| Temporomandibular disorder (TMD) is a common condition in adolescent patients seeking for orthodontic care. It is caused by a complex multiple factors. Despite the dispute, occlusion is one of its pathogenic factors, and has been accepted by many clinicians. As verified by numerous studies, the malocclusion is related to TMD, e.g.(anterior opening, deep overbite, posterior crossbite, scissor bite, bite interference at the non-working side, and mandibular deviation). TMD mainly includes:functional disorder, structural disorder and joint organic destruction. Clinically, the TMD patients often have an abnormality in the mandibular movement, i.e. muscle tenderness at or around the joint area, and joint clicking/noise. In asymptomatic patients,the radiography showed a change of joint space and cortical bone surface (i.e. absorption or hardening) or a displacement of joint disc. At present, there is yet no effective treatment method for TMD. The occlusion therapy can effectively improve the clinical symptoms, stabilize the mandibular position, so as to reliably guarantee the correct diagnosis, treatment and efficacy of orthodontics. Objective:To explore the change in the clinical symptoms, the position of condylar, the position of joint disc, the relationship of maxillary and mandibular after the RW-splint treatment of malocclusion with TMD, and offer the theoretic basis for TMD patients before the orthodontic treatment. Methods:1.Subjects:This study selected13TMD patients at the Orthodontics Dept. of Stomatology Hospital of Guangdong Province during2010-2012. There were2male patient and11female patients, at an age of14-22years old (mean19.5). Inclusion criteria:(1) Up to the diagnostic criteria for TMD study (RDC/TMD);(2) Cone beam CT with joint space change or (and) resorption in Condylar surface;(3) tooth tabulates firm location requirements that could satisfy RW-splint;(4) Patients has treatment requirements and could cooperate with treatment. Exclusion criteria:(1)2or more posterior tooth loss;(2) Acute issues temporomandibular pain patients or joint inflammation patients;(3) Limited mouth opening, the range of motion was less than3cm;(4) There was traumatic history or temporomandibular operation history;(5) Patients with systemic immune system disease or supersession disease;(6) Patients with psychological problem.2. Study content2.1Fricton craniomandibular was calculated to assess the improvement of13patients’ clinical symptoms after RW-splint treatment. Fricton craniomandibular index includes TMJ dysfunction index (dysfunction index, DI) with palpation index (palpation index, PI),dividing for Fricton craniomandibular index (craniomandibular index, CMI) equally DI and PI.2.2Cephalometry films analysisCephalometry films were taken before and after RW-splint treatmentUsing Winceph7.0software to measure ZANB,ZSN-MP,S-GO/N-Me and the anterior overbite, overjet.Observing the change of jaw position.2.3Examination upper and lower first molar and canine relationRecord the siggital distance of both sides’ first molar and canine before and after RW-splint treatment.2.4Measurement of temporomandibular joint space Cone beam computed tomography were performed before and after treatmentjLinear measurements of anterior space,posterior space, superior space,lateral space,medial space were made to evaluate the position of the condyle.the position of condyle at joint fossa was also judged through the1nP/A(P represent posterior joint space,A represent anterior space)calculation.concentric positions of the condyle were defined if InP/A between-0.25and+0.25.If InP/A was greater than+0.25,the condyle’s position was defined anteriorly eccentric.Posteriorly eccentric positions were indicated for values InP/A less than-0.25.2.5The relationship between joint disc and condylarIn13patients, the temporomandibular area at both sides was scanned at the maximum intercuspid and mouth open position through the1.5T superconducting MRI apparatus (General Electric Corporation, U.S.A.), with the axial position, coronal position T1-weighted image, oblique sagittal T1-weighted image, oblique sagittal T2-weighted image and oblique sagittal PD weighted image for the mouth closing state; and with the axial position, oblique coronal T2-weighted image, oblique sagittal T1-weighted image, oblique sagittal T2-weighted image for mouth opening state. SE array.The relationship between joint disc and condyle was measured through the Trace criteria (i.e. disc demarcation angle method). In the oblique sagittal T1-weighted image at the mouth closing state, there is an obvious demarcation line between posterior band and bilaminar region of joint disc (i.e. disc demarcation line). The posterior band of joint disc is at the top of condyle, and the angle between disc demarcation line and perpendicular line at12’o clock position of condyle is called "disc demarcation angle". When this angle is within±10°, there is a normal disc; and when this angle is more than±10°, there is a forward movement of joint disc. The angle between joint disc and condyle at the oblique sagittal position of mouth closing state and the length of joint disc were measured through the MRI, so as to evaluate the degree of displacement and the morphological change of joint disc.2.6MCD record The position of condylar was recorded with MCD recording sheet by the articulator transfer.3. Results3.1. Fricton craniomandibular disorder index:After the treatment, the mandibular movement (MM), joint noise (JN), dysfunction index (DI), palpation index (PI) and craniomandibular index (CMI) decreased significantly (P<0.05), and the joint palpation (JP) decreased but not significantly (P>0.05). After the RW-splint treatment, the clinical symptoms improved significantly, the joint pain relieved significantly and even disappeared, the limited mouth opening relieved, and the joint clicking relieved.3.2. Cephalometry films:The ZANB and ZSN-MP increased, S-Go/N-Me decreased, anterior overbite decreased, the overjet increased and the mandible rotated downward and backward.3.3. Relation between first upper molar and canine teeth:After the treatment, the first upper molar at the left and right side moved distally by1.923±0.757mm and2.046±1.413mm, and the canine teeth at the left and right side moved distally by1.994±1.015mm and2.122±1.243mm respectively.3.4. Joint space CBCT examination:After the treatment, every joint space of11patients increased to some extent. In the left temporomandibular joint, the lateral space widened significantly (P<0.05), the anterior,mesial,upper and posterior space widened but not significantly (P>0.05). In the right temporomandibular joint, the posterior and mesial widened significantly(P<0.05),the anterior,upper and lateral space widened but not significantly(P>0.05). Descriptive statistical analysis results display the median rate of condyle in13patients increased from30.8%to50%after treatment.3.5. Angle of disc-condyle:After the treatment, the angle of disc-condyle in10patients decreased from23.662±11.740°to20.378±14.688°at the left side, and increased from19.528±7.983°to21.272±12.653°at the right side. After the treatment, the joint disc did not change significantly at both sides. Descriptive statistical analysis indicating after RW-splint treatment mild disc displacement decreased from75%to50%,25%returned to normal disc-condyle relationship.3.6. Length of joint disc:After the treatment, the length of joint disc decreased from10.01±2.03mm to9.26±2.04mm at the left side, but increased from9.00±1.75mm to9.45±1,67mm at the right side.3.7. MCD record:Before the treatment, the central relation did not consist with the maximum intercuspid position in all subjects, and the condylar located posteriorly and downward, and had a horizontal shift in the most subjects.4. Conclusion4.1. The RW-splint treatment could improve the clinical symptoms of TMD patients, rapidly significantly relieve the joint pain, improve the mandibular movement, relieve the joint clicking, but did not significantly improve the joint clicking in the TMD patients with a scissor bite of joint and a serious displacement of joint disc.4.2. The RW-splint treatment could change the position of condylar process in joint fossa, and tended to resume the dislocated condylar process to central position.4.3. The RW-splint treatment could improve the relation of disc-condyle. After treatment,25%patients return to normal disc-condyle relation.4.4. In a word, the RW-splint could relocate the mandible, display the actual malocclusion conditions, and thus play an auxiliary role in the diagnosis,design/preparation of treatment protocol for orthodontist. |
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