Synthetic fillers: pros and cons

Synthetic fillers and soft tissue implants are non-biological materials that are injected or surgically inserted to increase soft tissue volume and correct folds, scars, and contour defects. Unlike biodegradable fillers based on hyaluronic acid or lactic acid, synthetic materials either do not degrade at all or have an extremely long lifespan.

The basic idea behind their use was simple and very attractive: place or inject the material once and achieve a nearly lifelong effect without regular repeat procedures. Liquid silicone, polymethyl methacrylate microspheres, two-phase silicone composites, porous polytetrafluoroethylene, and other alloplastic materials were used. However, experience has shown that longevity comes with increased long-term risks, including late inflammatory reactions and difficult-to-treat defects.

Today, aesthetic medicine is shifting its focus toward temporary, biodegradable fillers, primarily hyaluronic acid. Current recommendations emphasize that the ability to control the outcome, dissolve the filler in case of complications, and not leave foreign material for decades is often more important than a "lifelong" effect. Permanent synthetic fillers are increasingly viewed as the exception rather than the standard. [1]

However, synthetic implants have not completely disappeared. Porous polytetrafluoroethylene continues to be used in reconstructive and aesthetic surgery for soft tissue and framework correction. Polymethyl methacrylate microspheres, in the form of certain registered products, are used for the correction of nasolabial folds and post-acne scars, albeit with caution. The choice of such materials requires careful patient selection and an honest discussion about irreversibility.

The key message for patients: synthetic fillers are rarely an "easy and safe way to permanently make a face beautiful." They are a serious intervention with potential consequences years and decades later. Therefore, the same rule applies to oncology and cardiac surgery: first weigh all the alternatives, assess the potential for complications, and only then choose a permanent material. [2]

Table 1. Synthetic fillers and implants in aesthetics

Material type	Examples	General idea
Liquid injections	Liquid silicone	Constant increase in volume
Microspherical	Polymethyl methacrylate fillers	Long-term volume and support
Two-phase silicone composites	Bioplastique and its analogues	Constant volume with fibrosis
Solid alloplastic implants	Porous polytetrafluoroethylene	Frame and soft tissue correction
Biodegradable (for comparison)	Hyaluronic acid, polylactic acid	Temporary, controlled effect

Liquid silicone

Liquid medical silicone has historically been widely used for injections into soft tissues of the face and body. It is a clear, chemically inert liquid made from dimethylsiloxane polymers. The first medical forms were developed in the mid-twentieth century and were seen as a promising permanent material for filling defects, including the lips, cheeks, nose, and other areas.

The mechanism for increasing volume with silicone injection is related not so much to the gel itself as to the tissue reaction. Microdroplets of silicone are injected directly into the dermis and subcutaneous fat. Each drop is surrounded by a fibrous capsule, around which fibroblasts are activated and dense connective tissue gradually forms. Ultimately, the volume is created by a combination of silicone and the fibrosis it causes, and the effect is considered lifelong.

While this solution seems theoretically appealing, in practice it causes a wide range of long-term complications. Numerous cases of chronic inflammation, indurations, uncomfortable nodules, skin discoloration, material migration, the formation of silicone granulomas, and even delayed systemic reactions have been described. Importantly, such problems can arise 5-10 years or more after the injection, sometimes due to trauma, infection, or immune activation.

An additional hazard is created by the use of uncertified or counterfeit silicone materials, which may contain impurities, oils, and organic solvents. The literature describes many severe cases associated with "street" silicone rather than medical grade products. However, the fundamental problem lies elsewhere: even pure silicone remains a foreign body that cannot be completely removed without damaging the tissue.

Today, liquid silicone is approved for limited ophthalmological and orthopedic indications, but is not approved as a dermal filler for lip augmentation or wrinkle correction. Regulators and professional societies explicitly warn of the risks of irreversibility and severe complications, and many experts consider liquid silicone injections for cosmetic purposes an outdated and potentially dangerous practice.

Table 2. Liquid silicone: pros and cons

Parameter	Potential advantage	Main problems
Duration of effect	Lifetime volume	Inability to safely roll back the effect
Mechanism of action	Fibrosis around microdroplets	Chronic inflammation, granulomas
Cost and availability	Relatively inexpensive material	Risk of uncertified products
Correction of defects	Possibility of filling large volumes	Irregular contour, material migration
Regulatory status	Limited medical use	No approval for cosmetic tissue augmentation

Polymethyl methacrylate microspheres: long-lasting effect and late granulomas

Polymethyl methacrylate (PMMA) is used as microspheres suspended in a collagen or other gel carrier. The particle diameter is selected to be large enough to avoid phagocytosis but small enough for intradermal or subcutaneous administration. After injection, the gel phase is gradually resorbed and replaced by newly synthesized collagen, which, together with the microspheres, creates a long-lasting scaffold.

The first generation of PMMA fillers (Artecoll and similar) was used to correct wrinkles, nasolabial folds, drooping corners of the mouth, and for lip augmentation. The material was marketed as long-lasting and biocompatible. The main early reactions were similar to those of temporary fillers: swelling, redness, and mild soreness. However, experience has shown that in cases of displacement, infection, or severe inflammatory reaction, surgical treatment, including tissue excision, is required.

Modern PMMA products (such as the PMMA collagen matrix filler, registered in the US) demonstrate a more favorable safety profile when used correctly and with appropriate technique. Long-term studies show high patient satisfaction and a low incidence of confirmed granulomas when used correctly for the correction of nasolabial folds and post-acne scars. However, even with a low complication rate, it is important to remember that this is a permanent material that will remain in the tissue for years. [3]

A particular problem with PMMA is the potential for late granulomatous reactions. Cases of giant granulomas and chronic inflammatory processes have been described, appearing 5-10 years after injection, sometimes following systemic infection, trauma, or other immune activation. Treatment for such conditions is long-term and complex, involving corticosteroids and immunomodulation. Hyaluronidase is ineffective, and surgical removal is often technically challenging. [4]

Therefore, many modern guidelines recommend extreme caution when using PMMA in mobile areas such as the lips, and avoiding multiple "layering" of other materials over permanent fillers. Consensus documents on hyaluronic acid explicitly state that the injection of temporary fillers over hard-to-break fillers is undesirable, as it complicates the diagnosis and treatment of potential complications. [5]

Table 3. Polymethyl methacrylate fillers: where are the strengths and weaknesses?

Characteristic	Plus	Minus
Duration of effect	Years, sometimes closer to constant	Difficulty or impossibility of removal
Application areas	Nasolabial folds, post-acne scars	Risk of problems in mobile areas, lips
Early reactions	Similar to temporary fillers	In case of technical errors - knots, unevenness
Late complications	Rare according to statistics	Granulomas and chronic inflammation
Therapeutic possibilities	Partially amenable to drug correction	In severe cases, surgery is required.

Two-phase silicone composites: volume due to a foreign body

Biphasic silicone composites, such as Bioplastique, are a mixture of solid silicone rubber particles and a gel carrier. The particles are typically larger than those of PMMA microspheres, making them inaccessible to macrophage phagocytosis. The gel phase allows for injection and then resorbs, leaving solid particles surrounded by connective tissue.

These materials developed as an attempt to combine the stability of silicone with a "controlled" tissue response. They were used to correct sunken scars, cheek hollows, nasal bridge deformities, and for lip augmentation. A key feature was considered to be the large particle size, which prevented them from migrating through blood vessels or being phagocytosed. However, this very feature leads to a prolonged giant cell reaction and chronic inflammation around the particles.

Histological studies revealed a characteristic pattern: initially acute inflammation, followed by fibrin formation, active fibroblast infiltration, and subsequently the appearance of multinucleated giant cells incapable of phagocytizing a large fragment. These cells can persist for years, maintaining a low-intensity inflammatory process. Clinically, this manifests as dense nodules, tenderness, asymmetry, and persistent deformities.

The key problem is that superficial injection or overcorrection results in excess palpable mass that cannot be "dissolved" or gently redistributed. In severe cases, microliposuction, surgical excision, and complex reconstruction are necessary, but the result may still be far from the original. This has significantly limited the use of such composites in aesthetic practice.

In recent years, interest in two-phase silicone composites has declined significantly. They are not approved by regulators in many countries for widespread aesthetic use, and surgeons prefer more predictable and manageable technologies. Data on long-term safety and outcome remain limited, further urging caution in the use of these materials.

Table 4. Two-phase silicone composites

Parameter	Content
Compound	Large particles of silicone rubber in gel
Volume mechanism	Long-term presence of particles and fibrosis
Main indications	Scars, sunken areas, deformations
Common problems	Dense nodes, chronic inflammation
Current role in aesthetics	Severely limited due to risks

Porous polytetrafluoroethylene: soft tissue implants and their evolution

Porous polytetrafluoroethylene (ePTFE) is a well-known material for vascular prostheses and hernia repair. Due to its biocompatibility and inertness, it has been adapted for aesthetic and reconstructive facial surgery in the form of soft tissue implants used to correct nasolabial folds, soft tissue defects, and lip augmentation. The implants are available in tubes and strips of varying diameters and lengths.

The structure of ePTFE resembles a network of nodes connected by fine fibrils with a defined pore size. These pores allow limited cell and connective tissue ingrowth, ensuring implant fixation and minimizing rejection. Furthermore, the material is virtually non-resorbable, retaining its shape and size, and its microfibrillar architecture makes it relatively flexible and easy to contour.

Despite its excellent biomaterial properties, the use of ePTFE in aesthetics is not without complications. Large case series describe four most common problems: extrusion (implant extrusion), displacement, infection, and persistent swelling. The incidence of complications varies across studies but is considered clinically significant, particularly when using tubular implants in the lips and nasolabial folds.

Implants have evolved toward thinner walls and modified geometry to reduce the risk of tight palpability, shortening, and the "accordion" effect when contracting the lips. Newer designs demonstrate improved tactile properties and a lower incidence of problems, but complications cannot be completely eliminated. On the plus side, the implant can be relatively easily removed, especially if tissue ingrowth is limited.

Today, ePTFE implants are used primarily in the hands of experienced surgeons and more often in reconstructive situations where a stable framework is required. For purely aesthetic lip augmentation, many specialists prefer hyaluronic acid fillers or autologous fat, reserving ePTFE as an option for carefully selected patients who understand that this is a surgical procedure with incisions, sutures, and long-term follow-up. [6]

Table 5. Porous polytetrafluoroethylene in facial aesthetics

Characteristic	Advantage	Limitation
Biocompatibility	Minimal tissue reaction	There is still a foreign body present.
Structure	Tissue ingrowth secures the implant	Shortening and compaction are possible
Reversibility	Relatively easy to remove	Surgery is needed, risk of scarring
Application areas	Nasolabial folds, lips, soft tissue defects	Risk of extrusion, infection and displacement
Current status	A highly specialized tool	Not the default method

Comparison of synthetic implants and temporary fillers

Temporary fillers, primarily those based on hyaluronic acid, are now considered the first choice for most aesthetic rejuvenation and contouring procedures. Their key advantages include biodegradability, the ability to partially or completely dissolve the filler with hyaluronidase, and a well-studied complication profile with existing treatment algorithms. [7]

Synthetic permanent materials promise the elimination of repeat procedures, but the price is the risk of late and difficult-to-predict complications. With liquid silicone, PMMA, two-phase silicone composites, and even ePTFE, problems can arise many years later, when neither the patient nor the doctor remembers the details of the initial procedure. In such cases, a "simple" extraction often turns into a complex reconstructive surgery. [8]

Modern safety reviews emphasize that correction of late complications from temporary fillers is possible in most cases with medication or minimally invasive techniques, whereas with permanent fillers, extensive excision is often necessary, and the aesthetic result is far from ideal. Recommendations also indicate that "layering" hyaluronic acid over existing permanent materials is undesirable, as it complicates the diagnosis of complications and can mask the granulomatous process. [9]

The psychological aspect is also important. The ability to "roll back" the result if the patient doesn't like it after a few weeks reduces anxiety and makes the decision to undergo the procedure less dramatic. With permanent implants, this option is limited or involves extensive interventions, which increases the risk of disappointment and conflict. Therefore, the market and professional standards are trending toward manageable temporary solutions. [10]

Nevertheless, synthetic implants still have a niche: reconstructive surgery, deep defects, and situations where temporary fillers provide too short-lived an effect or require unreasonably large volumes. But when it comes to purely aesthetic lip augmentation or wrinkle smoothing, many experts believe the principle of "temporary fillers first, then, if proven necessary and only after careful analysis, permanent techniques" is justified. [11]

Table 6. Synthetic implants versus temporary fillers

Criterion	Synthetic implants	Temporary hyaluronic acid fillers
Duration of effect	Years or life	On average 6-24 months
Possibility of "rollback"	Limited, requires surgery	There is an enzyme for dissolution
Typical complications	Late nodules, granulomas, extrusion	Swelling, bruising, rare vascular incidents
The complexity of treating problems	Often surgical	Most often medicinal, minimally invasive
Psychological comfort	Less due to irreversibility	More due to the controllability of the result

Indications, contraindications and patient choice

The primary indications for the use of synthetic implants in modern practice are shifting toward reconstructive procedures: correction of post-traumatic and post-oncological defects, and framework restoration when alternatives are either unavailable or produce significantly inferior results. A separate niche is represented by patients with a strong, well-considered desire for long-term correction, who have already completed the temporary filler procedure and understand the risks of permanent materials.

A purely aesthetic desire to "make lips permanent" without prior experience with hyaluronic acid is now considered by many specialists to be a weak indication for synthetic implants. Before discussing permanent materials, it is advisable for the patient to undergo several cycles with temporary fillers to ensure the new lip shape or facial proportions are truly pleasing and do not interfere with daily life. [12]

Absolute contraindications remain severe, uncontrolled systemic diseases, active infections, severe blood clotting disorders, as well as severe mental disorders and pronounced dysmorphophobic attitudes toward appearance. In such situations, the risk of complications and dissatisfaction with the result greatly outweighs the potential benefit. [13]

Relative contraindications include a high likelihood of future cosmetic changes (e.g., in very young patients), unstable hormonal status, and planned major dental or orthognathic procedures. In these situations, the permanent implant may eventually become inadequate for the altered anatomy and require complex correction. [14]

The decision to use a synthetic implant should always be made after comparing it with temporary fillers, lipofilling, and other alternatives. The doctor and patient jointly evaluate whether the potential gain in long-term results justifies the "price" of irreversibility and possible late complications. When in doubt, it is wiser to begin with safer temporary techniques. [15]

Table 7. When to consider synthetic implants and when not to consider them

Situation	Feasibility assessment
Reconstruction after injuries and tumors	It may be justified
Many years of experience with temporary fillers and a desire for a more lasting effect	Allowed after detailed discussion
The primary desire to “make lips permanent” in a young patient	Rather not recommended
Unstable mental state, dysmorphophobia	Contraindicated
Upcoming major dental or jaw surgeries	Requires caution and delay

Prevention and correction of complications

Preventing complications from synthetic fillers begins with choosing the right patient and indication. Experts emphasize that many severe cases are related not only to the material but also to attempts to use permanent fillers for conditions where a temporary filler is sufficient. Choosing certified products and avoiding "home injections" and procedures in unauthorized salons are also important. [16]

The injection or implantation technique is critical. For liquid silicone and microspherical fillers, the concept of very small volumes with multiple sessions has been described; however, even with this technique, the risk of late granulomas remains. For ePTFE implants, precise tunneling, correct depth, and length are crucial to reduce the risk of extrusion and displacement. However, even an ideal technique cannot eliminate the biological response to the permanent material.

When localized nodules, asymmetry, or signs of chronic inflammation appear, the first step is differential diagnosis: infection, late granuloma, mechanical displacement, or reactivation of a latent infection. Imaging, biopsy, and microbiological studies are used. Treatment may include antibiotics, corticosteroids, immunosuppression, and, if necessary, surgery for partial or complete removal of the material. [17]

Particular attention is paid to the prevention and treatment of vascular complications with any filler injections, including synthetic ones. Modern protocols offer action algorithms for suspected vascular occlusion, but with permanent materials, rapid "dissolution" is not possible, and the prognosis is worse than with hyaluronic acid. This is another argument in favor of the rationale for correcting areas with high vascular risk with temporary fillers. [18]

A long-term follow-up strategy is important. A patient with a synthetic implant should understand that if unusual pain, swelling, skin discoloration, new nodules, or asymmetry occur years after the procedure, they should consult a doctor rather than attempting to "re-inject" a temporary filler. Early diagnosis allows for limited intervention and the maintenance of an acceptable aesthetic outcome. [19]

Table 8. Key steps to reduce risks and manage complications

Stage or situation	Recommended actions
Before the procedure	Strict selection of indications, certified product
During the procedure	Neat technique, minimally sufficient volume
Early complications	Evaluation of infection, hematoma, asymmetry, conservative therapy
Late nodules and granulomas	Diagnostics, antibiotics, steroids, surgery if necessary
Unusual vascular symptoms	Urgent assessment according to vascular occlusion protocols

Brief FAQ

Is liquid silicone even worth considering for lip and facial augmentation today?
Current data and the majority of experts strongly recommend against using liquid silicone for aesthetic injections due to its irreversibility and high rate of serious late complications.

Is it true that PMMA fillers are "safe when done by a good doctor"?
Technique and the doctor's experience do reduce the risk, but they don't eliminate the fundamental characteristic of PMMA: the material's permanence and the possibility of late granulomas. This means that even with ideal injections, complications can arise years later.

Is porous polytetrafluoroethylene safer than liquid fillers?
It's well-studied as a biomaterial and is used in vascular surgery, but as a soft tissue facial implant, it also has complications, including extrusion, displacement, infection, and compaction. The advantage is that the implant can be relatively easily removed, but it's still a surgical procedure.

If I want a long-lasting effect, wouldn't it be better to get a permanent implant right away rather than getting fillers every year or two?
It's not just about duration, but also about manageability. Temporary fillers allow for contouring, adapting to age-related facial changes, and addressing potential issues more safely. A permanent material is always a compromise between convenience and the risk of serious long-term complications.

What's a reasonable course of action if you want "long-lasting beautiful lips"?
Most often, it's logical to start with hyaluronic acid, choose the shape and volume, experience the results, and evaluate how comfortable they are in everyday life and in photos. After that, if you have a strong desire and have discussed all the risks, you can consider longer-term solutions, but for most people, proper temporary filler treatments are sufficient.