Introduction
A gummy smile, characterised by excessive gingival tissue display during smiling, is primarily a subjective clinical observation rather than a quantifiable cephalometric measurement. The variability in underlying causes, ranging from soft and hard tissue origins to functional aspects, necessitates a nuanced approach to diagnosis and treatment. Visibility of the periodontium, which comprises the gingiva and supporting structures, depends on the smile line’s position. The smile level, a line that follows the lower margin of the upper lip and frequently has a convex contour, plays a crucial role in this evaluation. Excessive gingival exposure leads to what is commonly known as a ‘high gingival’ or ‘gummy smile’.
Orthodontics focuses on enhancing smiles and should value that factors like tooth shape, position and colour do not solely influence a pleasing smile. In contemporary dentistry, both patients and dental professionals must acknowledge the substantial influence of gingival health on the overall aesthetic of an individual’s smile.
Gender differences are evident in the dimorphic concept, influenced by both age and gender. , Research indicates that an aesthetically pleasing smile for women typically involves approximately 3 mm of the gingival display during a natural smile. At the same time, men are expected to show only their anterior teeth without a continuous gingival band. Studies demonstrate that women tend to exhibit more gingiva in their smiles than men, and the prevalence of a gummy smile decreases with age. Age-related factors, such as the loss of muscle tone, contribute to the reduced visibility of upper teeth and increased visibility of lower teeth. Various researchers have noted that normal gingival display typically ranges from 1 to 4 mm. However, it is widely recognised that gummy smiles can significantly impact facial aesthetics. , ,
A gummy smile can vary in severity, falling into categories of mild (2–4 mm of excessive gingival display), moderate (4–8 mm) or severe (>8 mm). In 88% of cases, it manifests as a continuous band of gingival display in the anteroposterior direction; however, it can be limited to the anterior or posterior regions in specific cases. ,
Once an abnormality in the smile level has been identified, it is essential to determine the underlying causes of a gummy smile. The origins of a gummy smile are typically multifactorial complex and usually result from a combination of factors classified as skeletal, dental and soft tissue related ( Fig. 87.1 ).
Multifactorial aetiology of high gingival/gummy smiles.
This chapter offers a comprehensive overview of the multifaceted aetiology of gummy smiles, highlighting the importance of distinguishing between soft and hard tissue origins. The focus is on orthodontic treatment approaches to address moderate to severe gummy smiles. Management of gummy smiles requires diverse orthodontic strategies stemming from different aetiological factors, facilitating more precise and effective treatment outcomes aligned with patient expectations.
Clinical examination and assessment of the patient
During the clinical or photographic examination aimed at assessing gingival visibility in gummy smiles, it is crucial to consider three key points:
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1.
Evaluate the gingival display
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2.
Consider both social and natural smiles
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Consider the use of video recording and intensive observation
Incorporating these considerations into the examination process enables a detailed assessment of gingival visibility in gummy smiles. It acknowledges the dynamic nature of smiles and the need to account for both posed and natural expressions when evaluating a patient’s condition. Dalia El-Bokle and Amany Hassan Abdel Ghany have provided a systematic diagnostic tool for assessing the aetiology of gummy smiles that involves several key steps, each of which helps to identify and quantify potential contributing factors. The steps proposed by the authors are summarised in Figs 87.2 and 87.3 .
Assessment tool for gummy smile.
Source: Dalia El-Bokle, Amany Hassan Abdel Ghany. A systematic diagnostic scheme for excessive gingival display ‘gummy smile’. AJO-DO Clinical Companion, 2022;2(4):335–43.
Assessment chart using Dalia El-Bokle and Amany Hassan Abdel Ghany’s diagnostic scheme (FEOP- Functional esthetic occlusal plane).
Source: Dalia El-Bokle, Amany Hassan Abdel Ghany. A systematic diagnostic scheme for excessive gingival display ‘gummy smile’. AJO-DO Clinical Companion. 2022;2(4):335–43.
Treatment approach
Treatment approaches based on specific aetiology may be grouped as follows:
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1.
Periodontal surgery
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i.
Gingival contouring/gingivectomy
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ii.
Surgical crown lengthening
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i.
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2.
Orthognathic and plastic surgery
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i.
Lip repositioning
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ii.
Botox injections
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iii.
Le Fort I impaction of the maxilla
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i.
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3.
Orthodontic treatment
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i.
Orthodontic intrusion of the maxillary anterior segment
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ii.
Intrusion while retracting with palatal crown torque on the anterior segment
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iii.
Orthodontic intrusion using TADs in the anterior region
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iv.
Orthodontic intrusion of the whole maxillary arch
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v.
Retraction of proclined incisors for a natural lip posture
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vi.
Orthodontic intrusion of the canted segment to correct asymmetric high gingival smiles
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i.
Periodontal surgery
Gingival contouring/gingivectomy
Gingivectomy is indicated where the clinically desired reduction is limited to the sulcular gingiva (free gingiva), does not require reduction of the supracrestal attached tissues, and there is sufficient keratinised tissue of 2 mm or greater. A gingivectomy is also indicated in type IA altered passive eruption cases.
Surgical crown lengthening
Surgical crown lengthening is indicated where the desired quantity of gingival reduction exceeds the sulcular gingiva depth, such as altered passive eruption types IB and IIB. Clinical probing and radiographic assessment are required to plan surgical crown lengthening; both analogue and digital stents can be fabricated to facilitate the surgery.
Orthognathic and plastic surgery
Lip repositioning
Lip repositioning surgery is an effective surgical procedure to treat certain gummy smiles. , This surgical procedure is especially advantageous for patients who exhibit excessive gingival exposure when smiling due to moderate cases of vertical maxillary excess (VME) or the presence of a hypermobile upper lip. The primary goal of lip repositioning surgery is to modify the anatomical vestibule to reduce muscle tension. In addition, this surgical approach can be coupled synergistically with other periodontal procedures, such as crown lengthening or gingivectomy, to obtain the most desirable aesthetic results. Subjects with minimal attachment zones of the gingiva and severe vertical maxillary are unsuitable for lip repositioning surgery.
Botox injections
Botulinum toxin type A is a neurotoxin (Botox) that induces temporary paralysis or relaxation when injected into muscles. Botox is strategically administered to the hyperactive muscles that elevate the upper lip excessively while smiling, namely the labii superioris, nasal alar elevator, zygomaticus minor, and zygomaticus major muscles. This muscle relaxation effectively prevents the upper lip from ascending excessively during smiling, reducing exposure to the gums. According to a meta-analysis and meta-regression study, the effects of Botox may be seen for at least 12 weeks, returning close to initial values within 24 weeks after application. After this period, the muscles gradually regain their normal function, and repeat injections may be necessary to maintain the desired results.
Orthodontic treatment
If the occlusal plane inclination indicates dental hypereruption, with maxillary anterior segment overeruption, orthodontic intrusion of the anterior segment is a suitable treatment option. Intrusion arch options include a basic intrusion arch, temporary anchorage device (TAD)-supported intrusion arches or intrusion with anchorage derived directly from anterior TADs. According to a study by El Namrawy et al., in the TAD-supported intrusion group, overbite correction was found to be 2.6 ± 0.8 (0.49 mm per month), while in the intrusion arch group, it was found to be 2.9 ± 0.8 (0.60 mm per month). Similar levels of maxillary incisor intrusion were reported in both groups. TAD-supported intrusion raises concerns about root resorption following intrusion. Therefore, to avoid any iatrogenic effects, the force of the intrusion must be kept to a minimum.
Orthodontic intrusion of the maxillary anterior segment
A one piece intrusion arch may be a viable technique to intrude the maxillary anterior teeth to correct the gummy smile. This intrusion, however, is difficult to achieve and is frequently accompanied by molar extrusion, which is undesirable, particularly in hyperdivergent patients with gummy smiles. To offset the extrusive moment on the molars, a transpalatal arch (TPA) would be required.
In the author’s experience, adding a retractive force vector combined with an intrusive force on the maxillary anterior teeth is favourable because intrusion alone would cause a counterclockwise rotation along the axis of the maxillary incisors, thereby proclining them at the same time ( Fig. 87.4 ). This effect may be advantageous in class II division 2 situations with severe maxillary incisor retroclination.
An intrusion arch used alongside retraction using two posterior TADs.
Net movement on the maxillary anterior teeth is retraction and intrusion.
TAD-supported intrusion arches decrease the tipping moment and extrusive force exerted on molars compared to conventional intrusion arches. Because anchorage comes from the posterior TADs, there are no adverse effects on the vertical position of the maxillary molars ( Fig. 87.5 ).
A 36-year-old female patient with a class II division 2 malocclusion and a gummy smile treated with a posterior TAD-supported intrusion arch.
Intrusion while retracting with palatal crown torque on the anterior segment
The use of TADs in combination with increased positive crown torque in the anterior segment on a continuous archwire can result in incisor retraction with an intrusive vector. This technique may be beneficial for correcting mild gummy smiles or developing iatrogenic gummy smiles that can occur during extraction treatments.
Fig. 87.6 demonstrates an additional intrusive force applied from the posterior miniscrew to the molar buccal tube. This is in addition to the positive crown torque exerted on the base archwire and the retractive distal force from the posterior infrazygomatic crest (IZC) TADs. This biomechanics is employed to prevent any posterior extrusion during the retraction of the anterior teeth.
TADs in conjunction with increased positive crown torque in the anterior segment on the base archwire resulting in incisor retraction and simultaneous intrusion.
Direct anchorage using tads in the anterior region
To address some cases of gummy smiles caused due to hypereruption of maxillary anterior teeth, a single miniscrew placed in the frenulum area between the maxillary central incisors and an intrusive force from the TAD to the base archwire between the two central incisors is a smart alternative. Intrusion biomechanics should be employed on well-aligned arches with a rigid base archwire, to resist arch form changes and maintain anterior torque. Unfortunately, the nature of force distribution from single midline TAD may result in significant intrusion of the central incisors, creating a vertical offset with lateral incisors or the canines, resulting in a flat smile arc or, in some cases, a reverse smile arc. In such circumstances, the brackets should be repositioned with subsequent use of low gauge wires or tiny second-order bends placed on the archwire to restore the patient’s natural smile arc at later stages.
Using two temporary anchorage devices
TADs in the anterior region to actively intrude the anterior segment, along with a retractive force applied distally, can help avoid the previously mentioned effects. In cases where space closure is not a factor, this distal force can be minimised to 50% of the typical retraction force, just enough to counteract any proclination due to the anterior intrusion ( Figs 87.7 and 87.8 ).
Anterior dental hypereruption treated with two anterior and two posterior TADs.
Distal forces are kept to a minimum (50%) with the purpose of countering the incisor proclination alone.
A 23-year-old female patient with bidental protrusion and a 4 mm gingival display when smiling.
The first bicuspids in all 4 quadrants were extracted; retraction and simultaneous intrusion of the anterior segment were performed using four TADs.
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