional Settings is Driven by Stent Design and Deployment, and Protected by Polymer-Drug Coatings

During the resorbable-polymer-boom of the 1970s and 1980s, polycaprolactone (PCL) was used in the biomaterials field and a number of drug-delivery devices. Its popularity was soon superseded by faster resorbable polymers which had fewer perceived disadvantages associated with long term degradation (up to 3-4 years) and intracellular resorption pathways; consequently, PCL was almost forgotten for most of two decades. Recently, a resurgence of interest has propelled PCL back into the biomaterials-arena. The superior rheological and viscoelastic properties over many of its aliphatic polyester counterparts renders PCL easy to manufacture and manipulate into a large range of implants and devices. Coupled with relatively inexpensive production routes and FDA approval, this provides a promising platform for the production of longer-term degradable implants which may be manipulated physically, chemically and biologically to possess tailorable degradation kinetics to suit a specific anatomical site. This review will discuss the application of PCL as a biomaterial over the last two decades focusing on the advantages which have propagated its return into the spotlight with a particular focus on medical devices, drug delivery and tissue engineering.

The return of a forgotten polymer : Polycaprolactone in the 21st century

Plasma-sprayed titanium coating to polyetheretherketone improves the bone-implant interface

We present a simple and customizable microneedle mold fabrication technique using a low-cost desktop SLA 3D printer. As opposed to conventional microneedle fabrication methods, this technique neither requires complex and expensive manufacturing facilities nor expertise in microfabrication. While most low-cost 3D-printed microneedles to date display low aspect ratios and poor tip sharpness, we show that by introducing a two-step “Print & Fill” mold fabrication method, it is possible to obtain high-aspect ratio sharp needles that are capable of penetrating tissue. Studying first the effect of varying design input parameters and print settings, it is shown that printed needles are always shorter than specified. With decreasing input height, needles also begin displaying an increasingly greater than specified needle base diameter. Both factors contribute to low aspect ratio needles when attempting to print sub-millimeter height needles. By setting input height tall enough, it is possible to print needles with high-aspect ratios and tip radii of 20–40 µm. This tip sharpness is smaller than the specified printer resolution. Consequently, high-aspect ratio sharp needle arrays are printed in basins which are backfilled and cured in a second step, leaving sub-millimeter microneedles exposed resulting microneedle arrays which can be used as male masters. Silicone female master molds are then formed from the fabricated microneedle arrays. Using the molds, both carboxymethyl cellulose loaded with rhodamine B as well as polylactic acid microneedle arrays are produced and their quality examined. A skin insertion study is performed to demonstrate the functional capabilities of arrays made from the fabricated molds. This method can be easily adopted by the microneedle research community for in-house master mold fabrication and parametric optimization of microneedle arrays. A low-cost, simple, customizable method has been developed for fabricating microneedle molds by means of a commercially available stereolithography 3D printer. Microneedle arrays (MNAs) are devices composed of micron-sized needles that allow the transfer of compounds, such as drugs, across the outer layer of a tissue, usually the skin. Conventional methods to fabricate the microneedles for such MNAs demand complex, expensive manufacturing facilities and expertise in microfabrication. However, a team headed by Kevin Krieger in Dr. Eoin O’Cearbhaill’s Medical Device Design Group at University College Dublin, Ireland was able to develop a simple fabrication method using a commonly available, affordable 3D printer that allows rapid production of microneedle master molds with easily customizable needle parameters and demands no microfabrication expertise. The authors believe that their method can be readily adopted by researchers for master mold fabrication and parametric optimization of MNAs.

/pdf/simple-and-customizable-method-for-fabrication-of-high-1hwhfn86xh.pdf

Simple and customizable method for fabrication of high-aspect ratio microneedle molds using low-cost 3D printing

Bio-resorbable polymer stents: a review of material progress and prospects

The drilling of bone is ubiquitous in many fields of surgery including orthopaedics, neurosurgery, plastics and reconstructive, craniomaxillofacial and ear nose and throat (ENT). A cylindrical tunnel is typically prepared in bone using a surgical drill-bit to accommodate a screw or other threaded device for rigid fixation which is provided by the integration of bone (cancellous and/or cortical) with the screw threads. In this configuration bone screws are resistant to axial and shear forces as well as bending moments and therefore suited to the load-bearing function of the skeleton during locomotion. Drill-bits are also used in the preparation of bony tunnels, such as in anterior cruciate ligament reconstruction. Drilling is associated with the conversion of mechanical work energy into thermal energy causing a transient rise in temperature of adjacent bone and soft tissues to above normal physiological levels (Matthews and Hirsch 1972; Lavelle and Wedgwood 1980; Eriksson and Albrektsson 1984; Eriksson, Albrektsson et al. 1984b; Abouzgia and Symington 1996; Natali, Ingle et al. 1996; Toews, Bailey et al. 1999; Bachus, Rondina et al. 2000; Davidson and James 2003; Augustin, Davila et al. 2008; Franssen, van Diest et al. 2008; Bertollo, Milne et al. 2010). Primary sources of this thermal energy are plastic deformation and shear failure of bone and friction at the machining face. The magnitude of this temperature rise is determined by a number of factors, including drill geometry and diameter, rotational speed (rpm), feed-rate (mm.s-1), axial thrust force (N), initial drill-bit temperature and internal or external cooling. The negative effect of elevated temperature on the viability of bone is well-acknowledged and measures to reduce them during surgery are frequently employed, such as manual irrigation with sterile saline (Matthews and Hirsch 1972; Jacob and Berry 1976; Lavelle and Wedgwood 1980; Camargo, Faria et al. 2007; Augustin, Davila et al. 2008). Viability (Eriksson, Albrektsson et al. 1984b) as well as the structure and mechanical properties (Bonfield and Li 1968) of bone are indeed compromised through exposure to elevated temperatures. Another important variable that can influence the biological response for drilled bone is the time which a temperature above a threshold value is maintained. Excessive temperatures and durations at these elevated levels can result in the necrosis (death) of bone, a phenomenon termed osteonecrosis, or the impairment of osteogenic

/pdf/drilling-of-bone-practicality-limitations-and-complications-3macas1d8b.pdf

Nicky Bertollo

Papers

Plasma-sprayed titanium coating to polyetheretherketone improves the bone-implant interface

Simple and customizable method for fabrication of high-aspect ratio microneedle molds using low-cost 3D printing

Bio-resorbable polymer stents: a review of material progress and prospects

Drilling of Bone: Practicality, Limitations and Complications Associated with Surgical Drill-Bits

A comparison of the thermal properties of 2- and 3-fluted drills and the effects on bone cell viability and screw pull-out strength in an ovine model.