Orthodontic-surgical treatment for a patient with Class II malocclusion and inadequate maxillary incisor inclination

Dental health and patient satisfaction at the end of orthodontic treatment are needed if the treatment is to be considered successful. This case report highlights the importance of proper diagnosis for a patient initially treated with camouflage, despite the indications for surgery. A 16-year-old male patient sought treatment complaining about his appearance. He had been using an appliance for 6 years without improvement. He had a convex profile, an enlarged lower third of the face, reduced cervical-mandibular line, and Class II molar relationship. The maxillary incisors had excessive buccal root torque, throbbing pain, and dental mobility, with no visible bone coverage in the tomographic sections. The cephalometric analysis confirmed the skeletal Class II relationship (ANB, 11.6°; Wits appraisal, 14.2 mm) because of severe mandibular deficiency (SNB, 71.2°), aggravated by the vertical growth tendency (FMA, 27.3°). Changes in IMPA (108.1°) and U1-NA (0.9°; −2.9 mm) reflected the previous orthodontic attempt to compensate for the malocclusion. After periodontal and endodontic evaluation, a new treatment plan was developed. The incisors would be positioned in their bone bases, the mandibular first premolars would be extracted to create space for the second molars and increase the overjet, and the patient would be referred for orthognathic surgery. The patient was satisfied with the esthetic and functional results of this treatment.

Highlights

  • Understanding the limits to orthodontic camouflage is paramount for success.

  • Orthodontics combined with orthognathic surgery may be a useful option.

  • Exams that generate 3-dimensional images can aid in orthodontic-surgical planning.

In a patient with skeletal Class II relationship, the sagittal discrepancy can involve mandibular retrognathism, maxillary prognathism, or both. In mild cases, the impact of the sagittal discrepancy on facial esthetics is less noticeable compared with mild Class III relationships. In more severe cases, it may have a particularly negative impact on the profile. Facial esthetics have gained even greater importance with the increasing demand for cosmetic treatment. In addition, esthetics can affect the quality of life, ranging from social relations to work opportunities.

During the mixed dentition phase, it is possible to partially redirect a patient’s growth, especially in patients with skeletal Class II malocclusion with maxillary protrusion. Classic treatment approaches for these patients usually involve appliances such as Thurow or Herbst. , , However, they must be used during the growth spurt and the results may not be adequate in more severe cases.

After the growth spurt, the treatment options are to compensate the skeletal disharmony orthodontically or to prepare the patient for orthognathic surgery, depending on the severity of the case and on the facial esthetics. Patients with larger ANB values present a challenging situation when treated exclusively with orthodontic camouflage. Such an approach would increase treatment time and, consequently, raise the risks of periodontal and root damage, while further aggravating the excessive convexity of the face. For these patients, orthognathic surgery ensures that the treatment outcome will favor facial esthetics and will achieve a proper occlusion. Therefore, the correct identification of dental compensation limits in orthodontics is important for accurate diagnosis and treatment planning.

The following case report illustrates the deleterious effects of an inappropriate orthodontic camouflage treatment during the growth spurt in a patient with severe Class II malocclusion, its negative effects on his face and occlusion, and the subsequent interdisciplinary treatment plan to correct the malocclusion.

Diagnosis and etiology

A male patient, aged 16 years 8 months, sought orthodontic treatment at the clinic of 1 of the authors (F.A.R.C.) accompanied by his parents. His chief complaint was his facial appearance, especially the increased convexity of his profile. Besides that, he also had a poor occlusal relationship. He reported being under orthodontic treatment for 6 years without any noticeable improvement, and more specifically, noticing some degradation on his facial and dental appearance.

Copies of the initial documentation ( Fig 1 ) were requested, and new pretreatment records ( Figs 2-4 ) were collected to register his condition after that unsuccessful initial treatment. Clinically, elongation of the lower third of the face was noted, with maxillary protrusion and reduced neck-chin line and angle, accompanied by a nerve weakness of the lower lip. He presented complete permanent dentition, with Class II molar relationship, moderate mandibular anterior crowding, reduced overjet and overbite, midline discrepancies in both arches, and distal impaction of the mandibular second molars ( Fig 2 ). Severe buccal root torque was evident on the maxillary central incisors, associated with increased mobility and throbbing pain. Radiographic evaluation ( Fig 3 ) showed the presence of all 32 permanent teeth, with impaction of the mandibular second and third molars. The clinical status of the maxillary incisors associated with the noticeable dentofacial deformity, as well as the impaction of the mandibular molars and the important protrusion of the mandibular incisors, justified the request for a cone-beam computed tomography (CBCT) scan. The CBCT showed completely inadequate root positioning relative to the bone; it was impossible to identify bony cover, even over incisor apexes, in certain tomographic slices ( Fig 4 ).

Fig 1
Facial and occlusal photographs of the mixed dentition before any orthodontic intervention.

Fig 2
Photographs of his first appointment, registering the results of his inadequate previous orthodontic treatment.

Fig 3
Pretreatment radiographs and cephalometric tracings.

Fig 4
Pretreatment CBCT, highlighting incisor relation with the alveolar bone.

The cephalometric measurements ( Table ) confirmed the skeletal Class II diagnosis, with an ANB angle of 11.6 o , primarily because of a retrognathic mandible, as shown by the reduced SNB angle (71.2 o ), but aggravated by his vertical growth tendency, confirmed by the increased FMA angle (27.3 o ). The IMPA (108.1 o ) and the SN-U1 (83.9 o ) angles reflected the previous orthodontic attempt to adjust the malocclusion despite his skeletal limitations, leading to lower incisors’ excessive proclination, and the upper incisors retroclined to the inadequate position observed on the CBCT.

Table
Cephalometric analysis
Measure Normal Pretreatment Preoperative Posttreatment
Skeletal pattern
SNA (°) 82 82.8 80.6 79.8
SNB (°) 80 71.2 71.8 75.1
ANB (°) 2 11.6 8.8 4.7
Wits appraisal (mm) −1 14.2 11.5 3.3
FMA (°) 25 27.3 25.5 26.7
SN.Go.Gn (°) 33 33.5 30.7 32.1
Dental pattern
SN-U1 104 83.9 99.8 108.5
1.NA (°) 22 −0.9 24.1 20
1-NA (mm) 4 −2.9 1.5 2.8
IMPA (°) 95 108.1 100.8 97.4
1.NB (°) 25 34.9 25.9 26.6
1-NB (mm) 4 10.3 4.2 6.4

The intraoral photographs of the patient taken at his first visit, with the previous orthodontic appliance still in place ( Fig 2 ), show the unconventional bracket positioning and 0.018-inch nickel-titanium archwires. Moreover, the history of prolonged headgear therapy helps us elucidate the cause of the retroclination of the maxillary incisors.

Before initiating a new orthodontic treatment, the patient was referred to a periodontist to assess tooth mobility and bone loss, and to an endodontist to assess the vitality of the maxillary incisors. These specialists agreed with a gloomy prognosis, but they believed that trying to reposition the incisors would be the best option.

Treatment objectives

After analyzing the patient’s condition, the main treatment objectives were to (1) improve his facial esthetics through orthognathic surgery; (2) correct his tooth positions, establishing a functional and esthetic occlusion; and (3) control the periodontal damage caused by previous orthodontic treatment, as well as avoid or minimize any new damage.

With that in mind, it was planned to correct the torque and position of the maxillary incisors, reinserting them into the alveolar bone. It was also planned to extract the mandibular first premolars to retract the anterior lower teeth, increasing the overjet, which was necessary for the orthognathic surgery.

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May 12, 2020 | Posted by in Orthodontics | Comments Off on Orthodontic-surgical treatment for a patient with Class II malocclusion and inadequate maxillary incisor inclination
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