Baseline Volume Loss — The Deflated Cheek
Aging and genetics erode fat pads and bone, sinking facial contours.
- 2–5 mm: Deficit depth (typical cheek fat pad loss)
- ~30s+: Onset age (progressive facial fat atrophy)
- 3: Common sites (cheeks, lips, nasolabial folds)
- Restore: Correction goal (not overfill, native contour)
Why volume is lost with age
Subcutaneous fat compartments shrink; underlying bone slowly resorbs.
Target correction zones
Cheeks, lips, and nasolabial folds are common filler targets.
Cross-Linked HA Gel — Injected at Depth
A viscous cross-linked HA gel is placed subdermally to physically fill the deficit.
- Subdermal: Injection depth (supraperiosteal plane)
- BDDE: Cross-linker (common HA cross-linking agent)
- 0.5–3 mL: Typical dose (per treatment area)
- Cannula: Delivery tool (or fine-gauge needle)
Placement technique
Gel deposited in small boluses along the deficit plane.
Cross-link density
Higher cross-linking gives firmer gel, slower degradation.
Water-Binding — The Gel Draws In Water
HA is intensely hygroscopic, binding water molecules to swell and plump tissue.
- ~1000×: Water binding (HA mass in bound water)
- 24–72 h: Swelling window (post-injection plumping)
- 20–45%: Added swelling (above injected volume)
- Anionic: Osmotic driver (carboxyl groups attract water)
Hygroscopic mechanism
Anionic HA chains osmotically pull water into the gel mesh.
Post-injection plumping
Visible volume rises further over the first few days.
Immediate Lift & Tissue Integration
Volumizing effect is visible immediately, gel settles into tissue over days.
- Immediate: Visible effect (at time of injection)
- ~2 weeks: Full settling (swelling resolves, gel settles)
- 90–100%: Integration (anchored within tissue planes)
- 2–4 wk: Touch-up window (for correction assessment)
Immediate volumizing
Contour is restored the moment gel fills the deficit.
Tissue settling
Surrounding tissue conforms around the gel over days.
Outcome — Gradual Enzymatic Degradation
Native hyaluronidase enzymes slowly break cross-links, resorbing gel over months.
- 6–18 mo: Longevity (depends on cross-link density)
- Hyaluronidase: Degrading enzyme (native tissue enzyme)
- Gradual: Degradation mode (volume fades progressively)
- Yes: Reversibility (injectable hyaluronidase dissolves gel)
Enzymatic breakdown
Hyaluronidase cleaves cross-links, gel volume slowly shrinks.
Product longevity
Denser cross-linking resists degradation for more months.