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What Are Nasolabial Folds (Smile Lines)?

By July 28, 2020August 4th, 2022Skin

Causes, Treatment And Prevention

Nasolabial Folds  (smile lines) are natural grooves in the skin that run down the nose wings to the mouth corners. With youthful skin, these are virtually invisible with neutral facial expression, however, as the skin ages to lose elasticity and musculature, these grooves deepen to the point where they’re permanently visible.

Figure 1 – There are three main types of nasolabial folds; convex, concave and straight which determine the shape. Short, extended and continuous are used to describe the length of the fold.²

Why Do Nasolabial Folds Affect Facial Aesthetic?

In short, nasolabial folds are an indicator of age. Their presence can make the midface appear disproportionately aged. This is because they form linearly with age-related changes such as skeletal remodelling, reduction of muscular and skeletal support and changes to the soft tissue envelope, all of which disrupt aesthetic proportions.¹

What Causes Nasolabial Folds?

Loss of facial musculature and sagging fat compartments are the main causes of nasolabial folds deepening in their absence. Also, a reduction in skin thickness, excessive fat or weakening fat-support ligaments can contribute to making these folds more visible.

Fat Compartments

As upper cheek fat pads descend downwards, they come to overhang on the nasolabial fold. As buccal fat loses volume, there is less support for the cheek pads to be propped up, leading to the characteristic deflated look that comes with ageing.⁷ This gives the impression of loose skin with less volume underneath the skin to hold it taut. Hence, dermal fillers are a potential solution as they help to replace this lost, youthful volume, rather than shrinking the skin to aged proportions. Much like fat, however, dermal fillers can also migrate or be absorbed into the skin, hence their need for reapplication.

Ligament Laxity

Continous use of our facial muscles causes the ligaments responsible for holding them to stretch which allows for soft tissue to migrate.⁸ Most notably, the laxity of the zygomatic ligament (cheekbone support) allows for the malar fat pads to descend downwards, creating a sharp nasolabial valley as excess fat pools in the cheeks.⁹

Skeletal Remodelling

With ageing, parts of the skull can move as the skull itself isn’t one entire structure but a combination of smaller bone fragments. In particular, the midface loses vertical height, compressing fat pads over a smaller area and increasing their outward projection. This leads to more emphasised troughs and valleys as fat accumulates particularly at the cheeks. Typically, more bone loss is seen in woman than men, so there is evidence that women are more likely to develop these folds.¹⁰ Likewise, those with recessed maxillas or midfaces, in general, have less support to hold the soft tissue taut and are more prone to developing nasolabial folds regardless of age.¹¹

How To Prevent Nasolabial Folds?

Nasolabial folds are inevitable with ageing as their grooves are required for a healthy smile profile. However, the degree of indentation can be slowed down with anti-ageing care.

Sun Damage

Proper suncare is crucial for protecting skin elasticity. This is because the effects of UV exposure accumulate on the skin daily and breaks down the collagen necessary for keeping skin looking youthful and taut. Also, sun exposure has been shown to increase skin laxity, skin yellowing and the obvious fears of skin cancer.

Flament Et al’ s 2013 study¹² on skin ageing showed that skin with 85% and higher sun damage aged the skin by a minimum of 3 years from its actual age. Conversely, those with marginally less sun damage at 78% looked up to 3 years younger than their actual age.

Smoking Damage

Smoking is known to darken skin pigmentation with cigarettes being known to produce melanin-producing melanocytes.¹³ Also, smoking reduces skin thickness at the cheeks which is one of the factors mentioned in the causes of nasolabial folds.¹⁴ Most importantly, smoking affects the biophysical properties of the skin, making the skin thicker in certain places and thinner in others. This reduces skin density which likewise reduces skin elasticity. In both smoking men and women, skin hydration was also found to be significantly lower, partially due to reduced blood flow.¹⁵

Figure 2 – The angle of the nasolabial fold increases with length.

How Are Nasolabial Folds Corrected Surgically?

The most obvious solution would be to use dermal fillers to lessen the depth of the nasolabial groove. However, according to Dr Souphiyeh Samizadeh, this approach results in disharmony as it’s only a temporary approach to an ageing face. For instance,  a youthful midface with fillers contrasts heavily with ageing forehead and brow wrinkles. Also, she warns that injecting in the incorrect spot may add additional mass to the cheeks and cause them to sag even further. Some alternatives may include:

Non-ablative Radiofrequencies

Electromagnetic waves vibrate water molecules in the skin to generate heat. Lax skin is heated at the dermis to 50-70C  where collagen fibres reshape themselves under the heat and shrink by 30%, essentially tightening the skin and forcing new collagen to form within weeks.³

Botulinum Toxin (Botox)

Botulinium Toxin is typically injected into the nasolabial muscles responsible for dilating the nostrils and lifting the upper lip (levator labii superioris alaeque nasi).⁴ This relaxes the muscle to smoothen the nasolabial groove but treatment at this region carries more risk due to being close to the mouth muscles.⁵

Surgical Threads

Serrated polypropylene threads are used to suture the lax soft tissue into the correct aesthetic position. This provides structural tissue support against gravity without the puffiness and added mass of surgical implants.⁶

Figure 3 – Patient getting a facelift using surgical threads. The face appears more natural as no extra mass is added.  Sulamanidze Et al 2002

Fillers can be a useful tool if they’re used to address the underlying issues that cause nasolabial folds, explained previously. Properly correcting this cosmetic flaw requires increasing the midface volume loss, reducing skin laxity and compensating for the stretched-out ligaments. Without correctly supporting the sagging soft tissue and replacing lost volume, the problem will only return with a vengeance in due time. A routine of only dermal fillers themselves can cause the fold to migrate to the middle which is worse for aesthetics and gives the characteristic ‘botched’ look. Applying dermal fillers to this region needs special care to avoid the facial artery which is why the application is often done with multiple smaller volumes.

How QOVES Studio Can Help


Skin Retouching

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  1. Pessa JE, Zadoo VP, Yuan C, et al, ‘Concertina effect and facial aging: nonlinear aspects of youthfulness and skeletal remodeling, and why, perhaps, infants have jowls,’ Plast Reconstr Surg, (1999) 103(2) p.635-644.
  2. Benedetto A, ‘Botulinum Toxins in Clinical Aesthetic Practice’, CRC Press (2011).
  3. Kalil, Célia & Reinehr, Clarissa & Esteves, Celso. (2018). Non-ablative Radiofrequency for Facial Rejuvenation. 10.1007/978-3-319-16799-2_27.
  4. Kane, Michael & Monheit, Gary. (2017). The Practical Use of AbobotulinumtoxinA in Aesthetics. Aesthetic Surgery Journal. 37. S12-S19. 10.1093/asj/sjw285.
  5. Hexsel D, Spencer JM, Woolery-Lloyd H, Gilbert E. Practical applications of a new botulinum toxin. J Drugs, Dermatol. 2010;9(3 Suppl):s31-s3
  6. SULAMANIDZE, M. & FOURNIER, P. & PAIKIDZE, T. & Sulamanidze, George. (2002). Removal of Facial Soft Tissue Ptosis With Special Threads. Dermatologic Surgery. 28. 367-371. 10.1097/00042728-200205000-00001.
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  8. Wulc AE, Sharma P, Czyz CN, ‘The anatomic basis of midfacial aging. Midfacial Rejuvenation’, Springer, (2012) p.15-28.
  9. Rossell-Perry P, ‘The zygomatic ligament of the face: a critical review’, OA Anatomy (2013) 1(3).
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  11. Pessa JE, Zadoo VP, Mutimer KL, et al., ‘Relative maxillary retrusion as a natural consequence of aging: combining skeletal and soft-tissue changes into an integrated model of midfacial aging’, Plast Reconstr Surg, (1998) 102(1) p.205-212
  12. Flament F, Bazin R, Laquieze S, Rubert V, Simonpietri E, Piot B. Effect of the sun on visible clinical signs of aging in Caucasian skin. Clin Cosmet Investig Dermatol. 2013;6:221-232. Published 2013 Sep 27.
  13. Oral melanin pigmentation related to smoking in a Turkish population. Unsal E, Paksoy C, Soykan E, Elhan AH, Sahin M. Community Dent Oral Epidemiol. 2001 Aug; 29(4):272-7.
  14. Smoking and skin: a study of the physical qualities and histology of skin in smokers and non-smokers. Knuutinen A, Kallioinen M, Vähäkangas K, Oikarinen A. Acta Derm Venereol. 2002; 82(1):36-40.
  15. International guidelines for the in vivo assessment of skin properties in non-clinical settings: Part 2. transepidermal water loss and skin hydration. du Plessis J, Stefaniak A, Eloff F, John S, Agner T, Chou TC, Nixon R, Steiner, Franken A, Kudla I, Holness L. Skin Res Technol. 2013 Aug; 19(3):265-78.
Dr Khaled Mahmoud

A medical researcher with more than 5 years of professional academic and medical writing experience. My main goal is to provide readers with evidence-based, data-driven, detail-oriented content to help them make the best choices.