Orthodontic treatment for a patient with anterior open bite and severe condylar resorption

A 23-year-old woman with condylar resorption and a skeletal Class II pattern and anterior open bite were treated with 4 premolar extractions and temporary skeletal anchorage devices in both maxillary and mandibular arches. Before the start of orthodontic treatment, her unstable condylar position was stabilized with a stabilization splint for 6 months. Sequential evaluation of her condylar position was performed using a mandibular position indicator. The total active orthodontic treatment time was 30 months. After treatment, her occlusion, soft tissue profile, and unstable jaw position were significantly improved. Posttreatment records after 36 months showed excellent results with a good, stable occlusion.


  • The patient had an anterior open bite with condylar resorption.

  • Jaw position was stabilized with a stabilization splint.

  • The maxillary posterior teeth were intruded with temporary skeletal anchorage devices.

  • The patient was in braces for 30 months.

  • Her occlusion, smile esthetics, and unstable jaw position were significantly improved after treatment.

Treatment of patients with condylar resorption is challenging for orthodontists. Idiopathic condylar resorption (ICR), also known as progressive condylar resorption, is a degenerative disease of the temporomandibular joint (TMJ), found mostly in female adolescents and young women. Patients with ICR present with pathognomonic features, including a loss of condylar mass, which thereby decreases the height of the ramus and an opening rotation of the mandible, which produces Class II open bite. Condylar resorption is the result of TMJ inflammation caused by joint compression because of an unstable occlusion, parafunction, macrotrauma, internal derangement, and systemic overlay related to illnesses or hormonal imbalances. Patients with condylar resorption show symptoms of temporomandibular disorder (TMD) and unstable occlusion. Establishment of a healthy occlusion is one of the most important goals of orthodontic treatment, so appropriate treatment protocols are essential for patients having condylar resorption.

Many studies claim that evaluation of the stability of the condylar position should precede orthodontic treatment in patients with condylar resorption and the symptoms of TMD. Stabilization of TMJ allows clinicians to identify the true mandibular position and make an accurate diagnosis. It may also alleviate the patient’s TMD symptoms. A stabilizing splint is used for these purposes. After stabilization, the occlusion on that position should be reevaluated when establishing an orthodontic treatment plan. During treatment, orthodontists should be aware of the stable position of the condyles when moving teeth, and the occlusion should be finalized in relationship to this position.

This case report presents the successful orthodontic treatment of a 23-year-old woman with anterior open bite and condylar resorption based on an evaluation of her condylar stability. It suggests a treatment protocol for patients with condylar resorption.

Diagnosis and etiology

A 23-year-old woman visited a private office requesting orthodontic treatment. Her chief complaints were lip protrusion and anterior open bite. She showed lip fullness and convex profile with clockwise rotation of the mandible without any significant facial asymmetry.

Occasional joint sounds during her mouth opening and chewing were found, and she reported migraines and reduced mouth opening. A bilateral click of her TMJ was detected with mouth opening and closing movements during a clinical examination. Joint pain was detected with bilateral TMJ palpation in the lateral and posterior aspects of TMJ. Mouth opening was 35 mm without pain and 40 mm with forced opening. She also showed a centric-related occlusion (CRO)-maximum intercuspal position (MIP) discrepancy, so dental models were mounted on a semiadjustable articulator (SAM Präzisionstechnik GmbH, München, Germany), and the mandibular position indicator (MPI) of the SAM articulator was used to determine reliability and the presence of distinct jaw positions. The CRO-MIP discrepancies at joint level were evaluated by MPI data. Cone-beam computed tomography (CBCT) scans were also conducted for more information on the mandibular condyles.

Intraorally, she had an anterior open bite, moderate crowding in both arches with a 6.0-mm overjet, and a 2.5-mm anterior open bite on her maxillary left central incisor. End-on Class II canine and molar relationships were found on both sides, and dental midline in the mandibular arch deviated 1 mm to the right. The MPI measurement showed a 1.0- to 1.5-mm downward condylar distraction. When she swallowed, she showed horizontal tongue position and tongue thrust habit ( Figs 1-3 ).

Fig 1
Pretreatment facial and intraoral photographs.

Fig 2
Pretreatment dental casts in MIP.

Fig 3
Pretreatment dental casts mounted in CRO and MPI data. MPI data shows CRO-MIP discrepancies at the joint level. Our patient presented a downward direction of CRO-MIP condylar distraction.

A panoramic radiograph showed flattened and backwardly inclined condylar heads on both sides. All third molars were impacted. A lateral cephalometric analysis indicated a skeletal Class II pattern (ANB, 7.5°) with a hyperdivergent growth pattern (SN-MP, 45.5°). The maxillary and mandibular incisors were proclined (U1-SN, 113.0°; IMPA, 100.8°). On a CBCT image, both mandibular condyles were flattened and covered with thin cortical layer. On the basis of the classification of the condylar morphology by Kinzinger et al, coronal images of mandibular condyles showed flat or angled form, which indicated resorption of the condyle ( Figs 4 and 5 ; Table ). Her American Board of Orthodontics Discrepancy Index score was 74 ( Supplementary Fig 1 ).

Fig 4
Pretreatment radiographs: A, lateral cephalogram; B, posteroanterior cephalogram; C, panoramic radiograph.

Fig 5
Initial CBCT scans showing condylar resorption on both sides. Loss of the continuity of cortical bone and the thin condylar surface is present: A, cross-sectional images; B, volume rendering images.

Cephalometric measurements
Measurement Norm Pretreatment Poststabilization Posttreatment Postretention (3 y)
SNA (°) 82.0 80.0 80.0 79.0 79.0
SNB (°) 80.0 72.5 71.8 72.5 72.5
ANB (°) 2.0 7.5 8.2 6.5 6.5
Wits (mm) 0.0 3.3 4.1 2.8 2.8
SN-MP (°) 32.0 45.5 47.0 42.2 42.2
Ramus height (mm) 44.0 37.2 37.0 36.0 36.0
LFH (ANS-Me/N-Me) (%) 55.0 57.4 58.0 56.6 56.6
U1-SN (°) 104.0 113.0 113.0 92.5 92.5
U1-NA (°) 22.0 33.5 33.5 14.5 14.5
U1-NA (mm) 4.0 5.4 5.4 0.0 0.0
IMPA (°) 90.0 100.8 100.8 92.0 92.0
L1-NB (°) 25.0 36.6 40.3 32.5 32.5
L1-NB (mm) 4.0 10.2 10.5 7.1 7.1
U1/L1 (°) 131.0 101.2 100.5 130.5 130.5
Upper lip to E-plane (mm) −4.0 1.5 1.5 0.0 −0.5
Lower lip to E-plane (mm) −2.0 6.0 6.7 1.2 2.0

Treatment objectives

The following treatment objectives were established: (1) improve TMD symptoms, (2) achieve and maintain stable position of the condyles, (3) correct anterior open bite, (4) relieve crowding in both arches, (5) establish Class I canine and molar relationships, (6) obtain normal overjet and overbite, (7) obtain a stable occlusal relationship, and (8) improve facial and dental esthetics.

Treatment alternatives

Based on diagnostic data, it was determined that a definitive diagnosis should be made after stabilization of the TMJ. A stabilization splint was fabricated on the SAM III articulator and applied to the patient. The splint was regularly checked and adjusted to be maintained in the mutually protected occlusion. In closure, there were simultaneous centric contacts of mandibular posterior teeth with slight contact of the anterior teeth. Moreover, the splint was adjusted to provide suitable anterior guidance, which provided immediate disclusion of posterior teeth in eccentric movement. These functions of stabilizing splint could eliminate protective contraction of the muscles and lead in an orthopedically stable joint position. , , The most orthopedically stable joint position is where the condyles are located in their most superoanterior positions in the articular fossa, resting against the posterior slopes of the articular eminences. MPI records were taken regularly to monitor the condylar position. After 6 months of splint therapy, the MPI marks remained constant in the anterior and superior positions over time, and symptoms of TMD such as migraines and reduced mouth opening were improved. We confirmed the stabilization of the condyle by identifying a clear cortical bone continuity and no further changes in the shape of the mandibular condyles on CBCT images ( Figs 6-8 ).

Fig 6
Intraoral photographs during splint therapy.

Mar 9, 2020 | Posted by in Orthodontics | Comments Off on Orthodontic treatment for a patient with anterior open bite and severe condylar resorption

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