Long-term stability of a Class III malocclusion with severe anterior open bite and bilateral posterior crossbite in a hyperdivergent patient

Anterior open bite malocclusion is generally associated with several causes. This case report describes the 2-phase treatment of a 13-year-old boy with a Class III malocclusion, severe anterior open bite, and bilateral posterior crossbite treated without surgical intervention. An orthopedic approach was performed in phase 1 with a hyrax-type palatal expander, followed by maxillary protraction with a facemask for a 10-month period to promote the correction of transverse and sagittal deviations. In phase 2, a comprehensive orthodontic approach using fixed preadjusted appliances associated with intermaxillary elastics was performed. These approaches, combined with good patient compliance, established a functional and esthetic occlusal relationship, normal overjet and overbite, and a well-balanced facial appearance. The 4.5-year follow-up indicated that treatment results were stable.

Highlights

  • A classical treatment modality for growing patients presenting Class III open bite.

  • Nonsurgical approach requiring patient compliance and mechanical control.

  • Function establishment of occlusion and tongue provided long-term stability.

  • Functional and esthetic results improved patient’s quality of life.

Anterior open bite malocclusion represents one of the most challenging issues in orthodontics, and relapse is prone to occur after treatment. Furthermore, treatment difficulty increases considerably when associated with a Class III malocclusion and bilateral posterior crossbite. Anterior open bite etiology is multifactorial, including unfavorable vertical growth pattern, mouth breathing, oral habits, and abnormal position and function of the tongue. , The morphology of an anterior open bite with a skeletal component includes an open mandibular plane angle and an increase in anterior facial height, which primarily reflects the clockwise rotation of the mandible and the vertical growth of the maxilla.

Posterior crossbite can be of skeletal origin when a transverse skeletal deficiency of the maxilla is present, or it can be of dental origin when an altered tooth position in the palatal or buccal direction is present. ,

Class III malocclusion etiology is multifactorial and occurs because of interactions involving heredity and environmental factors. Moreover, Class III malocclusion may present dental or skeletal implications. However, the Class III dental relationship can be treated orthodontically with a good prognosis. Depending on its severity, a skeletal Class III relationship is more difficult to treat and tends to relapse and require, on several occasions, to perform orthodontic-surgical procedures for adequate correction. This problem is characterized by the presence of one or a combination of the following factors: maxillary retrognathism and mandibular prognathism.

This case report presents the clinical case of a 13-year-old boy with a Class III malocclusion, severe anterior open bite, and bilateral posterior crossbite treated without surgery over 2 phases of treatment using orthopedic and comprehensive orthodontic approaches.

Diagnosis and etiology

A 13-year-old boy arrived with his older sister to the orthodontic consultation with the chief complaint of open and inverted bite. An extraoral evaluation showed a hyperdivergent pattern of growth, symmetrical face, and a straight profile with a relatively strong chin projection ( Fig 1 ).

Fig 1
Pretreatment facial and intraoral photographs.

Intraorally, he exhibited a severe angle Class III malocclusion on both sides, bilateral posterior crossbite, and a 4.5-mm anterior open bite. The maxillary arch presented an excess of space of 8 mm, and an excess of space of 3.5 mm was in the mandibular arch ( Fig 2 ). Maxillary and mandibular midlines were coincident with his facial midline. No signs and symptoms of temporomandibular joint disorder were observed. The patient exhibited a habit of anterior position of the tongue at rest and a tongue-thrust swallowing pattern.

Fig 2
Pretreatment dental casts.

The panoramic radiograph indicated that the third molars were in development ( Fig 3 ). Despite the dental Class III malocclusion presented (AoBo= -7°), the lateral cephalometric analysis indicated a skeletal Class I relationship (ANB = 3°) with a marked hyperdivergent growth pattern (SN-GoGn = 42°; FMA = 37°). The maxillary incisors were slightly proclined (U1-NA = 24°), and the mandibular incisors were also proclined (L1-NB = 30°) but uprighted considering the IMPA angle = 80°. In the concave profile, the Z angle = 70° ( Table ).

Fig 3
Pretreatment panoramic, lateral cephalometric radiograph, and tracing.

Table
Cephalometric measurements
Measurements Norms Pretreatment Progress Posttreatment Follow-up
SNA angle (°) 82 87 87 87 86
SNB angle (°) 80 84 82 82 82
ANB angle (°) 2 3 5 5 4
Ao-Bo (mm) 0 ± 2
1 ± 2
−7 −2 −1 0
Facial angle (°) 87 91 90 91 91
Convexity (°) 0 6 12 8 7
FMA (°) 25 37 38 37 37
GoGn-SN (°) 32 42 44 43 44
y-axis (°) 59 62 63 62 62
1-NA (mm) 4 4 4 3 3
1-NA (°) 22 24 23 22 25
1-NB (mm) 4 7 6 7 7
1-NB (°) 25 30 28 24 23
IMPA 90 80 76 74 74
Interincisal angle (°) 132 124 127 133 134
Z angle (°) 75 74 76 78 81

Denotes female.

Denotes male.

Treatment objectives

The following treatment objectives were established: (1) correct bilateral posterior and anterior crossbite, (2) correct the habit of anterior posture of the tongue at rest and tongue-thrust swallowing, (3) correct anterior open bite (4) obtain Class I molar and canine relationship on both sides, (5) obtain normal overjet and overbite, and (6) maintain facial profile.

Treatment alternatives

The following treatment alternatives were proposed: (1) Perform rapid maxillary expansion (RME) with a banded hyrax palatal expander, followed by maxillary protraction with a facemask. In phase 2, bond complete fixed appliances and bilaterally insert miniplates in the maxillary and mandibular bones to perform intrusion of the maxillary posterior teeth and intrusion and distalization of the mandibular ones, thereby aiding open bite closure and correction of the sagittal discrepancy. Perform orofacial myofunctional therapy to correct the anterior posture of the tongue at rest. (2) Perform RME with a banded hyrax expander, followed by maxillary protraction with a facemask and placement of tongue spurs in the mandibular arch to control the anterior posture of the tongue at rest. In phase 2, bond complete fixed appliances and bilaterally insert miniscrews between the maxillary and mandibular first and second molars, performing intrusion of maxillary and mandibular posterior teeth to aid open bite closure and use of Class III and vertical elastics. (3) Perform RME with an acrylic splint hyrax-type expander, followed by maxillary protraction with a facemask. In phase 2, bond complete fixed appliances and use Class III and vertical elastics. Perform orofacial myofunctional therapy to correct the anterior posture of the tongue at rest.

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Mar 9, 2020 | Posted by in Orthodontics | Comments Off on Long-term stability of a Class III malocclusion with severe anterior open bite and bilateral posterior crossbite in a hyperdivergent patient
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