Extreme skeletal open bite correction with vertical elastics

The etiology of anterior open-bite (AOB) malocclusion may be attributable to a combination of genetic and environmental factors.^1,2  Some characteristics of AOB are divergent maxillary and mandibular occlusal planes, mesial angulation of the posterior teeth, and increased skeletal vertical dimension.^1,3,4  Treatment in the permanent dentition depends on the balance between dentoalveolar and skeletal characteristics. If there is a predominance of skeletal imbalance, the greater will be the chance of a need for combined surgical–orthodontic intervention.^5,6  Sometimes patients may refuse the surgical option for various reasons, and in these cases orthodontic camouflage may be attempted.⁷ 

Conventional orthodontics can be performed with or without extractions, with anterior teeth extrusion^6,8  or with combined posterior teeth uprighting and anterior teeth extrusion with elastics.^3,9,10  Intrusion of the posterior teeth allows autorotation of the mandible and consequently AOB closure.^11–13  Temporary anchorage devices (TADs) are a good option when posterior teeth intrusion is planned.^11–15  The multiloop edgewise archwire (MEAW) technique could be used as an alternative to achieve proper vertical positioning of the anterior teeth, acceptable inclination of the maxillary and mandibular occlusal planes, and uprighting with vertical control of the posterior teeth.^3,10  The use of MEAW requires patient compliance with continuous use of elastics. This treatment approach has been shown to be efficient, providing stable results in severe AOB correction.^10,16,17  The treatment choice would depend on the patient's chief complaint and compliance level, AOB severity, and professional skills.

This case report presents the nonsurgical treatment of a severe AOB malocclusion by means of posterior teeth uprighting and intrusion combined with anterior teeth extrusion using the MEAW technique and vertical elastics.

An 18-year-old male patient presented to the orthodontic clinic with chief complaints of “severe open bite and self-esteem and speech problems.” He had a history of tooth extractions. The clinical examination showed a straight to convex profile, vertical growth pattern, mild chin deviation to the left, lack of maxillary incisor exposure upon smiling, lip incompetence at rest, and an infantile swallowing pattern. He had an open bite involving the anterior (10 mm) and posterior teeth up to the first molars, bilateral posterior crossbite, bilateral Class III molar and left Class II canine relationships, 2 mm of maxillary dental midline deviation to the right and 6mm of mandibular dental midline deviation to the left in relation to the midfacial plane, mild anterior crowding, and an absence of the maxillary right canine and mandibular left first premolar (Figures 1 and 2).

Cephalometric examination showed a skeletal Class III sagittal relationship, large mandible, steep mandibular plane, increased lower anterior face height, and maxillary and mandibular incisors with normal and lingual inclinations, respectively (Figure 3, Table 1). He was in the last maturational stage.¹⁸  The temporomandibular joint showed no symptoms and had normal function and structure. There were no signs of active periodontal disease (Figure 4). He had no contributory medical history, and he expressed a strong desire to avoid orthognathic surgery.

The patient was diagnosed with a severe Class III skeletal open-bite malocclusion, increased lower anterior face height, steep mandibular plane, bilateral posterior crossbite, dental midline deviations, lip incompetency, and infantile swallowing pattern.

The primary orthodontic treatment objectives were to close the AOB, correct the posterior crossbite and dental midline deviations, achieve Class I canine and functional molar relationships as well as ideal overbite and overjet, improve facial esthetics, and obtain passive lip competence.

The following three treatment options were considered: (1) surgical orthodontic treatment (ideal option), which could correct the vertical, transverse and sagittal problems and improve facial appearance; (2) combined maxillary and mandibular posterior teeth intrusion with TADs^11–15  and anterior teeth extrusion with elastics^6,8; (3) vertical control and uprighting of the posterior teeth combined with anterior teeth extrusion with MEAW mechanics and elastics.^3,10,16  The two nonsurgical options included dentoalveolar posterior expansion for posterior crossbite correction, maxillary right canine space creation, and mandibular right first premolar extraction to correct the maxillary and mandibular dental midline deviations, respectively, and to obtain acceptable overjet and bilateral functional Class III molar relationships.^19–21 

These treatment alternatives were discussed with the patient and the third option was chosen.

Before treatment began, the mandibular third molars were extracted to improve the prognosis for mandibular posterior uprighting mechanics. Treatment was initiated with 0.022 × 0.028-inch slot standard edgewise appliances placed in both dental arches. After the mandibular right first premolar was extracted, 0.014, 0.016, and 0.016 × 0.022-inch nickel-titanium (NiTi) archwires were used for leveling and alignment. Concomitantly, maxillary right canine space was created with an open NiTi coil spring (Figure 5A). The anterior open bite decreased by 3 mm after this first phase of treatment (6 months). Then 0.016 × 0.022-inch blue elgiloy multiloop archwires with 5° tip-back activations per loop (generating an accentuated and reverse curve of Spee of 25° in the maxillary and mandibular arches, respectively) were placed, and short Class III anterior elastics (3/16-in, 6.5 oz) were prescribed to be used full-time by the patient (Figure 5B). The activated maxillary multiloop archwire was expanded before insertion to control the transverse dimension.

After 2 months of MEAW mechanics, a significant reduction of the anterior open bite by 7 mm was achieved (Figure 5C). Posterior crossbite correction was initiated with an overlay 0.036-inch blue elgiloy expanded archwire placed in the maxillary first molar tubes in addition to intermaxillary palato-buccal cross-elastics until an acceptable posterior transverse relationship was obtained (Figure 5D). During this phase (6 months), MEAW mechanics continued until the overbite was quite satisfactory. At that time, compensation bends (progressive flattening of the posterior tip back bends) were made and a 0.018 × 0.025-inch stainless steel archwire was placed in the mandibular arch for space closure (Figure 5E). Then 0.018 × 0.025-inch blue elgiloy multiloop archwires were placed in both arches, with some individual bends, and intercuspation elastics were used during the finishing phase (Figure 5F). The patient received orofacial myofunctional therapy during the last 6 months of treatment. The total orthodontic treatment time was 24 months.

The patient had significant facial improvements as demonstrated in the extraoral photographs. The profile was balanced with lip competence at rest and an esthetic smile with maxillary incisor exposure upon smiling (Figure 6). The intraoral and dental cast photographs showed satisfactory overbite, adequate overjet, Class III functional molar relationships, Class I canine relationship on the left side, adequate space for the maxillary right canine restoration, corrected dental midline deviations, and limited correction of the posterior crossbite (Figures 6 and 7). Periodontal heath was satisfactorily maintained. There were no signs of periodontal disease at the end of treatment (Figure 8).

The skeletal changes included an increase in mandibular projection, decreases in facial convexity, and apical base sagittal relationship and vertical relationship (Figures 9 and 10, Table 1).^22–24  Regarding the dentoalveolar changes, there was labial inclination and extrusion of the maxillary incisor; lingual inclination, retrusion, and moderate extrusion of the mandibular incisor; mild intrusion of the maxillary first and second molars; uprighting and mild intrusion of the mandibular first molars; and uprighting and moderate intrusion of the mandibular second molars (Figures 9 and 10, Table 1). There was a decrease in soft tissue convexity and concomitant protrusion of the upper and lower lips (Figure 10).

Cone-beam computed tomography (CBCT) total superimpositions at the cranial base registration²⁵  showed a counterclockwise pitch rotation of the mandible and mandibular residual growth (Figure 11A, Table 2). Maxillary regional superimposition²⁶  confirmed the cephalometric changes: small maxillary changes and posterior teeth extrusion (Figure 11B). Mandibular regional superimposition²⁷  also supported the results described, and residual growth of the mandible was noted. No evidence of condylar remodeling was observed (Figure 11C).

Based on the cephalometric and CBCT superimpositions, there was posterior teeth intrusion that contributed to produce a counterclockwise rotation of the mandible (Figures 10 and 11).

A modified wrap-around prosthetic retainer with an orifice in the incisive papillae region to help correct the positioning of the tongue in the rest position (learning in the orofacial myofunctional therapy) and a lingual fixed retainer including second premolars were placed in the maxillary and the mandibular arches, respectively (Figure 12). The maxillary retainer was prescribed to be used until definitive restoration of the maxillary right canine could be performed. Then a new wraparound with the same palatal orifice was used.

The 2-year posttreatment follow-up records showed stability of the open-bite correction and of the Class III functional molar relationship. The posterior transverse relationship did not worsen (Figures 13 and 14). Periodontal evaluation showed a healthy condition at the 2-year posttreatment follow-up as well (Figure 15).

A combined surgical–orthodontic treatment approach could have been ideal for this patient, simultaneously correcting the vertical, transverse, and sagittal relationships.⁵  Nevertheless, because the patient refused the surgical option, the treatment alternatives were reduced to TADs and conventional orthodontics. However, the patient did not want to use TADs as well.

Counterclockwise mandibular rotation could have been expected when performing posterior teeth intrusion, which helps to improve the open-bite malocclusion. This is normally achieved with TADs.^11–15  However; when conventional orthodontics is planned, as in this case, posterior teeth intrusion is difficult to obtain. Treatment mechanics are based on maintaining vertical control of the posterior teeth, with different appliances, to control the vertical dimension, and the anterior open bite is generally corrected by means of extrusion of the anterior teeth.^6,8 

In the present case, anterior teeth extrusion combined with uprighting and vertical control of the posterior teeth was planned using MEAW and anterior elastics. The activated multiloop archwires generated an accentuated and reverse curve of Spee in the maxillary and mandibular aches, respectively. This activation effect alone could aggravate the open-bite malocclusion. However, short Class III anterior elastics were used to extrude the anterior teeth and correct the Class III relationship. These anterior extrusive forces counterbalanced the MEAW activations and achieved vertical control of the posterior teeth by means of uprighting and intrusion.^3,10,16  Maxillary anterior teeth extrusion was necessary to increase maxillary incisor exposure and achieve a harmonious smile (Figure 6). However, in addition to the uprighting and vertical control of the posterior teeth that the MEAW technique and anterior elastics provided to the case, different degrees of intrusion of the posterior teeth were observed. Mild intrusion of the maxillary first and second molars and mandibular first molar was achieved. In addition, greater intrusion of the mandibular second molars was noted. Before treatment, the patient only had occlusal contact between the mandibular second molars and the maxillary first and second molars. Therefore, intrusion of these teeth contributed to the achievement of satisfactory results. Posterior teeth intrusion was achieved using activated MEAWs and using anterior elastics as anchorage, thus producing occlusal plane rotation and a consequent mandibular counterclockwise rotation that contributed to open-bite correction and resulted in improvements to the patient's facial profile as a result of increased chin projection after treatment (Figures 10 and 11).

CBCT superimpositions corroborated all of the changes observed in the cephalometric tracing superimpositions (Figures 10 and 11). CBCTs were superimposed at the cranial base to visualize the skeletal displacements of the maxilla and mandible.²⁵  Regional superimpositions at the maxilla and mandible^26,27  were performed to observe the intrinsic changes in the apical bases. Reproducibility and reliability of the methods used to perform the three-dimensional superimpositions have been demonstrated.^25–27 

Based on the findings, it can be assumed that the mechanics described produced dentoalveolar changes and rotational modifications of the mandible in this particular case that contributed to the closing of the open bite (Figures 6 to 11). An increase of 2.13 mm in the overbite for each millimeter of reduction of posterior molar height (combined sum of maxillary and mandibular second molar heights) was reported previously when occlusal adjustment was performed.²⁸  In addition, counterclockwise rotation of the mandible between 2.3° and 3.9° consequent to maxillary and mandibular molar intrusion with TADs was reported.²⁹  In this particular case, open-bite correction was obtained by a combination of extrusion of the anterior teeth (greater for the mandibular incisors), intrusion of the posterior teeth (greater for the mandibular second molars), and counterclockwise rotation of the mandible, consequent to posterior teeth intrusion (Figures 10 and 11).

Similar results have been reported with other treatment approaches without the use of TADs. The use of NiTi archwires with accentuated curve of Spee in the maxillary arch and reverse curve of Spee in the mandibular arch combined with anterior elastics showed efficiency for the open-bite correction.⁹  Another option could be to mesially angulate the accessories on the posterior teeth to obtain the MEAW effect.⁶  Obviously, the use of anterior elastics is a critical factor for treatment success because they will deliver the required force to distally angulate and sometimes to intrude the posterior teeth.^3,6,9 

The dental midline deviations were corrected by creating adequate space for the maxillary right canine and by closing the space following the mandibular left first premolar extraction. After dental midline deviation corrections were made and when some overbite was present, the combined mesial movement of the mandibular posterior teeth and retraction of the mandibular incisors were necessary to obtain adequate overjet and Class III functional molar relationships in both sides (Figure 5).^19–21  The combination of mandibular left first premolar extraction, retrusion of the mandibular incisors, and mesial movement of the mandibular posterior teeth may have contributed to the overbite correction and counterclockwise mandibular rotation as well.

Bilateral posterior crossbite correction was initially planned. However, it was only achieved for the maxillary right second premolar and mandibular right first molar. End-to-end transverse relationships were obtained for the maxillary first molar and mandibular second molar on the right side and for the maxillary second premolar and mandibular first molar on the left side. The crossbite between the maxillary first molar and the mandibular second molar on the left side could not be corrected. Despite these limitations, the amount of vertical and facial improvements was considerable, and the patient's chief complaints were satisfied. Premature occlusal contacts were eliminated to ensure that this posterior transverse relationship did not impair the occlusion.

Although the patient was advised to pursue implant-supported fixed prosthetic restoration for the right maxillary canine area, he decided on a conventional tooth-supported fixed prosthesis. Unfortunately, that procedure was not under our control and was performed during the follow-up period.

Anterior open-bite treatment stability of 94.4% and 90% in growing and nongrowing patients, respectively, has been reported for the treatment approach described.^16,17  Stability greater than 75% for different conventional orthodontic treatments has been reported.^6,8,17  In addition, it has been reported that posterior teeth intrusion with TADs results in a relapse of between 20% to 30% and that the greatest percentage of that relapse occurs during the first posttreatment year.^11,12,14  For this reason, the patient's records at the 2-year posttreatment follow-up were considered essential.

Satisfactory overbite correction, orofacial myofunctional therapy, and the customized retainer were considered to be important contributors to the stability observed at the 2-year posttreatment follow-up. Although there was some residual mandibular growth in the posttreatment period, it did not impair the stability of the results (Table 2). As a result of the amount of overbite observed at the 2-year posttreatment follow-up, long-term stability should be expected (Figures 13 and 14).

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  Treatment of an adult patient with a severe skeletal open bite malocclusion was performed using MEAW mechanics and elastics (without using any TADs) by means of posterior teeth uprighting and intrusion along with anterior teeth extrusion, which produced a counterclockwise rotation of the mandible.

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  This treatment approach demonstrated efficiency and good stability for open bite correction over the period observed.