Written by Dr. Tanya Prasad, BDS, MDS (Ortho) | Medically Reviewed by Dr. Shaista Salam, BDS, Dr. Zein El Hammouz, DDS, MFD/RCSI
An anterior open bite (AOB) is when there is a lack of vertical overlap or contact between the maxillary and mandibular anteriors when the posterior teeth are in occlusion. Whereas a posterior open bite (POB) occurs when there is no interdigitation between the posterior teeth.
Open bites in adults often require orthodontic intervention. The development of open bite can stem from various etiological factors such as thumb sucking and habitual forward positioning of tongue, incorrect swallowing habits and skeletal growth abnormalities(1).
Treatment for open bite includes habit control along with orthodontic treatment. Recently, aligners have proven to be effective at controlling and correcting open bites while also reducing the vertical gap in patients. This is made easier with the help of auxiliaries like TADs (temporary anchorage devices).
Moreover, bite corrections via traditional braces can cause varying degrees of root resorption which is easily avoidable with the help of removable clear aligners.
The diagnosis of an open bite is done following a clinical examination by a dentist or orthodontist, along with a cephalometric analysis.
Extra orally, a patient with a skeletal open bite exhibits some characteristic features such as:
Once a diagnosis is reached, the correct course of action can be decided in terms of the treatment plan (3). The open bite malocclusion can be classified into the following terms:
In this malocclusion, there is no contact between the maxillary & mandibular anteriors while the posterior teeth are in occlusion. Such open bites can be dental or skeletal: dental open bites can be treated with orthodontic treatment whereas skeletal open bites may require orthognathic surgery (4).
Adults with open bites are presented with a few treatment options that include fixed appliance therapy with extraction as a viable option. However, the treatment time is usually prolonged, and the patient experiences unsatisfactory facial aesthetics during the treatment. There is also a chance of root resorption. Over the past few years, the search for more aesthetic and effective treatment modalities have expanded the horizons of orthodontic treatment of open bite malocclusion.
Open bite correction with clear aligners provide adult patients with a quicker and more aesthetic treatment alternative. Literature has reported that open bite correction via clear aligners facilitate a better mechanical advantage due to additional occlusal coverage. This provides a better vertical dimension control when compared with traditional braces(8).
A ‘bite block’ effect is exerted via aligners on the posterior dentition, due to the thickness of the material covering them. Assisted by the masticatory forces, this leads to posterior intrusion (2).
Clear aligners have proven to be an effective method of resolving anterior open bite in adult non extraction cases. Studies have reported clear aligners can provide consistent maxillary molar intrusion while simultaneously maintaining the vertical position of lower molars (8).
The treatment of an open bite can entail simple habit control procedures with orthodontic treatment. Aligners can achieve the biomechanics for correction of open bite malocclusion through extrusion of anteriors , intrusion of posteriors or a combination of both (6).
Anterior extrusion: Relative or absolute extrusion of anteriors can be achieved via the help of attachments. Extrusive attachments are bonded on the anterior teeth that provide aligners a surface to push against (7). Furthermore, elastics can be used to aid in anterior teeth extrusion.
Treatment planning softwares can map out the placement of these extrusive attachments on the incisors, allowing aligners to gently correct the open bite malocclusion.
Posterior intrusion: Horizontal rectangular bevelled attachments are used when intrusion of posterior teeth are required. The attachments aid in anchorage or retention of the appliance on the adjacent teeth. Additionally, the placement of mini implants in the upper posterior area can help in achieving optimal posterior occlusion (7). Since each case is different, eon’s clinical support team will help you choose the best modality.
The below presented case has been successfully treated by an Eon Aligner doctor: Dr. Jamal Zoubi
A 52 year old female patient presented with a dentoalveolar open bite. Intraoral examination revealed a severe open bite of 4 mm, molar Class I malocclusion and a bilateral Class II canine relationship. The upper midline showed a shift towards the right with a lower midline shift towards the left. The patient exhibited a Class II skeletal relationship.
Clinical examination revealed veneers w.r.t 14, 13, 12, 11, 21, 22, 23, 24 and a prosthetic crown w.r.t 36, which needed special consideration in the treatment plan.
The treatment objectives for this patient were:
No extraction was indicated in this case.
Since, the patient did not present with any skeletal discrepancies, treatment of the open bite was carried out through a series of aligners.
A series of 31 aligners were planned for the upper arch and 29 for the lower arch.
Later, two rounds of refinements were made using a total of 15 Upper and 15 lower aligners. The wear cycle for each aligner was 1 week.
The open bite was resolved with relative extrusion of the anteriors. Some amount of absolute extrusion was also planned. Ultimately, the intrusive effect of the posterior teeth with the aligners assisted in closing the anterior bite. Interproximal reduction ranging from 0.4-0.6 mm was performed on each of the 9 upper teeth, with a total IPR of 3.9 mm on the upper arch.
Lower incisor crowding was addressed with proclination, derotation and retraction combined with expansion and IPR. A total of 5 mm of IPR was performed on the lower arch to make space for alignment.
After 15 months of treatment, there was resolution of the anterior open bite with the establishment of proper overbite and overjet relationships. The lower arch was levelled and aligned with the resolution of lower arch crowding and centralization of upper and lower midlines. Treatment of open bite with aligners resulted in a harmonious facial balance, aesthetic smile and functional intercuspation
Open bite correction via clear aligners occurs due to a combination of anterior extrusion (relative/absolute) and posterior intrusion. The resulting auto rotation of the mandible helps in closure of open bite along with retraction of maxillary and mandibular incisors. The case report demonstrates the efficacy of clear aligners in resolving complex dentoalveolar malocclusions such as an open bite which were earlier only treat via fixed mechanotherapy. Clear aligners are currently an effective and aesthetic orthodontic modality in resolving an open bite malocclusion.
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