Dr Souphiyeh Samizadeh outlines how to create an aesthetically pleasing smile through awareness of perioral ageing and dental structure
When we start our training to become aesthetic practitioners, the first things we learn are to fill the nasolabial folds and marionette lines. But how much do we actually know about perioral ageing? The lips and the perioral soft tissues play a key role in facial attractiveness. Lips have physiological functions (protection, eating, speaking and position of teeth) and are central to non-verbal and psychological communication. Plump and well-defined lips represent youth, attractiveness, sexuality and beauty.1,2 Teeth are an integral part of a beautiful smile, and the dentition and smile are significant features in determining facial attractiveness.3 Healthy and well- aligned teeth have been shown to have a positive effect on an individual’s confidence and psychosocial wellbeing.3,4,5 From my own findings, as well as media reports, ageing of the perioral region (e.g. thin lips, mouth furrows, and downward corners of mouth) seems to be amongst the main reasons people seek surgical or non-surgical aesthetic treatments.6 Understanding the components of facial ageing will result in a better understanding of the patient’s individual needs and therefore better-tailored treatment plans.
The perioral region is defined as the lower third of the face, extending from the subnasale to mentum (Figure 1). The key perioral landmarks are:
The philtrum
Cupid’s bow
Lips and vermillion border
Nasolabial folds
Labiomental folds (Marionette lines)
Figure 1: The perioral region: Lower third of the face (indicated by dark blue line). The width of oral commissures is equal to the distance between the medial limbi (light blue lines). The lips should be parallel to interpupillary line (green lines).
Skeletal structure and relationships, soft tissue contours, the dentition and gingival contour, and the lip framework determine a patient’s lower face aesthetic. Skin ageing, subcutaneous fat atrophy and skeletal remodelling are the key factors that contribute to facial ageing. Other factors include smoking, stress, lifestyle, work habits and diet.7,8,9 Treatment and rejuvenation of this region without an in-depth understanding of the anatomy and the ageing process can produce undesirable results.For example, as we age lower facial volume increases, thus, the desired ‘inverted triangle’ facial aesthetic decreases. I also find patients lose fine lip movement and sometimes require additional dental or surgical treatment. Dentition and dental treatment play a significant role in restoring the perioral complex. Conversely, rejuvenation of the perioral complex will further enhance the aesthetic outcome of cosmetic or restorative dentistry. When treating perioral ageing, it is important to bear in mind that facial characteristics are different in men and women. Men have larger philtrum widths, and total lip height, wider mouth width, and their pogonion (the most forward- projecting point on the anterior surface of the chin) is located more inferiorly than in women.10,11,12
Characteristics of ideal lips
The width of the lips: approximately 40% of width of the lower face16,17
The ideal lip ratio on the frontal view is 1:1:6; 40% the upper lip and 60% the lower lip18
The lips are parallel to the inter pupillary line19
The length of the upper lip from subnasale is approximately half the length of the lower lip from the chin10,19
The width of oral commissures is equal to the distance between the medial limbi17
Subnasale to the vermilion border of the lip is curved
There are specific break points on the lips
There is an anterior projection of the central cutaneous lip10
The upper lip: well-defined Cupid’s bow with the apexes at the inferior aspect of the philtral columns20,21
The lower lip: fuller than the upper lip, with slight eversion and more vermillion border show
On profile, the upper lip will extend beyond the lower lip by a couple of millimetres21
Figure 2: Youthful lip, full volume, slight eversion of the lower lip, vertical rhytides are preserved and the ‘wet-dry junction’ of the lower lip is visible. A: Cupid’s Bow B: anterior projection of the central cutaneous lip
The lip framework
When discussing ideal aesthetics and treatment planning for patients, it is important to recognise the differences in races, genders, cultures and aesthetic ideas. The position of lips is affected by the skeletal make up of an individual and the underlying dental support.13,14,15 Abnormal dental-skeletal relationships should be recognised. These patients may need orthognathic surgery or orthodontic treatment, which is beyond the scope of this article. Regardless of cultural and ethnic differences, youthful lips are characterised by fullness and well-defined curvatures.
Lip-teeth relationships
The position and alignment of the dentition influence position of lips, smile, phonetics and functional balance. The maxillary incisal edge curvature would be parallel to the curvature of the lower lip in an ideal smile arc (Figure 4). At rest, there should be 2-4mm vertical exposure of the maxillary incisors in relation to the upper lip.21,22,23 Evaluation of anterior smile aesthetics must include both static and dynamic evaluations of profile, frontal and 45° views to optimise both dental and facial appearance.23,24 Position of the upper and lower teeth, crowding, lost dentition, discoloured teeth or different coloured restorations and tooth wear, all affect the aesthetic of a smile. During advanced facial and smile analysis, tooth proportions and symmetry, the dental midline, gingival aesthetics, the smile arc, width of the smile, buccal corridors (the negative space between buccal surface of upper first premolars and the commissure of lips when patients smile), contacts, embrasures, and incisal and gingival display should be taken into consideration.21,25
Figure 4: The ideal aesthetic smile arc has the maxillary incisal edge curvature parallel to the curvature of the lower lip
Changes with ageing: the hard tissue structures
The hard tissue structures that shape the perioral complex include the mandible, the maxillary bone and the dentition. These bony components are central to the overall facial three- dimensional contour of the face and suspension of the soft tissues. The ageing process affects all of these structures. Genetics, occlusal relationship (the relationship between upper and lower teeth), dental integrity, midface development and skeletal maturity are some of the factors that influence skeletal ageing. Therefore, the rate of skeletal ageing varies in different individuals.7,26,27
The maxilla
Studies have shown that ageing results in:
Maxillary retrusion in both dentate and edentulous individuals, in both men and women16,28
Changes in the bony contour of maxilla: The maxilla rotates clockwise26
Decrease in the maxillary angle and height may play a role in the malar fat pad moving down and forward. This results in a posterior positioning of the upper lip and deepening of the nasolabial folds.28
The mandible
The mandible is the structural foundation of the lower face. Any changes in the dimensions of the mandible will affect the overall aesthetic of a patient’s face. Studies have shown that with ageing:9,16,26,29
The ramus height and mandibular body length decreases significantly as both men and women get older, therefore decreasing chin projection
The bigonial width does not change significantly
The mandibular angle increases in both genders, this may result in blunting or the loss of jawline definition
Loss of mandibular volume contributes towards laxity of platysma and soft tissues of the neck
Figure 5: Perioral ageing: Volume loss, loss of skin elasticity, soft-tissue atrophy, loss of bony support and projection. Loss of mandibular volume also means decreased support of the soft tissues and may contribute to laxity of platysma
The dentition
Chronological tooth wear may result in flattening of the incisal edges, and consequently adversely affect the smile arc. Tooth loss affects the thickness of cortical bone; edentulous patients suffer from significant cortical bone loss and maxillary and mandibular alveolar ridge resorption. This is more pronounced in the mandible than maxilla, and more in women than men, and results in reduced lower face height.30 Tooth loss from the lateral areas of the jaw can result in narrowing of the face and hollowing of the cheeks, whilst loss of anterior teeth will produce a concave profile.31 Severe tooth wear can also reduce the vertical dimension of the lower face. Dentures affect the position of soft tissues and lips, and have a direct effect on the lower face height.27,29
Changes with ageing: the soft tissue structures
Skin
The most important environmental insult that contributes to the age- related clinical changes in skin (changes in colour, surface texture, and functional capacity) is chronic solar exposure. Photoageing is distinct from intrinsic or chronologic ageing. Chronologically aged skin shows epidermal thinning, with flattening of the dermal- epidermal junction and loss of collagen, which results in increased water loss and decreased elasticity of the skin. Drier skin is also the result of reduced water binding capacity and sebaceous gland activity.9 Loss of skin elasticity and volume, in addition to repeated perioral muscle activity, contributes to perioral rhytides.5
Fat compartments and the perioral muscles
Facial fat is divided into deep and superficial compartments and planes. With ageing, the perioral fat compartments become lipodystrophic and ptotic.8 There is a superficial fat compartment characterising the philtrum, which has a particular vascular anatomy.32 With ageing, the malar fat pad descends and overlaps medially and inferiorly over the firmly attached retaining ligament and creates a fold.8 Ptosis of the chin pad, mandibular resorption and lip depressor muscle function, contribute to a prominent labiomental crease.9 The mandibular septum separates the jowl from the submental fat and is adherent to the body of the mandible. The recession of this septum with the ageing mandible results in soft tissue rolling over the border of the mandible.23 Orbicularis oris atrophy, in combination with thinning of the overlying skin, results in formation of vertical rhytides above the vermilion border. This is made worse by smoking.18
Ageing of the lip framework
Structural changes with age
Figure 6 – Perioral ageing: The upper lip loses its volume, lengthens and inverts; the lower becomes thinner and rolls inward. The intercommissural width becomes longer and commissures droop. The vermilion border and philtral columns become thinner; there is flattening of the vermillion border and partial loss of Cupid’s bow; perioral rhytids become apparent and the nasolabial folds and labiomental folds become more noticeable.
Changes in lip morphology during ageing include the position of the lip lines, a decrease in lip volume and thickness (degeneration of elastic and collagen fibres), lip tonicity, changes in lip length and retraction of the lips. On average, there is 2-4mm increase in upper lip length with age.2 It has been observed that the natural curves of the lips are lost through ageing and lip dryness is shown to be statistically more marked in aged women. The lower lip becomes dominant over the upper lip and is more noticeable in women. Vertical wrinkle lines start to appear during the fourth decade of life but become more visible during the fifth decade (there have been some suggestions that this corresponds to menopause).11 The commissures descend and inter-commissural distance increases with age.11
Changes in dynamic of lip movement with age
In a youthful and harmonious smile, the maxillary incisors should be visible and exposed by the upper lip by 2-4mm at rest. On smiling, the entire crown of the maxillary incisors and up to 2mm of associated gingiva should be exposed.
As a result of ageing:11,32,33
The smile gets narrower vertically and wider across
There is a decreased display of maxillary anterior teeth
Exposure of mandibular anterior teeth increases
There is a reduction in the muscles’ ability to raise the upper lip, therefore less display of incisors
We see increased intercommissural width at rest
The buccal corridor increases
Figure 7: The images depict how, with ageing, the smile becomes wider transversely and narrower vertically, showing less maxillary teeth. In addition, the buccal corridor space increases. Older individuals tend to smile with the low lip covering the maxillary anterior incisal edges.
Conclusion
The focus of human communication is the face, thus it is key to social interaction and the perception of attractiveness. The correct soft-hard tissue balance is important for achieving and maintaining a pleasing aesthetic appearance and function. Better understanding of facial ageing leads us towards a three- fold facial rejuvenation technique: restoring volume (loss of bony volume), lifting and reducing the soft-tissues and skin rejuvenation. Advanced rejuvenation involves multidisciplinary treatment and may necessitate dental restorations or plastic surgery. Overfilling and volumising where there is advanced bone resorption or dental problems may lead to undesirable aesthetic results. Likewise, perioral rejuvenation without midface correction is not recommended as this can result in an unnatural look.
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