Hydroxyapatite-coated surface
Also known as: HA-coated surface, HA coating, Plasma-sprayed hydroxyapatite, Calcium phosphate coating
An implant surface carrying an added layer of hydroxyapatite, the calcium phosphate ceramic chemically related to the mineral phase of bone, most commonly applied by plasma spraying.
Research in progress. Some fields on this entry are not yet verified against a primary source, so we have left them blank rather than filling them in — and this page is not published to search engines until they are.
Key facts
| Production process | Applied by plasma spraying: hydroxyapatite powder is fed into a plasma flame of roughly 6,000-16,000 degrees Celsius and propelled onto the metal substrate, whose own surface temperature rarely exceeds 150 degrees Celsius.Verified spec[1] |
|---|---|
| Manufacturer-described indication | The stated purpose of the coating is to promote early formation of strong bonds between the metal implant and living bone.Verified spec[1] |
| Surface roughness | Requires manual verification(Coating thickness, crystallinity and roughness depend on the spraying parameters and are not covered by the source we consulted.) |
| Geographic availability | Requires manual verification(Plasma-sprayed hydroxyapatite is far less common in current dental implant ranges than it was in the 1990s, but we have not verified a current product list and so do not state a status here.) |
| Surface category | Insufficient evidence(A hydroxyapatite coating is defined by an added ceramic layer rather than by a roughness band, so the usual Sa classification does not describe it well.) |
Overview
Hydroxyapatite coating takes a different route to the same goal: instead of texturing the titanium so bone will grow into it, it puts a layer of bone-like mineral on the outside so the interface is chemically familiar to the body. Plasma spraying is the usual method, and it is a violent one - powder is melted in a flame of several thousand degrees and thrown at the fixture. That process is the source of the long-running argument about these surfaces, because what lands on the implant is not necessarily the same material that went into the gun, and because a coating is a separate layer that can in principle come away from the metal beneath it. Patients occasionally encounter the term in older records or in marketing that presents "bioactive" coating as a premium feature; the honest position is that this is a mature technology with a contested history rather than a current mainstream standard, and we have not yet attached sources adequate to characterise its present-day role.
Sources
Numbers match the citations beside each claim above.
Clinical evidence
- [1]Plasma-sprayed coating of hydroxyapatite on metal implants — a review — Medical Journal of Malaysia (PubMed record), 2004. Accessed 2026-07-21.