What Titanium Grade Do Premills Use? Grade 5 vs. Grade 23 (ELI)
Short answer
Titanium premills are normally made from Ti-6Al-4V. Grade 5 is the standard version of that alloy; Grade 23, called ELI, is the same alloy with extra low interstitial content — less oxygen, nitrogen and iron. Lower interstitials give better toughness and fatigue behaviour, which is what matters at a fixture interface under cyclic load.
Every premill is "titanium," but not every titanium is the same grade. The number on the spec sheet is directly tied to fatigue strength and the safety of the connection with the implant fixture.
The base alloy: Ti-6Al-4V
Nearly all dental premills are made from Ti-6Al-4V alloy — titanium alloyed with 6% aluminum and 4% vanadium. Thanks to its high strength-to-weight ratio and biocompatibility, it's the standard material for medical and dental implant components.
Dentalrix premills, for example, are made from this same Ti-6Al-4V alloy.
What Grade 23 (ELI) is, and how it differs from the standard grade
ELI stands for Extra Low Interstitial: a version of the same alloy in which interstitial impurities — oxygen in particular — are tightly controlled. Lower oxygen means a more uniform grain structure and higher fatigue strength under repeated loads, such as everyday chewing forces.
That's why Grade 23 is the standard for implantable components in medicine and dentistry — not just for better performance, but for predictable long-term behavior under cyclic loading.
Covision premills are explicitly supplied in Ti-6Al-4V ELI (Grade 23).
Why the grade matters at the implant connection
The lower portion of a premill — the part that directly engages the implant fixture — is under repeated chewing load. If the alloy doesn't have enough fatigue strength, the risk of fracture or loosening at the connection rises over the long term — not on delivery day, but months into use.
That's why alloy grade should be treated as part of the purchasing decision, not just appearance or brand.
The international reference standard
The composition and purity of Ti-6Al-4V ELI for implantable components is defined by standards such as ASTM F136 and ISO 5832-3, which specify the maximum allowed interstitial elements, including oxygen.
If the exact grade isn't listed on a product page, ask the seller to show documentation before ordering — a number without proof shouldn't be assumed.
Grade 5 vs. Grade 23 (ELI)
| Criterion | Grade 5 | Grade 23 (ELI) |
|---|---|---|
| Base alloy | Ti-6Al-4V | Ti-6Al-4V |
| Interstitial content | Standard | Lower (Extra Low Interstitial) |
| Toughness | Good | Better |
| Fatigue behaviour | Good | Better |
| Common use | Industrial and medical | Implants and demanding medical use |
Frequently asked questions
What's the difference between Grade 5 and Grade 23 titanium?
Both belong to the Ti-6Al-4V family; Grade 23 (ELI) has lower oxygen and interstitial impurities, which raises fatigue strength and stability under repeated load. That's why Grade 23 is the standard for implantable components.
Why does titanium grade matter for a premill?
Because the lower portion of a premill directly engages the implant fixture and is under repeated chewing load. A lower-fatigue-strength alloy raises the long-term risk of fracture or loosening.
What grade are Dentalrix and Covision premills?
Covision's published specs explicitly state Ti-6Al-4V ELI (Grade 23). Dentalrix's specs list the Ti-6Al-4V alloy; ask us for the exact grade documentation before ordering.
What's the international standard for this alloy?
ASTM F136 and ISO 5832-3 define the composition and purity of Ti-6Al-4V ELI for implantable medical and dental components.
Key takeaways
- Both grades are Ti-6Al-4V; the difference is interstitial content.
- ELI means extra low interstitial, not a different alloy.
- Lower interstitials give better toughness and fatigue behaviour.
- The fixture interface sees cyclic stress — that is where grade matters.
- Ask your supplier to state the grade on the specification sheet.