INTRODUCTION

Smiling has a significant impact on the satisfaction of individuals, it is related to skeletal, dental, and soft-tissue problems.[1] Common factors have negative impacts on the beauty of a smile, such as buccal corridor, maxillary central incisor crown width to height ratio, maxillary lateral to central incisor ratio, maxillary midline to face, maxillary to mandibular midlines, the teeth alignment, canine and posterior crown torque, incisal edge discrepancy, and maxillary gingival display.[2]

Buccal corridors as the spaces between the anterior surfaces of the posterior teeth and the corners of the lips when the patient is smiling. Having small buccal corridors is considered an attractive characteristic for both males and females. Significant buccal corridors should be identified as an issue during the diagnosis and planning stages of orthodontic treatment.[3,4] Significant buccal corridors in adult patients were commonly addressed through orthognathic surgery or surgically assisted rapid palatal expansion.[5-7] However, the inherent surgery risks, high costs, long-term hospitalization, and attendant morbidity are huge concerns for patients to undergo these procedures.[8]

To overcome those drawbacks, miniscrew-assisted rapid palatal expansion (MARPE) was developed.[9,10] MARPE has two variants, a tooth-bone borne or a solely bone-borne device with a rigid component linking to mini-screws implanted into the palate, enabling the direct expansion force to the basal bone of the maxilla. It was designed to maximize skeletal effects because the incomplete ossification of the mid-palatal suture in humans, even among older individuals, is demonstrated through recent histological research.[10] Therefore, MARPE is considered a non-surgical treatment for maxillary transverse deficiency.

Expression, symmetry, and appearance of the teeth and gingival display also have significant impacts on smile attractiveness. Many patients who require orthodontic treatment are motivated by dental esthetics.[11] The gummy smile is related to the visibility of an excessive amount of gingiva during smiling. The major etiological factors consist of a short upper lip, hyperactive upper lip, skeletal conditions, or altered passive eruption.[12] This study aimed to describe a successful case report regarding the treatment of buccal corridor and gummy smile by MARPE appliance, Niti wire bending, and gingivoplasty.

CASE REPORT

The 20-year-old female patient presented with a chief complaint of protruding lips, maxillary and mandibular incisors that were proclined, a gummy smile, and an excessive buccal corridor [Figure 1].

Figure 1: (a-d) initial extraoral, (g-k) intraoral photographs, (e and f) panoramic and lateral cephalometric X-rays, (l and m) cone beam computed tomography (CBCT) scans.

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Clinical findings Soft tissue Dental

Molar relationship: Class I

Canine relationship: Class II (both sides)

Archform:

Lower arch:

6 mm crowding

Flat curve of Spee

Bolton discrepancy:

Midline: Upper and lower coincident with facial midline.

Skeletal

Skeletal jaw relationship: Class I

Maxilla and mandible: Relatively normal position (SNA 82.4°, SNB 79°, and ANB 3.4°)

Lower facial height: Reduced (FMA 21.4°).

Incisor angulation

Diagnostic assessment Lip position assessment

Upper and lower lips protrusive

Both lips anterior to E-line

Smile: Gummy smile

Buccal corridors: Present.

Dental assessment Skeletal Treatment objectives

The objectives were to fix skeletal Class I malocclusion, with buccal corridors exceeding 4 mm, a gummy smile, and lingual tipping of the lower posterior segments.

Potential alternative treatments

In discussions with the patient regarding this case, we presented several treatment options, including the choice between the current treatment plan and extraction/distalization combined with the intrusion of the entire upper arch. However, the patient expressed concerns about the buccal corridor and preferred not to pursue the option involving the intrusion of the whole upper arch. Consequently, she opted for the treatment involving MARPE and gingivoplasty following the treatment process.

In the case of vertical maxillary excess, intrusion using temporary anchorage devices can be employed. Severe instances may require orthognathic surgery as part of the treatment.

Treatment timeline

First stage: MARPE appliance (three weeks)

Second stage: Fixed appliance with metal brackets (18 months)

Third stage: Gingivoplasty after one month of debonding

Treatment progress

The initial step involved the installation of the MARPE appliance, using a tooth-bone-born design. Teeth separators were placed mesiodistally of the U6s. One week later, the bands were fitted, and an impression was made to create the MARPE with an 8 mm body. The appliance was cemented in place a week later, and 4 mini-screws (1.8 × 12 mm) were inserted through the body of the MARPE. These screws were guided by four holes in the MARPE body, positioned between the second premolar and first molar, with two mini-screws installed at the back with bicortical support.

The braces were bonded on the same day, and a 0.014 Nitinol wire was inserted in both the upper and lower arches. During treatment, upper archwires were utilized for both upper and lower arches. The lower archwire was expanded in the posterior sector to aid the uprighting process, along with lingual buttons and a ¼ 3.5 oz cross elastic for facilitation.

The MARPE was expanded at a rate of 0.25 mm/turn, with an activation pattern of six turns on the first day, followed by two turns in the morning and evening until spacing occurred between 11 and 21 (on the fifth day). Subsequently, one turn was applied in the morning and evening until 4 mm of palatal expansion was achieved. Post-expansion, the MARPE was retained in place for eight months to allow for retention and palatal suture bone remodeling. Moreover, on the first day of bracket bonding, the upper wire was cut between 11 and 21.

In the second stage, after three weeks of MARPE, a continuous archwire and thread elastic were introduced to initiate the closure of the space. The upper cutting remained separated into two segments during the entire MARPE phase, and continuous wires were employed thereafter. When reaching the Nitinol 0.016 × 0.022 stage, a V bend was added between 11 and 21 to facilitate a translation movement while closing the space. For the finishing stage and addressing Bolton discrepancies, interproximal reduction (IPR) was performed on the lower anterior from distal 33 to distal 43 using IPR blades of 0.1 mm, 0.2 mm, and 0.3 mm, followed by fluor polishing. Post this, a 0.017 × 0.025 SS wire on the upper and 0.020 SS wire on the lower, along with Class II elastics (1/8 3.5), were utilized from L6s to U3s to correct the dental Class II relationship [Figures 2 and 3].

Figure 2: (a) MARPE appliance, and (b) MARPE design, (c and d) immediately after MARPE installation, (e-i) three weeks after MARPE installation, and (j and k) cone beam computed tomography (CBCT) scans three weeks after MARPE installation; MARPE: miniscrew-assisted rapid palatal expansion.

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Figure 3: MARPE: miniscrew-assisted rapid palatal expansion.

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In the last stage, gingivoplasty was conducted, involving smile design before treatment presentation to the patient and guidelines for the gingivoplasty procedure. The process involved 2 mm gum cutting, flap opening for gum recontouring, alveolar bone trimming, and closure using medical sutures [Figure 4]. Finally, the Essix appliance was used for the retention protocol, with full-time wear in the first year and in the evenings from the second year onward.

Figure 4: (a) Immediately after gingivoplasty, and (b,c) two weeks after gingivoplasty.

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Treatment results

All treatment objectives were successfully met, resulting in a well-aligned dentition and improved facial esthetics. The expansion of the mid-palatal suture reached 4 mm with minimal buccal crown tipping of the upper posterior teeth. Retraction of both upper and lower incisors effectively corrected severe overjet, utilizing the space created from the MARPE expansion.

The achieved outcomes include the maintenance of a Class I molar relationship and a slight Class II relationship on the canines, attributed to tooth size discrepancies; however, the occlusion is considered acceptable. The maxilla was expanded through MARPE, whereas the mandibular intra-arch width experienced slight expansion due to molar uprighting, as evidenced in cone-beam computed tomography (CBCT) scans [Figure 2].

Throughout the treatment, the retraction of both upper and lower lips facilitated a passive lip seal, contributing to a notably straight profile post-treatment. Minimal root resorption was observed, with good root parallelism achieved across most teeth, aside from tooth 44. There was a notable improvement in incisor inclination and soft-tissue profile, particularly evident in the E-line and nasolabial angle. Cephalometric analysis confirmed these changes, showing a decrease of 5.9° in the inclination of the maxillary incisors [Figures 4-7 and Table 1].

Figure 5: Niti bending (V bend on 16 22 Niti between 11 21 and elastic thread for closing diastema), Niti: Nickel-titanium.

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Figure 6: Nickel-titanium (Niti) bending for buccal tipping posterior lower teeth.

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Figure 7: (a-d) post-treatment extraoral, (e, f) panoramic and lateral cephalometric X-rays, (g-k) intraoral photographs.

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Table 1: Comparison of cephalometric measurement between pre-and post-treatment

Measurement Normal Pre-treatment Post-treatment SNA (°) 78–82 82.4 82.4 Skeletal SNB (°) 76–82 79 78.2 ANB (°) 0–4 3.4 4.1 A-N Perp FH (mm) −1.9–2.7 2.8 3.1 B-N Perp FH (mm) −5.5–−1.5 −0.6 −1.7 FMA (°) 25 24.4 23.7 Y-Axis (°) 59 (53–63) 60.4 60.2 U1-SN (°) 104 121.7 114.8 Dental U1-NA (mm/°) 4/22 8/39 4.5/32.4 U1-MaxP (°) 110–116 127.9 122 U1-L1 (°) 131 102.6 112.5 L1-NB (mm/°) 4/25 8.7/34.8 6.4/31 L1-MP: IMPA (°) 90 100.8 98.2 UL-E line (mm) −4–−1 −1.3 −2 Soft tissue LL-E line (mm) −2–0 0.7 0.4

After a 2-year follow-up, the results remain stable, and the patient expresses satisfaction with the outcome [Figure 8].

Figure 8: (a-b) two years after treatment: extraoral, (c-d) panoramic and lateral cephalometric X-rays, and (e-f) cone-beam computed tomography (CBCT) scans.

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DISCUSSION

This case report demonstrates a successful compensatory treatment of the buccal corridor and gummy smile with MARPE, Nickel-titanium (Niti) wire bending, and gingivoplasty.

The purpose was to expand the mid-palatal suture and address the buccal crown tipping of the lower posterior, aiming to reduce the issue of excessive buccal corridor and enhance the esthetic appearance of the smile. MARPE was considered a suitable choice for this case due to the normal crown torque of the upper posterior teeth, the need for an interproximal reduction on the lower anterior teeth, and the implementation of Class II elastics to reduce the proclination of the upper incisors, ultimately aiming to achieve a favorable occlusion. As the gummy smile originated from a gingival-based cause, surgery was selected as the treatment method. The CBCT revealed that the intermaxillary suture was at a stage B maturation level (the scalloped appearance of the high-density sutural line),[13] which has been linked to a high success rate with MARPE. However, some molar tipping occurred due to the appliance being tooth-bone-borne rather than bone-borne. Utilizing a MARPE appliance, a degree of buccal tipping is anticipated, despite significantly less compared to rapid palatal expansion (RPE), as teeth continue to serve as anchor units alongside mini-screws. The tendency for buccal tipping is directly linked to the resistance exerted by the mid-palatal suture.

Finally, to optimize the cosmetic outcome, an adjunctive procedure involving gingivoplasty was recommended post-treatment. Gingivoplasty was selected as the treatment choice due to the presence of altered passive eruption as the etiology, coupled with a favorable positioning of the incisal edge concerning the lower lip.

Research conducted by Gurgel et al.[14] and Christie et al.[15] has similarly highlighted a certain level of buccal tipping. Previous studies have suggested more pronounced alterations in molar inclination compared to premolars.[16] This greater buccal inclination observed in the first molar, as opposed to the first premolar, could potentially be attributed to the increased density of the buccal cortical bone in the maxillary canine and premolar areas.[17-19]

CONCLUSION

Utilizing bicortical mini-screws in MARPE has been shown to be an effective method in addressing buccal corridors. In addition, combining fixed orthodontic treatment with labial appliances and gingivoplasty has proven to be successful in correcting malocclusion and improving smile esthetics, demonstrating lasting and stable outcomes.