Adverse reactions to injectable soft tissue permanent fillers

Area of Science:

• Dermatology
• Biomaterials Science
• Plastic Surgery

Background:

• Synthetic injectable facial fillers, while generally safe, can elicit host responses.
• These fillers act as foreign bodies, potentially leading to inflammatory nodules years after injection.
• The reasons for delayed inflammatory reactions vary among different filler compositions.

Purpose of the Study:

• To investigate the causes of late inflammatory nodules following the injection of permanent facial fillers.
• To compare the host response to different types of injectable fillers.
• To understand why some fillers lead to delayed adverse reactions while others do not.

Main Methods:

• Analysis of 5 biopsies from unreactive tissue after polyacrylamide hydrogel (Aquamid) injection.
• Examination of 28 biopsies from inflammatory nodules after injections of polyacrylamide hydrogel (Aquamid), hyaluronic acid-based gel (Dermalive), and polylactic acid-based gel (New-Fill).
• Comprehensive review of existing literature on adverse reactions to permanent fillers.

Main Results:

• Unreactive tissues showed minimal host response to Aquamid.
• Inflammatory nodules exhibited foreign body reactions and bacterial infections, particularly with Aquamid, Dermalive, and New-Fill.
• Literature indicates inflammatory nodules can appear from 1 year (polyacrylamide hydrogel) to 28 years (silicone gel) post-injection.

Conclusions:

• Low-grade infections within biofilms are the likely cause of inflammatory nodules with hydrophobic fillers like silicone and combination gels.
• Polyacrylamide hydrogel (Aquamid) may inhibit biofilm formation due to its high water-binding capacity.
• This property of Aquamid likely explains the absence of late inflammatory nodules observed with this specific filler.