The delineation of excessive gingival display and review of current treatment options. Discussion over periodontal and prosthetic treatments, mucosal stripping procedures, myotomies, Botox therapy, and orthognathic procedures for correction of the “gummy smile.”
Key points
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A review of the diagnostic criteria and discussion of excessive gingival display (EGD).
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Discussion over the indications and limitations of conservative surgical therapy for EGD.
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Examples of orthognathic correction of EGD are presented.
Introduction
As with all surgical interventions, appropriate clinical diagnosis is paramount. Excessive gingival display (EGD)—the gummy smile (GS)—is a clinical diagnosis. It is important to note that although quantifying criteria for facial aesthetics exist, the continuum of acceptable aesthetics to the unaesthetic facial form depends on both the patient’s and the clinician’s perspective and their interpretation of the facial form. The adage that “Beauty is in the eye of the beholder” holds true. Multiple studies assessing smile aesthetics with quantification of facial norms are used as guidelines to define the degree of EGD.
The key components of EGD are assessments in the “at rest” and “full smile” positions, the full smile can be categorized in 2 phases, posed and spontaneous. The spontaneous position is an unconscious reflex as opposed to the deliberate smile as seen in most portrait photographs. Dynamic movement highlights aspects of the face and smile that are missing from a static evaluation, , the GS needs repeated evaluations so the true baseline can be noted.
Orthognathic evaluation has specific cephalometric and clinical facial norms that many practitioners use, the patient with vertical maxillary excess—excessive gingival show at rest demonstrating poor tooth to lip aesthetics—should be considered as an orthognathic candidate ( Fig. 1 ). An acceptable tooth to-lip-position at rest and EGD upon smiling should not be addressed with orthognathic surgery. EGD while smiling is not a clinical trigger for LeFort surgery. A gummy smile is not diagnostic of vertical maxillary excess and performing vertical maxillary impaction will result in premature aging of the face. With age, the natural soft tissue drape lengthens, resulting in less exposure of the maxillary incisors and more exposure of the mandibular incisors. Vertical maxillary excess with EGD at rest has been described by Garber and Salama designating 2 to 4 mm of gingival exposure as degree I, which can be corrected with periodontal, prosthodontic, and orthodontic treatments. Degree II exhibits 4 to 8 mm and degree III, more than 8 mm; both indicate treatment options with periodontal, prosthodontic, and/or orthodontic treatments with orthognathic correction.
There is a direct correlation between the severity of EGD when smiling and the degree of the perceived unaesthetic appearance. Among 20- to 30-year-olds, 10% have EGD. EGD more common in women than men. The upper lip length on average is 20 to 24 mm. , , The incisor display at rest is 3 to 4 mm for women and 2 mm for men; upon smiling, the upper lip should rest along the gingival margin, with 2.5 mm of gingival display. , , The unaesthetic EGD smile is described with a gingival display of 4 mm or more.
The GS has a multifactorial etiology, and the basis of the diagnosis is an assessment of 3 factors, the dentoalveolar component, the dimension and mobility of the labial soft tissue, and the facial skeletal component. , Success for adequate correction of the GS requires a precise surgical plan. A review of common surgical techniques and their inherent limitations is presented.
Periodontium
The dentoalveolar unit can undergo surgical change in both hard and soft tissue components. Correction in the tooth/crown dimensions, the height of the gingival crevice, the gingival architecture, and the alveolar bone height are common procedures, particularly within the aesthetic zone. Acquired EDG owing to excessive retrusion and poor axial inclination of anterior maxillary dentition secondary to orthodontic movement, classically exhibited with upper premolar extractions and can leave a truly unaesthetic facial appearance with a functional occlusion ( Fig. 2 ). An acquired deformity significantly limits the operative techniques available for correction and is often challenging, incurring prolonged orthodontic management, prosthodontic rehabilitation, and potential orthognathic correction, all of which is an unexpected turn for many orthodontic patients.
Various surgical treatment procedures for short tooth syndrome, altered passive eruption, inadequate crown dimensions, gingival hyperplasia, and gingival biotype , , , have limited success owing to the anatomic limitations inherent to the periodontium. Esthetic prosthodontic correction can provide minimal correction of EGD, although it can greatly improve the hard tissue aesthetic ( Figs. 3 and 4 ). Periodontal procedures addressing thick biotypes or frank hyperplasia have predictable results. The recontouring of the soft and hard elements of the periodontium has a proven record of improved aesthetics with regard to tooth shape and gingival architecture, again resulting in great improvement within the aesthetic zone, yet the impact of EGD remains minimal.
Orthodontic intrusion mechanics, with or without skeletal anchorage or temporary anchorage devices (TADs), in combination with surgical corticotomies, , have demonstrated success. The limitations of TADS include a prolonged treatment time, patient compliance and comfort, loss of TAD stability at the bone interface resulting in TAD failure, root resorption, and long-term vertical instability of dental correction. Corticotomy procedures allow for less treatment time a and decreased incidence of root resorption. ,
Aggressive reduction of alveolar bone is often required with full arch implant reconstruction. Alveolectomy is indicated to achieve appropriate the interarch space, which is the distance required from the implant platform to the occlusal plane. The interarch space is critical for long-term prosthetic success. Lower arch alveolectomy is more common and, when performed on the maxillary arch the procedure, the change in bone height can favorably impact vertical tooth to lip position with the final prosthesis ( Fig. 5 ).
Mucosal stripping
Mucosal stripping along the buccal vestibule to address EGD, with or without frenectomy, , has unfortunately not demonstrated stable long-term results. Parallel incisions within the nonkeratinized tissue are made contingent on the height of the keratinized mucosa and the depth of the vestibule. Mucosal stripping tethers the mucosa to an inferiorly based position, but does not address muscular position nor action. The vertical dimension of the mucosal excision is 1.5 to 2.0 times the desired vertical correction of the EGD. The literature reports acceptable clinical results at 6 months postoperative; however, reports of long-term results are not numerable, with few noting a 10- to 12-month follow-up and commentary on full relapse of EGD beyond 1 year.
The stability of the maxillary midline lip position when not performing a labial frenectomy is obvious, although expecting increased lip length with labial frenectomy is unwarranted. Separation of the frenum does not anatomically impact the muscular bed or the position of the upper lip. Frenectomy is a common procedure and does not lengthen the lip, even with larger LeFort type incisions within the substance of the lip, using the V–Y advancement closure has minimal long term impact on lip length. , The justification for mucosal stripping being effective is based on scarring of the labial vestibule, limiting the elevation of the upper lip. However, supraperiosteal excision of the mucosa has a minimal impact on the anatomic basis of muscular function, and long-term correction of EDG cannot be expected.
Myotomy
Myotomy procedures in conjunction with mucosal stripping have demonstrated better long-term results for the correction of EGD, as well as improved upper lip architecture on smiling. Various myotomy procedures have been described, even in conjunction with rhinoplasty procedures. The separation of the muscular fibers, amputation, or disinsertion of muscular attachments with an emphasis on preventing muscular reattachment is of paramount importance. Myotomy is a more complicated procedure, requiring further dissection with the identification of specific muscular bundles and a definitive means to prevent reinsertion of the levator muscles with the interposition of soft tissue or insertion of an alloplast as a barrier. An increased risk of bleeding, infection, excessive scaring, paresthesia, and reoperation have been reported.
Myotomy procedures are most often directed to the levator labii superioris muscle. With successful disinsertion of the muscle, diminished elevation of the medial aspect of the lip is noted with a minimal effect on the lateral aspect of the lip position. Repositioning of the levator labii superioris origin using circumdental suturing has been documented. Various techniques for approaching the levator labii superioris with amputating, separating, or repositioning have been described.
The short upper lip dimension is a challenging problem with no definitive aesthetic surgical procedure for correction. Lip lengthening procedures are fraught with unpredictable results. Tissue grafting, columellar lengthening, and injectable fillers are invasive and result in changes of the overall dimension of the lip architecture. Addressing the empiric length of the lip is relegated to tissue transfer, mostly for the treatment of cleft lip and palate reconstruction or traumatic injury where there exists an absence or loss of soft tissue. Owing to the inherent need for skin incisions and scarring, there is limited value with these reconstructive techniques when addressing aesthetic correction of EGD. Mucosal grafting procedures increasing labial vestibular height, does not change skin length nor the mechanics of the muscular elevators, and therefore yield unpredictable results.
BOTOX
Facial aesthetic surgery has changed worldwide with botulinum toxin type A (BOTOX). Lip dynamics leading to EGD have been effectively curtailed with the use of BOTOX, which diminishes the upward movement of the lip. Altering lip movement and position with Botox is inherently a good option owing to ease of use and low morbidity. Botox protocols differ slightly, dosage is consistent, though injection sites vary, complications are few and most often temporary. The obvious limitation is the duration of action of BOTOX, lasting only 4 to 6 months. Most protocols involve 2.0 to 2.5 units of BOTOX delivered in specific muscular sites, changes in dosing can be altered to the proportional degree of EGD correction desired. Multiple authors have described their techniques and their associated shortcomings. A combination of periodontal, prosthetic, lip repositioning, and BOTOX procedures have improved individual outcomes and are often staged to optimize patient outcomes. ,
Orthognathic surgery
Orthognathic surgery has gone through 2 recent paradigm shifts. These technological developments cannot be understated with regard to how orthognathic surgery is planned and performed, a great advancement in the practice of surgery similar to internal fixation replacing wire fixation. The advent of virtual surgical planning has had a significant impact on surgical treatment planning, replacing model surgery and the streamlining of intraoperative procedures and is now the preferred manner to plan orthognathic correction ( Fig. 6 ). Custom plating, the second major advancement in orthognathics, allows for splintless surgery and predictable maxillary repositioning.
Addressing the ideal superior repositioning of the maxillary complex for correction of VME can be determined with linear measurements as outlined by Wolford, with X = ( Y – 2)/0.08, where Y is the amount of upper incisor showing and X is the amount of impaction needed. Many practitioners simply use the linear distance of the tooth to lip drape at rest to delineate the vertical degree of maxillary impaction.
The ideal vertical position for the maxillary complex is noted in the rest position. Correcting the vertical midfacial height by measuring the EGD with the animated face would produce an unaesthetic result. A large EGD discrepancy noted between at rest position and smiling position can only be corrected by reassessing the EGD after the completion of orthognathic surgery.
Changes in the maxillary position can be achieved with anterior segmental surgery, LeFort impaction, or segmental LeFort surgery with differential impaction. A critical aspect of maxillary surgery is the need for an intraoperative extraoral reference point, which allows for the measurement of midfacial vertical height. A K-wire placed into the radix of the nose works exceedingly well, is minimally invasive, and has excellent replication of linear measurements. Internal reference points along the facial aspect of the maxillary bone have inherent limitations.
Anterior segmental surgery
Isolated segmental surgery ( Fig. 7 A) was at the forefront of orthognathic surgery before a better understanding of the perfusion of the midfacial structures and the biological safety of the LeFort I osteotomy. There are 3 well-described variations, all if which have undergone various modifications by Wunderer, Wassmund and Cupar. All 3 permit for an anterior-posterior reduction and correction of the axial incisor angulation with vertical impaction of the anterior segment. The Wunderer/Wassmund procedure ( Fig. 7 B) would not be the osteotomy of choice for anterior vertical impaction, because surgical access to the palate is limited. The Cupar osteotomy ( Fig. 7 C) provides direct access to the piriform rim and the floor of the nose. However, vertical repositioning is limited by the step deformity in the palatal shelf and the restriction of palatal soft tissue.
