Polymethyl Methacrylate (PMMA) is a synthetic compound used in dermal fillers designed for long-term volume restoration. Unlike temporary fillers, PMMA is classified as a non-resorbable material, meaning the body cannot naturally break it down and absorb it over time. This non-biodegradable nature provides enduring cosmetic results for issues like deep folds and acne scars. The primary question surrounding PMMA injections is whether their effects are truly permanent and what implications that permanence carries for both the cosmetic outcome and the potential for long-term consequences.
How PMMA Works to Create Volume
PMMA fillers are composed of tiny, smooth microspheres of Polymethyl Methacrylate suspended in a carrier solution, often bovine collagen or a hyaluronic acid-based gel. When injected beneath the skin, the carrier gel provides an immediate mechanical filling effect, offering instant volume correction. This initial volume is temporary, as the carrier material is absorbed and metabolized by the body over one to four months.
The long-term effect comes from the PMMA microspheres, which are not absorbed. These microspheres act as a scaffold, triggering a biological response known as neocollagenesis. The body responds by depositing new connective tissue, primarily native collagen, around each sphere.
This encapsulation process secures the microspheres in place, preventing migration, while the newly formed collagen provides sustained volume. Over several months, the body replaces the temporary carrier gel with its own tissue, creating a structural foundation. The microspheres, typically 30 to 50 microns, are intentionally sized to prevent immune cells from fully engulfing them, ensuring they remain indefinitely.
The Reality of Permanent Dermal Fillers
PMMA injections are considered permanent because the polymer microspheres are structurally stable and remain integrated within the tissue indefinitely. The body cannot degrade this synthetic material, making the physical component of the filler non-reversible. This sets PMMA apart from temporary fillers, such as hyaluronic acid, which the body naturally breaks down within six to eighteen months.
The results of PMMA are often cited as lasting five years or more, sometimes enduring for ten years or longer. While the PMMA material is permanent, the visible cosmetic outcome changes due to the natural aging of surrounding tissue. The material does not stop volume loss in untreated areas, which may necessitate maintenance injections over time to sustain the aesthetic result.
For FDA-approved PMMA products, treatment is typically delivered in a series of two or more injection sessions to achieve the desired correction. This staged approach allows the practitioner to precisely layer the material and monitor the body’s collagen induction response. The classification of PMMA as a permanent structural implant emphasizes the need for precise injection technique and careful patient selection.
Understanding Permanent Adverse Reactions
Because the PMMA microspheres are permanent, any adverse reactions they cause are also long-lasting and difficult to resolve. One significant long-term complication is the formation of foreign body granulomas. These are hard, inflammatory nodules that can develop months or years after injection, resulting from an over-aggressive immune response as the body tries to wall off the foreign material.
Other adverse reactions include chronic swelling, palpable lumps, and persistent redness or inflammation. The filler material can also migrate from the injection site, leading to local asymmetries and deformities. These delayed inflammatory reactions can sometimes be triggered by infection, severe illness, or vaccination, making their appearance unpredictable.
The incidence of granuloma formation has been estimated to be around 1.9% in some studies. Since the PMMA microspheres integrate with native connective tissue, the complication is not easily separated from healthy surrounding tissue. This difficulty of correction underscores the gravity of choosing a permanent filler.
Addressing and Removing Permanent Fillers
Managing complications from permanent PMMA fillers is complex and significantly more challenging than addressing issues with temporary fillers, which can often be dissolved. For non-severe complications like small nodules or mild inflammation, non-surgical management is attempted first. This typically involves intralesional injections of corticosteroids, sometimes combined with other agents, to shrink the inflammatory tissue surrounding the microspheres.
Non-surgical protocols are not always successful, especially for large or deep-seated granulomas. When complications are severe, such as significant disfigurement or persistent inflammation, surgical excision becomes the only definitive option for removal. Surgical removal is complicated because PMMA is intimately integrated with the body’s own collagen, requiring the surgeon to cut out the affected tissue, which can lead to scarring and contour irregularities.
The procedure for surgical removal often involves techniques similar to a facelift, with strategic incisions to access the altered tissue. Since PMMA cannot be dissolved, the goal of surgical intervention is to remove as much of the foreign material and associated reactive tissue as possible. This highlights the fundamental limitation: intervention involves managing the permanent presence rather than eliminating it.