Skeletal open bite treated with clear aligners and miniscrews

This case report describes the treatment of a 16-year-old female patient with a skeletal open bite and temporomandibular dysfunction. Clear aligners and miniscrews were used to control the occlusal plane and improve the skeletal problem. At the end of treatment, the mandible had rotated counterclockwise, allowing bite closure, upgrading dental and facial esthetics, and improving temporomandibular dysfunction.

Highlights

  • Skeletal open bite was treated with clear aligners and miniscrews.

  • Occlusal plane control and counterclockwise rotation of mandible allowed bite closure.

  • Dental and facial esthetics improved, and temporomandibular disorder was alleviated.

An anterior open bite remains one of the most complex clinical cases in the field of orthodontics, mostly because of the mechanisms needed to treat this condition and its high rate of relapse. This alteration can be due to a dentoalveolar anomaly or a skeletal problem. Skeletal problems often have poor prognoses compared with dentoalveolar problems and surgery combined with orthodontic treatment is often indicated in such cases. , The etiology can be multifactorial and may include nonnutritive sucking or tongue thrusting, and it is often correlated with a genetic or familial predisposition.

Although extrusion of anterior segments may be required, it seems important to perform posterior intrusion in order to correct the open bite. , , True molar intrusion, without the use of skeletal anchorage devices, is difficult to correct. To achieve it, miniscrews have been developed with advantages that include easy handling, simple and less-invasive treatment mechanics, shorter treatment time, and greater comfort. , Treatment with aligners seems to be the best way to avoid molar extrusion because of the material between the occlusal surfaces. It also allows anterior mandibular rotation, thereby reducing facial height and improving pogonial projection with correct torque, inclination, and maxillary-molar distalization. ,

In the literature, a relationship between Class II malocclusions exhibiting steeper occlusal planes, posterior premature tooth contacts, and temporomandibular disorder (TMD) has been described. The purpose of this case report is to describe the treatment of a patient with a skeletal open bite in which orthodontic treatment with aligners (Invisalign system [Align Technology, Inc, Santa Clara, Calif]) and miniscrew was used to control the occlusal plan and improve the skeletal problem. This procedure also appears to be important for temporomandibular disorder (TMD) management to achieve normal occlusion and functional improvement.

Diagnosis and etiology

A 16-year-old female presented with a skeletal open bite and temporomandibular dysfunction ( Fig 1 ). Clinical examination revealed a bilateral click during mouth opening, mainly on the right side, with a history of muscle and articular pain followed by headaches in the temporal area. A molar and canine Class III tendency was observed on the right and left sides, which became a Class II bilateral in centric relation with an open bite worsening ( Fig 2 ). Dental midlines were centered with the facial midline.

Fig 1
Pretreatment extra and intraoral photographs.

Fig 2
Pretreatment dental casts.

A panoramic radiograph showed an asymmetrical condylar morphology, with a smaller condyle on the left side and the absence of tooth 4.8 ( Fig 3 ).

Fig 3
Pretreatment panoramic x-ray.

Lateral cephalometric radiography in maximum intercuspation exhibited a hyperdivergent profile (Frankfort mandibular plane angle [FMA] = 38°), with a skeletal and alveolar Class II (ANB = 6.1°, A-B distance = 8 mm) and mandibular retrognathia ( Fig 4 ; Table ).

Fig 4
Pretreatment lateral cephalometric radiograph and tracing.

Table
Pretreatment and posttreatment cephalometric analysis
Cephalometric analysis Normal Before treatment After treatment
FMIA (°) 70.0 ± 5.0 54.3 53.2
FMA (°) 25.0 ± 3.0 38.0 32.1
IMPA (°) 89.5 ± 2.5 87.7 93.0
SNA (°) 82.0 ± 2.0 81.7 81.4
SNB (°) 80.0 ± 2.0 75.7 77.0
UI/NA (°) 22.0 ± 2.0 27.0 22.8
ANB (°) 3.0 ± 2.0 6.1 4.5
Overbite (mm) 2.5 ± 2.5 −1 2.7
Overjet (mm) 2.5 ± 2.5 5.8 2.8

There was also a skeletal open bite with negative overbite (−1 mm) and an increased overjet (5.8 mm) leading to labial incompetence. The patient’s maxillary incisors were characterized by high tipping, and there was a lack of space on both arches, resulting in crowding in the anterior sector ( Fig 1 ).

Treatment objectives

The following treatment objectives were established: (1) closure of the anterior open bite by re-establishing the occlusal plane, thereby improving intercuspation and increasing the overbite, first through posterior molar intrusion (specifically on the mandibular-posterior teeth), relative extrusion of the anterior teeth, and then, only if necessary, through true extrusion; (2) expansion of the maxillary arch to create more space for the tongue and to correct the slight crowding, avoiding proinclination; (3) for facial objectives, improving the smile and retrognathic profile and decreasing the high lower-third of the face by counterclockwise rotation of the mandible; and (4) improvement of TMD, reducing temporomandibular joint clicks and muscular pain by occlusal plane control and stabilizing occlusal contacts and function.

Treatment alternatives

Because there was a skeletal open bite, a Class II facial profile associated with a retrognathic mandible and temporomandibular dysfunction, orthodontic-orthognathic surgical treatment was initially proposed. However, the patient refused this treatment plan.

We could have chosen to reorient the occlusal plane using a multiloop edgewise archwire; however, doing so would not completely correct the position of the maxilla or the retrognathic mandible. Furthermore, this was not an esthetic treatment, and the intermaxillary elastics would have had to be worn for extended periods of time, a situation that would not be beneficial for the TMD.

Therefore, the treatment agreed on was to camouflage the skeletal open bite with Invisalign Comprehensive Package (on a total of 40 aligners at this first stage) and mandibular miniscrews. The aim of this treatment plan was to achieve occlusal stability and control the occlusal plane with only true molar intrusion and relative maxillary-anterior extrusion on the first 25 aligners, and then, if necessary, doing anterior true extrusion on the remaining aligners.

Treatment progress

At the first phase, bilateral miniscrews were used on the mandibular shelf, and bilateral buttons were placed on the buccal face of the first and second mandibular molars ( Fig 5 ), connected by an elastic chain to intrude the posterior mandibular teeth as much as possible ( Figs 6 and 7 ), and later connected by a wire to maintain intrusion movement ( Fig 8 ). To improve the aligners’ retention, horizontal attachments were placed. Horizontal attachments were placed on the maxillary molars on the buccal and palatal faces to address the true intrusion.

Feb 28, 2021 | Posted by in Orthodontics | Comments Off on Skeletal open bite treated with clear aligners and miniscrews
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