This document discusses synthetic fillers used for facial rejuvenation. It begins by providing statistics on the popularity and growth of soft tissue filler procedures. It then discusses several synthetic fillers - calcium hydroxyapatite (CaHA), poly-L-lactic acid (PLLA), polymethyl methacrylate (PMMA), and silicone. Specifically, it outlines the composition, FDA approval history, injection techniques, and benefits of CaHA and PLLA, which provide long-lasting volume replacement through biostimulation of collagen production. Complications are rare but can include nodules, which can be treated through massage or injection of other substances.

1. Synthetic Fillers for Facial
Rejuvenation
Johnson C. Lee, MDa,
*, Z. Paul Lorenc, MDb
INTRODUCTION
According to the American Society of Plastic Sur-
geons’ 2014 Plastic Surgery Statistics Report, soft
tissue filler procedures were the second most
common minimally invasive procedures with 2.3
million procedures performed.1
This number rep-
resents a 3% increase from the previous year.
Since the start of the century, soft tissue filler pro-
cedures have increased 253%, whereas cosmetic
surgical procedures overall have decreased 12%.
With the boom in the soft tissue filler industry,
patients and physicians in the United States are
encountering an increasing number of available
products to choose from (Box 1). Soft tissue filler
materials can be naturally (animal) sourced or syn-
thetically produced. Mechanisms of action include
volume replacement and biostimulation of autolo-
gous collagen production by native fibroblasts.
Volume replacement occurs primarily through the
use of hyaluronic acids, in which the hydrophilic
biomaterial acts as a spacer within the tissue
planes. Synthetic fillers such as calcium hydroxy-
apatite (CaHA), polymethyl methacrylate (PMMA),
and poly-L-lactic acid (PLLA), and silicone provide
initial volume replacement but have an additional
biostimulatory effect to supplement volumization.
This article specifically addresses synthetic fillers
in the management of facial aging.
CALCIUM HYDROXYAPATITE
CaHA was first approved as an injectable implant by
the US Food and Drug Administration (FDA) as a soft
tissue radiographic marker in 2001 before quickly
expanding its indications to include vocal fold
augmentation, repair of oromaxillofacial defects,
andsofttissueaugmentationforstressurinaryincon-
tinence. In 2006, the FDA approved Radiesse (Merz
Aesthetics, Raleigh, NC) as a CaHAfiller foraugmen-
tation of moderate to severe nasolabial folds (NLFs)
and human immunodeficiency virus (HIV)–associ-
ated facial lipoatrophy. Most recently, in 2015, Rad-
iesse was approved for hand rejuvenation.2
Radiesse is considered a semipermanent filler
composed of nonimmunogenic synthetic bone
(CaHA) with microspheres 25 to 45 mm in diameter
within a 70% carboxymethylcellulose carrier gel.
Disclosures: None of the authors have any direct financial or corporate interest in the subject matter or mate-
rials discussed in this article.
a
Private Practice, Enhance Medical Center, 462 North Linden Drive, Suite 333, Beverly Hills, CA 90212, USA;
b
Lorenc Aesthetic Plastic Surgery Center, 983 Park Avenue, New York, NY 10028, USA
* Corresponding author.
E-mail address: JCLMD@enhancemedicalcenter.com
KEYWORDS
Fillers Injectables Synthetic PLLA CaHA PMMA Silicone
KEY POINTS
Calcium hydroxyapatite is a versatile semipermanent filler with a high elastic modulus for composite
lifting.
Poly-L-lactic acid can continue to induce local collagen formation for several months to years after
injection for significant long-term results.
Polymethyl methacrylate is effective for distensible atrophic acne scars.
Silicone oil is a permanent filler with vitreoretinal indications, but is considered off-label use for
facial injections, with potential serious complications.
Synthetic fillers can provide long-lasting results through biostimulation of neocollagenesis.
Clin Plastic Surg 43 (2016) 497–503
http://dx.doi.org/10.1016/j.cps.2016.03.002
0094-1298/16/$ – see front matter Ó 2016 Elsevier Inc. All rights reserved.
plasticsurgery.theclinics.com

2. Within several weeks after injection, the carrier gel
is absorbed and net neutral volume replacement
occurs through neocollagenesis. Because an im-
mune response is not elicited, no skin testing is
needed. The CaHA degrades into calcium and
phosphate ions over time and is excreted slowly
from the body, creating lasting volume for an
average of 12 to 18 months.3
Radiesse has a particularly high elastic modulus
(G’). G’ is the measure of the gel’s ability to resist
deformation when pressure is applied. The higher
the G’ of a substance, the greater its stiffness, and
the less likely the substance is to deform under
pressure from its surroundings. In a study by Sun-
daram and colleagues,4
the G’ of Radiesse was
measured to be 1407 Pa compared with a range
of 28 to 863 Pa in hyaluronic acid products. This
property results in a greater amount of lift when
injected under the skin envelope.
Because of its unique chemical composition,
safety profile, and lifting properties, Radiesse has
become an increasingly popular filler option. Its
versatility extends to treatable facial zones, depth
of injection, and delivery method. Radiesse has
been used in marionette lines, the prejowl sulcus,
oral commissures, and the posterior mandible.5–7
There are also reports of positive clinical results
from injections in the temple and malar/submalar
areas, which are considered off-label uses.8–11
Although early instructions for the use of CaHA
were limited to the mid-dermis to target rhytids,
practitioners have steadily expanded injection
depths to the deep dermis and down to the
supraperiosteal to structurally lift and contour the
face12,13
(Fig. 1). This composite lift can be visual-
ized under high-resolution ultrasonography, with
which CaHA appears as hyperechoic deposits
with variable degrees of posterior acoustic shad-
owing (Fig. 2).
CaHA can be further modified by combining lido-
caine in a mixing process rather than using the
established protocol of preanesthetization of the
treatment site before injection.14
The senior author
(ZPL) recommends a 3-tiered dilution approach
depending on associated areas of treatment and
depth of injection (Table 1). The amount of lidocaine
varies according to facial zones, whereas the vol-
ume of CaHA remains steady to facilitate ease of
preparation and for consistent clinical results.
Rare complications of CaHA injections include
palpable nodules and vascular occlusion. Although
there is no reversal agent or enzyme for CaHA,
small nodules can be broken up with digital mas-
sage. Larger nodules can be treated with an injec-
tion of 5-fluorouracil and lidocaine 1:1 to reduce
fibroblastic activity in these sites while breaking
up the nodule. This technique is preferred to steroid
injection because of potential chronic atrophic
effects on overlying skin. For the exceedingly rare
instances of vascular occlusion, the same proto-
cols are advised as with other filler agents,
including the use of hyaluronidase.2
POLY-L-LACTIC ACID
PLLA has been in clinical use for more than 20
years as a major component of some absorbable
sutures, such as Vicryl (Ethicon Inc, Somerville,
NJ) and in surgical screws, pins, and staples
used in maxillofacial and orthopedic procedures.
It was FDA approved as an injectable implant in
2004 under the name of Sculptra (Galderma, Fort
Worth, TX) for restoration or correction of the signs
of facial fat loss in patients with HIV with facial
lipoatrophy.15
More recently, in 2009, Sculptra
Aesthetic was approved for immunocompetent
Box 1
Soft tissue fillers
Collagen
Cymetra
Fascian
Polymethyl methacrylate
Bellafill
Hyaluronic acid
Restylane-L
Restylane Lyft
Restylane Silk
Belotero
Juvederm Ultra XC/Plus XC
VOLUMA XC
Prevelle Silk
Calcium hydroxyapatite
Radiesse
Radiesse1
Poly-L-lactic acid
Sculptra
Silicone
Silikon 1000
Sil-Ol 5000
Autologous cell therapy
Platelet-rich plasma
LaViv
Lee Lorenc498

3. patients for treating shallow to deep NLFs and
other rhytids.
Sculptra is composed of 150 mg of PLLA
microparticles ranging from 40 to 63 mm and sus-
pended in sodium, carboxymethylcellulose, and
nonpyrogenic mannitol.16
PLLA is a nontoxic and
resorbable polymer (approximately 40–50 kDa)
from the alpha-hydroxy acid family, and must be
reconstitutedwith3 to 5 mLofsterile water for injec-
tion at least 2 hours before use and may be stored
Fig. 1. (A) A 60-year-old woman before Radiesse injection. (B) Two weeks after Radiesse injection into the tem-
poral, malar, and piriform areas.
Fig. 2. High-resolution ultrasonography at 12 mHz reveals distinct soft tissue layers within the temporal fossa.
Injection of Radiesse at the supraperiosteal level is clearly visualized with composite lifting of overlying soft tis-
sue. Black, dermis; red, temporalis muscle; white, Radiesse; yellow, subcutaneous layer (left and right images are
not shown to equal scale). RT, right.
Synthetic Fillers 499

4. for up to 72 hours. Similar to CaHA, PLLA provides
immediate volumization on injection but this effect
initially fades as the carrier solution is reabsorbed.17
There is a gradual increase in dermal thickness as a
foreign body response is induced and local fibro-
blasts encapsulate the microparticles. The PLLA
is then slowly converted into lactic acid monomers
that are metabolized into carbon dioxide or incor-
porated into glucose.18
As the initial inflammatory
response wanes over 6 months, type 1 collagen
deposition continues to occur for up to 2 years
and results can last for several years19
(Fig. 3).
Standard volumization protocols require up to 4
sessions scheduled 4 to 6 weeks apart with a deep
dermal grid pattern (cross-hatch) injection, subcu-
taneous injection, or supraperiosteal placement of
the agent. Individualization of treatment is based
on the size of the area and the depth of correction
involved. Although label instructions describe the
use of needles for injections, blunt cannulas can
beusedtominimizetissuetrauma.Becausemultiple
treatments are required to achieve desirable out-
comes, in order to avoid possible nodule formation
it is critical to ensure that PLLA is well hydrated
before the injection and is diluted to the appropriate
extent.20
Patients must be informed that end point
volumization is not immediate and will occur gradu-
ally over time. Some cliniciansadvocate 24 hours for
reconstitution in an effort to ensure adequate hydra-
tion and even distribution.21–23
Other investigators
recommend reconstitutions of up to 10 mL of vol-
ume and waiting 4 to 8 weeks between injections;
these techniques have shown significantly
decreased papule/nodule formation.24–27
In order
to minimize complications, the senior author recom-
mends adjusting both hydration time and dilution
volumes according to facial zones similar to CaHA
preparation28
(Table 2).
Areas of injection should be gently massaged
during and immediately after injection to evenly
distribute the material and minimize nodule forma-
tion. The patient is further instructed to vigorously
massage the treatment area for 5 minutes, 5 times
per day for 5 days, using an over-the-counter
petrolatum-based ointment. Persistent visible or
palpable nodules may be removed via intralesional
injection of corticosteroids, injection of hyaluronic
acid into the surrounding transition zone, or surgi-
cal excision. Similar to treatment of CaHA nodules,
injection of an antimitotic such as 5-fluorouracil of-
fers a reduced risk of skin atrophy compared with
corticosteroids.28,29
Other adverse events include
ecchymoses, transient soreness, and mild to mod-
erate hematomas typical of injectable dermato-
logic agents.
POLYMETHYL METHACRYLATE
PMMA was first used, and still most commonly
used, as a biocompatible cement in neurosurgery,
orthopedics, and otolaryngology.30
Bellafill
(Suneva Medical, San Diego, CA) is the only FDA-
approved PMMA injectable filler available in
the United States. First approved as Artefill in
2007 as a dermal filler for NLFs, it recently became
approved for acne scarring in 2014 for the treat-
ment of moderate to severe, atrophic, distensible
facial acne scars on the cheeks of patients more
than 21 years of age.
Bellafill is composed of 30-mm to 50-mm smooth,
round PMMA microspheres suspended in a water-
based gel containing 3.5% bovine collagen and
0.3% lidocaine. Eighty percent of the microsphere
is composed of the collagen carrier, which is
absorbed 1 to 3 months after injection. The remain-
ing nonbiodegradable PMMA microspheres act as a
scaffold for neocollagenesis over an estimated
period of 3 months.31
Because of the presence of bovine collagen,
Bellafill requires a hypersensitivity skin injection
test 4 weeks before treatment on the volar fore-
arm. A positive skin test response includes symp-
toms of erythema, induration, and/or swelling
appearing within the first 24 hours and lasting
more than 24 hours after injection, or appearing
at any time more than 24 hours after injection.
An equivocal response is one with only systemic
signs and symptoms of arthralgias or myalgias.
Patients showing a positive skin test or 2 equivocal
skin tests should not be considered candidates
Table 1
Three-tiered dilution of lidocaine
Tier Injected Volumes (mL) Areas Treated Injection Depth
A 0.3 of lidocaine 1%;
1.5 of CaHA
Malar and submalar regions,
temples, piriform aperture
Supraperiosteal
B 0.5 of lidocaine 1%;
1.5 of CaHA
Oral commissures, prejowl
sulcus
Postsubcutaneous-presupraperiosteal
C 1.0 of lidocaine 1%;
1.5 of CaHA
Cheeks, hands Juncture of the dermis and the
subcutaneous layer
Lee Lorenc500

5. for treatment. Patients showing an anti–bovine
collagen serum immunoglobulin G level outside
the normal range at baseline should not be consid-
ered candidates for treatment.32
Patients best treated by Bellafill are those
with atrophic distensible acne scarring. Similar to
Sculptra, Bellafill continues to induce long-term
collagen formation and is best used in broad-
based scars. Therefore, conservative treatment
spaced across 4-week intervals as necessary
should be planned to avoid overcorrection. The
final correction of any defect should be at or below
the level of normal surrounding skin.33
Bellafill is
intended for injection into the deep dermis. When
treating scars, using the included 26-gauge needle
facilitates ease of use, in contrast with the blunt
cannulas used with other fillers. When scar fibrosis
is encountered, fanning the needle tip across the
scar bed several times, in a subcision fashion, cre-
ates sufficient space for filler to be injected.
Fig. 3. (A) A 51-year-old woman before Sculptra injection. (B) Thirteen-month follow-up after 2 Sculptra injection
sessions treating the temporal, submalar, and midface zones. Each session required 2 vials at 9 mL dilution.
Table 2
Reconstitution and injection technique for injectable PLLA based on anatomic areas
Area Reconstitution Volume (mL) Injection Technique
Malar
Pyriform
Mandibular angle
Prejowl sulcus
Temple
9–10 16-mm (5/8-inch), 25-gauge needle/cannula
Supraperiosteal injection
Posttreatment massage recommended for
5 min, 5 times/d, for 5 d after injection session
Lower cheek 9–10 38-mm (1.5-inch), 25-gauge needle/cannula
Subcutaneous injection
Posttreatment massage recommended for
5 min, 5 times/d, for 5 d after injection session
Synthetic Fillers 501

6. Although considered a semipermanent filler,
Bellafill has been shown to be very safe. The Bellafill
US Acne Scar pivotal study was a prospective, ran-
domized, placebo-controlled, multicenter, double-
blinded clinical trial of 147 subjects older than 18
years who desired correction of moderate to se-
vere, atrophic, distensible facial acne scarring on
the cheek.34
There were no reports of hypertrophic
scarring or keloid formation, granulomas, infec-
tions, or vascular occlusions. Eight percent of sub-
jects reported mild to moderate effects, including
erythema, swelling, bruising, pain, itching, lumps/
bumps, and skin discoloration related to injection,
which resolved within 7 days. There was an 83%
overall satisfaction rate of the treated subjects,
which is consistent with 87.5% in subjects treated
in the malar region.35
In a separate study by Joseph
and colleagues,36,37
there was a 1.7% granuloma
formation rate among 1000 patients treated with
Bellafill at 5 years.
In situations of overcorrection, persistent nod-
ules, or granuloma formation, treatment may be
difficult because of the permanence of the
PMMA microspheres. Steroid injection to reduce
inflammation or surgical excision is an option.
There are anecdotal reports of off-label use of Xia-
flex (Auxilium Pharmaceuticals Inc, Chesterbrook,
PA), an injectable collagenase used as nonsurgical
treatment of Dupytren contractures. The goal is to
manually break down the fibrotic capsule forma-
tion around the PMMA microspheres, although
the cost may be prohibitive.
SILICONE
Unlike the other synthetic fillers composed of sus-
pended materials, silicone is injected as a highly
purified long-chain polydimethylsiloxane trimethyl-
siloxy terminated silicone oil. In the United States,
it is FDA approved for retinal hemorrhage or retinal
detachment surgery in vitreoretinal surgery (Adato
Sil-Ol 5000, Bausch Lomb, Rochester, NY; and
Silikon 1000, Alcon, Fort Worth, TX). It is also avail-
able in Latin American countries from different
manufacturers, although there are multiple reports
of complications resulting in inconsistent formula-
tion and impurities in the products. Facial injection
techniques reported in the 1980s consist of micro-
droplet application with a 30-gauge needle at the
dermal-subcutaneous junction.38,39
Silicone oil
causes a local inflammatory response to stimulate
a fibrotic reaction and capsule formation. If used
off-label for facial injection, significant adverse re-
actions include infection, dyschromias, migration,
extrusion, ulceration, granuloma formation, and
vascular occlusion, which may occur years after
injection and rarely resolve. Silicone is considered
permanent and difficult to treat; surgical excision is
often required for removal.39
SUMMARY
Proper choice of a synthetic biostimulatory agent
can provide a versatile, customizable agent for
enhancement of all anatomic areas. The mode of
action is that of stimulating neocollagenesis using
the patient’s own fibroblasts to replenish lost vol-
ume secondary to the aging process. Because of
the agents’ semipermanent and permanent nature,
careful consideration must be given to hydration,
dilution, injection method, and postprocedural
care to avoid postinjection complications.
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