INTRODUCTION

Rheumatoid arthritis (RA) is an autoimmune disease that causes chronic inflammation in joint tissues; it is usually seen in other joints prior to temporomandibular joint (TMJ) involvement. The common clinical findings in RA of the TMJ are tenderness, pain, clicking, crepitation, stiffness, and limitation in jaw movements.12 In patients with progressive disease, the joint space becomes obliterated due to loss of condylar height and retrognathia, and an anterior open bite deformity occurs due to destruction, erosion, sclerosis, and flattening of the articular surface of the condyle and eminence.34 These patients occasionally require a surgical approach, such as TMJ replacement therapy or costochondral grafting of the TMJ to solve the anterior open bite deformity.5–7 However, condylar resorption in RA is multifactorial, based on the patient's adaptive capacity and on mechanical stimuli. When predisposing patient factors are not present, occlusal treatments (orthodontics, orthognathic surgery, prosthetics) normally result in functioning remodeling.8 TMJ is changeable, and changes in occlusion and mandibular position resulting from forces generated during orthodontic/orthognathic manipulations can contribute to remodeling of the articular structures of the TMJ.9

We report the case of an RA patient in remission with an open bite deformity who had severely eroded articular surfaces of both condyles and in whom occlusion was orthodontically reconstructed. Considerable improvement of the TMJ condition has been sustained after approximately 4 years of follow-up.

CASE REPORT

The patient was a 32-year-old Japanese woman, who had a severe open bite deformity with a Class I molar relationship (Figure 1A) at the time of the initial examination in May 2000 (Table 1). Overbite and overjet were −4 mm and +2 mm, respectively. She complained mainly of pain during jaw movement and masticatory dysfunction accompanied by an anterior open bite.

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Table 1.  Cephalometric analysis

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In November 1995, the patient had consulted a nearby orthopedist because of pain in the shoulder. She was diagnosed as having RA based on the presence of rheumatoid factor in the blood. At that time, the patient had mild symptoms of RA. In January 1999, the patient deteriorated acutely and developed joint stiffness in the neck, shoulder, hands, wrists, and feet, and she was managed with oral prednisolone and bucillamine, as well as injections of gold sodium thiomalat. By June 1999, the RA had compromised both TMJs, and clinical examination revealed a very limited mouth opening (33 mm) with bilateral TMJ pain during jaw movement and when eating slightly harder food. By then, she had also developed a substantial anterior open bite.

On cephalometric analysis, the patient demonstrated a skeletal Class II tendency with bimaxillary protrusion. Sagittal tomography showed severe erosion of the condyles on both sides (Figure 2-Pre). Magnetic resonance imaging (MRI) revealed medial-anterior disc displacement without reduction based on coronal and lateral images (data not shown), and there were marked morphological changes in the condyles of both sides (Figure 3-Pre). Based on these findings, reestablishment of a normal disc-condyle relationship was considered difficult, and the patient chose not to have surgery. Therefore, an orthodontic approach was carried out in an attempt to improve the patient's occlusal and articular conditions by reconstructing the occlusion, promoting functional mandibular adaptation, and creating an unloaded situation of the TMJ that may lead to some type of condylar adaptive remodeling.

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At the beginning of the orthodontic treatment, the patient's RA condition was considered stable, and her general condition improved as a positive response to the pharmacologic therapy, with a negative rheumatoid factor test. Fortunately, her RA status changed from stable to inactive or asymptomatic disease during the orthodontic treatment, and her RA remained inactive after the completion of the treatment without any pharmacologic support.

In August 2000, orthodontic treatment was started using 0.018- × 0.025-in slot standard edgewise brackets, and very light and continuous forces were slowly applied with 0.014-in Ni-Ti archwires during the initial leveling, to minimize mechanical loading on the TMJ as much as possible (Figure 1B). After leveling, 0.016- × 0.016-in Ni-Ti and stainless-steel archwires were placed for alignment. From January to October 2002, 0.016- × 0.022-in blue Elgiloy multiloop edgewise arch wires (MEAW) with tip back bend activation and bending of crown lingual torque gradually from first premolar to second molar in both arches, and the use of short Class II or up and down elastics (3/16, 6 oz) at the anterior part,1011 were simultaneously started. This was to control the occlusal plane and to prevent flaring of the anterior teeth (Figure 1C). Detailing was done with 0.016- × 0.016-in stainless-steel archwires and up and down elastics (1/4, 3.5 oz) while asleep at night to settle the occlusion until debonding in August 2003. The retention phase was accomplished using Hawley retainers, which were worn at all times during the first 12 months after braces were removed and then only at night for another year.

After a total treatment time of 3 years, a reconstructed stable occlusion was attained and almost all of the TMD symptoms disappeared (Figure 1D). Sagittal tomograms and MRI of the TMJ showed that both condyles were remodeled adaptively (Figure 2-Post and Figure 3-Post), even though the reference position (RP) − intercuspal position (ICP) difference at posttreatment was longer than that of pretreatment on the MPI analysis (Figure 5A,B).12 However, adaptive morphological change of the condyles was continuously induced (Figure 2-Ret and Figure 3-Ret) from posttreatment to postretention at 4 years 2 months. In addition, the reconstructed occlusion was acceptable (Figure 1E,F). The stability of the advanced mandibular position obtained at the end of the treatment was evaluated by cephalometric analysis and superimposition of lateral cephalographic tracings of pretreatment, posttreatment, and postretention at 4 years 2 months. It was evident that the final advanced position has been well maintained through the follow-up period (Figure 4A,B). Furthermore, the RP-ICP difference gradually decreased during the postretention period from 2 to 4 years (Figure 5C,D). Her RA, fortunately, was inactive and remains asymptomatic during posttreatment and postretention, even though she has discontinued all medications.

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It is worth noting that informed consent was given by the patient to publish the previous data.

DISCUSSION

The TMJ is often involved in patients with RA, although, in general, the TMJ symptoms have been thought to be not as severe as those in other joints. Nevertheless, occasionally some patients develop progressive TMJ arthritis, which ultimately results in distracted condylar surface-induced pain, dysfunction of mandibular movement, and the development of an anterior open bite.1–4

Our case developed an anterior open bite deformity (Figure 1A) due to the severely eroded articular surfaces of both side condyles, as noted on the lateral tomograms and MRI (Figures 2 and 3). In general, TMJ replacement therapy or costochondral grafting of the TMJ provides a surgical solution for such patients.4–6 At the time of diagnosis, we explained the benefit of a surgical procedure in her case, but the patient did not wish to have surgery. Therefore, she was managed orthodontically after the RA was considered stable and the seronegative rheumatoid factor was confirmed by blood tests. After orthodontic treatment (Figure 1D), the patient's occlusal and articular conditions improved considerably and the TMD symptoms had almost totally disappeared. There were some significant morphologic changes in the eroded condyles based on radiographic and MRI findings (Figure 2-Post, Figure 3-Post).

Remodeling of the articular structures of the TMJ is reported when orthodontic-orthopedic forces are applied in adolescents and young adults.1314 However, Tanaka et al15 reported that splint therapy together with an orthodontic approach might be able to induce adaptive change of the condyle in an adult patient with severe osteoarthrosis of the TMJ accompanied by an anterior open bite. Although repositioning of the disc was not achieved, the reason for such adaptive responses of the eroded condyle was attributed to the achievement of a stable occlusion, reestablishment of uniform joint spaces (antero-superior), and elimination of excessive or unbalanced stress on the condyle that may have reduced TMJ loading because of an optimum condylar position. Moreover, Sato et al16 also demonstrated that occlusal reconstruction using a prosthetic approach might be of considerable value for inducing the desirable remodeling of the condylar heads on a topographical study in two of six adult RA cases. Therefore, after our patient had undergone RA remission, we used an orthodontic approach with MEAW1011 techniques plus short Class II elastics with a vertical component to provide a mandibular position with reduction of TMJ loading, creation of proper joint space, and establishment of stable occlusion.

Our outcomes are especially interesting, since our case not only maintained the reconstructed occlusion (Figure 1E,F) but also continued to exhibit adaptive morphological changes of the eroded condyles from posttreatment to postretention. These findings are based on topographic and MPI follow-up data despite the difference between the deranged RP-ICP, resulting in a bigger distance at posttreatment (Figure 2-Ret and Figure 3-Ret). The induced mandible position was obviously maintained during the postretention period (Figure 4). Also interesting is that MPI findings indicated that the RP-ICP difference decreased during postretention from 2 years 3 months to 4 years 2 months (Figure 5C,D). It could be speculated that the stable and/or functional occlusion might be responsible for continuously promoting the displayed adaptive remodeling of the eroded condyles. Therefore, it may be possible that the reconstructed functional occlusion by orthodontics was effective in promoting the remodeling of the resorbed condyles even in a patient with a history of RA of the TMJ.

In conclusion, this case suggests that an orthodontic, rather than a surgical, approach to eliminate molar interference, change occlusal contacts, and reconstruct a stable functional occlusion was associated with a functional remodeling of destroyed condyles. This occurred by reducing their mechanical loads at the same time that the open bite condition was corrected by anterior mandibular rotation (Figure 4A). These changes remained stable in the postretention period (Figure 4B) (functional repositioning), even though this middle-aged patient had a history of RA of the TMJ. However, further clinical and basic research regarding this treatment approach, in these particular cases, is necessary.