TMJ Adaptations by Orthodontic Treatment in Adolescent Females 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 females
      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. Hypertrophic
      masticatory muscles as documented in class II division 2 are directed in more anterior
      direction leading to increased magnitude of occlusal forces and hence increased TMJ loading.
      TMJ morphology depends, to an extent on occlusal loads acting on it, so class II division 2
      malocclusion patients are expected to have specific TMJ complex morphology. 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. According to Akar et al "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. Franco et al found that Frankel therapy resulted in a 'more normal'
      articular disc morphology. Arat et al. concluded that disc positions were insignificant after
      6 months of Activator therapy Chintakanon et al. concluded that Twin Block therapy had
      neither positive nor negative effects on disc position, and there was little evidence that
      the disc was recaptured. They also noted anterior positioning of the condylar head (CH) in
      the glenoid fossa after 6 months of Twin Block therapy. 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.

      Aidar et al have studied changes in temporomandibular joint disc position and form following
      Herbst and fixed orthodontic treatment and found that at the end of the bi-phasic treatment
      the position and form of the initial articular discs were maintained. Kinzinger, et al.
      studied the effects of fixed orthodontic treatment in the case of skeletal class II on the
      position of the articular disc and condyle using MRI on 20 subjects and concluded that
      treatment did not alter the position of articular disc and even noticed an improvement in the
      anterior disc displacement in 8 joints out of 40. 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
      females 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 females.

      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 females
      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

      Stage- A (pre-treatment), Stage- B (after pre-functional therapy) 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 1.5/3 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 following parameters:

      ANGULAR AND LINEAR MEASUREMENTS The eminence angle and 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 PC line to be drawn directly on the MRI scan, while the FH
      plane transferred from the lateral cephalogram to the MRI scan, according to the method given
      by Nebbe et al.

      Transfer of FH plane Determination of long axis of the condyle will be done by two step
      circle center method by Nebbe et al.

      ANGULAR MEASUREMENTS 1-2) The eminence angle and the coronal disc position will be evaluated
      by the method described by Chintakanon et al.

      3) The sagittal disc position will be evaluated using PC line and FH plane as described by
      Chintakanon et al.

      4) Sagittal condylar concentricity will be evaluated using the method described by Pullinger
      et al.

      5) The glenoid fossa angle will be measured on the sagittal films as the angle between the
      tangents to the anterior and posterior slopes of the glenoid fossa.

      LINEAR MEASUREMENTS 6) Condyle and glenoid fossa displacements: The position of the glenoid
      fossa, and that of the condyle, will be evaluated with respect to the centre of the external
      auditory meatus (c-EAM). by marking one point at the centre of condyle (c-CH) and the linear
      distance of the c-CH from the c-EAM will be evaluated as the shortest distance from the
      constructed FH perpendicular.

      7) Distance between c-PGS (crest of the post-glenoid spine ) & c-EAM : One point will be
      marked at the crest of the post-glenoid spine (c-PGS) and the linear distance of the c-PGS
      from the c-EAM will be evaluated as the shortest distance from the constructed FH
      perpendicular.

      8) Superior joint space will be measured from the shortest distance between the most superior
      point of the condyle and the most superior point of the mandibular fossa.

      Statistical analysis The final data recorded will be processed by standard statistical
      analysis.
    

Intervention name(s): orthodontic treatment
Intervention type(s): Procedure
Intervention description(s): fixed orthodontic treatment in adolescent females 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
Masking: None (Open Label)
Primary purpose: Treatment