Lateral open bite and crossbite correction in a Class III patient with missing maxillary first premolars

Posterior and Class III elastics were used to correct lateral open bite and anterior crossbite in a 29-year-old man. His occlusion, smile esthetics, and soft tissue profile were significantly improved after 25 months of active orthodontic treatment combined with 4 anterior restorations.


  • This difficult case had a DI score of 30 and an ABO cast-radiograph evaluation of 14.

  • Total active treatment time was 25 months.

  • We corrected a lateral open bite and crossbite without temporary skeletal anchorage devices or surgery.

An open bite is difficult and complex to treat because it is caused by multiple etiologic factors such as heredity, abnormal mandibular growth patterns, imbalance between jaw postures, airway obstruction, finger-sucking habits, and tongue posture and function. Skeletal Class III malocclusions are also difficult to treat, so when Class III patients have open-bite components also, the treatment becomes even more challenging.

Ellis and McNamara investigated the frequency of anterior open bite in a large sample of Class Ill adult patients and reported that approximately 30% of the entire sample had an open bite. In their study, when compared with the Class III nonopen-bite group, the Class III open-bite group showed a higher mandibular plane angle, larger gonial angle, longer mandibular length, decreased mandibular protrusion, posterior vertical excess of the maxilla and mandible, and increased total anterior facial and lower anterior facial height. Since abnormalities exist in both jaws of the average adult Class III open-bite patient, they recommended 2-jaw surgery to correct the deformities.

A deficiency in transverse maxillary growth is common in Class III skeletal patterns; hence, these patients often have maxillary constriction that is manifested as an anterior or posterior crossbite. Patients with crossbites have more chance of occlusal interferences than do those with a normal transverse occlusion. Therefore, a functional shift occurs frequently when the mandible closes into centric occlusion. In adults, if lateral open bites are associated with posterior lingual crossbites, treatment is more complicated because clinicians must control both the transverse and vertical dimensions.

This case report describes camouflage treatment used to correct a skeletal Class III malocclusion with lateral open bites and crossbites. Clinically acceptable and esthetically pleasing treatment results were achieved.

Diagnosis and etiology

A 29-year-old white man was referred to Arizona School of Dentistry and Oral Health in Mesa, Ariz, for an evaluation of orthodontic treatment. His chief complaints were that he ground his front teeth and his bites were deteriorating. He had a mesofacial, symmetrical face and a straight profile with a relatively strong chin projection ( Fig 1 ). He exhibited no temporomandibular joint symptoms such as pain, restricted jaw movement, joint noise, or other symptoms during a temporomandibular joint evaluation.

Fig 1
Pretreatment facial and intraoral photographs.

Intraorally, he was missing his maxillary first premolars, and had anterior crossbites on his maxillary lateral incisors and canines, posterior crossbites on his maxillary second premolars, and edge-to-edge bites on the maxillary central incisors and the right maxillary first molar. He also had bilateral open bites. He was observed to have a lateral tongue-thrust habit with forced opening of his lips when swallowing.

He also showed attrition on his maxillary and mandibular incisors from occlusal trauma. He had end-on Class III canine relationships on both sides, a Class I molar relationship on the right side, and an end-on Class II molar relationship on the left side. His maxillary arch had open space because of the missing first premolars, and the mandibular arch showed mild crowding with a rotated mandibular left second premolar. His maxillary dental midline was coincident with his facial midline. When his mandible was guided into centric relation, a functional shift was detected because of the anterior and posterior crossbites ( Figs 1 and 2 ).

Fig 2
Pretreatment dental casts.

The clinical examination and a panoramic radiograph showed that he had all of his third molars, which were only occluding in the posterior segments except for the maxillary right second premolar. The maxillary canine roots were long, and the apical third of the right canine root was close to the apical third of the second premolar root ( Fig 3 ).

Fig 3
Pretreatment radiographs: A, lateral cephalogram; B, cephalometric tracing; C, panoramic radiograph.

The lateral cephalometric analysis indicated a skeletal Class III pattern (ANB, −2.9°; Wits appraisal, −7.2 mm) with a slightly hypodivergent growth pattern (SN-MP, 30.1°). The maxillary incisors were proclined (U1-SN, 113.9°), and the mandibular incisors had a normal inclination (IMPA, 90.8°). He had an acute nasolabial angle (114.0°), and his upper (−9.0 mm) and lower (−4.7 mm) lips were retrusive to the E-line ( Fig 3 ; Table ). He was not aware of any history of familial skeletal Class III pattern. His premolars were extracted for orthodontic treatment, but he never had the treatment. This may have exacerbated an already midface deficient profile. His American Board of Orthodontics Discrepancy Index score was 30 ( Fig 4 ).

Cephalometric measurements
Measurement Norm Pretreatment Posttreatment
SNA (°) 82.0 80.0 80.0
SNB (°) 80.0 82.9 82.4
ANB (°) 2.0 −2.9 −2.5
Wits (mm) −1.0 −7.2 −5.0
SN-MP (°) 32.0 30.1 29.7
FH-MP (°) 24.0 21.7 20.6
LFH (ANS-Me/N-Me) (%) 55.0 56.7 56.9
U1-SN (°) 104.0 113.9 123.2
U1-NA (mm) 4.0 7.4 8.1
IMPA (°) 90.0 90.8 87.1
L1-NB (mm) 4.0 2.8 2.2
U1/L1 (°) 131.0 130.7 122.0
Upper lip to E-plane (mm) −4.0 −9.0 −7.9
Lower lip to E-plane (mm) −2.0 −4.7 −5.2

Dec 19, 2018 | Posted by in Orthodontics | Comments Off on Lateral open bite and crossbite correction in a Class III patient with missing maxillary first premolars

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