A 20-year-old woman had a severe anterior skeletal open bite and a moderate skeletal Class III relationship with a prognathic mandible and a straight profile. She declined surgery. However, molar intrusion in a Class III patient with a straight profile can cause forward mandibular rotation and deterioration of the profile to a concave pattern. We used digital facial profile prediction software to determine whether the orthodontic compensation treatment would be acceptable to the patient. The final treatment plan consisted of extraction of the third molars, maxillary molar intrusion, and total distalization of the mandibular dentition with multiple microscrew implants. The patient cooperated with the use of Class III interarch elastics. The active treatment period was 20 months. Proper overbite and overjet, good occlusion, and an acceptable facial profile were achieved.
Highlights
- •
Nonsurgical approach was used for a complex skeletal discrepancy with open bite and Class III malocclusion.
- •
Digital profile prediction was used to show patient the likely result of orthodontic camouflage.
- •
Six miniscrew implants were placed for the nonsurgical orthodontic treatment.
- •
Maxillary molar intrusion was carefully performed to prevent tooth inclination.
A skeletal anterior open bite is regarded as a challenging orthodontic problem. In adults with skeletal anterior open bite, 2 treatment options are usually considered because facial growth, especially growth of the posterior maxillary portion, cannot be restricted: orthognathic surgery and orthodontic compensation.
There is no reasonable diagnostic guidance on how much vertical and sagittal discrepancy an orthodontist can correct with orthodontic compensation. However, it is clear that the applications of microscrew implants have made the range of orthodontic compensation far more extensive than before.
Orthodontic treatment of an anterior open bite with molar intrusion generates mandibular counterclockwise rotation and forward movement of the chin point. When this orthodontic approach is used in a skeletal Class II patient with a short retruded mandible and convex profile, it has a better prognosis for profile improvement. However, when this orthodontic approach is applied to a Class III patient with a straight profile, molar intrusion induces forward rotation of the mandible and can deteriorate a patient’s profile to a concave pattern.
Therefore, it is beneficial to show a digitally altered profile prediction image to patients who are reluctant to undergo surgery. It provides simple information regarding the adverse effects of orthodontic compensation to the facial profile and helps the patient to accept the treatment results readily.
This article describes the diagnosis and treatment of an adult patient with a severe anterior open bite and Class III malocclusion, using multiple microscrew implants and digital profile prediction.
Diagnosis and etiology
The patient, a 20-year-old woman with no significant medical history, visited the clinic in Seoul, Korea, with the chief complaints that she was unable to eat properly, and her teeth were “too sharp.”
The intraoral examination showed that she had a Class III malocclusion with a severe anterior open bite. Overjet and overbite were –2.0 and –5.0 mm, respectively, and both canine and molar keys showed Class III relationships on both sides. The teeth were not occluded with the exception of the first and second molars. The extraoral examination showed that she had a straight profile with a prominent chin and competent lips ( Fig 1 ). There was no apparent facial asymmetry, and she did not have temporomandibular disorder symptoms or oral habits. Dental casts confirmed the Class III molar and canine relationships and showed a broad dental arches ( Fig 2 ).
The cephalometric analysis showed that the patient had a hyperdivergent facial pattern with a moderate skeletal Class III relationship with a decreased ANB angle (0.47°) ( Table ). The mandibular incisor was moderately inclined lingually (90°) to compensate for the skeletal sagittal discrepancy. A panoramic radiograph showed that all third molars were impacted, and the distal surface of the mandibular left second molar was impaired by the adjacent impacted third molar ( Fig 3 ).
| Variable | Pretreatment | Posttreatment | Retention (3 years) | Normal |
|---|---|---|---|---|
| Angular (°) | ||||
| ANB | 0.5 | −0.3 | −0.1 | 2.4 |
| FMA | 30.4 | 30.0 | 30.2 | 24.2 |
| U1 to FH | 114.2 | 119.1 | 118.8 | 116 |
| U1 to SN | 103.6 | 108.5 | 108.1 | 107 |
| IMPA | 90.3 | 88.2 | 89.1 | 95.9 |
| Occlusal plane | 15.1 | 14.4 | 14.8 | 17.9 |
| y-axis to SN | 73.2 | 72.4 | 72.9 | 70.9 |
| Linear (mm) | ||||
| Pog to N perpendicular | −4.9 | −2.8 | −3.3 | −5.0 |
| U6/PP | 23.1 | 22.5 | 22.8 | 24.7 |
| L6/MP | 32.0 | 31.6 | 31.8 | 34.2 |
| U6 to PTV | 15.1 | 15.7 | 15.6 | 12.6 |
| L6 to PTV | 18.7 | 16.5 | 17.2 | 15.3 |
| Anterior facial height | 120.8 | 120.1 | 120.3 | 127.4 |
| Wits appraisal | −8.5 | −9.4 | −8.9 | −2.7 |
| Upper lip to E-line | −3.0 | −3.5 | −3.5 | −0.9 |
| Lower lip to E-line | −1.5 | −1.8 | −1.9 | 0.5 |
Treatment alternatives
In adults with a skeletal Class III anterior open bite, we can consider the following 2 treatment options.
- 1.
Combined surgical and orthodontic treatment with maxillary posterior impaction and mandibular setback.
- 2.
Dentoalveolar compensation with intrusion of the maxillary molars and total distalization of the mandibular dentition by using multiple microscrews after extracting all third molars. Class III interarch elastics are also used for relieving the dental anteroposterior discrepancy.
From the aspect of stability of the treatment outcome, there is a controversy regarding the superiority of 1 approach over the other. Considering the esthetic result, however, it was not difficult to predict that orthodontic compensation in this patient would have resulted in a more concave facial profile because of the mandibular counterclockwise rotation and chin advancement.
Although the patient was reluctant to undergo surgery and was willing to accept a less-than-ideal result, it was necessary to inform her that orthodontic compensation could cause changes in her profile that she might not like. Therefore, we used V-ceph software (version 6.0; Osstem Implant, Seoul, South Korea), a cephalometric analysis program to predict her facial profile after orthodontic compensation.
A digitally altered profile prediction image based on visual treatment objective which satisfied the treatment objectives was shown to the patient ( Fig 4 ). She accepted the predicted facial image, so the orthodontic compensation treatment plan was approved to correct her skeletal Class III anterior open-bite malocclusion.
