# An Accelerated Aging Test to Compare the Thermal Stability over Time between the Mint Lift+
###### Abstract  
It is allegedly known that the thermal stability of the Mint Lift(r) (the Mint Lift(r) 17 and the Mint Lift(r) Fine; HansBiomed Co., Ltd., Seoul, Korea) over time might be lower as compared with thread-lifts processed through ultrasonic molding technology, such as the MEDI ROPE (WSM 19-03; CNG Co., Ltd., Gyeonggi, Korea), because the Mint Lift(r) undergoes a thermal treatment during the manufacturing process. We conducted this accelerated aging test to compare the thermal stability over time between the Mint Lift(r) and the MEDI ROPE. Thus, we measured the degrees of strength of the MEDI ROPE, the Mint Lift(r) 17, and the Mint Lift(r) Fine at 0, 2, 3, 4, 5, 7, 8, 9, 10, 11, 14, and 17 weeks. Between 0 and 14 weeks, the Mint Lift(r) 17 and the Mint Lift(r) Fine had significantly higher degrees of strength as compared with the MEDI ROPE (\(p<0.05\)). At 0, 5, and 10 weeks, the Mint Lift(r) 17 and the Mint Lift(r) Fine showed no notable differences in microscopic findings as compared with the MEDI ROPE. At 20 weeks, however, the integrities of the Mint Lift(r) 17 and the Mint Lift(r) Fine were better preserved as compared with the MEDI ROPE. In conclusion, our results indicate that the Mint Lift(r) 17 and the Mint Lift(r) Fine might be less vulnerable to degradation over time as compared with the MEDI ROPE under thermal conditions. materials testing: aging; time; temperature; durability +
Footnote †: This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons. A thread-lifting is a minimally-invasive technique using a thread-lift; it is performed to correct the skin laxity by improving the contours of soft tissues [2,3]. The emergence of thread-lift has opened new era of non-surgical aesthetic procedures. To date, fillers or other procedures controlling hyperactive facial mimetic muscles have been used for the restoration of volume of the deflated facial areas. This is complemented by non-surgical facial rejuvenation using a barbed thread-lift [4].A barbed suture is a special type of suture that is used to anastomose the tissue without tying a knot [5]. It is characterized by the presence of barbs on its surface. Conventional types of sutures are dependent on surgeons' technical skills in tying secure knots. However, barbed sutures serve as a knotless alternative in some surgical settings; they are commonly used in the field of cosmetic surgery [6]. With technological advancements in the manufacturing process and the popularity of a barbed thread-lift in the field of aesthetic procedures, diverse types of polydioxanone (PDO) thread-lifts have become commercially available [7, 8, 9, 10]. Meanwhile, PDO thread-lifts have undergone scientific evolution, leading to improvements in their physicochemical and biomechanical properties [8,9]. Of various types of PDO thread-lifts, the Mint Lift(r) (HansBiomed Co., Ltd., Seoul, Korea) deserves special attention because it was approved by the U.S. Food and Drug Administration (US FDA) [11]. Moreover, its clinical efficacy and safety have been well described in the literature [4,12, 13, 14, 15, 16, 17, 18, 19, 20]. The accelerated aging test is commonly performed to assess the stability of a medical device, for which it accelerates the chemical or physical degradation of the device in such conditions as severe temperature for a short period of time relative to the actual shelf-life of the device [21]. The accelerated aging test for biomaterials has been traditionally performed using either solvent or thermal methods. Use of solvents or solutions for the accelerated aging test is a type of method for assessing the performance of the material once it has been implanted; it is advantageous in predicting toxicological concerns and changes in the properties of the material. Thermal methods have also been used for the accelerated aging test, although they are much less accurate as compared with those using solvents or solutions.