The process of facial aging results from a combination of skeletal and non-skeletal soft-tissue changes. This leads to specific alterations of the superficial and deep fat framework and skin layers. As the breakdown of collagen and elastic fibers takes place, noticeable weakening occurs in prominent facial regions. Cheeks, mandibular line, neck, and dermatochalasis of facial and neck soft tissue accounts for the distinctive signs of the process of facial aging.
The use of sub-dermal suspension with threads has gradually increased among many practitioners. Also attracted significant interest, given that it allows for the lifting of sagging tissue using a minimally invasive, closed procedure.
The shape, thickness, and composite materials of threads may differ. This depends on the preference of the practitioner and the needs of the patient.
It is generally stated that the placement of subcutaneous threads generates a non-specific local immune response to the implanted foreign material, which is known as a ‘foreign body reaction’ that lasts several months after the procedure and involves various cell types: the formation of a dense connective tissue capsule around the implanted material, chronic granulomatous inflammation, and fibrosis with neovascularization.
This fibrotic response to implanted material likely plays an important buttress role in the ability of barbed suspension threads to lift facial tissues and maintain their elevated position in the long term.
This fibrotic tissue and capsule formation ensures that the lifted tissues remain in place even after the thread has degraded. Therefore, it is possible to claim that the thread lifting effect is achieved and fortified by the cutaneous fibrotic reaction that appears along the thread itself. And that remains steady even when the thread has been completely absorbed.
More precisely, once the threads are inserted into the skin, the formation of new collagen fibers and elastic fibers ensues. This results in increased collagen and elastin volume.
Also, cells produce more hyaluronic acid in response to the threads with a concomitant increase in water retention. Collectively, this process results in visibly youthful skin. The most commonly used threads are composed of bioresorbable materials such as poly-L-lactic acid (PLLA), polycaprolactone (PCA), or poly-dioxanone (PDO).
Although the scientific literature contains numerous reports on the biocompatibility and host response to these compounds in both animals and humans, a systematic and comprehensive comparison of PLLA, PCA, and PDO in terms of collagen and elastic fibers formation in these thread types is lacking.