Which thread to choose? How material and shape make a difference

Thread selection can be organized by considering two factors: material and shape. Commonly used PDO, according to suture data, takes approximately 180–210 days to be absorbed[1]. As for shape, the U-shaped thread anchored at the temples produces a strong lift but comes with more complications, while the I-shaped thread shows the opposite, according to reports[2].

What is the difference between PDO, PLLA, and PCL?

They differ in degradation speed and how they work on collagen. PDO, as a suture material, shows strength that drops to 70% at 14 days, 50% at 28 days, and 25% at 42 days, with absorption taking 180–210 days[1]. However, this is data for closure sutures, and cannot be directly applied to lift threads, which differ in thickness, insertion location, and presence or absence of barbs[1]. PLLA is positioned for those seeking gradual improvement and long-term collagen remodeling[3].

Has the material difference been confirmed in humans?

The evidence is still mainly from animal studies. In a comparison dividing 30 aging-model rats exposed to ultraviolet light for 4 weeks into 6 groups, PDO, PLLA, and PCL all brought dermal collagen density closer to young individuals, with PCL showing the highest activity[4]. An experiment in pigs over 180 days with polylactic-co-caprolactone threads coated with hyaluronic acid also outperformed uncoated threads across multiple tissue markers[5]. Both authors note that human confirmation is still to come[4][5].

In other words, there are currently no randomized trials directly comparing the efficacy of different materials in humans. It is safer to understand explanations like "this material works" as extensions of animal findings to humans[4].

What changes between U-shaped and I-shaped?

The degree of lift and the types of complications are opposite. U-shaped threads anchored at the temples achieve visible tissue elevation in 85–90% of cases, while bleeding is reported in 15–20%, skin dimpling in 12–18%, and tissue damage at the thread exit in 5–10%[2]. I-shaped threads have less tissue damage and pain with complications under 5%, but the lift is more modest[2]. The stronger you want to lift, the more you accept the possibility of dimpling and bleeding[2].

The same review concludes that what ultimately determines the result is patient choice and individual planning rather than thread type[2]. Combining the strengths of both shapes has also been noted as a future direction[2].

How is it combined in actual clinical practice?

Mixing materials is the most common approach. In a tally of 111,948 procedures performed across over 100 clinics from 2020 to 2024, combining PDO and PCL threads was the most frequently used among 7 surgical combinations[6]. Whether the set contains mixed materials or a single material can be confirmed at the estimate stage[6].

What to confirm at consultation

The deciding factor is your priority. Do you want a dramatic lift, want to minimize the risk of dimpling, or want the longest-lasting support? Communicating this priority first makes the proposal for material and shape more concrete.

After that, ask for the thread material name and shape, number of threads, and insertion locations to be written out. Since the optimal combination changes depending on skin thickness and degree of Sagging (skin laxity), the final choice will be made with your doctor at the consultation.