Research Advancement of PEEK Materials in Oral Implantation and Restoration

• 1
  Why PEEK Fits Bone Better Than Metal
• 2
  Which Grade Survives a Real Implant Program
• 3
  Surface Treatment and Osseointegration Limits
• 4
  Machining PEEK Without Melting the Surface
• 5
  When PEEK Is the Wrong Choice
• 6
  Metrology and Cleanroom Handling for PEEK Parts
• 7
  PEEK Versus Titanium for Oral Components

Polyetheretherketone is a semi-crystalline thermoplastic built from repeating aromatic ether ketone units. The benzene rings stiffen the chain. The ether and carbonyl links let it flex without melting at sterilization temperatures. Melting point sits near 343 °C, and the glass transition is around 143 °C. That gap is wide enough for steam autoclave cycles at 134 °C without softening the part.

The number that matters most in oral work is elastic modulus. Cortical bone runs roughly 10–20 GPa. Titanium sits near 110 GPa. Unfilled PEEK lands around 3.6–4 GPa. Carbon-fiber reinforced grades reach 13–18 GPa, which is inside the bone window. When modulus matches, load transfers through the interface instead of concentrating at the crest.

This is the mechanism behind stress shielding. A stiff implant carries the bite load itself. The surrounding bone sees less strain and slowly resorbs. A PEEK implant shares that load. The effect is real but not unlimited. If the PEEK section is too thin, the part deflects and the interface opens. Design still has to be checked with FEA.

PEEK is also radiolucent. On CT and CBCT it produces no metal streak artifact, so a clinician can see the bone and the healing gap around the implant. Titanium cannot do that. For a patient who needs follow-up imaging, this changes the whole scan protocol.

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  Modulus targetAim for 10–20 GPa to match cortical bone.
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  Sterilization windowSteam at 134 °C, gamma, or EtO. Avoid plasma if geometry traps residue.
• 3
  Imaging benefitNo metal artifact, so bone contact stays visible.

Unfilled PEEK has the best imaging behavior and the lowest modulus. It is the choice for temporary healing abutments, provisional frameworks, and trial components where stiffness is not the job. It machines cleanly, holds a fine finish, and does not wear a cutter as fast as filled grades.

Carbon-fiber reinforced PEEK adds stiffness but changes everything else. CFR-PEEK is dark gray or black, so it is no longer radiolucent in the same way. It also wears tools faster and produces carbon dust that must be captured. If the design brief calls for radiolucency, CFR-PEEK is the wrong pick.

Barium sulfate filled grades exist to raise radiopacity on purpose. They show up lighter on a scan but keep the polymer base. The trade is a small drop in strength and a different set of machining parameters. Choose this only when the clinician needs to see the component itself.

For any grade, confirm the lot has a medical-grade certificate and a traceable batch number. GreatLight machines PEEK, carbon fibre, and the other plastics listed in our material range. We keep lot records with the job so a failed part can be traced back.

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  Unfilled PEEKBest imaging, lowest modulus, easiest to machine.
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  CFR-PEEKHigher stiffness, not radiolucent, abrasive to tooling.
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  BaSO4 filledRadiopaque on purpose, slightly lower strength.

Bare PEEK is hydrophobic and chemically inert. Cells do not attach to it well. That is the core problem the research has attacked for two decades. Titanium forms a native oxide that proteins bind to. PEEK does not. So a machined PEEK surface needs help before bone will grow against it.

Plasma treatment, UV irradiation, and acid etching all raise surface energy. They add oxygen groups that let proteins adsorb. The effect fades over time if the part sits on a shelf, so treated parts should be packaged and used within a controlled window. Check with the coating or treatment supplier for that window.

Hydroxyapatite or titanium dioxide coatings go further by presenting a mineral surface. They improve early bone contact in animal studies. But coating adhesion on a curved implant neck is hard to guarantee. A coating that spalls is worse than no coating, because loose debris sits at the interface.

This is where the research advancement of PEEK materials is still open. No single surface recipe has become the default the way titanium grit-blasting did. Surface treatment is a design decision tied to the specific implant, not a commodity step.

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  Plasma or UVRaises surface energy. Shelf life is limited.
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  HA or TiO2 coatingBetter early contact, adhesion risk on curved faces.
• 3
  Machined finishRa 0.8–1.6 μm is a practical baseline for bonding steps.

PEEK cuts like a soft metal if the tool is sharp and the feed is high. It cuts badly if the tool rubs. Rubbing generates heat, and heat above the glass transition turns the surface white and smeared. That smeared layer will not bond and will not hold a seal.

Use carbide tooling with polished flutes and a positive rake. Keep the cutting edge sharp and change it before it dulls. A dull cutter on PEEK is the most common cause of a failed cosmetic surface. For thin walls, support the part or the wall will flex into the cutter.

Coolant choice matters. Flood coolant with a water-soluble fluid controls heat and clears chips. Some shops use compressed air for open parts to avoid moisture pickup. Either way, dry the part and keep it dry before packaging. PEEK absorbs very little water, but surface moisture still affects bonding.

Hold tolerances with the thermal growth of the material in mind. PEEK expands more than aluminum per degree. If the shop is warm, measure the part after it cools. GreatLight works to ±0.005 mm (±0.0002 in) on machined parts and inspects 100% before shipment, with reports on request.

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  ToolingPolished carbide, sharp, positive rake, replace early.
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  CoolantFlood or air. Dry the part before packing.
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  CheckMeasure after thermal stabilization, not at the machine.

PEEK is not a drop-in replacement for titanium in every position. A single-tooth implant under high occlusal load in a molar site may need more stiffness than unfilled PEEK provides. If CFR-PEEK is needed for stiffness, the radiolucency benefit disappears. At that point the design brief has to say which property wins.

Wear is another limit. PEEK against PEEK or PEEK against enamel can generate debris over millions of cycles. That is acceptable for a healing abutment used for weeks. It is not acceptable for a permanent bearing surface unless the wear couple has been tested.

Long-term clinical data is thinner than for titanium. For a permanent implant, that data gap is a real risk factor. For provisional restorations, custom healing caps, drill guides, and trial frameworks, the risk profile is different and PEEK is often the better answer.

Decide by function. If the part must be invisible on CT, share load with bone, and live for weeks, use unfilled PEEK. If it must be stiff and permanent, the evidence still favors metal. Good design picks the material for the job, not the trend.

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  Good fitProvisional, healing, guides, trial frameworks.
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  Risky fitPermanent high-load bearings without wear data.
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  Hard stopDo not assume PEEK replaces titanium everywhere.

PEEK parts for oral use are usually small and have curved, non-critical cosmetic faces plus tight critical bores. CMM inspection with a touch probe handles the bores. Optical scanning handles the freeform surfaces. A dial bore gauge or pin gauge is enough for a simple through-hole check on the shop floor.

Do not clamp a thin PEEK part hard for measurement. It deflects and the number is wrong. Use light fixturing or a fixture that matches the mounting condition. For a component that screws to a mating part, measure it in that mounted state, not free.

Cleaning matters as much as dimension. Machining leaves fine chips and coolant residue. A medical program needs a documented wash, rinse, and dry sequence, then packaging that keeps the part dry. Ultrafine PEEK particles are light and stick to surfaces. Blow them off before the final wash.

GreatLight holds ISO 9001:2015, IATF 16949:2016, ISO 13485:2016, and ISO 27001:2022. Uploads are secure and confidential, and an NDA is available on request. We run raw material checks, in-process monitoring, and a final inspection before shipment.

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  Measure mountedCheck the part in the condition it will be used.
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  Light fixturingHard clamps distort thin PEEK walls.
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  Clean dryDocumented wash, dry, and dry packaging.