Consensus Recommendations for the Reconstitution and Aesthetic Use of Poly-D,L-Lactic Acid Microspheres – Comment on the Facial Injection Techniques [Letter]

Dear editor

We read with great interest the article entitled “Consensus Recommendations for the Reconstitution and Aesthetic Use of Poly-D,L-Lactic Acid Microspheres”, by Magacho-Vieira et al, published in a recent issue of Clinical, Cosmetic and Investigational Dermatology.¹ The article provides valuable recommendations on the reconstitution and injection techniques of injectable poly-D,L-lactic acid (PDLLA; AestheFill, REGEN) for both facial and non-facial treatments. In this context, we would like to offer differing perspectives and further elaborate on the facial injection techniques for injectable PDLLA.

The reconstitution volume of sterile water for injection (SWFI) for a vial of injectable PDLLA can vary widely, accommodating diverse applications. The suspension can be categorized into four groups based on thickness: D1.5–3, the thickest suspension for bony projections; D3-6, a thick suspension for deep wrinkles; D6-12, a thin suspension for shallow wrinkles; and D12-24, a super-thin suspension for skin texture improvement. Consequently, injectable PDLLA is regarded as a versatile filler.^2,3 However, many practitioners find it challenging to determine the appropriate concentration or thickness for individual patients. Furthermore, injecting thicker suspensions superficially increases the likelihood of uneven distribution due to their higher elastic modulus, greater cohesivity, and lower lateral spreading ability.

We concur with the consensus recommendations in advocating for the use of D9-10 suspension in facial areas via wide-range, superficial injections. For moderate to severe wrinkles or depressions, treatments can be repeated at intervals exceeding one month until the desired outcome is achieved. However, for deep injections, we recommend using the thickest suspension instead of the D9-10 suspension suggested in the recommendations.⁴ As noted, the thickest suspension, with its highest elastic modulus, is ideally suited for bony projections.^2,3 Using suspensions other than the thickest for this purpose may yield suboptimal results.

When injecting the thickest suspensions, the primary technique involves bolus injections using sharp needles targeting the supra-periosteum layer. To minimize the risk of palpable nodule formation, the injection volume per point should be carefully controlled.⁵ While 0.2 mL can serve as a general reference, adjustments should be made based on the thickness of the overlying soft tissue. For instance, larger volumes may be appropriate in the temple region, whereas smaller amounts should be employed in the zygomatic arch region.

In 2024, based on 10 years of injection experience, we developed the “AestheCode system” as a guide for injectable PDLLA procedures in different facial regions.⁴ (Figure 1 and Table 1) This guide comprises two components: AestheZone, which focuses on thin suspensions for superficial injections, and AestheLift, which addresses the use of the thickest suspensions for deep injections. The AestheCode system provides recommendations not only on filler thickness and injection layer but also on the injection method, tools, and dosage. Presented in workshops and online forums worldwide in recent years, the system has demonstrated both safety and efficacy.

Table 1 The AestheCode System: Injection Guidance for Anatomical Sites Using AestheFill. (From Lin J-Y, Lin C-Y. The AestheCode System: A Safe and Efficient Guide for AestheFill Injection. Aesth Plast Surg (2024). https://doi.org/10.1007/s00266-024-04250-4; With Permission)

Figure 1 The facial surface maps of the AestheCode system: AestheLift(left) and AestheZone(right). (From Lin J-Y, Lin C-Y. The AestheCode System: A Safe and Efficient Guide for AestheFill Injection. Aesth Plast Surg (2024). https://doi.org/10.1007/s00266-024-04250-4; with permission).

The injection techniques for PDLLA can vary. Ensuring both safety and efficacy is paramount during its administration. Utilizing AestheCode guidance can help clinicians minimize complications while enhancing efficacy.