Orthodontists often have trouble treating patients who have temporomandibular joint disorders because occlusion changes depend on the position of unstable condyles. This characteristic means the patients do not have definite criteria with which to make an accurate orthodontic diagnosis, so clinicians are unable to establish a reliable treatment plan. This article reports on the treatment of a patient with skeletal Class II relationship and condylar resorption. A stabilization splint was used before any active orthodontic tooth movement to stabilize her condylar position. Although the patient exhibited dramatically increased open bite and a retruded mandibular position after splint therapy, her occlusion and facial esthetics were resolved by orthodontic camouflage treatment with appropriate orthodontic mechanics after extraction of 4 premolars.
Highlights
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An unstable jaw position can be stabilized with a splint.
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A visualized treatment objective was used to establish an effective treatment plan.
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The temporomandibular joint was protected during treatment.
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The patient’s occlusion, facial esthetics, and unstable jaw position all improved.
Orthodontic treatment of patients with a temporomandibular joint disorder (TMD) is one of the most challenging tasks for orthodontists because of constantly changing occlusion during the treatment as a consequence of the patient’s unstable condylar position. Patients with TMD often show degenerative changes of the temporomandibular joint (TMJ) structures characterized by lysis and repair of the articular fibrocartilage and underlying subchondral bone. Degenerative changes in TMJs are regarded as the result of a decreased adaptability in the articulating structures caused by unsuitable physical stress on the TMJ structures. , These changes at the condylar level consequently result in specific skeletal and dental characteristics such as a retrusion of the chin and an anterior open bite.
Although a patient’s TMD might not have progressed into a severe degenerative state, the condyles of TMD patients are usually in an unstable position because of comprehensive changes in the surrounding articular and muscular structures. This condition appears as discrepancies between centric relation occlusion (CRO) and maximum intercuspal position (MIP) at the occlusion level. In daily practice, clinicians are often horrified to find that a patient who originally presented with an Angle Class I canine and molar relationship has developed a Class II relationship once orthodontic treatment has begun. Having CRO-MIP discrepancy means that orthodontists lack definitive criteria for orthodontic diagnosis because the condition denies them access to reliable information about the patient’s occlusion. , ,
Therefore, clinicians need a way to establish the stability of the patient’s TMJ, and splint therapy is regarded as the most effective and reliable tool for stabilization of the TMJ. Stabilization splints have been popular in treating musculoskeletal disorders in TMJs. They also allow clinicians to predict patient response to future occlusal reconstruction with orthodontic treatment. ,
Patients with TMD often undergo significant changes in occlusion and facial profile after the use of a stabilization splint. The patient’s Class II relationship usually worsens with a tendency to open bite and sometimes facial asymmetry if unilateral changes are outstanding. It is not a pathologic change, but the result of revealing the patient’s preexisting positional discrepancies at the joint level. For improvement of anteroposterior relationship and open bite tendency, an orthodontic modality to control the vertical problem which induces counterclockwise rotation of the mandible is widely used. In some patients, severe open bite or mandibular retrusion may require orthognathic surgery, but orthodontic camouflage treatment with temporary skeletal anchorage devices (TSADs) can be an alternative treatment option.
Many studies have reported successful molar intrusion with orthodontic TSADs to improve both occlusion and facial esthetics for patients with severe Class II and/or anterior open bite. The intrusion of the posterior teeth produces similar effects on the profile as osteotomies on the maxilla, resulting in counterclockwise rotation of the mandible, which leads to improvement not only of the molar relationship but also of the chin prominence.
This article presents the successful orthodontic treatment of a female adolescent patient with TMD and suggests appropriate treatment protocols on the basis of an evaluation of her condylar stability. It also suggests other treatment objectives, such as achieving functional occlusion and good facial esthetics.
Case report
An 18-year-old female presented with concerns about her anterior protrusion and reported having pain during mastication, a condition that has persisted for a year. Incompetent lips and a convex profile were observed, whereas an intraoral examination found mild maxillary and mandibular crowding with 8.0 mm overjet and 2.0 mm overbite. A panoramic radiograph showed flattening of anterosuperior parts of the condylar heads on both sides and mild root resorption on her maxillary central incisors. Continuity of the cortical layer covering the condylar head was clear enough to confirm that her condylar resorption was in the repair stage as it presented considerably flattened, and the corticated bone layer indicated that a destructive cup-shaped defect had passed. A bone scan can be used to assess active condylar bony changes, but its diagnostic accuracy and specificity have been reported to be inadequate to evaluate these changes. Lateral cephalometric analysis indicated a skeletal Class II malocclusion (ANB, 6.0°) with a hyperdivergent growth pattern (Mp-SN, 47.0°). Her maxillary and mandibular incisors were proclined (SN-U1, 115.0°; IMPA, 99.5°) ( Fig 1 ; Table I ).
During a clinical examination, the patient showed a dual bite, indicating that she had a CRO-MIP discrepancy. To visualize and determine the quantitative amount of CRO-MIP discrepancies, we mounted her dental models on a semiadjustable articulator (SAM Praezisionstechnik GmbH, Muenchen, Germany). The mandibular position indicator (MPI) of the SAM articulator was used to evaluate the CRO-MIP discrepancies at the joint level, and the MPI measurements showed a 4-mm downward condylar distraction on both sides. On the basis of the diagnostic data, it was determined that her mandible was not in a stable position, and therefore, her occlusion was not reliable enough to make a definitive orthodontic diagnosis.
| Measurement | Korean norm | Pretreatment | Poststabilization | Posttreatment |
|---|---|---|---|---|
| SNA (°) | 81.5 | 78.0 | 78.0 | 78.0 |
| SNB (°) | 79.0 | 72.0 | 69.5 | 71.0 |
| ANB (°) | 2.5 | 6.0 | 8.5 | 7.0 |
| Saddle angle (°) | 126.0 | 130.0 | 128.0 | 128.0 |
| Articular angle (°) | 149.0 | 145.0 | 154.0 | 152.0 |
| Gonial angle (°) | 118.5 | 131.0 | 131.0 | 131.0 |
| SUM (°) | 393.0 | 406.0 | 413.0 | 411.0 |
| Facial angle (down’s) (°) | 89.0 | 83.0 | 80.5 | 82.0 |
| Wits (mm) | −2.5 | 0.5 | 5.5 | 0.0 |
| Mp-SN (°) | 33.5 | 47.0 | 53.0 | 50.5 |
| Ramus height (mm) | 51.5 | 45.5 | 41.0 | 41.0 |
| Post. FH/Ant. FH (%) | 66.8 | 57.5 | 53.5 | 54.5 |
| SN-U1 (°) | 104.0 | 115.0 | 115.0 | 95.0 |
| U1-FH (°) | 116.0 | 125.0 | 125.0 | 105.0 |
| U1-NA (°) | 22.0 | 36.5 | 36.5 | 17.0 |
| U1-NA (mm) | 4.0 | 9.5 | 9.5 | 2.5 |
| IMPA (°) | 90.0 | 99.5 | 99.5 | 96.5 |
| L1-NB (°) | 25.0 | 37.5 | 37.5 | 36.0 |
| L1-NB (mm) | 4.0 | 14.0 | 14.0 | 10.0 |
| U1/L1 (°) | 124.0 | 99.0 | 95.0 | 119.0 |
| Upper lip (mm) | 0.0 | 4.5 | 5.5 | 2.5 |
| Lower lip (mm) | 0.0 | 6.5 | 8.5 | 4.0 |
To relieve the persistent pain in her TMJ area and to determine a stable position of her mandibular condyles, a stabilization splint was suggested, a process which she accepted. The splint was delivered and checked regularly and adjusted to maintain an ideal occlusal scheme, a mutually protected occlusion. The stabilization splint eliminated protective co-contraction of the surrounding masticatory muscles, which eventually lead to an orthopedically stable joint position of the mandible. , , , By using the splint, the pain in her TMJ was dramatically reduced over the first few weeks. However, she continued to use the splint for a sufficient amount of time for the related muscles to adapt around the mandibular condyles. After 9 months, a significant increase in anterior open bite and overjet were observed. When we were convinced that her condylar position was stable based on MPI data and the patient’s decreased symptoms, she was rediagnosed before we initiated active orthodontic treatment. Her mandible was rotated clockwise as the condyles were seated into the most forward and uppermost positions, resulting in an anterior open bite (−3 mm) and a more severe skeletal Class II pattern with a steeper mandibular plane (ANB, 8.5°; Mp-SN, 53.0°) ( Fig 2 , A – E ; Table I ).
With the rediagnosed data, 2 treatment alternatives were suggested to the patient according to the visualized treatment objective (VTO). The first included orthognathic surgery associated with maxillary posterior impaction and mandibular advancement with the extraction of 4 premolars. This treatment option should effectively resolve open bite and facial esthetics. The second involved orthodontic camouflage treatment with extraction of 4 first premolars and the intrusion of her maxillary and mandibular posterior teeth using TSADs to accomplish counterclockwise rotation of the mandible and to resolve the vertical and anteroposterior problems. Although she had dental Class II relationships after splint therapy, we extracted her mandibular first premolars rather than her second premolars because the second premolars offer more favorable surface contacts with the first molars, and her mandibular anchorage can be controlled with TSADs ( Fig 2 , F and G ). After a detailed discussion with the patient, she rejected the surgical approach and chose the camouflage treatment option using TSADs.
Before orthodontic treatment, both maxillary and mandibular first premolars were extracted. Full fixed 0.022-in preadjusted edgewise orthodontic appliances (Avex; Opal Orthodontics, South Jordan, Utah) were bonded on both of her arches for leveling and alignment. At 6 months of treatment, the intrusion movement of both maxillary and mandibular posterior teeth had started to correct the anterior open bite. Two TSADs (diameter, 1.4 mm; length, 8 mm; Orlus, Seoul, South Korea) were placed in the buccal alveolar bone between the roots of the maxillary second premolars and first molars for the intrusion of the posterior teeth and retraction. Two TSADs were also installed between the mandibular canines and the second premolars for mesialization of the mandibular posterior teeth. The transpalatal arch was placed approximately 5 mm away from the midpalatal tissue for tongue exercise to intrude the posterior teeth more effectively. As interarch elastics might produce a change in the condylar position, we did not apply any force that would place an extrusion force on the TMJs ( Fig 3 ). The short roots of the maxillary anterior teeth were one of our concerns, so we applied slow and light retraction forces. The total treatment time was 29 months.
