Diagnosis and etiology

A 20-year-old woman had a slight mandibular retrusion and a Class l dental malocclusion, mainly associated with her AOB, which extended to the posterior teeth ( Fig 1 ). Her skeletal pattern was vertical, and the maxillary and mandibular incisor inclinations determined the convexity of the lips within adequate parameters for her ethnic background. Her main complaints were the dental esthetics altered by the AOB, the deficient occlusion of the posterior teeth with interference of the maxillary molar palatal cusps over the mandibular molar buccal ones ( Fig 2 ), and severe orofacial pain with episodes of migraine since her childhood.

Pretreatment facial and intraoral photos.

Occlusal relationship at pretreatment.

Radiographic examination showed bilateral condylar remodeling (more pronounced on the right side), third molar impactions, narrow symphysis, and AOB ( Fig 3 ). Muscular and articular temporomandibular disorder became apparent during the physical examination, with the right side the most affected. We also noticed bilateral TMJ clicking with deviation of the mandible to the right side on opening. Osteoarthritis was also considered as a diagnosis. Magnetic resonance imaging (MRI) and CBCT examinations of the TMJs were required to confirm the hypothesis. The MRI showed reduced mandibular condyles, increased cortical range, and signs of degeneration in the joint discs, with more pronounced degeneration on the right TMJ. The left disc had anterior displacement with reduction, and the right TMJ disc had anterior displacement without reduction ( Figs 4 and 5 ). The 3D models of the condyles before treatment were generated from the CBCT files using3D SLICER (SPHARM-PMD) and ITK-SNAP software. The 3D models showed areas with condylar flatness, cortical irregularities, and osteophytes that can be visualized in the online Supplementary Material ( Supplementary 3D Models , available at www.ajodo.org ). These symptoms confirmed the hypothesis of osteoarthritis, which was more advanced on the right side.

Pretreatment lateral cephalogram, panoramic radiograph, and cephalometric tracing.

Proton density weighted MRI of the right TMJ shows the mandibular condyle with irregular contours, flattening of the articular surface, and anterior osteophytes. There is marked condylar resorption with a low-intensity signal in the medullar bone. A, Closed-mouth view shows that the disc is anteriorly displaced, with irregular signal and heterogeneous format; B, open-mouth view shows nonreducible disc; C, coronal view shows marked reduction of the medullar bone.

Proton density weighted MRI of the left TMJ shows the mandibular condyle with posterior surface flattening with a homogeneous high-intensity medullar bone signal. A, Disc is anteriorly displaced on closed-mouth sagittal view; B, on total mouth opening, the disc is in normal position; C, the coronal view shows that medullar bone is preserved with homogeneous hypersignal.

Treatment objectives

The treatment objectives were to improve the dentofacial esthetics, maintain a dental Class l malocclusion, correct the AOB, minimize TMJ pain, and improve function.

Treatment alternatives

An AOB malocclusion has several etiologic possibilities, and the treatment is a challenge in orthodontics. The patient must first be correctly diagnosed so that stability can be maintained after the treatment. Interventions in skeletal AOB differ from growing to nongrowing patients. In growing patients, the reduction of the vertical skeletal growth with intraoral or extraoral force is the main treatment objective. In nongrowing patients, the treatment objective is to correct the dentoalveolar position with camouflage or surgical intervention. Extrusion of the anterior segment with elastics, retraction and vertical repositioning of the maxillary and mandibular anterior teeth by extraction of the premolars, and intrusion of the posterior teeth are also strategies used to treat skeletal AOB in nongrowing patients. Orthognathic surgery is indicated when the AOB is associated with skeletal discrepancies.

AOB, reduced overbite, and increased overjet are known to be associated with internal derangement of the TMJ and TMJ osteoarthritis. When condylar resorption is bilateral, the mandible rotates posteriorly and frequently presents as a skeletal Class II malocclusion with AOB. Many treatment options are described in the literature. In general, patients primarily undergo nonsurgical treatments, such as physiotherapy, occlusal splint therapy, and medication to relieve functional limitation and pain. After initial conservative treatment, orthodontics and surgery become options, such as intrusion of the maxillary molars with miniscrews or miniplates, maxillary or mandibular surgery for occlusal deformity correction, gradual mandibular advancement with distraction osteogenesis, and TMJ interventions followed, or not, by orthognathic surgery.

An alternative is to combine the orthodontic treatment with the use of a splint. After the initial splinting therapy, orthodontic treatment is conducted for occlusal reconstruction at the splint-induced condylar position. Both archwires (maxillary and mandibular) are used simultaneously with the splint and vertical elastics to prevent anterior intrusion. Afterward, the splint is reduced in size gradually according to the orthodontic progress. However, if a pathologic condition such as osteoarthritis with TMJ disc displacement is not treated, the long-term prognosis of this condition may allow a new progression of condylar resorption, occlusal relapse, and TMJ pain.

Our patient was eager to improve her facial and dental appearance and minimize the TMJ pain. Thus, the clinical approach consisted of surgical and orthodontic treatment that included bilateral TMJ articular disc repositioning surgery and fixed orthodontic appliances.

Treatment progress

Initial leveling and alignment of the maxillary dental arch was achieved with 0.016-in nickel-titanium thermal archwire, using the straight-wire technique and Roth prescription 0.022-in slot braces. The patient had requested rheumatoid, endocrine, and gynecologic screening. The results were negative for autoimmune disease and any other pathology. After 18 days, bilateral TMJ articular disc repositioning surgery and extraction of all 4 third molars were performed. It was noticed during the TMJ surgery that there was a high adherence of the disc on the right side with signals of degenerative joint disease. Fourteen days later, alignment and leveling of the mandibular dental arch was achieved with the same protocol as used in the maxillary arch. After a 1-month period, both archwires were replaced by 0.017 × 0.025-in nickel-titanium wires. The final 0.019 × 0.025-in stainless steel archwires were placed, and dental occlusal adjustments were performed during 9 months. The total active orthodontic treatment period was approximately 12 months, including the surgical time.