How Are PEEK Screws Used?

PEEK screws are replacing stainless steel and titanium surgical screws in many instances, and they can be found in various orthopedic and trauma fixation applications. Screws can be used to directly interface with bone, or they can be used in conjunction with other trauma fixation and orthopedic devices. For example, PEEK screws can be installed in bone plates to hold a fracture together. They can also be implanted in cortical or cancellous bone, so PEEK’s versatility is a valuable trait in this regard.

Why are PEEK screws emerging as a frontline option?

Stainless steel and titanium have traditionally been the favored materials for surgical screws. In recent years, the introduction of resorbable materials and high performance polymers like PEEK have given surgical teams additional options. Here’s why those surgical teams are increasingly turning to PEEK screws for their patients:

  1. Biocompatibility and bioinertness – PEEK’s biocompatibility has been confirmed through USP Class VI testing and through extensive patient reports. In 20 years of medical use, PEEK hasn’t demonstrated any toxic or allergic properties, so it can be trusted for long-term or permanent implantation.

    PEEK is bioinert in ways that metal implants may not be. For instance, patients can develop sensitivity to certain metals after prolonged exposure, but this hasn’t been seen with PEEK. Further, when PEEK is used as a bearing material, it does not liberate extremely small, potentially toxic particles like some metal implants have done in the past.

    In addition to its biocompatibility, PEEK also resists attack in an organic or aqueous setting, so it will not corrode and it will not absorb minimal moisture. PEEK screws can be implanted anywhere in the body and remain intact for years.

  2. Excellent material properties – PEEK is a high performance polymer, so it possesses an elite array of properties, several of them important for trauma fixation and orthopedic applications. High fatigue strength and an ideal flexural modulus are the standout traits, as they approximate cortical bone well. In short, PEEK ‘micro flexes, compresses and bears weight like bone, so it behaves more like a load-sharing material than a load-bearing one.

    This load-sharing capacity is especially important for trauma fixation and orthopedic procedures. Because it shares the load, PEEK does not cause stress shielding, a common complication among metal, weight-bearing implants. Research published in the European Spine Journal has shown that titanium implants cause bone subsidence (caving in) at rates that far exceed PEEK implants.

    PEEK’s fatigue strength is what makes it an ideal screw, as it can withstand tension and compressive forces without losing shape or integrity. The result is a screw that’s better designed for dynamic areas of the body, like the legs, arms, hands and feet.

    Since PEEK screws can be installed in cortical bone or softer cancellous bone, they can be used in additional hip and knee arthroscopic procedures.

  3. Radiolucency – In its natural state, PEEK is radiolucent, so it will not interfere with any form of medical imaging, whether X-ray, MRI or CT scan. This will allow surgical teams to make more accurate, timely assessments, especially where it concerns osteosynthesis.

    If radiolucency, or imaging transparency is undesirable, additives like barium sulfate can be incorporated into PEEK to provide radiopacity. The addition of barium sulfate does not adversely affect the PEEK, so it can be added without fear of affecting the implant’s function or durability. In either case, PEEK provides an imaging advantage.

  4. Processability – PEEK’s extensive processability may not be an obvious advantage to patients or physicians, but it’s still a critical consideration. PEEK is a thermoplastic, so it is converted at extremely high temperatures and while using special equipment. Experienced converters use a variety of methods, like extrusion and machining, to turn PEEK into an array of useful medical components.

    PEEK is almost endlessly processable when machined, as the polymer retains its strong material properties even when subjected to machining stresses. It is essential, however, that an experienced PEEK converter handle machining, as issues with fiber orientation, for example, may compromise the polymer’s function.

    For surgical teams, PEEK’s processability allows for a variety of screw sizes and designs, so it’s easier to produce and find screws for a particular patient or implant. PEEK can also be machined to extremely tight tolerances, making a custom fit possible.

  5. Easier to adjust – Although infrequent, trauma fixation or orthopedic implants may need to be adjusted after implantation. Some PEEK screw systems have been designed with this potential scenario in mind, and they are easier to remove than stainless steel or titanium screws.

In many areas of medicine, PEEK is so successful that it is pushing other biomaterials into lesser roles. That is also true of fixation hardware like screws, where PEEK’s fatigue strength, pullout strength and all-round durability are valuable properties to have. PEEK’s unmatched processability also ensures component manufacturers can develop a full spectrum of screw and screw system designs.

PEEK Interbody Device

PEEK interbody devices have been in use for well over a decade and are integral to several spinal fusion procedures. This includes anterior cervical discectomy and fusion (ACDF), anterior lumbar interbody fusion (ALIF) and oblique lateral interbody fusion (OLIF). In all cases, pairing a PEEK cage with a bone allograft produces better results than using iliac autograft, and there is plenty of research to back this conclusion.

Though spinal fusion was once a rare procedure, as the risks were considered too great for most patients, advanced spinal implants like PEEK cages have improved the procedure’s outcomes. One study, published in International Orthopaedics, reported the outcomes of patients that received a PEEK implant with a cancellous autograft. The study found that in 100 percent of patients, fusion was achieved, and that in 74 percent of cases, the procedure resulted in a good or excellent outcome.

How does PEEK improve an interbody procedure?

Without PEEK, allografts are prone to resorption, which can threaten the procedure’s efficacy. With PEEK, though, resorption is less of a concern, and the osseointegration process is easier to control.

Another important advantage PEEK offers is foraminal height maintenance. According to the International Orthopaedics study, the use of a PEEK cage increased disc height following surgery, from 5 millimeters on average to 7.3 millimeters. Once the implant settled, the average final disc height was 6.2 millimeters, which is still a significant jump over the original number. PEEK’s resilience and compressive strength factor into this, and ensure the implant site is stable and set up for optimal healing.

Who could benefit from a PEEK interbody device?

There are several conditions that spinal fusion is indicated for, including:

  • Degenerative disc disease – Occurs when the space between vertebrae shrinks, causing too much compression.
  • Spinal stenosis – Occurs when there is narrowing in the spinal canal, which is the space that nerves travel through.
  • Spondylolisthesis – Occurs when a defect or fracture in a part of the spine causes vertebrae to shift forward, putting additional pressure on the disc.
  • Scoliosis – Occurs when the spine is curved due to poor posture or genetics.
  • Fractures, tumors or infections

Not all patients will experience symptoms arising from these conditions, but those that do have pain may become more debilitated as the condition progresses. It’s these patients that could most benefit from a PEEK interbody device.

PEEK is the First Choice in Fusion Cages

PEEK has a long history of success in spinal fusion procedures, so it’s not a surprise that it’s an ideal support material for allograft applications. There are additional reasons that PEEK is well-suited for interbody fusion cages, including:

  1. A modulus similar to bone – In its natural form, PEEK has a flexural modulus that is extremely similar to cortical bone. This bone-like modulus is a powerful advantage for the material, because it means PEEK bends and bears weight like the body’s own tissues. It doesn’t bear too much weight and instead shares the load with native bone. This is necessary to avoid stress shielding, which can result in mineral density loss and subsidence.

    Subsidence refers to caving in of the bone, and it can threaten the implant’s efficacy. According to a study published in the European Spine Journal, titanium implants, which are strict loadbearing devices, produced subsidence rates in excess of 20 percent. PEEK implants, though, resulted in subsidence less than 10 percent of the time, so the polymer does help preserve bone near the implant site.

    If additional stiffness is need, PEEK can be reinforced with chopped carbon. This improves the polymer’s strength and weight-bearing capacity.

  2. Pure radiolucency – PEEK is compatible with most forms of medical imaging, and it is radiolucent (invisible) on X-rays, MRIs and CT scans. With its pure radiolucency, PEEK will not interfere with procedures to image and assess the implant site. Clear imaging also helps surgical teams forecast potential complications and assess osseointegration.

    In some cases where this pure radiolucency is not desired, PEEK can be mixed with barium sulfate to generate additional image contrast.

  3. Biocompatibility – PEEK has undergone the most demanding set of biocompatibility testing protocols in medicine. This includes ISO 13485 for materials that may be implanted in the body and USP Class VI testing, which looks at the material’s potential for producing a cytotoxic, genotoxic or immunogenic response. The USP Class VI tests expose the material to the body’s tissues, including the tissues expected to interface directly with the implant. In every instance, PEEK did not produce a notable response of any kind, meaning the high-performance polymer is safe to use in an organic environment.
  4. Potential – PEEK is naturally bioinert, but newer PEEK implants and interbody devices are designed to promote bone growth, resulting in an improved fusion between implant and bone. These implants are made with bone-attracting materials like zeolite and hydroxyapatite, and they feature microporous structures that lock the implant to the bone. Research into these new implants is positive, demonstrating improved osseointegration and a more secure fit.

Interbody devices are vastly improved with the presence of PEEK, as the high-performance polymer offers a bone-like flexural modulus, pure radiolucency, total biocompatibility and processing versatility. These advantages have made spinal fusion procedures more of a worthwhile treatment option, providing thousands of patients relief from their pain.

 

What Are The Advantages of PEEK in Rod Form?

Stock PEEK shapes like rods allow for thicker cross-sections and extended lengths, beyond what is possible with injection molding. PEEK rods can be extruded with cross-sections of 8 inches or more in diameter, and polymer converters have a full range of rod sizes available. Experienced converters will also be able to handle a diverse array of PEEK grades, including carbon-reinforced, or CFR PEEK. CFR PEEK is useful in medical applications that call for additional strength or stiffness.

The large majority of implantable PEEK devices are machined from PEEK rod stock. One reason for this is the polymer’s compatibility with modern machining methods.

PEEK’s Machinability Advantage

As a high performance polymer, PEEK can withstand the rigors of machining. In fact, PEEK is especially well-suited to precision machining, and is often used in conjunction with CAM processes. With CAM technology, device manufacturers can use 3D imaging to create customized PEEK devices that meet extremely tight tolerances. A popular application of PEEK and CAM is in dentistry, where dental device manufacturers use 3D images of patients’ bite patterns to create partial denture frameworks.

PEEK’s superb machinability is a significant reason why PEEK rod stock is in demand among device manufacturers.

What Are Some Additional Advantages of PEEK?

PEEK’s overall processability means it can be designed to fit into many roles, but it possesses additional advantages that make it an ideal biomaterial. Some of them include:

  1. Versatility – In its natural, unfilled state, PEEK possesses a flexural modulus that’s similar to cortical bone. This means PEEK is a frontline choice for interbody fusion cages and any application where the polymer must interface with native bone.

    In applications where additional stiffness and strength are needed, CFR PEEK, mentioned above, can be produced by augmenting PEEK with chopped carbon fiber.

    Some of PEEK’s other attributes, like its radiolucency, or transparency with imaging technologies, can be altered with other additives. Barium sulfate, for example, can make PEEK more visible on CT scans, MRIs and X-rays.

    PEEK can also be extruded into extended lengths for medical tubing, which makes it a valuable material for cardiovascular devices and medical equipment.

  2. Biocompatibility – PEEK is a proven biomaterial, and has the test results and patient reports to support it. PEEK has passed the most demanding biomaterial safety testing available (USP Class VI and ISO 10993) and has also been in use as a spinal implant for 20 years. In that time, patient reports have not demonstrated concern with the polymer. In fact, PEEK is now the primary biomaterial for interbody fusion cages with its excellent safety record.
  3. Durability – PEEK is a high performance polymer, so its material properties are elite among medical plastics. Durability is a standout property of PEEK as it possesses excellent wear resistance, strong corrosion resistance and all-round strength. PEEK’s tensile strength, for example, is comparable to aluminum and cast iron when processed in its CFR form. PEEK’s pullout strength is remarkable, too, which is why it is incorporated into anchoring systems for trauma fixation and other devices.

    PEEK’s resilience is also notable, as the polymer can withstand repeated compression and tensile forces without losing its shape or strength. This is also useful in dentistry, where PEEK components may be responsible for shouldering biting and chewing forces.

  4. Sanitary benefits – PEEK is also helping medical facilities in the fight against hospital-acquired infections, or HAIs. HAIs are a dire problem for hospitals, as the Centers for Disease Control and Prevention (CDC) states that nearly 100,000 people die every year due to a HAI.

    To stop HAIs from emerging or spreading from person to person, hospitals are increasingly investing in single-use instruments. Single-use instruments are disposed of after they are used with a patient, removing the chances of spreading an infection entirely. Some instruments, like medical tubing, are notorious for being difficult to completely clean, and PEEK, along with other medical plastics, offer an alternative.

  5. A bright future – PEEK is one of the most promising biomaterials for the future of medicine, and engineering firms are already developing the polymer in interesting ways. PEEK was first used in spinal implants, so it’s no surprise that improved PEEK based spinal implants are being introduced to the market. New implants utilizing advanced PEEK technologies demonstrate more effective osseointegration, which is key for interbody fusion cages. This new generation of improved PEEK implants is driven by improvements to the implant’s structure and composition.

    Even though PEEK is found in spinal fusion, orthopedic, dental, cardiovascular and trauma fixation applications, it is one of the newest biomaterials available. With time, PEEK will be improved on further and integrated into additional medical procedures.

PEEK rods offer a convenient way for device manufacturers to machine precise devices and components from PEEK stock shapes. Experienced PEEK converters will have a variety of PEEK grades and rod diameters available, so no matter your material needs, there is PEEK stock ready and waiting.

Materials Used In Medical Implants

Medical implants are tightly regulated by the FDA, and they can only be manufactured from biomaterials that have a proven safety record. This includes several polymers and high performance polymers like PEEK. PEEK is of particular interest to medicine as it has emerged as a frontline biomaterial for a diverse range of applications.

Other polymers used in medical implants include:

  • Polyurethane
  • Polyglycolide (PGA)
  • Polytetrafluoroethylene (PTFE)
  • Polyethylene (PE)

Non-polymer biomaterials are also prominent in medicine and include:

  • Titanium
  • Ceramics
  • Chromium
  • Cobalt

There are several more, but these are the most common biomaterial options.

What medical implants are PEEK used in?

PEEK is a notable biomaterial for its material properties and for its superb processability. As a high performance thermoplastic, PEEK is converted into medical components at high temperatures and using one of several methods. Those methods include injection molding, machining and extrusion, which is particularly useful for creating long segments of medical tubing.

Some of PEEK’s other primary medical applications include:

  • Interbody fusion cages – PEEK was first used in spinal fusion procedures, and it’s now a frontline option for interbody fusion cages. As interbody fusion cages represent an industry worth more than $1 billion, according to industry numbers, PEEK is a valuable biomaterial due to its role in spinal fusion alone.An active area of medical engineering research is making a better PEEK interbody fusion cage. The returns on this research are promising, as the current generation of fusion cages demonstrate better bone-in growth. This is due to superior design features like microporous structures and the use of materials like hydroxyapatite or zeolite.
  • Trauma fixation devices – PEEK has been manufactured into an array of trauma fixation components, including hardware and bone plates. PEEK’s excellent pullout strength and resilience makes it ideal in this role, especially when PEEK is augmented with chopped carbon. Termed CFR PEEK, this polymer grade offers added stiffness and strength and fatigue resistance over unfilled PEEK.
  • Joint replacement devices – Joint replacement systems must withstand a great deal of compressive forces while retaining their shape and position. PEEK is well-suited to these challenges, which is why it can be incorporated into knee and hip replacement procedures. PEEK has a good potential as an effective biomaterial for acetabular cups, in particular, as its wear resistance means it can function long term as a weight-bearing material.
  • Cardiovascular tubing and devices – PEEK is an extremely popular option for cardiovascular tubing, for several reasons. PEEK possesses excellent torsion resistance (the highest among polymer biomaterials), so it can weather the constant push and pull of the vascular network. PEEK also has a low coefficient of friction, so it offers a strong mix of pushability and navigation. In other words, PEEK can be inserted into the vascular network without the need for a lot of force, and it can move through nonlinear vascular segments with ease.PEEK’s processability and machinability means it can be converted into very small components without compromising its material properties. As cardiovascular devices can be inconceivably tiny, PEEK has an advantage in this area.

    Cardiovascular tubing is a commonplace PEEK application, and it has been incorporated into various device delivery systems, including valve replacement and stent placement. PEEK is also used in ablation catheters and auto defibrillators, where its electrical insulating capabilities are important.

  • Dental devices and implants – PEEK is quickly gaining attention in dentistry, and it’s already being used in partial dentures and in dental implants. Dental implants rely on a material that can readily fuse with bone, and PEEK does so better than most biomaterials.For partial dentures, it’s PEEK’s aesthetics and machinability that make it an attractive choice. Patients want their dentures to look natural and blend in with surrounding dental tissues. Patient comfort is also an important consideration, and a snug fit is what’s needed to ensure it. PEEK excels here again, as it can be precisely color matched to produce a natural look, to the point where it would be highly difficult for anyone to notice the difference. Since PEEK can be machined to precise tolerances, it is a perfect material for something as individual as a patient’s teeth and gums. Many practices now rely on computer-aided design and manufacturing, along with 3D imaging of the patient’s mouth, to create dental devices that fit perfectly.

    Furthermore, PEEK does not alter the patient’s taste and it does not trap heat or provoke an allergic response.

PEEK’s durability, processability and machinability has made it one of the most versatile biomaterials in existence. Engineers and device manufacturers are working hard to create better medical devices out of PEEK, providing better outcomes for patients.

 

Artificial Disc Replacement

In recent years, artificial disc replacements made from PEEK have garnered interest from researchers. The initial studies are promising and confirm that the high-performance polymer is ideal for the procedure.

Artificial disc replacement, or disc arthroplasty, is an alternative to anterior spinal fusion procedures, and is indicated in patients suffering from degenerative disc disease (DDD). During an artificial disc replacement procedure, the existing disc is either removed entirely, or only the nucleus is removed. The nucleus is the center of the disc, and is the only part that is replaced if the outside of the disc, the annulus, is in good condition.

Why consider artificial disc replacement?

Artificial disc replacement is used to treat the pain and lack of motion associated with DDD, but it’s not the only procedure available for the condition. Spinal fusion is also indicated in many DDD patients, and in these patients, a PEEK interbody cage is a common implant choice. In some cases, though, artificial disc replacement may make more sense. Here’s why:

  1. Disc arthroplasty preserves the spine’s motion – During spinal fusion, the space between the vertebrae is filled with an implant and a bone graft, locking, or “fusing” the bones together so that they move together. While this is often effective at reducing or eliminating pain, it can somewhat reduce the spine’s motion.

    Disc arthroplasty maintains the spine’s motion because it doesn’t lock vertebrae together. Instead, it replaces natural tissue with a device that aims to perform the same function.

  2. Disc arthroplasty helps patients get back on their feet faster – Following spinal fusion, patients are encouraged to take it slow in getting back to their normal activities. It takes time for the vertebrae to completely fuse, and during this time, it’s essential that the patient not strain or extend themselves.

    Disc arthroplasty, though, is intended to preserve motion, and patients are encouraged to start moving soon after surgery. This is also managed with gradual progression, but at a quicker pace than those who opt for fusion.

  3. Disc arthroplasty may reduce risk of certain complications – In rare cases, spinal fusion may cause other parts of the spine to bear more weight than normal. This may subject those parts to additional wear and tear, which could result in worsening symptoms.

    Disc replacement, though, doesn’t change the way the spine handles weight. It’s possible that this could lead to fewer complications, and according to a 2018 study published in Neurosurgery, the reoperation rate is extremely low among people who have undergone disc replacement surgery.

Why are PEEK artificial discs ideal?

Artificial discs can be made from one or more biomaterials, and PEEK is among the most promising materials for this procedure. The above Neurosurgery study looked at 33 patients who received a PEEK artificial disc, and in every instance, clinical improvements were seen with every patient. These improvements were maintained at two years, and included assessments of neck and arm pain. These results are comparable with artificial discs made from other biomaterials, so there is no loss in performance between metal and PEEK.

Beyond this, there are compelling reasons to believe that PEEK is the superior choice in artificial disc replacement. For example:

  • PEEK has excellent bearing and wear properties – PEEK is endlessly modifiable, but in its unfilled, natural state, the high-performance polymer has good bearing and wear performance and therefore can be a candidate for motion preservation applications and related device components.  Furthermore, since PEEK can be easily modified with specialty additives, the bearing and wear performance of PEEK can be improved to further reduce potential wear in various motion preservation devices, like artificial discs
  • PEEK offers pure radiolucency – PEEK offers pure radiolucency, so it is invisible on most forms of medical imaging, including MRIs and CT scans. This pure radiolucency is helpful when imaging and assessing the implant site for progress. It’s also useful for detecting any complications early.

    Metal implants, by contrast, produce a lot of image contrast, so they are not as easy to accurately image.

Though it’s a relatively new procedure, PEEK artificial discs are a promising treatment option for people suffering from degenerative disc disease. With the polymer’s excellent bearing and wear capabilities, its pure radiolucency and its biocompatibility, PEEK artificial discs represent a viable alternative to spinal fusion surgery.

 

Medical Plastic Devices

According to a report put together by Grand View Research, the medical plastics market is expected to climb above $33 billion by 2025, up from $17.2 billion in 2018. That means in just seven years, the medical plastics market is expected to double in value. There are several reasons for this, including an aging population, but the effectiveness of plastic biomaterials is one of the most important. Every year, new applications for medical plastics are found, and high-performance polymers like PEEK have shown promise in many medical fields.

Why Plastic Medical Devices Are Becoming Front-line Options

Plastic medical devices are used both in and out of the body, and in a diverse range of applications. Plastics are found in laboratory equipment and in surgical instrumentation. Plastic is also taking over the single-use instrument market, as it is much more practical compared to other materials in a single-use application. Plastic devices are also growing in popularity, as infection control is a major concern among medical facilities.

As impressive as this development is, high-performance polymers like PEEK are pushing medical technology forward. Since the introduction of the first PEEK spinal implant nearly 20 years ago, PEEK has found its way into many more medical devices while gaining more ground in spinal implant procedures.

Why is PEEK drawing so much attention among medical professionals?

  1. A similar modulus to bone – Ideally, biomaterials would mimic the tissues they’re replacing. This would guarantee optimal comfort and ensure the device behaves in a way that facilitates healing. Until the introduction of PEEK, however, it was impossible to find a biomaterial that could provide the same material advantages of cortical bone.

    PEEK, in both its unfilled state and carbon-reinforced state, possesses a modulus that is far more similar to bone than titanium. In fact, titanium’s modulus is about ten times greater than that of bone’s, which is a problem in applications where stress shielding could result.

    Since PEEK flexes and bears weight like bone, it will not cause stress shielding, ensuring nearby bone retains its mineral density and integrity. According to a 2017 study published in the Journal of Spine Surgery, PEEK’s ability to mimic the modulus of bone it interfaces is valuable in that it may reduce postoperative complications.

    PEEK’s modulus advantage isn’t relevant in all of its medical applications, but it is the main driver of PEEK’s success in spinal fusion, trauma fixation and orthopedic procedures.

  2. Radiolucency – PEEK’s radiolucency is a second compelling reason for its adoption among medical professionals. PEEK, in both CFR and unfilled grades, is transparent on X-ray, MRI and CT scans. It is extremely easy for surgical teams to image the implant site and monitor how the implant is positioned and interfacing with neighboring bone. Clear imaging is needed to spot potential complications, and PEEK doesn’t get in the way of this. It’s another point in PEEK’s favor over titanium, which does produce considerable opacity on most medical imaging.

    If, however, radiolucency is not desired, PEEK can be mixed with additives that improve its image contrast. Barium sulfate is the most common additive used for this purpose, and it can be added to PEEK without compromising its material properties.

  3. Processability – As a high-performance polymer, PEEK can be molded and shaped to almost any degree. This allows it to fit into a variety of applications that other biomaterials, because of their inferior processability, can’t match.

    Consider all the ways PEEK can be processed into a medical component. It can be injection molded, machined, extruded or run through exotic processes like film calendaring, which is used for extremely tiny medical components that require special medical film. It’s impossible to process other biomaterials in this fashion, which gives PEEK an advantage that designers and converters can both leverage.

  4. Future potential – PEEK is a worthy frontline biomaterial for some of the most delicate procedures in medicine, like spinal fusion. However, no other biomaterial is being developed at the rate PEEK is. PEEK’s few limitations are being resolved quickly, and they’re being resolved by next generation implants that are rapidly being introduced to the market.

    For example, PEEK implants augmented with hydroxyapatite achieve greater bone-in growth and integrate better with native bone. Implants designed with microporous structures, zeolite and other integration-enabling mechanisms are additional solutions available.

    What this illustrates is that PEEK can be developed and improved upon, whereas other biomaterials offer a lower potential ceiling. Medical professionals with one eye on the present and one on the future will find everything they want in PEEK.

Plastic medical devices offer a number of benefits that other biomaterials like stainless steel and titanium can’t match. Superior flexibility, weight-bearing, radiolucency and processability are all among PEEK’s defining characteristics, which means it can be integrated into a variety of medical devices. The future of medicine, then, is made with plastics.

PEEK Partial Denture

PEEK possesses a range of properties that make it ideal for partial dentures. These advantages are compelling to both dentists and their patients, which may be why PEEK is replacing other dental biomaterials, like titanium, chromium and porcelain. PEEK is a popular option for partial dentures and dental implants, for several reasons, including:

  • Improved aesthetics – A common concern among patients is that their partial dentures will be obvious and unattractive. The reason why it’s a common concern is because most dental materials are difficult to color match, and are easy to pick out as a result.

    However, PEEK doesn’t have aesthetic limitations. Instead, the high-performance polymer can be color matched with good precision. PEEK can be colored to fit patients, so no matter what aesthetic issues a patient is dealing with, PEEK offers a solution that will leave them feeling confident. Also, the gingiva, or gums, are less likely to resorb away from a PEEK denture, further enhancing aesthetics by not being seen due to resorption of the gingiva like with most materials

  • Improved comfort – After aesthetics, patients place a priority on comfort. Traditional partial dentures may trap heat or alter the patient’s taste. PEEK doesn’t do either, so patients tend to forget that the denture is there. PEEK is also lightweight and can be machined to incredible precision, so it can be used to provide a perfect, individual fit. PEEK weighs far less than metal and the reduction in weight may also help with comfort.
  • Excellent wear resistance – Partial dentures are subjected to a great deal of compressive and shear forces, and not many materials can handle it. However, PEEK is resilient enough to withstand daily chewing and grinding. PEEK’s wear resistance has been recognized in a variety of high-stress applications, so it is ideal for use in the oral cavity.
  • Total biocompatibility – Partial dentures aren’t rooted in the jawbone like implants, but they do remain in close contact with tissues in the oral cavity, so biocompatibility is still important. Some dental materials, including titanium and nickel, can provoke an allergic reaction, but PEEK hasn’t demonstrated immunogenic behavior. It can be placed in the mouth without fear of irritation, adding to patient comfort.

    PEEK has been through the toughest biocompatibility testing protocol there is, proven to be neither cytotoxic nor genotoxic. PEEK put up excellent marks during testing, demonstrating to researchers that it could remain in contact with human tissues for prolonged periods without causing damage. Patients can wear their PEEK partial denture without worry.

  • Hydrolysis resistance – PEEK is highly resistant to hydrolysis, so it will not lose its integrity in the presence of water, saliva or other bodily fluids. In fact, PEEK doesn’t absorb water to a significant degree, so it will remain stable for years.
  • Imaging friendly – In its unfilled state, PEEK does not interfere with medical imaging, including dental X-rays. It can be left in the mouth without fear of it scattering an image and making it difficult or impossible to read the scan.
  • Future potential – PEEK is already an important dental biomaterial, but there’s still plenty of research and development to go with the polymer. In the 20 years since PEEK was introduced to medicine, it has been improved upon steadily, and those improvements keep on coming. A promising area of research into PEEK involves the production of antimicrobial PEEK surfaces, which is of immediate use in the microbe-heavy oral cavity.

How PEEK’s Processability Makes for a Better Denture

Among PEEK’s noteworthy traits is its processability, as the polymer can be converted using one of many methods. It can be converted using conventional conversion technologies like injection molding or machining, or it can be converted using more esoteric methods like extrusion or film calendaring. Most PEEK medical components are machined, however, as this allows for the tightest tolerances and advanced component designs. PEEK’s excellent machinability makes this possible, as the polymer’s properties will not suffer during the process.

PEEK’s machinability is particularly helpful in dentistry and in the production of partial dentures. Before a patient receives their partial denture, their mouth is imaged using 3D imagining technology. These images can be used with computer-assisted manufacturing technology to machine a denture that fits the patient perfectly. PEEK’s ability to undergo extensive machining is key to this process.

A Complete Partial Denture

Partial dentures should be discreet, they should be comfortable and they should be reliable. PEEK partial dentures are all of the above, and they can provide this level of performance for years after placement. Put it all together, and PEEK is ready to be the frontline choice for partial dentures

What Is Medical Plastic And What Are Its Uses

Medical plastics are of great value to the healthcare industry and are used in everything from surgical instrumentation to life-preserving cardiovascular devices. Medical plastics come in a variety of compositions and grades, but what unifies them is that they are safe to use with human tissues. All medical plastics, including high-performance polymers like PEEK, have undergone extensive safety research and testing before they are incorporated into medical components and devices.

PEEK’s uses in medicine are wide-ranging and involve several critical applications. Some of those applications include:

  • Interbody fusion cages for spinal fusion procedures
  • Orthopedic and arthroscopic applications, for knee and hip components
  • Trauma fixation components, which include bone plates and hardware systems
  • Cardiovascular devices and components, like tubing, catheter components and defibrillator components
  • Dental devices, which include partial removable dentures and dental implants

Within these fields of medicine, PEEK is featured in dozens of components, and its number of uses is growing all the time.

How are medical plastics changing healthcare?

Medical plastics like PEEK bring many advantages to medicine, which is why they are quickly replacing other biomaterials. Here are some of the reasons:

  • Medical plastics can be sterilized easily –

    Hospital-acquired infections (HAIs) are a serious problem, resulting in nearly 100,000 deaths in the U.S. every year. Medical plastics are considered a major weapon in the fight against HAIs, as they can either be disposed of after a single use, or they can be designed with antimicrobial surfaces that resist pathogenic growth. PEEK polymer, for example, can also be sterilized for repeated use via all primary sterilization methods including steam, gamma, and ETO sterilization.

  • Medical plastics have a strong safety record –

    Several plastics are considered biomaterials, which means they are inert when in contact with the body’s tissues. Among plastic biomaterials, PEEK stands out for its long, impressive patient outcome history. PEEK has undergone the rigorous safety testing available for potential biomaterials (including ISO 10993 and USP Class VI), but it also has 20 years of patient reports verifying its biocompatibility.

  • Medical plastics exhibit excellent material properties –

    High-performance polymers like PEEK are especially useful for medical applications because they possess a unique combination of attractive physical properties. PEEK’s flexural modulus, for example, is nearly identical to cortical bone, so it bears weight and stress like bone. This makes it an ideal substitute for native bone in many applications, including spinal fusions. The material will move and support neighboring tissues, and it won’t cause stress shielding in nearby bone that can lead to mineral loss and subsequent bone weakness.

  • Medical plastics are extremely versatile –

    Medical plastics can be converted into components through one of several conversion methods. Those methods include injection molding, machining, extrusion, film calendaring and some even more esoteric methods. With several conversion methods available, device manufacturers have a lot of room in producing the most effective components possible.

    Most PEEK medical components are machined, as machining allows for the tightest tolerances, and that’s a priority for any implantable devices. However, medical plastics that aren’t used in vivo, but instead for instruments or equipment, can be converted using injection molding.

How is PEEK being used in medicine?

PEEK is a high-performance polymer, so it possesses a combination of properties that few other materials possess. This gives PEEK a great deal of potential, as it can withstand most any force it might encounter in the human body. As such, here is how medical facilities are making the most of those properties:

  • Interbody fusion cages – PEEK’s initial success in medicine was in spinal fusion procedures, where it serves as a frontline material for interbody fusion cages. Interbody fusion cages provide an optimal support for the vertebras to fuse together, so the implant must be safe and it must facilitate osseointegration.

    PEEK is safe and the newest generation of PEEK cages are designed to optimize bone-in growth, with the use of bone-attracting materials and microporous structures. It’s likely true, then, that PEEK’s status as the first choice in interbody fusion cages is certain.

  • Trauma fixation components – PEEK is regularly converted into bone plates and hardware to secure trauma fixation components. PEEK is perfect in this role because it exhibits excellent resilience and pullout strength.
  • Cardiovascular tubing and components – PEEK can be extruded into long, uniform segments, which makes it an ideal biomaterial for tubing. PEEK has a low coefficient of friction, so it can be steered through the cardiovascular network without getting stuck or causing harm to arteries or veins.

    PEEK tubing can be used to deliver a stent or a replacement heart valve. PEEK components are also found in defibrillators and ablation catheters, as it can prevent harmful electrical discharges.

  • Arthroscopic and orthopedic components – PEEK’s ability to handle weight and resist wear are impressive, and it’s a suitable biomaterial in hip and knee replacement components, as well as arthroscopic procedures. PEEK can be found in acetabular cups, where its resilience and wear resistance are highly valuable.
  • Dental devices – PEEK can function in several roles for dentists, serving as a primary partial denture material, or a dental implant material. PEEK is extremely well-suited for partial dentures, because it can be color matched to nearby tissues, it offers excellent wear resistance and it can be precisely machined to fit a patient perfectly. As a dental implant, PEEK’s bone-like modulus and total biocompatibility make it perfect for interfacing with the jawbone.

Medical plastics, like the versatile and durable PEEK, are found in hundreds of medical devices and instruments. Medical plastics are already achieving a great deal, and with so much research focused on making them even better, the future will continue to focus on plastic and its uses in medicine.

 

 

Advantages of a PEEK Cage vs Titanium Cage

PEEK and titanium are the primary biomaterials used in fusion cages, but PEEK has a few decisive advantages over titanium. Recently published research also suggests that the high-performance polymer is a better fit for fusion procedures.

Though PEEK is one of the newer biomaterials, it has quickly emerged as a top choice in several spinal fusion procedures, including:

  • Anterior cervical discectomy and fusion, or ACDF.
  • Anterior lumbar interbody fusion, or ALIF.
  • Posterior lumbar interbody fusion, or PLIF.

PEEK is also being considered for other spinal devices, including artificial discs. This makes sense, because PEEK is well-suited to handle the physical demands placed on the spine.

PEEK vs. Titanium: Fusion Rates and Subsidence

Studies comparing titanium and PEEK focus on fusion rates and subsidence. Fusion refers to the implant’s capacity to osseointegrate with native bone and subsidence refers to caving in of nearby bone.

Subsidence occurs as a result of stress shielding, and stress shielding occurs when the bone is no longer stimulated by weight bearing forces. Without this stress, affected bone tissue drops in mineral density, compromising its structure to an extent. A loss of bone mineral density could lead to a higher risk of fractures, as has been noted in studies with osteoporosis patients.

PEEK and titanium cages are similar regarding fusion rates, and the research confirms that there isn’t a statistically significant difference between the two. However, there is a significant difference in subsidence rates.

According to a 2013 study published in the European Spine Journal, titanium cages were associated with much higher rates of subsidence (over 30 percent) compared to PEEK (less than 10 percent). Additional studies, including a 2017 study published in the Journal of Clinical Neuroscience, reinforce this research and have found the same thing.

Subsidence remains a significant concern with titanium implants, but PEEK is much more promising in this area due to its bone-like flexural modulus. PEEK, in its unfilled state, possesses a similar flexural modulus to cortical bone, so it bends and bears weight like the body’s own tissues. This is how PEEK is able to avoid stress shielding, and how the polymer encourages more effective healing in native bone.

PEEK vs. Titanium: Radiolucency

PEEK’s flexural modulus is one of its primary advantages, but it’s not the only one. PEEK, again in its unfilled state, offers pure radiolucency. It is completely invisible on MRIs, CT scans and X-rays, so surgical teams can easily monitor post-operative progress and confirm that osseointegration is taking place. If there is a chance of complications emerging, PEEK’s pure radiolucency allows surgical teams to catch them sooner.

PEEK’s pure radiolucency can be modified with the addition of additives like barium sulfate. When mixed in, barium sulfate adds image contrast to the polymer, without affecting PEEK’s properties.

Titanium, unsurprisingly, doesn’t offer the same radiolucency that PEEK does. Titanium, like other metals, is an image-scattering material and creates significant artifacts. This can interfere with attempts to assess the implant’s position and its fusion progress.

PEEK vs. Titanium: Processability

Both PEEK and titanium cages are manufactured using modern CAM processes, and both to excellent tolerances. Titanium, though, poses difficulties during the machining process as it possesses low thermal conductivity. Both expose machining tools to additional wear, which can make the metal more expensive and more challenging to work with.

In the hands of a skilled converter, though, PEEK can be efficiently machined without compromising its properties. The key word here is “skilled,” because PEEK is vulnerable to subtle issues like fiber orientation. A converter experienced with PEEK will be equipped to sidestep these potential obstacles.

In addition to machining, PEEK can be converted using injection molding and extrusion processes. Medical processing facilities can maximize processing economy by opting for large runs of injected PEEK components. Via extrusion, PEEK can also be converted into durable stretches of medical tubing.

PEEK vs. Titanium: The Future

PEEK is a newer biomaterial, so there is more potential to unlock with the polymer. There are already several advanced PEEK cages on the market, mixed with materials that encourage bone growth and osseointegration. Zeolite and hydroxyapatite are two such materials, and initial research confirms that these new PEEK implants are achieving superior bone-in growth.

New PEEK implants are also designed with microporous structures, and these encourage native bone to grow into the implant, with a lock-like fit. Though there are similar initiatives targeted at titanium, PEEK’s superior processability likely means that there is more room to improve upon the polymer.

In the battle of biomaterials, PEEK offers a superior modulus, better radiolucency and a wider range of processing options. These advantages explain why PEEK is the first choice in spinal fusion procedures, and why it is an important biomaterial for several medical fields.

What are the Different Types of Plastic Grades for Medical Plastics?

Plastic in various forms has improved nearly every field of medicine and serves a variety of roles in a medical facility. For example, medical plastics can be incorporated in everything from single-use surgical instruments or tubing, to long term spinal and cardiovascular implants.

Some of the most common medical plastics include:

  • Polyetheretherketone (PEEK)
  • Polypropylene (PP)
  • Polyethylene (PE)
  • Polystyrene (PS)
  • Polyvinyl chloride (PVC)
  • Polyethylene terephthalate (PET)

Of these, only a couple medical plastics can be used for long-term implantable devices. Those include some resorbable plastics, like polylactic acid polyglycolic acid, PE and PEEK. While UHMWPE (Ultra-high molecular weight polyethylene) is used in orthopedic applications, PEEK’s material properties make it a frontline choice in an array of more demanding applications. That includes spinal fusion, cardiovascular, dental and trauma fixation applications.

PEEK and CFR PEEK

PEEK can be used in its unfilled form or with the addition of chopped carbon fiber to create CFR PEEK. Both are appropriate in many medical applications, but each possesses its own advantages. Unfilled PEEK is more flexible while still offering strong tensile strength. Unfilled PEEK is a frontline choice in spinal fusion and cardiovascular applications. Both grades are fully radiolucent.

CFR PEEK provides added tensile strength and a greater modulus and thereby is used for trauma applications like bone plates and screws. Both PEEK options are similar to cortical bone’s tensile strength making each an excellent choice in loadbearing or load sharing applications, including applications where bone healing is necessary. CFR PEEK can also be used in some dental implants.

Why are medical plastics replacing other biomaterials?

There are only a handful of materials that are biocompatible and effective enough to be used in the human body. Until the introduction of medical plastics, metal and ceramic were the biomaterials of choice, and titanium remains a primary biomaterial today. High-performance polymers like PEEK and UHMWPE, though, are replacing those biomaterials in many important applications. There are a couple reasons for this, including:

  • Stress shielding and subsidence – PEEK and CFR PEEK, due to their cortical bone-like moduli, can be used as load sharing materials. While titanium and ceramics are structurally strong enough to work as implants, their high moduli mean they bear too much weight in many instances, robbing nearby bone of important, constructive stresses. Over time, this can lead to loss of bone mineral density, and possible subsidence, or caving in. In multiple studies comparing PEEK and titanium, titanium has demonstrated higher rates of subsidence.
  • Efficient manufacturing – In some applications, including arthroscopic and trauma fixation applications, PEEK has shown resiliency, tensile strength and pull out strength comparable or favorable to other biomaterials. However, PEEK possesses a processability advantage over metal and ceramic, as it can be easily injection molded.Injection molding is an economical manufacturing method that is particularly cost-efficient when used to create high component volumes such as anchors, screw systems and any other component needed in large quantities.

What makes PEEK a medical plastic?

PEEK, like every biomaterial, has been subjected to extensive biocompatibility testing to ensure it is safe for use in the human body. ISO 10993 details the most up-to-date testing protocols available to medical device manufacturers, and several of those protocols are relevant to PEEK implant testing. They include:

  1. Cytotoxicity testing –

    Cytotoxicity testing assesses whether the material is likely to cause cell damage. This is usually done by exposing a cell culture directly to a material sample, and then incubating both. Following incubation, the cells are checked for any lysis or malformation, as this potentially indicates cytotoxicity.

  2. Sensitization testing –

    Sensitization testing checks for an immunological response to the material, which may indicate the material is causing adverse systemic effects to the subject. To perform this test, material extracts are applied to subjects and monitored for a response.

  3. Irritation testing –

    Irritation testing looks for the material’s irritant potential, either to the skin or mucosal membranes. For implantable materials, this test is normally done intracutaneously, so extracts are injected under the skin, and any signs of redness or swelling are noted.

  4. Acute system toxicity testing –

    Acute systemic toxicity testing checks for systemic (in contrast to local) effects to the body following extended exposure. Material extracts are injected in a group of test subjects, and are checked immediately for any adverse signs. The subjects are checked several more times before the test’s conclusion, to verify that the material is not affecting the subject’s vitals.

  5. Genotoxicity testing –

    Genotoxicity testing considers the material’s mutagenic potential, or its potential to cause genetic damage to the subject. During genotoxicity testing, the test subjects are salmonella bacteria, which are sensitive to mutagens. Following exposure to the material, only mutated salmonella will survive, so researchers can note the prevalence of mutations among the bacteria.

  6. Implantation testing –

    Implantation testing is designed to simulate the implantation environment, so the material is exposed to the tissues it is likely to contact when used in a human body. After extended implantation in an animal subject, tissue samples are taken from the subject and inspected microscopically for any signs of disease.

There are many medical plastics, but only a couple, like PEEK grades, are safe enough to use in the body. These plastics have undergone comprehensive biocompatibility testing to earn that distinction, and have proven their effectiveness in an array of medical applications.

FAQ

What is the difference between PEEK and CFR PEEK?

PEEK is an unfilled high-performance polymer, while CFR PEEK is PEEK polymer with the addition of chopped carbon fiber. CFR PEEK offers additional stiffness and strength, while unfilled PEEK provides additional flexibility. Both are radiolucent.

What standard is used to regulate medical plastics?

Medical plastics are tested for biocompatibility, and the recommended biocompatibility testing procedures are outlined in ISO 10993. ISO 10993 and ISO 13485 (which regulates medical device manufacturers) meet the regulatory guidelines of European and Asian agencies. The FDA also considers ISO standards to be sufficient for most medical devices, and will consider it during premarket approval.

Why is PEEK replacing titanium in bone healing applications?

Titanium, ceramic and other loadbearing biomaterials are strong and durable, but they may rob neighboring bone of important, bone-stimulating stresses. This is called stress shielding, and it can result in bone mineral density loss in nearby bone. That can lead to subsidence, or caving in of bone.

PEEK subsidence rates are much lower, according to several research studies. PEEK can also be injection molded, which gives it a major processability advantage in many medical applications.