Association of PDO threads and technologies— Facial treatment protocols

Background: Aging is part of the immutable characteristics of the human being, and the search for treatments to alleviate the undesirable effects of aging is frequent in the dermatological office. Aims: This work proposes the technique of association of PDO threads with technologies and the description of the facial treatment protocols. Methods: For contextualization, two case studies of two patients subjected to the procedure are analyzed. Conclusions: In recent years, there have been marked changes in facial rejuvenation techniques using PDO threads and these have shown satisfactory results for collagen biostimulation. Having technologies in dermatological clinics is a frequent reality, and sometimes, some doctors are in doubt about when to use them associated with PDO wires and in which sequence it should be done, ensuring patient safety and maintaining the integrity of the wires. This article aims to bring clarity about how to use technology and when is the right time. It is also intended to clarify that the PDO wire can be used in conjunction with the microfocused ultrasound technology, since the melting point of the PDO polymer is between 110° and 115°C.


| INTRODUC TI ON
The primacy of aesthetics has always been an integral part of human culture. Adorning, beautifying, and finding ways to soften the effects of time have accounts as far back as written information has been able to transmit to us. Nowadays, we live in an age where knowledge and technology work together to achieve better and better results.
In this work, it is proposed the explanation of the technique of association of PDO threads with technologies and the description of facial treatment protocols. For contextualization, two case studies of two patients undergoing the procedure will be analyzed.
The surgical facelift has often been used to achieve facial rejuvenation; however, patients who undergo this procedure are vulnerable to postoperative complications such as infection, skin necrosis, hematoma, seroma, nerve damage, and visible scarring. For those reasons, it has become essential to develop minimally invasive facial rejuvenation techniques; their benefits include lower morbidity and faster healing since the incisions are relatively small. 1 With the advent of technologies in dermatology and their incorporated into our therapeutic arsenal for facial rejuvenation, it has been possible to proceed to associations of techniques that have further elevated the level of results in slowing the aging process.

MIRANDA
In the early days of aesthetics, the focus of treatments was on the epidermis and dermis where laser treatments, intense pulsed light (IPL), and radiofrequency (RF) emerged as good options for collagen stimulation. 2 With a better understanding of the aging process, which also takes place in the fat pads, with ligament laxity of the face, technologies such as microfocused ultrasound (MFU), for example, are capable of generating neocollagenesis in these structures and in the superficial musculoaponeurotic system (SMAS), which are fundamental in supporting the face. 3 Each technology acts on a different site in the skin with its specific mechanism as shown in Figure 1.
PDO threads are a therapeutic tool for collagen formation in the subcutaneous tissue, and thus, new septa in the fat pads with the goal of tissue restructuring and reconnection. 4 In addition despite the advent of various skin tightening technologies, there is still a demand for achieving results approaching facelift surgery while maintaining the advantages of the non-invasive approach. Associating them with polydioxanone threads may bring more satisfactory results for face support and rejuvenation. However, this association can generate doubts about its safety and real efficacy in the potentiation of collagen biostimulation.
The concern of most medical professionals, when using these technologies, which by basic principle heat the skin, is the possibility of breakage or melting of the threads. However, it is well established that the melting point of the PDO polymer occurs at 110° to 115°C, a temperature well above the maximum temperature reached by the thermal damage to the tissues caused by technologies. 5 Even though there are not yet robust publications on protocols of association of PDO threads and technologies, however, through the scientific evidence already well established by the basic principles of technologies and their mechanisms of action and interaction with the tissue it is possible to make, safely, the association of these techniques.

| Non-ablative laser, LIP associated with smooth and screw-shaped threads
Laser light therapy performs selective photothermolysis by acting on specific chromophore such as water, melanin, and hemoglobin in the epidermis and dermis based on its wavelength. 6 IPL systems, on the contrary, are non-coherent, non-collimated light sources with distinct wavelengths. 7 These non-ablative technologies maintain the integrity of the epidermis and dermis, causing only a minimal inflammatory reaction without causing apparent edema. When performing the smooth or screw PDO threads in the superficial subcutaneous tissue, we can do it immediately before or right after the application of the non-ablative laser or LIP.

| Non-ablative laser, IPL, and barbed threads
When performing barbed threads, one must keep the spicules more adhered sustain the tissues until the collagen formation process around this wire is able to keep them fixed reconnecting and sustain the tissues. In the same way, we can do the smooth threads at the same time we do the non-ablative laser and IPL, the threads with spiculated or molded barbs can be done before or right after the threads. With the non-ablative laser technology, there is a discrete inflammatory reaction without the formation of edema, which will allow the spicules to fulfill their facial support role without the counterforce of the edema weighing down the underlying tissues.

| Fractional ablative laser associated with smooth and screws shaped threads
The fractional ablative laser is characterized by a pattern of microzones of tissue coagulation forming columns of thermal injury that present epidermal necrosis and collagen denaturation surrounded by intact tissue. 8 In this way, it removes the most superficial layers of the epidermis and dermis in columns and generates a moderate inflammatory reaction that produces cutaneous edema, which can cause a weight effect on the tissues, pulling them downward. In these cases, it is possible to use flat wires and screws, which have as their main function the collagen stimulus, and do not need to do traction and thus suffer the negative influence of the edema formed by the inflammatory reaction of the ablative fractional laser.
It is ideal that the threads are done before the fractional laser to avoid drug delivery of the antiseptics that we use during the application of the wires.

| Fractional ablative laser and wires with barbed threads
As mentioned before, ablative lasers generate a moderate inflammatory reaction in the epidermis and dermis capable of generating edema, weighing down the tissues thus leading to an instability of the claws of the PDO wires that need time for the collagen produced around this wire to be enough to keep them fixed, sustaining the subcutaneous tissue. After using ablative fractional lasers, one must wait until the edema is minimized so that, later, the placement of the wires with barbed threads can be performed. This estimated time can vary between 5 and 7 days after the fractional laser. But if the barbed threads were done first, wait about 15 days for the collagen formed around the spicules to be efficient in sustaining them against the edema that will be generated by the inflammatory reaction of the laser.

| Non-ablative radiofrequency associated with smooth and screw-shaped threads
Unlike lasers, non-ablative radiofrequency devices promote a three-dimensional volumetric heating from the natural resistance of the tissue to the movement of the electron current emitted by the device itself. It is known that the controlled volumetric heating of the deep dermis should reach 65-75°C for collagen shortening and release of the inflammatory response involved in the process of tissue repair followed by neocollagenesis over the following months. 9 In vitro studies have shown a greater effect on the dermis up to 2 mm in depth, 10 the site above thread placement. When topical or infiltrative anesthetics are used, the pain parameter, which is used to avoid complications such as RF burns, is lost. Thus, it is convenient to perform the RF technology first and only after the anesthesia to place the smooth or screw-shaped PDO threads.

| Non-ablative radiofrequency and barbed threads
Besides the need to avoid complications such as burns, the other reason that justifies the use of RF before barbed threads is that when performing the technique with non-ablative RF technology, the circular and linear movements performed to achieve the desired temperature in the skin could cause mobilization of the thread spicules, compromising the results. For these two reasons, RF should be performed first and then the placement of the PDO barbed threads.

| Microfocused ultrasound associated with smooth and screw-shaped threads
Microfocused ultrasound technology has recently been developed for skin lifting and tightening as an alternative for patients who do not wish to undergo more invasive surgical procedures. 11 The MFU platforms use tips that apply concentrated ultrasound in microdots (area of 1 mm 3 ) heating and coagulating the tissues at a temperature between 60° and 70°C 12 keeping the epidermis and papillary dermis integrated. These coagulation microzones will contract and stimulate neocollagenesis. Its tips range from 1.5 to 4.5 mm each acting at different skin depths. The 1.5 and 2.0 mm tips act in the reticular dermis. The 3.0 mm tip generates coagulation zones in the superficial fat pads, and the 4.5 mm leads to heating zones and collagen stimulus in the muscular aponeurotic system, the SMAS.
When performing smooth threads, we can do it immediately before or after the MFU as the melting point of the PDO polymer is between 110° and 115° C, not being influenced by the heating that is achieved with the HIFU technology. If the patient previously had smooth PDO wires and wishes to perform the UMF, he/she should wait 15 days for the performance of this technology in order not to interfere in the collagen cycle initiated by the PDO polymer, since both are done in the same plane of the skin, the superficial subcutaneous.

| Microfocused ultrasound and barbed threads
For patients with sagging and exuberant ptosis of the fat pads, it is necessary to associate techniques to achieve better results for face support. Therefore, associating the barbed threads to the MFU may potentiate the results of the traction of the barbed threads.
However, it is not convenient to move the facial tissues after the placement of the claws. For this reason, it is ideal to perform the technology first, and then to place the PDO wires with claws.
We can see the results of the association of the MFU with barbed threads in a 40-year-old patient with a bulky face and moderate laxity after 60 days (Figures 1-3). their mechanisms of action, their interaction with the tissue, and the reactions expected by its use, it is possible to make, with safety, the association of these techniques. A summary of the associations of the most common current technologies with PDO threads is contained in Table 1.

| CON CLUS IONS
In recent years, there have been marked changes in facial rejuvenation techniques using PDO threads and these have shown satisfactory results for collagen biostimulation. Having technologies in dermatological clinics is a frequent reality and sometimes, some doctors are in doubt about when to use them associated with PDO wires and in which sequence it should be done, ensuring patient safety and maintaining the integrity of the wires. This article aims to bring clarity about how to use technology and when is the right time. It is also intended to clarify that the PDO wire can be used in conjunction with the microfocused ultrasound technology, since the melting point of the PDO polymer is between 110° and 115°C.

E TH I C A L A PPROVA L
Authors declare human ethics approval was not needed for this study.

DATA AVA I L A B I L I T Y S TAT E M E N T
The data that supports the findings of this study are available in the supplementary material of this article.