Treatment of orthodontic patients with temporomandibular disorder (TMD) is challenging for orthodontists because of the TMD signs and symptoms and unstable mandible position, which may lead to improper diagnosis and treatment design. This case report presents a 22-year-old woman with proclined maxillary incisors and TMD. First, stabilization splint therapy was implemented to eliminate temporomandibular joint pain and to obtain the stable adapted centric posture. Subsequently, orthodontic treatment was initiated on the basis of a definitive diagnosis made from the postsplint records. Temporary anchorage devices were used to intrude maxillary molars and distalize the maxillary dental arch. Favorable soft tissue, skeletal, and dental relationship were accomplished after 12 months of comprehensive orthodontic treatment. Functional occlusion was established with teeth as well as vacuum-formed retainers. Excellent posttreatment stability was maintained after a 20-month retention.
A patient with an unstable mandibular position was diagnosed and treated.
Treatment included stabilization splint therapy.
Class I relationship was achieved with maxillary arch distalization and molar intrusion.
Clear retainer provided functional occlusion and protected teeth from attrition.
Temporomandibular disorder (TMD) is a comprehensive term that encompasses a group of musculoskeletal and neuromuscular conditions that involve the temporomandibular joint (TMJ), the masticatory muscles, and all related tissues. , Although poorly understood, the etiology of TMD is believed to be multifactorial, involving factors such as genetic factors, psychological factors, and anatomic factors. Pain in the masticatory musculature and TMJ area, limited mouth opening, and clicking or crepitus during jaw movement are common signs and symptoms of TMDs.
Despite that the connection among occlusal factors, condylar position, and TMD remains part of an extensive discussion, multiple occlusal risk factors have been identified to be closely associated with TMD, with uncertain recognition of their cause-and-effect relationship. It has been demonstrated by numerous studies that when the centric slide, defined as “the movement of the mandible while in centric relation (CR), from the initial occlusal contact into maximal intercuspal position (MIP),” reaches a certain value, usually 2 mm, it could be correlated to TMD. , In addition to the related signs and symptoms, a large centric slide can also be troubling because the discrepancy between the 2 positions may interfere with the proper diagnosis and treatment planning.
It is widely believed that no aggressive, irreversible occlusal treatment should be given to patients with TMD when the disease is in the active stage. The therapy begins with the release of the TMD symptoms, the pause of condylar resorption, and confirmation of a reliable mandibular position for occlusal treatment.
A stabilization splint can provide temporary ideal occlusion to eliminate occlusal factors and reduce abnormal muscle activity. It is sometimes called a muscle relaxation appliance because it can effectively reduce muscle pain. , Furthermore, a stabilization splint allows the condyles to sit in their most musculoskeletally stable position by reproducing functional occlusion.
In the present case report, we demonstrate the 2-phase treatment of a female patient with TMD and a large centric slide. Alleviation of TMD symptoms and stable, functional occlusion were achieved by stabilization splint therapy and subsequent nonsurgical orthodontic treatment.
Diagnosis and etiology
The patient, a 22-year-old woman, had a chief complaint of maxillary incisor protrusion and jaw pain. She also mentioned joint noises, limited opening, and pain in front of the ears on both sides occasionally for over 3 years. The jaw pain was greater in the morning and during mastication. She claimed no history of dental trauma and orthodontic treatment but admitted sleep bruxism and unilateral mastication.
Clinical examination revealed a convex facial profile, hyperdivergent mandible, and skeletal Class I relationship ( Fig 1 ). The maxillary dental midline was coincident with the facial midline, whereas the mandibular midline was shifted to the right by 1.5 mm. Meanwhile, her chin point was deviated to the right side.
Intraoral and dental cast examination showed an Angle Class I molar relationship bilaterally with normal anterior overbite and overjet ( Fig 1 ). There was mild crowding in both dental arches with maxillary incisor procumbency.
The cephalometric analysis ( Fig 2 ) revealed a skeletal Class I relationship (ANB, 3.5°) with a hyperdivergent growth pattern (SN-MP, 41.0°). Normal interincisal angle was obtained by proclined maxillary incisors and reclined mandibular incisors (U1-L1, 121.1°; U1-SN, 108.2.0°; L1-MP [IMPA], 90.0°). The panoramic radiograph showed that all teeth were present except the maxillary left third molar. There were mild root resorptions of both maxillary central incisors, the crooked root of maxillary second premolars, and abnormal condyle shape on the left side.
The TMJ evaluation was performed in accordance with the diagnostic criteria for TMD guidelines. We revealed bilateral crepitus in her TMJ during mouth opening and closing. The distance of maximal mouth opening was 41 mm, and excursive and protrusive movements were longer than 8 mm. Moderate pain in the lateral pole of TMJ on both sides and anterior aspect of temporalis muscle on the left side was detected with palpation. Meanwhile, the obvious centric slide was discovered by the bilateral manual manipulation technique, according to Dawson. This indicated a discrepancy of condylar position between CR and MIP. Cone-beam computed tomography (CBCT) scans were reconstructed into 3-dimensional images with Dolphin Imaging software (version 11.8, Dolphin Imaging and Management Solutions, Chatsworth, Calif). The long axis of the condyle was determined, and the vertical plane bisecting the long axis was defined as the sagittal section. The CBCT images showed a discontinued cortical layer of the condylar head on the left side ( Fig 2 ). Magnetic resonance imaging (MRI) of the TMJs demonstrated that on either side of the TMJ, the posterior band of the disc was located anterior to the condylar head in the MIP, with the intermediate zone located between the articular eminence and the condylar head during maximal mouth opening (MRI data missed). On the basis of these findings, the patient was diagnosed with arthralgia at both sides of the TMJ, degenerative joint disease in both TMJs, local myalgia in the left temporalis, and anterior disc displacement with reduction of both TMJs.
On the basis of the data, a definitive diagnosis should be made after the stabilization of the mandibular position. The patient was advised to chew on both sides alternatively. Meanwhile, a full-time maxillary stabilization splint was prescribed to the patient to achieve a musculoskeletally stable position.
After 9 months of stabilization splint therapy, a stable, comfortable jaw position was determined. No discomfort was discovered during the load testing. Given that the patient had bilateral anterior disc displacement with reduction, this stable completely seated condylar position was more appropriate to be described as adapted centric posture rather than CR. , Postsplint records for definitive diagnosis were taken, including intraoral photographs, cephalograms, and CBCT scans ( Figs 3 and 4 ). Split casts were mounted on a semiadjustable articulator and then scanned ( Fig 4 ). Cephalometric and CBCT superimpositions showed a clockwise rotation of the mandible and a posterosuperior shift of the condyles ( Fig 3 ). The CBCT image showed an improved cortical continuity of the left condylar head. Three treatment goals were achieved through stabilization splint therapy: (1) both condyles were completely seated in a musculoskeletally stable position, (2) pain in TMJ and masticatory muscle were eliminated, and (3) no progressive condylar resorption was discovered.
After splint therapy, this patient was diagnosed with an Angle Class II malocclusion with skeletal Class II base, deep overjet, anterior open bite, mandibular midline deviation, and degenerative joint disease at left TMJ.
The treatment objectives were to (1) align and level both dental arches, (2) obtain an Angle Class I molar and canine relationship, (3) coordinate dental midlines, (4) rotate mandible counterclockwise for the improvement of facial esthetics, (5) establish ideal anterior overbite and overjet, (6) monitor the condylar position closely and shorten orthodontic treatment duration, (7) achieve functional occlusion after orthodontic treatment with and without retainers, and (8) give up unilateral chewing habit.
Two treatment options were considered for this patient. The first option was combined orthognathic surgery and orthodontic treatment. LeFort I osteotomy for maxilla uplift and bilateral sagittal split ramus osteotomy for mandibular advancement and counterclockwise rotation were designed. This treatment option would be favorable for the correction of the skeletal discrepancy and improvement of facial and smile esthetics. The second option involved camouflage orthodontic treatment without extraction. The intrusion of the maxillary posterior teeth by using TADs was designed to achieve counterclockwise rotation of the mandible. Meanwhile, TADs could also provide direct anchorage for the distalization of the maxillary dental arch to alleviate an Angle Class II relationship, excess anterior overjet, and maxillary incisor procumbency. Three of the third molars were suggested to be extracted no matter which treatment was chosen. The patient refused orthognathic surgery because of concerns of the surgery-related risks and high treatment costs and thus decided on the second option.
To relax the masticatory muscle and locate the musculoskeletally stable position of the condyles, an anterior deprogramming splint was prescribed to the patient before the stabilization splint was fabricated. The initial musculoskeletally stable position was determined by bilateral manual manipulation technique, and the anterior deprogramming splint provided even contact of mandibular anterior teeth to the splint and guidance of protrusive and excursive movements. Because the posterior disocclusion eliminated the existing occlusal condition and muscle engrams associated with muscular protection, it allowed the complete seating of the condyles in their musculoskeletally stable position. After 1 week of splint use, the refined musculoskeletally stable position was acquired and was double-checked with the bilateral manipulation technique, which may be more predictable and accurate to fabricate the stabilization splint. , Then, the acrylic resin was added to the occlusal surface of the splint to fabricate a stabilization splint on the basis of this jaw relationship. The stabilization splint provided a smooth surface for all buccal cusps or incisal edges of mandibular teeth to contact against and provided immediate disocclusion of posterior teeth in all protrusive and excursive jaw movement ( Fig 5 ). The bite marks on the occlusal surface of the splint were checked and adjusted after 1 week, 3 weeks, and every month afterward to ensure a mutually protected occlusion. With the use of stabilization splint, the jaw relationship gradually shifted as indicated by the continuous changing of the anterior relationship and bite marks on the occlusal surface of the splint ( Table I ). A 2.5 mm increase of anterior overjet and 1 mm decrease of anterior overbite were detected after 3 months of treatment and remained stable afterward. Her mandibular dental midline deviation was decreased, as shown by intraoral photographs ( Figs 1 and 4 ). No discomfort was discovered in this jaw relationship during the load testing experiment. The pain of muscle or joint origin showed gradual improvement and was eliminated after 6 months of splint therapy. The stable, comfortable, adapted centric posture (final musculoskeletally stable position) was determined by stabilization splint therapy. The patient reported that she had quit unilateral mastication. However, the bilateral crepitus remained unchanged during the whole treatment duration.
|Duration||Anterior OJ and OB||TMD symptoms||TMJ Noises||CBCT|
|Pretreatment||5.5 mm; 2.4 mm||Moderate pain in TMJ on both sides and temporalis muscle on left side||Bilateral crepitus||Discontinued cortical layer of the left condylar head|
|1 mo||6.5 mm; 1.9 mm||No change||No change|
|3 mo||8.0 mm; 1.4 mm||Mild pain in TMJ of left side||No change|
|6 mo||8.0 mm; 1.4 mm||No pain in TMJ or masticatory muscle||No change|
|9 mo||8.0 mm; 1.4 mm||No pain in TMJ or masticatory muscle||No change||Improved cortical continuity of left condylar head|