PDO Threads FAQ
Part 1 — The material
Q1. What are PDO threads made of?
PDO threads are made of polydioxanone, a synthetic absorbable polyester with decades of use as a surgical suture material.
Three properties define it in practice:
Monofilament construction. A polydioxanone lifting thread is typically one solid strand with no braided interstices — a single continuous filament rather than multiple strands twisted together. Monofilament construction has no interstitial spaces within the filament body.
Class II regulatory status in the US. Absorbable polydioxanone surgical suture is a Class II device type with special controls under 21 CFR 878.4840. This classification covers the suture material; the regulatory status of any specific lifting-thread product is a separate matter — see the Compliance Guide.
Absorption by hydrolysis. The polymer breaks down through hydrolysis and is metabolized rather than removed. Timing is covered in Q3.
Polydioxanone is the most represented of the three thread materials in published thread-lift literature, and carries the widest design and dimension range — the practical reason it forms the base of most clinic menus.
Material remains one variable among several. Sterile handling, placement depth and practitioner technique influence outcome more than material selection does.
Q2. How does polydioxanone behave once placed?
Two processes run in parallel — one immediate and mechanical, one gradual and biological.
Mechanical, from placement. Barbed (cog) polydioxanone threads carry angled projections that anchor in tissue, allowing repositioning along the direction of pull. Smooth mono and screw constructions have no barbs and do not reposition tissue — they act through the second process only. This distinction is a function of the thread's architecture, not its material.
Biological, over months. As the polymer hydrolyzes, the process is associated with new collagen formation around the thread. This is documented in clinical studies (Suh DH et al., 2015; Kim H et al., 2016, cited by APAX Medical), and is why improvement continues after placement and typically peaks at 3–6 months.
The stocking consequence: a smooth polydioxanone thread and a barbed polydioxanone thread are not interchangeable. Same material, different mechanism, different clinical purpose. A mono thread does not produce a lift regardless of gauge or quantity.
Because the collagen response outlasts the material, the result persists after absorption is complete — which is why absorption time and result duration are two separate figures (Q3 and Q4).
Design-by-design detail: Thread Types & Specifications FAQ.
Part 2 — Timing
Q3. How long do PDO threads take to dissolve?
Reported absorption for polydioxanone lifting threads is approximately 4–9 months . Published figures vary between product lines, and the binding figure for any given product is on its own IFU and certificate.
Four variables move the actual timing within any line:
- Thread diameter — a thicker filament takes longer to hydrolyze
- Design — surface architecture affects exposed area
- Placement — depth and tissue environment
- Individual physiology — metabolic variation between patients
Two practical notes for clinic staff:
Where a manufacturer's documents give different figures, the IFU governs — not the catalog, not the website, not the sales sheet. This applies to any supplier including ourselves; if you find a discrepancy in our published material, the IFU shipped with the product is authoritative and we would appreciate the report.
Absorption is not a guaranteed endpoint by a fixed date. One published case documents a thread too thick to absorb, requiring removal (PMC7507174). See Q5.
Absorption time is not result duration — see Q4.
Q4. How long do PDO thread lift results last?
Our Auro line documentation reports results of approximately 2 years. Independent professional education sources report a general range of 12–18 months for polydioxanone lifting threads (GLPbase; APAX Medical) — roughly double the absorption time in Q3.
Both figures appear here because they differ. A brand figure records what a manufacturer's own documentation states; an independent range records what professional education sources report across the category. For planning purposes the independent range is the conservative basis; for any specific order, the IFU governs.
Why the result outlasts the thread. The mechanical lift ends as the material degrades, but the collagen response it triggered persists. A thread absorbing within months can therefore be associated with a result measured in years.
Two timelines, two mechanisms — do not quote the absorption figure when a patient asks how long the result lasts.
| Stage | What happens |
|---|---|
| Immediately | Mechanical lift visible; swelling may exaggerate it |
| 3–6 months | Collagen-driven improvement typically peaks |
| 6–9 months | Material absorption completes |
| 12–18 months | Independent reported duration of the overall result |
| Up to ~2 years | Auro line reported duration (⚠ confirm against IFU) |
Duration also depends on thread type and count, placement technique, skin quality, age and lifestyle. The 2025 meta-analysis identifies operator technique as the main determinant of complication rates; longevity likewise varies case by case.
Full longevity data and maintenance scheduling: Results & Longevity FAQ.
Q5. Do PDO threads dissolve completely?
The accurate statement: absorbable thread materials are assessed for biological safety, including degradation products, under the ISO 10993 series. Passing biological evaluation supports a safety assessment for the stated intended use.
What that does and does not establish:
- It supports a safety assessment of the material and its degradation products for the intended use
- It does not establish complete clearance across every gauge, batch and individual patient
The documented exception is relevant to product selection: one published case reports a thread too thick to absorb, requiring removal (PMC7507174). Thread diameter is a variable in absorption behaviour, not an incidental specification.
A separate point often confused with residue: the tissue response persists after the material is gone. Documented longer-term findings include fibrosis or tethering that may complicate a future surgical facelift, and rare granulomatous reactions (HMP Global; RealSelf Q&A). This is a tissue effect rather than undissolved material — but it is why patients should disclose thread history to any future surgeon.
For patient-facing copy, "the thread absorbs over months" is supportable; statements that nothing remains go beyond what the evidence establishes.
Part 3 — Material properties and selection
Q6. Is polydioxanone biocompatible, and can it cause a reaction?
Polydioxanone thread materials undergo biological evaluation including sensitization testing under the ISO 10993 series, conducted within a risk-management framework. Passing that evaluation supports a safety assessment for the stated intended use.
What this does not mean: any medical device can trigger an individual allergic or immune response. Biological evaluation supports a risk assessment; it does not exclude individual reactions, and it is not a guarantee across every gauge, batch or patient. No absorbable material can be described as incapable of causing a reaction.
Q7. Which thread designs are available in polydioxanone?
Polydioxanone carries the widest design and dimension range of the three thread materials — smooth mono, screw, cog, tornado and multi-strand constructions, in both sharp-needle and blunt-cannula delivery formats, across gauges from 18G to 30G.
This breadth is the practical reason polydioxanone anchors most clinic menus: a single material covers both skin-quality work (smooth constructions) and repositioning work (barbed constructions), across facial and body applications.
Design definitions, USP designations and the full gauge–length lookup: Thread Types & Specifications FAQ · Thread Specifications Guide.
Product range: Shop PDO threads.
Sources for this FAQ
Absorption and duration figures cited as ⚠ are drawn from our own Auro. They describe our published product positioning and do not replace the IFU, label or certificate supplied with a specific SKU. Where an independent range is given, the source is a professional education publication rather than a manufacturer.
- 21 CFR 878.4840 — Absorbable polydioxanone surgical suture — Class II classification with special controls.
- ISO 10993-1 — biological evaluation of medical devices.
- PMC7507174 — published complication cases including a non-absorbing thread requiring removal.
- APAX Medical — Facelift Thread Lifting — collagen-response literature (Suh 2015; Kim 2016) and duration context.
- GLPbase — PDO Threads Guide — professional education on materials, duration and regulatory status.
- medRxiv 2025 meta-analysis — 26 studies, 2,827 patients; operator technique as the main determinant of complication rates.
- HMP Global — PDO thread complications — longer-term findings including granulomatous reactions.