Tremendous advances in the eld of cosmetic surgery using minimally invasive techniques in recent years have led to the introduction of many different types of llers. However, just as with cosmetic surgery, these minimally invasive procedures rst introduced from the West provided injection guidelines and protocols tailored to Caucasians. Therefore, to effectively perform these procedures on Asians, various issues had to be considered. One of the most important issues is the identication of facial features that distinguish Caucasians from Asians. To ensure the recommendation of the appropriate minimally invasive procedure, it is crucial to gain an accurate understanding of Caucasian and Asian facial characteristics.

Caucasians who have slimmer faces with distinct contours prefer a more three-dimensional face with angled jawlines. In contrast, Asians have wider anterior malar areas, protruding lateral cheeks, square jawlines, and paranasal depressions. Consequently, Asian faces look uneven from the prole view and appear wider and atter with rather faint contours in the frontal view. Accordingly, Asians prefer smooth threedimensional contours as opposed to Caucasians who prefer protruding, dened three-dimensional contours. In other words, Westerners prefer angular, prominent faces, whereas Asians prefer slimmer, smooth contours.

There are many anatomical differences in the facial skin and soft tissues as well. First, Asians have thicker, heavier, and rmer skin than Caucasians, and as a result, they have fewer age- related wrinkles. However, Asians have larger skin volume per surface unit area, so compared to Caucasians, a greater force is needed to add overall volume to the face or lift the skin.

The supercial muscular aponeurotic system (SMAS) is a layer supercial to the skin that contains supercial and deep retinacula cutis. The

SMAS connects the skin to the deeper structures located by the bone. In regard to the soft tissue structure, the retinacula cutis formed by retaining ligaments is denser in Asians than in Caucasians, and as a result, the subcutaneous tissue of Asians tends to be tougher.

In terms of vasculature, Caucasians have greater collateral circulation whereas Asians have more vertically running perforating vessels and blood vessels tend to be more developed. This increases the risk of bleeding and serious vascular complications such as tissue necrosis in Asians. To prevent these accidents, it is important to locate injection sites and layers that are anatomically safe for the procedure.

It is known that with aging severe depression of orbital and other facial bones that support the midface occur. In an article published in 2000, Dr. Pessa claims that to correct depression, adequate volumization is needed in the periorbital region and midface area. Following the claim by Dr. Pessa, procedures were performed based on the assumption that such changes in facial bones occurred in Asians as well. However, recent ndings indicate that unlike Caucasians, Koreans do not experience the same changes in the bones of the midface as they age. Therefore, the at midface observed in some Asians is a trait that they were born with and not an age-related change in bone structure. For Koreans whose faces have become atter over time, this depression has been caused by ptosis of skin and soft tissues overlaying the bones of the midface. Such differences should be taken into account when coming up with a treatment plan.

Because Asians have thicker, denser, and heavier skin than Caucasians do, Asians require rmer llers with relatively higher elasticity to enhance facial volume. Moreover, because of tougher subcutaneous tissue and well-developed vasculature, there is a higher risk of serious vascular complications due to bleeding or vascular occlusion. Therefore, it is of utmost importance to identify anatomically safe and effective injection sites and planes for each part of the face to avoid such complications.

1.3 Dierences Between Asian andWestern Beauty Concepts

Table 1.2

1. Caucasians—Relatively prominent supraorbital ridge, high cheek bones, strong nose and chin, fully-

2. Asians—Slightly smooth facial 4S line prole (from the forehead to chin) with balanced convexity and

3. The skin of Asians is oily, rough, thick, and tight.—Difcult to contour the face with only small sized

4. The subcutaneous layer of Asian is tighter and thicker with a more abundant and complex vascular

5. Requests of Asian patients—Youthful, charming, small face with a cute and cheerful smiling appearance

prefer facial types with appropriately sized cheeks that impart a smiling appearance, a slim and smooth facial contour, a well-balanced jawline, and a nose of suitable proportion and height. For Caucasians seeking prominent “apple cheeks,” the superolateral quadrant (quadrants dened by Hinderer’s lines) is augmented. On the other hand, because the goal is to create a smoother ogee curve in Asians, the inferomedial aspect is targeted to enhance the anterior malar area.

truding zygomatic arches, Asians do not need zygomatic arch augmentation procedures performed on Westerners. When lateral cheek hollow is present, there is loss of smooth contours in the lateral aspect of the face due to the protruding zygomatic arch. The ller procedure is thus performed in the hollow region inferior to the zygomatic arch to create a smoother facial prole. To summarize, unlike in Caucasians who need zygomatic arch augmentation, Asians need treatment inferior to the zygomatic arch.

face. As a result, they prefer procedures that create well-dened mandibular angles. Conversely, Asians, who have a wider lower face with a prominent square jawlines, prefer the slim “eggshaped” face that becomes narrower toward the bottom, similar to a kiwi or heart. Accordingly, many Asians augment just the mental region and

Differences in facial characteristics in Caucasians and Asians

dened lips, and a square jaw line

concavity rather than high cheek bones and strong triangle with prominent nose and chin, and small face with slim oval-shaped jawline rather than a well-dened and square jaw

particle llers

plexus.—Safer selection of the injection entry site point and injection plane to avoid severe bleeding and vascular compromise

In terms of the frontal view of the face, Asians

do not receive llers in the mandibular angle and jawline (Table1.2).

In most people, the lower face increases in volume and becomes wider with aging. This causes the face to appear wider. To create a more three-dimensional and slimmer face shape, botulinum toxin or a lipolytic agent can be used in combination with llers. Chin augmentation with llers and treatment with botulinum toxin/lipolytic agent in the lower cheek muscles, skin, or soft tissues decreases volume to create a slimmer lower face. In patients in whom the wide lower

Since most Asians already have wide and pro-

face is caused by sagging skin rather than skeletal structure, face-lifting with thread or laser treatment can smoothen the lower-face contours. Combination treatment can maximize the effects of lower face ller procedures.

In addition, procedures that are performed more commonly in Korea compared to the West are lower eyelid charming roll formation for cuteness, paranasal augmentation to reduce protrusion of the mouth for elegance, columellar augmentation to lift the depressed nasal tip for a cat-like appearance, and sunken eyelid correc-

Caucasians congenitally have a narrow lower

tion to ll the upper eyelid. The brow lift procedure, which involves volumizing the sunken region by the brows to lift them, is commonly performed in Western countries. However, this procedure is not performed as much in Korea because Koreans do not prefer the strong, aggressive image that elevated eyebrows may impart (Table1.3).

1 The Art andScience ofFiller Procedures foraMore Attractive Face

Table 1.3

1. Use of ller and toxin for a cheerful smiling effect

2. Oval face toxin injection for a small face and slimmed jawline with ller for the stereographic T-zone

3. Lower eyelid roll formation using ller for a charming eye

4. Paranasal region augmentation using ller for a smart and noble appearance

5. Depressions and irregular shape due to prominent and widened zygomatic arch—Lateral cheek and temple

7. Sunken eyelids make Asians’ eyes appear more ptotic with multiple eyelid lines due to small eyes and

1.4 Medical Reference Values

Filler and toxin treatments specic to Asian patients

augmentation to smooth out irregular lateral facial contours Nasal tip elevation and widening of columello- labial angle with anterior nasal spine and columellar ller

injection for a cat-like appearance

weak eyelid levator muscle function—Correction of sunken eyelid and multiple eyelid lines to correct sleepy, tired eye appearance

The ideal reference values to create an attrac-

toCreate anAttractive Face

tive face that takes racial differences into account can be found in the facial proportions and harmo-

As demonstrated by numerous different studies, the standards of beauty tend to be consistent, regardless of age and sex. For example, most people consider features that symbolize youthfulness to be beautiful. People are innately drawn to what is attractive, and there is even a theory that even newborn infants perceive beauty. It has been experimentally shown that babies show interest in attractive faces and focus more on such faces.

To ensure the attractive facial image that the patient desires is achieved, treatment approach should be based on medical references values that consider the absolute and relative standards of beauty discussed above. Generally, Asians consider a face with the following characteristics to be an ideal face: smooth forehead with minimal curvature, appropriately sized cheek bones that give a smiling expression, sleek but smooth facial contours, full lips, bilaterally balanced jawline, nose with appropriate proportion and height, and egg-shaped or oval face.

First, accurate facial analysis with knowledge in the references values of a well-balanced face with good facial proportions and harmonization is necessary. Assess patient in the upright position, aligning the Frankfort horizontal line (line that projects from the external auditory canal to the lower rim of the orbit) and the oor to be parallel. Evaluate the frontal, prole, and threequarter views of the face.

nization of faces we are most familiar with. As shown in the left illustration in Fig.1.2, when the face is divided into thirds—trichion to glabella, glabella to subnasale, and subnasale to gnathion—Westerners consider a 1:1:1 ratio to be ideal. In the past, procedures were performed in Asia based on this standard. However, Asians today tend to prefer a shorter lower face, considering this facial type to be more youthful. Accordingly, procedures are performed on the chin and jawline so that the midface to lower face ratio is 1:0.8~0.9.

When the face is divided into ve vertical sections from the right ear to the left ear, as shown in the right illustration in Fig.1.2, a 1:1:1:1:1 ratio is considered ideal. Asians faces are wider than that of Caucasians, and as a result, their eyes and nose may appear broader. Regardless of the absolute width of the nose, for a face to appear wellbalanced, the intercanthal distance to width of the nose ratio should be close to one. Accordingly, ller and thread lifting procedures on the nasal tip and columellar area to make the ala nasi look narrower are becoming more popular. More favorable outcomes can be achieved by combining ller with botulinum toxin injections into the muscles responsible for dilating the nares and plunging of the nasal tip which cause the ala nasi to look attened when smiling or making facial expressions (Fig.1.3).

Horizontal thirds with symmetryAttractive : Equal vertical fifths

1.4 Medical Reference Values toCreate anAttractive Face

Upper

Middle

Lower

Fig. 1.2 Ideal facial proportion and line

Fig. 1.3 Ideal

proportion and line of nose and lip

The Ricketts line, which extends from the nasal tip to the mentum, is used to determine the degree of mouth protrusion and assess facial balance of the prole. Relative to the Ricketts line, which spans the nasal tip, lips, and mentum, Westerners consider the ideal location of the lower lip and upper lip to be 2mm and 4mm posterior to the line, respectively. To achieve this in Asians, the procedure must involve excessive anterior projection of the nasal tip and mentum.

In Asians, the lower lip located on the Ricketts line is considered appropriate. If the line extending from the nasal tip to the forehead is symmetrical with the Ricketts line, the forehead is considered to have appropriate volume (Fig.1.4).

The conditions for a three-dimensional, wellbalanced, and youthful face from the prole view can be explained using the specic values shown in Fig. 1.5. Clinically, the lines connecting the forehead to nose, nose to lips, lips to mentum,

1. The arc of forehead, convexities of the temples

2. The concavity between the glabella and the nasal root area (135°)

3. Strong nose and nasal tip projection(30°-45°)

4. Ideal columello-labial angle (90°-100°)

5. Anterior cheek projection, extending as an unbroken convex line from the lower eyelid to the cheek

6. Not depressed paranasal space

7. Upper and lower lip fullness

8. Sharp well-defined arc of the jawline

Tip of nose

Tip of chin

Fig. 1.4 Difference of Ricketts line between Caucasians and Asians

1 The Art andScience ofFiller Procedures foraMore Attractive Face

Supraorbital ridge

Lower lip

Fig. 1.5 Conventional criteria for ideal facial prole

and the anterior cheek line should be S-shaped curves, as shown in Fig.1.6.

In the frontal view, the face should be eggshaped or oval. The face is youthful and slim, resembling an inverted triangle or heart, as shown in Fig. 1.7. In addition, combination treatment with other minimally invasive procedures may be considered to eliminate wrinkles and rejuvenate the skin.

Achieving facial balance to create an attractive face requires a holistic approach. Harmony in interpersonal relationships between medical

professionals, hospital staff, and patients is crucial in optimizing outcomes of minimally invasive procedures and maximizing patient satisfaction. In line with this thought, the “Harmony Program” was recently developed in Europe. This is an advanced patient management program that provides total approach, consultation, and management services for patients undergoing minimally invasive procedures. With respect to the specics of the program, the medical consultation is conducted based on medical background and patient self-assessment. The

The youthful face :balanced harmonyofconvexity andconcavity

1.4 Medical Reference Values toCreate anAttractive Face

Fig. 1.6 Facial 4S lines for ideal facial prole

From forehead to nose

From nosetoupper lip

From lower lip to chin

Apple cheek (Anterior malar area) for ogee curve

Fig. 1.7 Inverted triangle or heart shape

consultation is a collaborative process that actively involves the patient and the treatment plan is established based on the results of the consultation. Subsequently, the treatment plan is carried out. Lastly, plans for post-treatment follow- up and, if necessary, plans for additional procedures are established.

The details of the program are as follows: In Step 1, a standardized questionnaire and pretreatment interview are conducted to identify specic

details about the patient: patient medical history, including previous surgery or interventions, motivation behind and desire for the procedures, self-assessment of patient face, specic requests, personality, and current nancial situation.

In Step 2, the medical professional evaluates the patient’s face based on the aforementioned standards of beauty including facial symmetry, facial volume, degree of sagging, wrinkles, and skin condition. Based on the ndings, an indi-

1 The Art andScience ofFiller Procedures foraMore Attractive Face

vidually tailored treatment plan for the facial region to be treated, necessary procedures, degree of correction possible, and which combination of treatments should be attempted to optimize outcomes is established. Ultimately, the treatment method and cost are determined through the nal consultation. When establishing an individually tailored treatment plan, the physician must comprehensively consider both patient-related and clinical factors. The physician must think about the following: the type of change the patient desires and to what extent; any procedurerelated concerns the patient may have, including pain, bleeding, swelling, and bruising; the affordable amount of ller, toxin, and thread that can be used based on patient’s nancial status; product selection; and if alternative procedure options are available.

Step 3 is the actual treatment stage. The goal should be to achieve overall harmony in the face in line with the aforementioned beauty standards of improving facial proportions and balance. In cases when patient expectations exceed what is feasible with injectable llers, it is important to inform the patient about this. Doing so will build a trusting relationship and encourage the patient to come in for subsequent treatments.

Step 4 includes follow-up planning. Typically, a follow-up visit for evaluation and correction 2 weeks post-procedure is recommended. Additional procedures for harmony and balance or combination treatment using other procedures are discussed, and a long-term treatment plan reecting the expectations of the patient is established. The follow-up visit is also an opportunity for business-related aspects, such as introduction of potential patients, continuous visits for addi-

tional treatment, and sales of cross-treatment and other products.

One of the procedures that has been used recently in combination treatment with ller procedures is oval face injection. Filler injections add volume to the entire face, whereas oval face injections reduce the volume of bulging soft tissue in the lateral border of the face to create a slimmer face type. Oval face injection, which consists of a cocktail solution mixed with botulinum toxin, is injected into the muscles, skin, and soft tissues in the cheek and chin area to inhibit excessive contraction of the masseter muscle, tighten the skin of the cheeks, and reduce volume of soft tissue including the skin and subcutaneous fat. In combination, the oval face injection has the effect of both slimming the face and maximizing the three-dimensional volumization of the ller. While excessive dieting can lead to hollowness and dry, akey skin, egg injection is effective in creating a slim face that is natural and healthy looking. The slimming effects vary depending on individual differences in skeletal size, amount of soft tissue, and skin condition. However, unlike PPC injections which have been banned, oval face injection is a safe and effective treatment option without major discomfort and adverse events (Fig.1.8).

Lastly, the future directions physicians should pursue when performing minimally invasive procedures, including ller procedures, will be discussed.

First, with the full-face approach, the primary goal should be to achieve balance and overall harmony, including left-right symmetry. With this approach, even patients who have received prior cosmetic surgery or aesthetic procedures

Fig. 1.8 Before (left) and after (middle, right) treatment of oval face injection

can expect some degree of correction and improvement through minimally invasive procedures. In the full-face approach, the focus shifts from assessing the facial wrinkles and shape in the expressionless, static state. In clinical practice, it is important to take into consideration the dynamic nature of soft tissues and wrinkles, which change with smiling and the formation of facial expressions.

Second, more emphasis should be placed on soft tissues. Compared to Caucasians, ageinduced facial skeletal changes tend to be less pronounced in Asians. Therefore, it is important to consider the anatomical location and conguration of the soft tissue covering the facial bones, rather than merely focusing on the location of and changes in the skeletal structure

Lastly, beauty standards should shift from traditional, denitive standards of the past to beauty standards that encompass patients’ personality, race, culture, geographical region, and aspirations/goals for treatment.

Further Reading

1. Bray D, etal. A review of dermal llers in facial plastic surgery. Curr Opin Otolaryngol Head Neck Surg. 2010;18:295–302.

2. Edsman K, etal. Gel properties of hyaluronic acid dermal llers. Dermatol Surg. 2012;38:1170–9.

3. Kablik J, et al. Comparative physical properties of hyaluronic acid dermal llers. Dermatol Surg. 2009;35:302–12.

4. Matarasso SL, etal. Consensus recommendations for soft-tissue augmentation with nonanimal stabilized hyaluronic acid (Restylane). Plast Reconstr Surg. 2006;117(3):3S–34S. discussion 35S

5. Cohen SR, et al. Facial rejuvenation with llers. Elsevier Limited; 2009.

6. Kim P, etal. Structured nonsurgical asian rhinoplasty. Aesthet Plast Surg. 2012;36:698.

7. Liew S.Ethnic and gender considerations in the use of facial injectables: Asian patients. Plast Reconstr Surg. 2015;136(5):22S–7S.

8. Pierre S, et al. Basics of dermal ller rheology. Dermatol Surg. 2015;41(1):120S–6S.

9. Tezel A, etal. The science of hyaluronic acid dermal llers. J Cosmet Laser Ther. 2008;10:35–42.

10. Gold MH. Use of hyaluronic acid llers for the treatment of the aging face. Clin Interv Aging. 2007;2(3):369–76.

11. Sundaram H, et al. Comparison of the rheological properties of viscosity and elasticity in two categories of soft tissue llers: calcium hydroxylapatite and hyaluronic acid. Dermatol Surg. 2010;36:1859–65.

12. Casabona G, et al. Microfocused ultrasound with visualization and llers for increased neocollagenesis: clinical and histological evaluation. Dermatol Surg. 2014;40:194S–8S.

13. Kenner JR. Hyaluronic acid ller and botulinum Neurotoxin delivered simultaneously in the same syringe for effective and convenient combination aesthetic therapy. J Drugs Dermatol. 2010;9:1135–8.

14. Lee, et al. Rejuvenating effects of facial hydrolling using Restylane Vital. Arch Plast Surg. 2015;42(3):232–87.

15. Kim, etal. Development of facial rejuvenation procedures: thirty years of clinical experience with face lifts. Arch Plast Surg. 2015;42:521–31.

16. Flynn TC, etal. Ultrastructural analysis of 3 hyaluronic acid soft-tissue llers using scanning electron microscopy. Dermatol Surg. 2015;41:143S–52S.

17. Narurkar V, et al. Facial treatment preferences in aesthetically aware women. Dermatol Surg. 2015;41:153S–60S.

18. Kim J.Effects of injection depth and volume of stabilized hyaluronic acid in human dermis on skin texture, hydration, and thickness. Arch Aesthet Plast Surg. 2014;20:97–103.

19. Carruthers J, et al. Introduction to llers. Plast Reconstr Surg. 2015;136:120S–31S.

20. Friedman PM, etal. Safety data of injectable nonanimal stabilized hyaluronic acid gel for soft tissue augmentation. Dermatol Surg. 2002;28:491–4.

21. Ablon G. Understanding how to prevent and treat adverse events of llers and neuromodulators. Plast Reconstr Surg Glob Open. 2016;4(12S):e1154.

22. Perrett D.In your face: the new science of human attraction. 2012.

23. Ioi H, etal. Inuence of facial convexity on facial attractiveness in Japanese. Orthod Craniofac Res. 2007;10(4):181–6.

24. Pessa JE, Rohrich RJ. Facial topography: clinical anatomy of the face. St. Louis: Quality Medical Publishing; 2012.

25. Farkas LG, etal. Is photogrammetry of the face reliable? Plast Reconstr Surg. 1980;66:346.

26. Park HS, etal. Harmonized proloplasty using balanced angular prole analysis. Aesthet Plast Surg. 2004;28:89–97.

27. Mendelson B.In your face: the hidden history of plastic surgery and why looks matter. Published by Hardie Grant Books; 2013.

28. Pearson DC, etal. The ideal nasal prole: rhinoplasty patients vs the general public. Arch Facial Plast Surg. 2004;6(4):257–62.

29. Jones BC, etal. When facial attractiveness is only skin deep. Perception. 2004;33(5):569–76.

30. Kaipainen AE, et al. Regional facial asymmetries and attractiveness of the face. Eur J Orthodont. 2015;13:1–7.

1 The Art andScience ofFiller Procedures foraMore Attractive Face

31. Berneburg M, et al. Changes in esthetic standards since 1940. Am J Orthod Dentofacial Orthop. 2010;137(4):450.

32. Lee HB, etal. Evaluation of inuence of individual facial aesthetic subunits on the cognition of facial attractiveness in public. J Korean Soc Plast Reconstr Surg. 2010;37(4):361–8.

33. Meneghini, etal. Clinical facial analysis (elements, principles, and techniques). Berlin: Springer; 2012.

34. Rhee SC, et al. Balanced angular prole analysis. Plast Reconstr Surg. 2004;114(2):535–44.

35. Liew S, etal. Consensus on changing trends, attitudes, and concepts of Asian beauty. Aesthet Plast Surg. 2016;40:193–201.

36. Zhuang Z, et al. Facial anthropometric differences among gender, ethnicity, and age groups. Ann Occup Hyg. 2010;54(4):391–402.

37. Swift A, etal. Beautiphication: a global approach to facial beauty. Clin Plast Surg. 2011;38:347–77.

38. Farkas LG, etal. International anthropometric study of facial morphology in various ethnic groups/races. J Craniofac Surg. 2005;16(4):615–46.

39. Narins RS, etal. Validated assessment scales for the lower face. Dermatol Surg. 2012;38:333–42.

40. Soh J, etal. Professional assessment of facial prole attractiveness. Am J Orthod Dentofacial Orthop. 2005;128(6):690–6.

41. Choe KS, et al. The Korean American woman’s face: anthropometric measurements and quantitative analysis of facial aesthetics. Arch Fac Plast Surg. 2004;6(4):244–52.

42. Farkas JP, et al. The science and theory behind facial aging. Plast Reconstr Surg Global Open. 2013;1:e8–e15.

43. Ek C, et al. Esthetic evaluation of Asian-Chinese proles from a white perspective. Am J Orthod Dentofacial Orthop. 2008;133(4):532–8.

44. Sadick NS, et al. A novel approach to structural facial volume replacement. Aesthet Plast Surg. 2013;37:266–76.

45. Fitzgerald R, etal. Update on facial aging. Aesthet Surg J. 2010;30(Suppl):11S–24S.

46. Farkas LG, et al. Anthropometric measurements of the facial framework in adulthood: age-related

changes in eight age categories in 600 healthy white North Americans of European ancestry from 16 to 90 years of age. J Craniofac Surg. 2004;15:288–98.

47. Oh HS, etal. Correlations between cepharometic and photographic measurements of facial attractiveness in Chinese and US patients after orthodontic treatment. Am J orthod Dentofacial Orthop. 2009;136(6):762. e1–14. discussion 762–3

48. Kahn DM, etal. Overview of current thoughts on facial volume and aging. Facial Plast Surg. 2010;26:350–5.

49. Radlanski RJ, etal. The face: pictorial atlas of clinical anatomy. Quintessence Publishing. 2012;

50. Ekman P, etal. Facial signs of emotional experience. J Pers Soc Psychol. 1980;39:1125–34.

51. Krumhuber EG, et al. Can Duchenne smiles be feigned? New evidence on felt and false smiles. Emotion. 2009:807–20.

52. Surakka V, et al. Facial and emotional reactions to Duchenne and non-Duchenne smiles. Int J Psychophysiol. 1998;29:23–33.

53. Talarico S, etal. High patient satisfaction of a hyaluronic acid ller producing enduring full-facial volume restoration: an 18-month open multicenter study. Dermatol Surg. 2015;41(12):1361–9.

54. Budai M, etal. Relation between anthropometric and cepharometric measurements and proportions of the face of healthy young white adult men and women. J Craniofac Surg. 2003;14(2):154–61.

55. Fattahi TT.An overview of facial aesthetic units. J Oral Maxillofac Surg. 2003;61:1207–11.

56. Bocchialini G, Castellani A, Negrini S, Rossi A.New management in bilateral masseter muscle hypertrophy. Craniomaxillofac Trauma Reconstr. 2017;10:325–8.

57. Liew S, Dart A.Nonsurgical reshaping of the lower face. Aesthet Surg J. 2008;28:251–7.

58. de Maio M, Wu WTL, Goodman GJ, et al. Facial assessment and injection guide for botulinum toxin and injectable hyaluronic acid llers: focus on the lower face. Plast 251 Reconstr Surg. 2017;140:393e–404e.

59. Rawlani R, Qureshi H, Rawlani V, etal. Volumetric changes of the mid and lower face with animation and the standardization of three-dimensional facial imaging. Plast Reconstr Surg. 2019;143:76–85.

Types ofFillers andRheological Considerations forHA (Hyaluronic Acid) Fillers

2.1 Classication ofFillers According toRaw Materials

Ofcial llers that are used nowadays can be rst classied according to their raw materials. The most widely used llers are hyaluronic acid (HA) llers, which means that llers can be mainly divided into HA llers and non-HA ones. Under the latter category, Ca, PMMA, PLLA, collagen, PAAAG, and PCL are the types of llers on the market and in use. One important criterion to classify the many different types of llers is whether they can be dissolved with a solvent in case of side effects or dissatisfaction. Only HA llers can be dissolved with a solvent as llers comprised of other components contain no enzyme materials that can be dissolved by melting a ller component.

Fillers made of any other components except for HA llers are classied as llers that cannot be dissolved at will when users wish it. Such llers can be removed by diluting them before suction or pressing out. To remove llers that are calcied and hardened, one should inject a saline solution, break them down in ne sizes with pressure, and expect a macrophage action to happen. When such serious foreign body reactions happen and are accompanied by inammation, llers should be scraped out in a surgical method, which can cause various issues. In some ways, the emer-

gence of HA llers as the safest and most popular llers is attributed to their advantage of being removed through dissolution.

2.1.1 HA Fillers

With individual variations, the skin is the biggest organ of the human body, accounting for 6~7% of the body weight and weighing 3~4kg on average. The skin is made up of three layers that include the epidermis, dermis, and hypodermis. Dermis contains extracellular matrix components including collagen, elastin, and hyaluronic acid. An average adult body holds approximately 12~15g of hyaluronic acid in total, half of which is present in the skin (Fig.2.1).

Fig. 2.1 Collagen, elastin and hyaluronic acid of the skin

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Соседние файлы в папке Библиотека им академика М.И. Перельмана

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29.08.202689 Мб0Книга_521_Библиотеки_им_академика_М_И_Перельмана.pdf
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31.08.202638 Мб0Книга_5210_Библиотеки_им_академика_М_И_Перельмана.pdf
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31.08.202637 Мб0Книга_5211_Библиотеки_им_академика_М_И_Перельмана.pdf
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31.08.202631 Мб0Книга_5212_Библиотеки_им_академика_М_И_Перельмана.pdf
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31.08.202631 Мб0Книга_5213_Библиотеки_им_академика_М_И_Перельмана.pdf
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31.08.202631 Мб0Книга_5214_Библиотеки_им_академика_М_И_Перельмана.pdf
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31.08.202630 Мб0Книга_5215_Библиотеки_им_академика_М_И_Перельмана.pdf
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31.08.202628 Мб0Книга_5216_Библиотеки_им_академика_М_И_Перельмана.pdf
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31.08.202626 Мб0Книга_5217_Библиотеки_им_академика_М_И_Перельмана.pdf
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31.08.202624 Мб0Книга_5218_Библиотеки_им_академика_М_И_Перельмана.pdf
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31.08.202624 Мб0Книга_5219_Библиотеки_им_академика_М_И_Перельмана.pdf