Calcium hydroxylapatite (CaHA):
what the term means

Where calcium hydroxylapatite matters on this site

CaHA appears wherever this site discusses support on bone rather than volume in soft tissue. Because the microspheres are firm and cannot be dissolved, every page that uses it pairs it with ultrasound mapping and a conservative first placement.

CaHA is chosen for support on bone; if a plan needs something that can be taken back, it is the wrong material.— Dr Sin Yong

• Radiesse: the product page, separating undiluted structural work on the chin, jawline and hands from hyperdiluted skin-quality work on the neck and body.
• CaHA nose filler: why the bridge and tip are built with a fine needle on the bone, and why CaHA or PCL is usually chosen there over a hyaluronic acid-only product.
• 4D Scar Reconstruction: CaHA as the support step placed beneath a released acne scar so the floor can rise.
• Hand rejuvenation: the backs of the hands, one of the more studied areas for diluted CaHA.
• Lumps after non-HA fillers: what is done when a CaHA deposit can be felt or seen, given that hyaluronidase has no action on it.

Regulatory status. Radiesse holds US FDA premarket approval, first granted in December 2006 for facial folds and HIV-associated lipoatrophy. In Singapore, fillers are medical devices regulated by the Health Sciences Authority; the page on how aesthetic medicine is regulated in Singapore explains what can be checked.

Not to be confused with

Several materials are sold with similar promises, and the differences decide what can be undone and how a complication is managed.

• Hyaluronic acid filler. A water-binding gel that hyaluronidase can dissolve. CaHA is a mineral suspension that it cannot touch, which is why reversibility is part of the choice between them.
• Polycaprolactone (Ellansé). Also microspheres in a carboxymethylcellulose gel, also a collagen response afterwards, but a synthetic polyester rather than a mineral, with its own placement rules.
• Poly-L-lactic acid (Sculptra). A reconstituted powder that adds little on the day and works almost entirely through collagen; CaHA gives visible support straight away.
• Calcium supplements and bone grafts. The same mineral family in a different form. Oral calcium has no effect on facial support, and the injected microspheres are broken down over time rather than turning into bone.

A clinic offering "Radiesse" may also mean either the undiluted or the hyperdiluted procedure, and it is worth asking which.

What decides whether CaHA matters for you

CaHA is a structural choice, so the assessment is about structure first and product second.

• Support or volume? Projection on bone at the chin, jawline or nose suits a firm product; broad deflation across the cheeks is usually better served by a different material, as the collagen biostimulators page sets out.
• Skin thickness. A firm product placed under thin, mobile skin can be seen, so it is kept deep and away from those areas.
• What is already there. Earlier filler or biostimulator is mapped with ultrasound before anything is added, because CaHA stacked on unknown product cannot be taken back.
• Which procedure. Undiluted structure and hyperdiluted skin quality are two different plans, and Dr Sin Yong does not mix them in one appointment without a reason.
• Reversibility. In the nose, where vascular risk is highest, some patients prefer a dissolvable product; the nose fillers guide explains that trade-off.

Where laxity rather than support is the real complaint, he says so and points to an energy-based lift instead.