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Orthodontics, Gummy Smile

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Last Update: October 27, 2018.

Introduction

Modern society emphasizes attractiveness. Facial attractiveness and a well-balanced smile are particularly important for self-esteem and social integration. Excessive gingival exposure during smile can severely alter esthetics. Therefore, offering an attractive smile is a crucial element in orthodontic patient satisfaction.

Anatomy

According to the literature, the gingival smile can be defined as a state in which the line of the smile moves in the apical direction beyond the anteroposterior teeth, causing excessive exposure of the maxillary gingiva during the smile.

The main etiology of gingival growth is bacterial plaque and tartar indicative of a lack of oral hygiene. Other general factors include the use of certain drugs known for their hyperplasic effects. These drugs include cyclosporin A used as an immunosuppressive agent in transplant patients to prevent tissue rejection and phenytoin prescribed for people with epilepsy.

Hormonal imbalances such as pregnancy and puberty, as well as certain hematological conditions such as leukemia, may be responsible for the genesis or aggravation of gingival enlargement.

Etiologies can vary widely, and various elements can interact while smiling. These elements involve labial, dental and gingival components of the smile and the dynamic relationships between them; not only lip length but also activity, clinical crown size, dentoalveolar extrusion, and vertical maxillary height excess are the main causes.

Indications

According to many authors, the gummy smile is prevalent with a percentage of 10% of 20 to 30 year-olds and occurs much more in women than men.

Excessive gingival display decreases with age. As a consequence, it can offer an esthetic aspect of a "youthful appearance."

Preparation

The diagnosis of a gummy smile has to be precise and based on a detailed and careful analysis of the factors and the degree of their participation in the gummy smile occurrence.

In contrast to a pleasant smile, a gummy smile is characterized by an excessive gingival display associated with a high smile line that can be linked to several causes.  These causes include abnormal dental eruption proved by a short clinical crown of teeth, low-length or hyperactivity of the muscles of the upper lip, or excessive vertical growth of maxilla.

The "smile line" is very commonly used a parameter to analyze and categorize a patient's smile. According to many studies on smile perception by both orthodontists and laypeople, it is a valid tool to evaluate the esthetic aspect of a smile and to quantify the amount of gingival display of a smile.

Necessary data for a proper diagnosis include medical and dental histories, extraoral and intraoral clinical examinations, study models, and photographs.

The cephalometric analysis provides comprehensive information on craniofacial structures. However, the evaluation of gummy smile is mainly clinical. Thus, this analysis serves to confirm the possible alveolar-skeletal etiologies.

Technique

Spontaneous and posed smiling records are highly recommended for diagnostic purposes. However, they do not give all the information needed for smile analysis. Because of a smile's dynamic nature, it is proposed to have video documentation of the smile. The use of dynamic documentation of the smile turns vital to esthetic rehabilitative treatment, enhancement of communication between the orthodontist and his patients, and integration between all specialists working in collaboration.

Complications

If there are no aesthetic and functional complaints, it is preferable to abstain from treatment. A slight gingival exposure when smiling outside of any malocclusion is aesthetically accepted, which can direct the practitioner toward abstention to avoid possible therapeutic failures.

A successful treatment needs various dental specialists to work together. Orthodontics, periodontics, prosthodontics and oral surgeons have to work together for a successful treatment plan. Depending on the severity of the problem, orthopedic, orthodontic and/or surgical therapeutic correction may be needed.

The orthodontic correction with mini screws is indicated for an intrusive root movement of incisors. In fact, their use, in combination with a continuous arch, is an effective and reliable therapeutic modality for torque control and intrusion of upper incisors.

Recent improvements in the design of the aligners have been made to improve the leveling of the Spee curve with incisor ingression and premolar and molar egression, allowing correction of excessive gingival exposure the supraclusion during the smile.

Early orthodontic treatment associated with vertical control can decrease the malocclusion, improve the prognosis, as well as enhance the appearance. In severe and complex cases, orthognathic surgery is the optimal solution. In these cases, LeFort 1 osteotomy for impaction surgery after orthodontic preparation is the right option.

Pre-surgical simulation is imperative before the orthognathic intervention. The surgical set-ups will allow to simulate the different bone displacements and to predict the final therapeutic results.

For a gummy smile, surgical management with a lip-repositioning procedure is accomplished by removing a part of the mucosa from the buccal vestibule of the maxilla and then suturing the labial mucosa to the mucogingival line. This leads to a narrower vestibule and a reduced gingival display when smiling.

Compared to extremely risky orthognathic surgery, lip repositioning is a simple, promising, and inexpensive technique for treating a gummy smile.

Injection of botulinum toxin may also be safe and cosmetically effective therapy when carried on by well-experienced practitioners. This toxin is a powerful paralyzing agent that acts at the level of the neuromuscular junction by inhibiting the release of acetylcholine causing a chemo-denervation leading to the reduction of muscle activity.

The rehabilitation of the gingival smile by fixed prosthesis aims to lengthen the short clinical crowns, especially in case of microdontia, impaired passive eruption or loss of dental substance by erosion.Generally, the prosthetic treatment of the gingival smile requires coronary elongation to benefit from sufficient hard dental tissue essential for prosthetic retention and to ensure adequate biological space.

Questions

To access free multiple choice questions on this topic, click here.

References

1.
Bolas-Colvee B, Tarazona B, Paredes-Gallardo V, Arias-De Luxan S. Relationship between perception of smile esthetics and orthodontic treatment in Spanish patients. PLoS ONE. 2018;13(8):e0201102. [PMC free article: PMC6089430] [PubMed: 30102694]
2.
Faus-Matoses V, Faus-Matoses I, Jorques-Zafrilla A, Faus-Llácer VJ. Lip repositioning technique. A simple surgical procedure to improve the smile harmony. J Clin Exp Dent. 2018 Apr;10(4):e408-e412. [PMC free article: PMC5937970] [PubMed: 29750105]
3.
Mohamed Ali J, Ines D. StatPearls [Internet]. StatPearls Publishing; Treasure Island (FL): Oct 27, 2018. Orthodontics, Gummy Smile. [PubMed: 29262052]
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Nahm KY, Shin SY, Ahn HW, Kim SH, Nelson G. Gummy Smile Correction Using Lingual Orthodontics and Augmented Corticotomy in Extremely Thin Alveolar Housing. J Craniofac Surg. 2017 Oct;28(7):e599-e603. [PubMed: 28806378]
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Wang XD, Zhang JN, Liu DW, Lei FF, Liu WT, Song Y, Zhou YH. Nonsurgical correction using miniscrew-assisted vertical control of a severe high angle with mandibular retrusion and gummy smile in an adult. Am J Orthod Dentofacial Orthop. 2017 May;151(5):978-988. [PubMed: 28457276]
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Gao X, Wang T, Song J. Orthodontic and surgical management of a patient with severe skeletal Class II deformity and facial asymmetry: A case report with a 5-year follow-up. Am J Orthod Dentofacial Orthop. 2017 Apr;151(4):779-792. [PubMed: 28364902]
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Bookshelf ID: NBK470437PMID: 29262052

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