TMJ Adaptations by Orthodontic Treatment in Adolescent Males With Angle's Class II Division 2 Malocclusion: MRI Study
Condition: Class II Division 2 Malocclusion
MeSH terms: Malocclusion; Malocclusion, Angle Class II
Study type: Interventional

Summary: 
      the aim of this study is to document the changes brought about in the internal anatomic
      relationships of the TMJ complex , positional changes of glenoid fossa with respect to
      adjacent cranial structures after completion of fixed orthodontic treatment in adolescent
      males initially treated with removable functional appliances for skeletal class II, Angle's
      class II division 2 malocclusion
    

Detailed description: 
      Angle's class II division 2 malocclusion is subtype of Angle's class II malocclusion with
      unique facial, dental and craniofacial features which differentiate it from other
      malocclusions so much that it has been said to be a syndrome itself. Its frequency lies
      between 1.5 and 5% of all malocclusions found in a white western population.. Condyle
      position changes from anterior to posterior with age in class II division 2 cases. The use of
      functional orthopedic appliances to correct Class II malocclusions associated with
      retrognathic mandibles is indicated for the first phase of orthodontic treatment. A second
      phase of treatment is undertaken with fixed orthodontic appliances to obtain occlusal
      refinement. Although various investigations have shown the efficiency of this method of
      treatment, the mechanism by which the temporomandibular joint (TMJ) responds to the treatment
      is controversial.

      Various techniques have been used to image the TMJ which include Magnetic Resonance Imaging
      (MRI), Cephalograms, Orthopantomograms , Tomograms , Bone scintigraphy with radiologic
      markers like 99mTc-MDP, Arthroscopy and Arthrography , CT scanning, Cone Beam Computed
      Tomography (CBCT).

      Magnetic Resonance Imaging (MRI), a multiplanar imaging technique, has the advantage of
      giving an accurate assessment of both the bony and the soft tissues. This technique is
      believed to be non-invasive, radiation free and gives more superior contrast resolution than
      any other imaging modality. MRI is considered the imaging modality of choice for assessment
      of internal derangements of the temporomandibular joint. Bony structures and especially soft
      tissues of the TMJ can be examined by means of MRI and the relations of the tissues with each
      other can be evaluated.

      MRI studies have been done on fixed functional appliances which show significant displacement
      of condyle during treatment but later condyles returned to pre treatment positions at the end
      of fixed functional appliance treatment. Results documented in fixed functional appliance may
      not be same in removable appliances. Effects of removable functional appliances on the
      condyle-glenoid fossa (C-GF) complex have been studied with respect to the Frankel,
      Activator, Twin block and Bionator appliances.It should be noted that all of above studies
      are limited to the phase of removable functional appliance therapy only in Class II division
      1 and no MRI study has attempted to evaluate the changes in the position of the
      Condyle-Glenoid Fossa (C-GF) complex treated with removable functional appliance therapy,
      followed by fixed orthodontic treatment in Class II division 2 malocclusion.

      No studies have been done on bi-phasic treatment of skeletal class II, Angle's class II
      division 2 involving removable functional appliances in the first phase followed by fixed
      orthodontic treatment in second phase.

      Therefore, the aim of this study is to document the changes brought about in the internal
      anatomic relationships of the TMJ complex , positional changes of glenoid fossa with respect
      to adjacent cranial structures after completion of fixed orthodontic treatment in adolescent
      males initially treated with removable functional appliances for skeletal class II, Angle's
      class II division 2 malocclusion,

      MATERIALS AND METHODS

      It is a longitudinal clinical trial to evaluate TMJ disc-condyle-fossa relationship using MRI
      scan following bi-phasic therapy in skeletal Class II, Angle's class II division 2
      malocclusion in adolescent males.

      The present study will be conducted in the Department of Orthodontics and Dentofacial
      Orthopedics, PGIDS, in association with the Department of Radiology, PGIMS, and Department of
      Oral Radiology, PGIDS, Pt B. D. Sharma University of Health Sciences, Rohtak.

      Ethical clearance- The study will be carried out in humans after the institutional approval
      obtained from ethical committee.

      Source of Data The study sample will consist of the subjects from the Department of
      Orthodontics and Dentofacial Orthopedics, PGIDS , who will be successfully completing the
      prefunctional and functional appliance therapy for correction of skeletal class II, Angle's
      class II division 2 malocclusion and will be ready for fixed orthodontic treatment for final
      finishing and detailing of occlusion

      INFORMED CONSENT OF THE PATIENT

      A valid, bilingual informed written consent of the patient or parent/guardian will be
      obtained from the patient before registering the patient in this clinical study. Patients
      will be informed of all the theoretical risks and benefits of the interventions under test.

      Intervention and design of study The study sample will consist of those 14 adolescent males
      who had been treated initially with pre functional and functional appliance therapy for
      skeletal Class II, Angle's class II division 2 malocclusion and had following MRI scans done
      during the treatment

        1. Stage- A (pre-treatment),

        2. Stage- B (after pre-functional therapy)

        3. Stage- C (After completion of Functional Appliance Therapy) These patients will be
           further treated with fixed orthodontic treatment for final finishing and detailing and
           an MRI will be taken after debonding of fixed orthodontic appliance (stage D). MRI scans
           thus obtained will be evaluated for documenting changes in the morphology and anatomic
           positions of condylar head, articular disc and glenoid fossa and will be traced for the
           various angular and linear metric measurements MRI scans of the TMJ will be obtained
           with a 1.5 Tesla Philips Intera Nova Gradient (Netherlands) scanner equipped with Sense
           Head 6 channel coil for simultaneous imaging of right and left joints. Sagittal images
           will be taken perpendicular to the long axis of the condylar head and the coronal images
           will be taken parallel to the long axis of the condylar head. The images will be
           recorded in maximum intercuspation after debonding of fixed orthodontic appliance. The
           MRI protocol will include PD TSE (Turbo Spin Echo) sequence (TR 1500/ TE 30/ FoV 150x150
           mm) T1 spin echo sequences (TR 450⁄TE 15⁄FoV 160x160 mm) and T2 TSE sequence (TR 2424⁄
           TE 100⁄FoV 160x160 mm).

      FIXED MECHANOTHERAPY TREATMENT PHASE

      The sample will be having cases in class I/ superclass I molar relation and lateral open bite
      may be present in premolar regions after the completion of functional phase. The final fixed
      orthodontic phase will be taken up for the final finishing and detailing of the occlusion
      after the retentive phase of functional appliance therapy is completed. It involves banding
      and bonding of both upper and lower arches with MBT 0.022" appliance. Progressive wire
      sequences to be used are 0.014" NiTi, 0.016" NiTi, 0.018" NiTi, 0.017" x 0.025" NiTi, 0.019"x
      0.025" NiTi, , 0.019"x 0.025" S.S., 0.014" S.S. Once stainless steel archwires are in place,
      class II elastics may be prescribed to the patient to prevent relapse of class I molar
      relation achieved. Cases are to be finished in class I molar intercuspation with normal
      overjet and overbite. Appliance will be debonded and final MRI (stage D) will taken for all
      the patients. Hawley's retainer with anterior bite plane will serve for retention of achieved
      results

      Evaluation of MRI stages This will be done with the help of various angular and linear
      measurements like the eminence angle, the sagittal disc position measured in relation to two
      reference lines: the posterior condylar line (PC line) and the Frankfurt Horizontal plane (FH
      Plane), the coronal disc position , Sagittal condylar concentricity 5) The glenoid fossa
      angle, Condyle and glenoid fossa displacements and Superior joint space

      Statistical analysis The final data recorded will be processed by standard statistical
      analysis.
    

Intervention name(s): orthodontic treatment
Intervention type(s): Other
Intervention description(s): fixed orthodontic treatment in adolescent males initially treated with removable functional appliances for skeletal class II, Angle's class II division 2 malocclusion,
Other intervention name(s): fixed mechanotherapy
Intervention model: Single Group Assignment
Intervention model description: study on 14 male adolescent patients having skeletal class II, Angle's class II division 2 malocclusion.
Masking: None (Open Label)
Primary purpose: Treatment