Correction of Maxillary Occlusal Plane Deviation with the Aid of Miniscrew Device

The therapy of the maxillary occlusal plane deviation differs depending on the etiology and pathogenesis. Canting caused by extruded teeth can be easily corrected with fixed orthodontic appliances combined with miniscrew anchorages. In this case, the canted maxillary occlusal plane was corrected by intruding extruded teeth with fixed orthodontic appliances combined with miniscrew anchorages, and a customized retainer was produced to prevent relapse.


Introduction
The maxillary occlusal plane deviation, also known as the canted maxillary occlusal plane, is one of the most frequent orthodontic disorders. Treatment varies to the point where surgical intervention may be required [1]. The Cant of the occlusal plane has been linked to a variety of etiologies. Canted occlusal planes caused by unilaterally extruded maxillary molars or uneven mandibular vertical development are common in patients with facial asymmetry [2]. According to Proffit et al. [3] "roll deformity" results from the orientation of the jaws and teeth rather than their position.
Since the introduction of miniscrew appliances into orthodontic practices, this equipment has played an essential role in resolving orthodontic difficulties that seem impossible to manage with conventional orthodontic equipment alone [4]. They can, for example, provide maximum anchorage, intrusion of elongated teeth, and other types of actions [5].
In this case report, we discuss a novel method for correcting a maxillary occlusal plane deviation with a miniscrew; a novel retention technique was also considered to assist in managing this case.

Case Presentation
A 31-year-old male patient complained of an occlusal plane deviation in the maxillary front teeth in January 2018. There was no history of orthodontic treatment, no family history of facial asymmetry, and no history of trauma; the problem developed approximately 17 years.

Clinical examination
1. Extraoral examination: mild asymmetry of frontal facial view (fullness at right side); normal of the profile view ( Figure 1A).

Radiography
1.There are no congenitally missing teeth, supernumerary teeth, or four third molars. The height of the alveolar bone was located at the cementoenamel junction, the mandibular ramus and bodies were symmetrical ( Figure 2A).
2. The analysis of cephalometric radiography before treatment was shown in Table 1.

1.
Soft tissue: frontal facial asymmetry, fullness at the right side; normal profile.

2.
Skeletal tissue: Skeletal Class I in the sagittal direction and flat angle of mandibular plane in the vertical direction.

3.
Dental: Angle Class I; crowded dentition; the maxillary occlusal plane was tilted (high in the left side and low in the right side); the deep anterior overbite; the midline deviation.

Treatment plan
The MBT appliance was utilized to align the upper and lower dentition in a non-extraction treatment. To correct the inclination of the maxillary occlusal plane, a miniscrew was implanted in the right maxillary.
The crowding and lingual inclination of upper anterior teeth were corrected after the eighth months of treatment. Adequate alignment was accomplished; further, the upper midline was corrected, simultaneously, 1 mm space was established between 13 and 23 teeth. The crowding of the lower anterior teeth was not totally alleviated, however. To alleviate the crowding, all mandibular incisors underwent interproximal enamel reduction (IPR).
An 11mm titanium alloy miniscrew (Ningbo Cibei Medical Instruments Co., Ltd., China) was planted between 12 and 13 at the 9 th month of treatment. The miniscrew was to intrude the extruded teeth and correct the canted maxillary occlusal plane. Additionally, a reverse curve of spee wire was used to the lower jaw to help correct a deep overbite in the mandibular anterior teeth ( Figure 1B).

Treatment result
After the treatment, dentitional alignment was achieved.  (Table 1).

MRD.000642. 6(4).2021
Copyright © Fei Wang Figure 4: superimposition of initial, after treatment, and after one year of the retention period.
Black: initial Green: after treatment red: one-year post retention.

Discussion
Occlusal plane deviation that manifests as bilateral occlusal plane asymmetry is a common malocclusion. In this case, we used mini-screw anchoring to intrude the elongated teeth. The intrusive effectiveness attained was quite high, and the patients were comfortable during treatment; also, oral hygiene may be readily maintained. The use of miniscrew anchorage for intrusion in clinical orthodontic practice is a very good technique [6,5].
Periodontal tissue has its own specificity, instability, and relapse can occur at any time after orthodontic treatment.
Therefore, it is important to avoid relapse during the retention period. There are several reasons resulting in relapse. The main ones include periodontal tissue rearrangement, muscular function maladjustment and lack of adequate retention [1,7,8].
The patient must wear the proper retainer to decrease the teeth movement and recurrence rate. The retainers currently employed were Hawley retainers, vacuum-formed retainers, and fixed lingual retainers. Each of the retainers has advantages and disadvantages [9][10][11]. Previous research discovered that conventional retainers could give good long-term clinical stability in orthodontic cases, including extraction cases [12]. In this example, we primarily carried out the vertical intrusion for the anterior maxillary teeth.

However, Traditional retainers show insufficient vertical control.
We used the resin attachments of the invisible appliance as a guide and created a customized retainer. There was no recurrence of occlusal plane deviation one year after treatment. The customized film retainer was a successful method and deserved to be promoted in clinical applications.

Conclusion
The maxillary occlusal plane deviation caused by extruded teeth were easily corrected combined with the regular orthodontic equipment with the miniscrew anchorage; however, post-treatment retention should be carefully planned.