2020, Number 2
Class II open bite malocclusion with a transverse maxillary deficiency corrected with a Hass expander
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Language: English/Spanish [Versión en español]
References: 21
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ABSTRACT
A 13-year-old male patient attended the Department of Orthodontics to improve his smile. He was diagnosed with class II division 1 skeletal malocclusion due to clockwise mandibular rotation, posterior edge-to-edge bite and an anterior open bite. The treatment consisted of 1) Orthopaedic phase: with Hass expander with acrylic support for rapid maxillary expansion and removable lower lingual arch; 2) Bracket phase: upper and lower placement of brackets and replacement of Hass expander with palatal arch with spurs to control lingual projection; 3) Detailing and settling phase; 4) Retention phase. The facial profile was maintained; a pleasant smile, alignment and levelling, correct overjet and overbite, good upper lip projection, centred midlines, class I molar and class I canine bilaterally, and few changes in cephalometric values were achieved. Orthopaedic treatment followed by orthodontic treatment with brackets in class II and growing patients gives excellent results.INTRODUCTION
Class II division 1 malocclusion is often associated with a protrusive maxilla and upper lip together with a convex facial profile. Although the main goal of treatment is the correction of the malocclusion, the beneficial effect of treatment on the facial profile is also appreciated.1-3 The aim of a maxillary expansion is to achieve a transverse skeletal expansion of the maxilla, aiming to avoid dental side effects as far as possible, e.g. tilting of the upper molars. The use of a stable maxillary expansion device is necessary to achieve this skeletal effect and is used in patients who do not suffer from clefts in the mandible and palate area.4-6
Rapid maxillary expansion (RME) leads to spontaneous forward positioning of the mandible before and after the retention period in cases of mixed dentition associated with maxillary constriction and has been the treatment of choice for more than a century. Although the procedure was initially used to correct posterior crossbites, a number of other possible indications have been proposed.7 Numerous RME devices have been widely used by orthodontists, such as Hass and Hyrax. However, long-term evaluation has shown a tendency to relapse in these cases.8,9
Patients sometimes present with an anterior open bite and there are numerous theories as to its aetiology, such as growth patterns, heredity, digital habits or environmental factors and lingual function. Treatments include habit breaking appliances, bite blocks, extra-oral arch, vertical brace chin rests, vertical elastics and surgical correction.10-15 The prevalence of open bite in US children has been reported to be 3.5% in the white population and 16.5% in the African-American population.16 Environmental factors include variations in tooth eruption, alveolar growth, disproportionate neuromuscular growth, or aberrant neuromuscular function related to abnormal tongue movements or oral habits, or both. A primary objective is to distinguish a dental open bite from a skeletal open bite as dental open bites are sometimes self-correcting or respond easily to myofunctional treatment and mechanotherapy, and skeletal open bites are more difficult to treat and tend to relapse. Early treatment of vertical dysplasia during the primary or mixed dentition period has been recommended to reduce the need for treatment in the permanent dentition, when surgery is a viable option.10,15,17
There are different treatment modalities including mainly functional appliances, multibracket techniques and extra-oral arches.17,18 An effective and clinically beneficial treatment would be an RME, however, disadvantages such as bite opening, relapse, microtrauma of the temporomandibular joint and mid-palatal suture, and root resorption have been reported.6,19 The latter can be caused by biological predisposition, individual genetics and the effect of mechanical factors. RME is the treatment of choice in growing adolescents.20
The applied force causes gradual opening of the mid-palatal suture, bending of the alveolar processes and dental inclination. Significant root volume loss after RME treatment has been reported with both Hyrax and Hass appliances, with more occurring with Hyrax.20 One study compared the Hass appliance with the Hyrax appliance using various dental and skeletal parameters, finding that both have similar effects on the dentofacial complex. Both appliances opened the bite, although the Hass appliance demonstrated a slightly more vertical change than the Hyrax.21
The following is a case of a class II division 1 patient with maxillary collapse and anterior open bite, which was corrected with a Hass expander and, to redirect the lingual projection, a palatal arch with spurs and anterior elastics were used.
CLINICAL CASE REPORT
Diagnosis and treatment plan. A 13-year-old male patient comes to the Orthodontic Specialty Clinic of the Autonomous University of Guadalajara because he wants to improve his smile and close his bite.
The patient presents a dolichofacial biotype with a convex profile due to clockwise growth, symmetrical facial thirds, thin lips, convex forehead, straight nasal bridge projection, good projection of the middle third, high nasal tip position, open nasolabial angle, straight labial step, low soft tissue pogonion projection, lip incompetence, dental midline does not coincide with facial midline, low smile, shows two teeth in the upper arch and ten teeth in the lower arch, no buccal corridors, incisal edges coincide with smile line and no gingival showing when smiling as can be seen in Figure 1A. In the intraoral analysis the patient presents ovoid upper and lower arches, anterior open bite, posterior edge-to-edge bite, anterior diastema, mismatched dental midlines, asymmetric upper and lower gingival margins, presence of temporary teeth, class III molar left, class I molar right, bilateral class canine not established, overjet of 3 mm, overbite - 4 mm and a Spee's curve of 0 mm as shown in Figure 1B and Figure 2.
Panoramic radiography (Figure 3A) showed the unerupted permanent teeth, apparently healthy condyles and slightly obstructed airway. It was diagnosed as a skeletal class II division 1 with a tendency to class III due to hypoplasia of the maxilla compensated by a clockwise mandibular rotation as shown in Figure 3B and Table 1.
ALTERNATIVE TREATMENTS
- 1. The use of Hyrax to uncross posterior bite by RME was considered for comfort and hygiene. However, the patient did not have teeth in the premolar area to provide a greater area of support, so this option was rejected.
- 2. The use of an extraoral high traction archwire was considered to achieve molar intrusion and at the same time mandibular rotation, but this option was rejected due to the lack of cooperation of the patient.
- 3. Extractions of upper and lower first premolars were considered, but this option was declined because the patient had a convex profile and an open nasolabial angle.
- 4. The use of a Hass type expander was considered to uncross the posterior bite and the use of elastics in the anterior box to close the bite. After explaining this alternative to the parents, they decided to opt for this treatment option.
Treatment goals
To expand the maxilla and uncross the posterior bite; to improve profile, alignment and levelling; to obtain bilateral class I molar and class I canine; to obtain adequate overjet and overbite, and periodontal health.
Treatment planThe treatment was divided into four phases. First orthopaedic phase: Hass expander with acrylic support was used for rapid maxillary expansion and removable lower lingual arch. The Hass was removed three months after superior expansion was achieved and re-evaluated. Second phase: The Hass expander was replaced with a palatal arch with spurs to control lingual projection and Alexander slot 0.018" upper and lower appliances were placed. Third phase: Detailing and seating was performed. Fourth phase: Lower fixed retention 3-3 and upper circumferential.
Treatment progressionThe treatment started with the cementation of the Hass and lingual arch as shown in Figure 4. It was decided to remove the Hass for two weeks because the patient had swelling in the area of the expander screw. Its use was continued for two more weeks and at four months Hass was removed and a palatal arch with spurs was placed to control the lingual projection (Figure 5).
At seven months, Alexander slot 0.018" appliances were placed in the upper and the use of the lower lingual arch was suspended.
Subsequently, brackets of dental organ #14 and #15 were cemented with spring to distalize dental organ #14, consolidated with metal ligature, and brackets of #24 and #25 were cemented as shown in Figure 6. At 11 months space was achieved for the upper canines and the placement of lower appliance 6-6 with 0.016" NITI SE archwire and bracket placement of dental organ #23 was performed. Dental organ #13 erupted from the cusp only and it was decided to place a button with elastic wire to the arch for traction along with the use of a left delta elastic from dental organ #23 to dental organs #33 and #34 of 3/16 3.5 oz. When alignment and leveling was achieved at 32 months 0.016" × 0.022" SS arch wires and ¼ 6 oz. anterior box elastic were placed.
At the end of 34 months the detailing and seating stage was completed and the upper and lower appliances were removed, 3-3 fixed lower retainer, upper circumferential and final photographs and radiographs were taken.
RESULTS
The facial profile was maintained, a pleasant smile was achieved, the posterior bite was uncrossed; the initial overbite was noticeably improved from -4 to 2 mm, a correct overjet was obtained, as well as a good projection of the upper lip, centred midlines, class I molar and bilateral class I canine (Figure 7A and B), good root parallelism (Figure 8A) and no radical changes in their cephalometric values (Figure 8B).
In Table 1, we can see the initial and final cephalometric values, at the end of the treatment a comparison was made obtaining excellent results without altering the cephalometric values by much. In the Figure 7A we can see how in spite of the notorious growth, the facial profile of the patient was maintained, and the closure of the anterior open bite was achieved without altering the inclination of the upper and lower teeth by much. Finally, in the superimposition we can see the dental and skeletal changes of the patient (Figure 8C).
DISCUSSION
This case report describes the treatment of a skeletal class II division 1 patient with maxillary collapse and anterior open bite, with left class III molar, right class I molar and unestablished canine class. It was decided to perform initial orthopaedic treatment with rapid maxillary expansion (RME) as it has been used for more than a century as an excellent treatment when maxillary constriction is present.7 Crossbite and dental crowding are two easily recognisable clinical signs that could be the result of maxillary deficiency.18 The patient presented functional habits such as anterior and inferior tongue position due to lack of maxillary development which was treated with RME and supported by the use of a palatal arch with spurs, effective when used in growing patients. The tongue projection was eliminated and the tongue was brought into its correct position in the oral cavity, while at the same time allowing the anterior open bite to close.
We agree with the literature7,17,18 that when diagnosing a narrow maxillary arch in young patients, the best option is the RME, because they are in the growth stage and still in the mixed dentition. When using the RME, a stable transverse correction is achieved by anchoring to the primary teeth, providing both dental and skeletal results.17,19 According to radiographic studies, the patient did not present any complications in terms of root resorption.20
The altered position of the maxilla with concomitant altered occlusion also causes bite opening. Hass A9 found that the mandibular teeth tend to follow the maxillary teeth by an increased buccal inclination which can lead to an anterior open bite, and the significant increase in buccal inclination probably due to a combination of several factors such as excessive activation force. In another study Basciftci F19 reports the downward and forward movement of the maxilla with the use of RME, the buccal tilt of the upper first molars and the extrusion of the palatal cusps cause the mandible to move downward and backward. The movement results in a decrease in SNB and an increase in lower facial dimensions,19 proving that molar tilt and extrusion are the cause of bite opening and increase in vertical dimensions after treatment with conventional RME. It has been reported that increasing the stiffness of an appliance reduces the rotational component of the forces along the longitudinal axis of the teeth. In the present study, in order to avoid tilting of the upper molars and to control the vertical facial dimension, a more rigid type of RME appliance, i.e. with modified acrylic bonding, was used. Furthermore, many authors have pointed out that the use of a vertical or oblique chin during or immediately after RME is sufficient to maintain and control the vertical dimension and prevent adverse effects.19
We differ with the literature that mentions that there may be anterior bite opening due to dental inclination of upper molars with set by not using an RME with rigid coverage.5,9,19,21 When orthopaedic treatment was carried out using the Hass expander to perform the RME with an initial anterior open bite (which was maintained until the use of the expander was completed), the posterior edge-to-edge bite was eliminated, resulting in correct occlusion of the maxillary and mandibular teeth.
Hass A5,9 in 1965 reported the disappearance of vector forces on the lower posterior teeth in the lingual direction due to the lateral movement of the buccal muscles associated with maxillary expansion. This expansion shifts the balance between tongue and cheek muscles in favour of the tongue.
It has been determined that the occlusal forces are altered by the expansion so that the normal lingual vector of force on the mandibular buccal teeth is lost. The widening of the lower arch is mainly due to "decompensation", which refers to the straightening of the lower posterior teeth, which are often in a more lingual orientation due to the collapsed maxilla.9,18 Consequently, lateral movement of the maxilla widens the attachment area of the buccal musculature resulting in a change of balance between the tongue and buccal musculature,9 assisting in the lower and anterior position of the tongue. The balance between the maxilla and the mandible allows the tongue to take its ideal position on the palate, eliminating the open bite, as was the case in our patient.
It should be noted that when evaluating the effects of treatment short and long term rapid expansion of the maxilla in two groups of subjects treated with the Haas device, the expander induced expansion at the dentoalveolar level in any stage of growth. At the skeletal level, however, the early-treated group presented with significantly greater increases for lateronasal width (1.1 mm more than the late-treated group), and with greater, though not statistically significant, increases for maxillary width (0.6 mm more than the late-treated group).6
CONCLUSIONS
Orthopaedic treatment with the Hass expander followed by orthodontic treatment with Alexander brackets in a patient with a Class II Division 1 malocclusion can give excellent results. It should be taken into account that orthopaedics in growing patients will give us a much better result than if we wait until the patient is full grown, where we might not be able to use certain treatment modalities such as the use of functional appliances.
REFERENCES
AFFILIATIONS
1 Especialidad en Ortodoncia. Universidad Autónoma de Guadalajara. Guadalajara, Jalisco, México.
2 Departamento de Clínicas Odontológicas Integrales, Instituto de Investigación en Odontología, Centro Universitario de Ciencias de la Salud. Universidad de Guadalajara. Guadalajara, Jalisco, México.
CORRESPONDENCE
Jacqueline Adelina Rodríguez-Chávez. E-mail: jacqueline.rchavez@academicos.udg.mxReceived: Enero 2020. Accepted: Abril 2020.