Correction of a gummy smile and lip protrusion by orthodontic retreatment with lingual appliances and temporary skeletal anchorage devices

A 28-year-old woman desired orthodontic retreatment for lip protrusion and excessive gingival display in both the anterior and posterior areas on full smiling. She had previously undergone an extraction orthodontic treatment for correction of open bite. She was diagnosed with skeletal Class Ⅱ hyperdivergence. To mimic LeFort Ⅰ maxillary impaction surgery, posterosuperior movement of the maxillary whole dentition was planned, and bodily distalization of both the maxillary and the mandibular whole dentitions to improve lip protrusion. A combination of lingual appliances, 2 appropriately fabricated power arms, and 1 midpalatal microimplant contributed to the posterosuperior intrusion and bodily distalization of the maxillary arch. With the use of lingual appliances, 2 lever arms, and 2 conventional microimplants, the mandibular arch was bodily distalized. The active treatment period was 37 months, and the results were stable 12 months after treatment.

Highlights

  • Gummy smile in adults with skeletal Class Ⅱ hyperdivergence is corrected orthodontically.

  • Orthodontic maxillary impaction can be obtained with one midpalatal microimplant.

  • Bodily distalization of the maxillary arch is also performed with the microimplant.

  • The microimplant allows the application of orthodontic forces in any direction.

A gummy smile can be caused by excessive maxillary vertical growth, overeruption of the maxillary incisors, incomplete anatomic crown exposure, hyperactivity of the elevator muscles of the upper lip, or a combination of these factors. A gummy smile of skeletal origin can be corrected by orthognathic surgery. A dentoalveolar gummy smile caused by overeruption of the maxillary incisors can be corrected by intruding the maxillary incisors. The dentogingival type of gummy smile is related to the abnormal eruption of teeth or lack of gingival recession and requires lengthening of the anatomic crown. The neuromuscular type of gummy smile is caused by hypercontractility of the upper lip elevator muscles and can be temporarily improved by injecting botulinum toxin type A.

With the advent of temporary skeletal anchorage devices (TSADs), the conventional concepts of anchorage control and biomechanics in orthodontics have changed, and many case reports have demonstrated orthodontic correction of a gummy smile. Lin et al proposed the use of multiple screws to simultaneously address gummy smile, vertical dimension, and mandibular autorotation. Shu et al used mini-implants in the posterior dental region for retraction and intrusion of maxillary anterior teeth, combined with a compensatory curved maxillary archwire. Kaku et al reported treatment of skeletal Class Ⅱ malocclusion with a convex profile and a gummy smile using miniscrews placed in the maxillary posterior and anterior areas. Hong et al showed spontaneous intrusion of the maxillary incisors during bodily retraction in a bimaxillary protrusion patient with normally inclined maxillary incisors using lever-arm mechanics and 1 midpalatal microimplant. Wang et al used 2 miniscrews in the maxillary anterior labial segment for the intrusion of the anterior teeth and 4 miniscrews in the posterior buccolingual segments for retraction of the anterior teeth and intrusion of the posterior teeth. Finally, Paik et al introduced simple mechanics for intrusive maxillary anterior retraction and posterior intrusion using TSAD, an archwire incorporating a curve of Spee, and a conventional transpalatal arch.

Most studies , , have demonstrated management of gummy smile and facial profile in extraction patients with adult Class Ⅱ hyperdivergent malocclusion by performing intrusive retraction of the maxillary anterior teeth with labial appliances and TSADs. Considering the center of resistance and the forces applied, this article describes the orthodontic impaction method of the maxillary whole dentition to improve a gummy smile and facial profile in a nonextraction case with the use of lingual appliances and one midpalatal TSAD.

Diagnosis and etiology

A 28-year-old Korean female patient presented with concerns about her gummy smile and lip protrusion, although she had previously received an extraction orthodontic treatment for correction of open bite. On smiling, she showed excessive gingival display in both the anterior and posterior areas, with a large difference in gingival heights between the maxillary anterior and posterior teeth ( Figs 1 and 2 ). However, there was no interlabial gap at the resting lip position. Dental analysis revealed Class Ⅱ canine and molar relationships with an overbite of 1.6 mm and an overjet of 3.5 mm; an overall Bolton ratio of 91.9% and an anterior Bolton ratio of 81.8% were measured. The patient had no history of trauma or severe disease, and no pathologic signs were found within the temporomandibular joint or in the mouth.

Fig 1
Pretreatment facial and intraoral photographs.

Fig 2
Pretreatment dental casts.

Cephalometric evaluation ( Fig 3 ; Table ) showed a skeletal Class Ⅱ relationship (ANB, 7.5°) with the retruded mandible (SNB, 71.0°), extrusion of maxillary incisors and molars (PP-U1, 32.9 mm; PP-U6, 27.2 mm), and a significantly increased mandibular plane angle (FMA, 32.4°). With reference to the Frankfurt horizontal plane, the maxillary incisors were retroclined (U1-FH, 96.6°), and the mandibular incisors were proclined (IMPA, 101.9°). The position of the maxillary central incisor edge relative to the upper lip at rest was within normal limits (U1-Lip line, 3.0 mm). The panoramic radiograph showed no pathology ( Fig 3 ).

Fig 3
Pretreatment radiographs: A, lateral cephalogram; B, panoramic radiograph.

Table
Cephalometric summary
Measurement Norm Pretreatment Posttreatment 1-year posttreatment
Skeletal
SNA (°) 81.6 78.5 77.5 78.3
SNB (°) 79.2 71.0 71.5 71.9
ANB (°) 2.5 7.5 5.9 6.4
FMA (°) 24.3 32.4 31.7 32.9
FH-NPog (°) 89.1 82.4 82.5 81.5
Dental
U1-FH (°) 116.0 96.6 97.0 98.1
IMPA (°) 96.3 101.9 95.8 96.9
FMIA (°) 59.8 45.7 52.5 50.2
Interincisal (°) 123.8 129.2 135.3 132.2
PP-U1 (mm) 28.5 32.9 30.3 30.6
PP-U6 (mm) 24.8 27.2 24.8 24.0
Mp-L1 (mm) 42.6 45.0 43.7 44.0
Mp-L6 (mm) 34.0 38.0 38.6 38.8
U1-Lip line (mm) 3.9 3.0 0.5 0.5
Soft tissue
Upper lip to E-line (mm) −0.9 1.3 1.6 1.2
Lower lip to E-line (mm) 0.6 3.9 1.3 0.8

Treatment objectives

Our treatment objectives consisted of reducing her excessive gingival display in both anterior and posterior areas, improving lip protrusion, and achieving a harmonious occlusion.

Treatment alternatives

Although the patient showed proper vertical positioning of the maxillary central incisor edges at rest and there was no interlabial gap at the resting lip position, she showed a gummy smile in both the anterior and posterior areas, which seemed to be a result of hyperactivity of the elevator muscles of the upper lip. To correct the gummy smile, 2 treatment options were discussed with the patient. The first was traditional orthodontic treatment combined with LeFort I surgery to reduce the maxillary height, which would reduce the gingival exposure. The second option was orthodontic impaction of the entire maxillary dentition using TSADs. After a review of the risks and benefits of the 2 options, the patient chose the latter, more conservative method. Therefore, nonsurgical orthodontic treatment combined with TSADs was selected for posterosuperior movement of the entire maxillary dentition and total distalization of the maxillary and mandibular dentitions.

Treatment progress

The patient requested esthetic lingual orthodontic treatment. In the maxilla and mandible, lingual brackets (Anboini; BioMaterials Korea, Seoul, South Korea) were bonded indirectly from the first molar to the first molar, and medium arch size 0.012-in nickel-titanium initial preformed lingual straight archwires (PLSAs) were placed in the main horizontal slots of both arches ( Fig 4 ). To avoid tongue irritation from the lingual bracket on the second molar, standard edgewise appliances were placed on the buccal surfaces of the first and second molars in both arches, and segmental wires were engaged in the buccal standard edgewise appliances to control the second molars. The size of the PLSAs was determined when customizing the brackets on the setup model ( Fig 5 ).

Fig 4
A, Anboini anterior bracket. The 0.018 × 0.025-in horizontal slot is designed for a main straight archwire, the 0.019 × 0.019-in vertical slot for effective rotation control, and the 0.016 × 0.016-in accessory slot for simple angulation control. B, Three types of PLSA. A comprehensive line of 3 forms of the PLSA is used for the maxilla and the mandible in lingual orthodontic treatment.

Oct 30, 2021 | Posted by in Orthodontics | Comments Off on Correction of a gummy smile and lip protrusion by orthodontic retreatment with lingual appliances and temporary skeletal anchorage devices
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