Anterior open bite is defined as a condition in which upper incisor crowns fail to overlap the incisal third of the lower incisor crowns when the mandible is brought into full occlusion. Within the limits of this definition, the degree or severity of malocclusion may vary from a mild edge-to-edge relationship of the incisor teeth to a severe and handicapping malocclusion.
The diagnosis, treatment, and successful retention of treated open-bite malocclusion continue to be a constant subject of discussion and study, contributing to the frustrations of clinicians. Studies related to the etiology, incidence, classification, characteristics, and treatment of this dysplasia have implicated many potential etiologic factors, including unfavorable growth patterns,[1,2–4] digit-sucking habits,[2,4–9] heredity,[1,6] lymphatic tissue,[7–10] tongue and orofacial muscle activity, orofacial functional matrices, mental retardation, and imbalances between jaw posture, occlusal and eruptive force, and head position.
Treatment of open bite is complicated by the difficulty of differentiating among many possible dentoalveolar and skeletal etiologic factors, depending on the patient’s growth pattern. Cephalometric measurements such as the mandibular plane angle, upper-to-lower facial-height ratio, and anterior-to-posterior facial height ratio have been used to identify vertical discrepancies, but these measurements do not always predict the treatment response and stability of an open-bite malocclusion.[15,16] The overbite depth indicator (ODI) proposed by Kim can be helpful in determining the skeletal pattern. ODI is the arithmetic sum of the angle of the AB plane to the mandibular plane and the angle of the palatal plane to Frankfort horizontal. The norm is 74° ± 6.07°; a value of 68° or less indicates a skeletal open-bite tendency.
An open bite will sometimes correct spontaneously after the elimination of detrimental habits in the early mixed dentition. Some of the treatment modalities are interceptive orthodontics treatment using removable Hawley appliance with screening device and habit breaker, tongue crib followed by phase II treatment, Haas appliance which is followed by Hawley retainer with tongue guard for stability (retention) after which phase II treatment follows, fixed orthodontic therapy with anterior elastics, and orthognathic surgery. A successful nonsurgical treatment for an adolescent female presented with Angle Class III malocclusion, excessive lower facial height, and the anterior open bite has been reported in previous studies. The patient refused the orthosurgical treatment modality and another option was suggested using multiloop edgewise archwire (MEAW) in association with a chin cup to correct the divergence of occlusal planes and molar relationship, without a major change in the patient’s profile.
Whatever form of treatment is chosen, goals should include correcting the inclination of the occlusal planes, aligning the maxillary incisors relative to the lip line, and uprighting the axial inclinations of the posterior teeth. This article presents a modification of the McLaughin, Bennett, Travesi (MBT) technique, using 0.017 × 0.025 reverse curves NiTi archwire in the upper and lower arch and posterior box elastics.
The appliance is a modification of the MEAW technique introduced by Charles Tweed. The multiple loops were replaced by the reverse curve of Spee in the lower arch and the exaggerated curve of Spee in the upper arch. Enacar et al. gave a modification by placing a reverse curve in both arches along with very heavy Class II elastics. In our study, we have used a 17 × 25 reverse curve NiTi archwire with posterior box elastic. The posterior box was given in the Class II pattern.
A 23-year-old female came to the department with the chief complaint of forwardly placed upper front teeth. The patient cited esthetics as the main reason for desiring orthodontic treatment. The patient had no relevant dental or medical history. Siblings and parents of the patient did not have similar malocclusion, confirming that there was no hereditary component responsible for the patient’s malocclusion. Patient’s written consent was taken before starting the treatment.
On extraoral examination, she had a mesocephalic, mesoprosopic face, a convex profile, anterior divergence, and incompetent lips. The patient displayed a nonconsonant smile arc and upturned nose in profile view. There was no history of respiratory problems. On functional examination, it was found that the patient has a tongue-thrusting habit. Intraoral examination revealed an anterior open bite of 6 mm with Angle’s Class I molar relation bilaterally. The intraoral examination also showed upper and lower anterior spacing [Figure 1].
Tongue size was normal as no lateral indentations were present on the lateral aspect of the tongue. The cephalometric tracing confirmed that the patient had a moderate Class II skeletal pattern with an ANB value of 4°. The patient had an average growth pattern and proclined maxillary and mandibular incisors. Cephalometric analysis for orthognathic surgery (COGs) dental analysis revealed intrusion of incisors and extrusion of posterior teeth confirming diverging maxillary and mandibular occlusal planes.
The objectives of the treatment were to eliminate the tongue-trusting habit and redefine perioral muscular function, close the open bite by correcting the inclinations of the maxillary and mandibular occlusal planes, correct the axial inclinations of the anterior teeth and improve facial appearance and labial balance.
Nonextraction treatment plan was decided for the patient. The patient was advised to perform tongue exercises to correct the tongue-thrusting habit. An innovative technique was decided upon which was a modification of the Enacar method of open-bite correction [Figure 2].
Preadjusted 0.022 slot mechanotherapy was used and initial wires were used for alignment. After alignment, 17 × 25 reverse NiTi was placed in the upper and lower jaw. Heavy Class II elastic was used in Enacar modification which was replaced in our case by box elastic placed in a Class II manner. About 3/16-inch box elastics were used which provided 4 oz force which was replicated from Kim’s method. Figure 3 depicts the occlusion status after the appliance removal. The total treatment time was 18 months. Posttreatment photographs have been shown in Figure 4. Pre- and postcephalometric changes are shown in Table 1. For retention, a removable Hawley appliance was placed in the upper arch and fixed lingual retainers were given in the lower arch as shown in Figure 5. As the patient responded well to the tongue exercise and once the bite was closed the tongue-thrusting habit stopped which meant that the patient had a secondary type of tongue thrusting. Thus, a tongue crib was not included during the treatment and retention. An open-bite bionator was given to the patient for nightwear.
Cangialosi suggested that most patients with anterior open bite have skeletal and dentoalveolar features contributing to the malocclusion. The distinction between skeletal and dental open-bite malocclusion is a practical matter because there should be different approaches for each condition to obtain an effective and stable treatment result. Various therapeutic modalities have been proposed for the treatment of anterior open-bite malocclusion in both growing and nongrowing patients, depending on the treatment objectives. Conventional orthodontic-orthopedic treatment has been directed at inhibiting vertical maxillary growth with headgear, retarding mandibular growth with chin cups, and extruding anterior teeth with vertical elastics.[23,24] Some other methods that have been used include tongue-crib therapy for habit control, posterior bite-blocks, posterior magnets, magnetic active vertical correctors, and functional appliances.
MEAW therapy for anterior open-bite malocclusion has been demonstrated to be effective in the treatment of this malocclusion. Kim et al. evaluating its long-term stability found no significant relapses in a 2-year follow-up. This mechanism was able to retract and extrude the anterior teeth and to upright the posterior teeth.[22,25] It is a good option for orthodontic treatment of skeletal open bite, although the technique has little or no effect on the skeletal pattern.
In Kim’s method, a precisely formed MEAW is used to obtain all objectives of open-bite correction. Originally 0.016 × 0.025” stainless steel (SS) wire was used on a double edgewise bracket with a 0.018 slot. In the current case report, we have used 0.017 × 0.015” reverse NiTi wire on 0.022 MBT prescription as it is widely used. In Kim’s method, 3/16 inch heavy elastics were placed in opposing posterior teeth with the force of 50 g when the jaw is closed. This was replicated in our study using box elastics with the Class II vector of the force applying a force of 50 g.
The MEAW system advocated by Kim extrudes the anterior teeth while uprighting the posterior teeth. This leads to individual uprighting of the posterior segment. Its loops of SS wire, placed in every interdental area, have the same effect as the more resilient nickel titanium archwire used in our technique. Upper accentuated-curve and lower reverse-curve wires are used because they are simpler, less time-consuming to place, and more hygienic, and they do not irritate the soft tissue. The bite closing mechanism and the treatment results in our case were similar to those of Kim.[26,27]
Stability is the most important criterion for selecting a method of treatment and retention of open-bite malocclusions. The articles presenting the MEAW system showed only one case that was stable for at least 2 years after treatment. This would traditionally have been treated surgically due to the severity of their skeletal problems. Our method of orthodontic treatment was successful in correcting the open bites without greatly affecting the patient’s facial proportions. This is one such appliance which could act as an aid to an orthodontist in the treatment of open bite.
Open-bite correction be it skeletal or dental in origin is difficult to treat and can be challenging for any orthodontist. Hence, this is one such mechanic which could act as an aid to an orthodontist in the treatment of open-bite malocclusion.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
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