Evaluation of Distal Movement of Maxillary Dentition With Zygomatic Miniplates Using Cone Beam Computed Tomography
Condition: Class II Division 1 Malocclusion
MeSH terms: Malocclusion
Study type: Interventional

Summary: 
      The main objective of this study is to quantify the distal movement of maxillary central
      incisors and molars achieved with miniplate anchorage.
    

Detailed description: 
      Premolar extraction treatment with multibracketed system and reinforced anchorage has been a
      common modality for correcting maxillary incisor crowding or Class II malocclusion in
      nongrowing patients. Treatment of Class II malocclusion without extraction frequently
      requires distalization of maxillary molars into Class I relation by means of extraoral or
      intraoral forces. Previously, it had been difficult to move maxillary molars distally after
      full eruption of maxillary 2nd molars. Extraoral headgear traction restricting the forward
      growth of maxilla and /or distalizing the maxillary dentition has been the most commonly used
      and oldest method to correct a Class II buccal segment molar relationship.This distalizes not
      only 1st molar but also maxillary 1st and 2nd premolars via transeptal fibers. Headgear is
      seldom an option in adults due to aesthetics and compliance concerns. The disadvantages of
      extraoral appliances have motivated many investigators to develop the mechanics of intraoral
      molar distalization.

      Various intraoral non compliance appliances like nickel-titanium spring , magnets , distal
      jet , pendulum appliances have been used to distalize maxillary molars. However, in these
      appliances, anchorage loss characterized by protrusion of maxillary incisors and an increase
      in overjet is seen. Also considerable amount of relapse occurred when the distalized molars
      were used as anchorage for the retraction of anteriors and premolar teeth.

      Absolute skeletal anchorage available 24 hours a day is an alternative method for molar
      distalization. It provides stationary anchorage for various tooth movements without the need
      for active patient compliance and with no undesirable side effects. Miniscrews, which are
      generally placed between the roots, limit the amount of distalization possible as they come
      in contact with surrounding roots during tooth movement. Also, proximity of miniscrews to the
      roots may lead to failure of screw anchorage .These disadvantages can be overcome by the use
      of miniplates which are fixed at a distance from the root apices, and therefore do not
      interfere in tooth movement.

      Until now, there have been only a few clinical studies on group distalization of posterior
      teeth. Thus, little information is available regarding the type of tooth movement that occurs
      and the limitations of distal movement. An attempt was also not made to study the root
      resorption and the amount of distal movement or tipping of maxillary 2nd molars since lateral
      cephalometric radiographs do not provide a clear view of this region.

      To the best of our knowledge, no previous study has been conducted on Cone Beam Computed
      Tomography to evaluate the amount of distal movement of entire maxillary dentition using
      miniplates placed in zygomatic region and assess the root resorption in all the roots of
      maxillary molars. The purpose of this study is to evaluate distal movement of maxillary
      dentition using Cone Beam Computed Tomography to overcome the shortcomings of the previous
      studies.

      MATERIALS AND METHOD Ours is a prospective clinical study to evaluate the distal movement of
      maxillary dentition achieved in three dimensions with miniplates placed in zygomatic region
      for the purpose of anchorage. The present study will be conducted in the Department of
      Orthodontics and Dentofacial Orthopaedics, in conjunction with Department of Oral and
      Maxillofacial Surgery, P.G.I.D.S., Pt. B.D.Sharma University of Health Sciences, Rohtak. The
      study will be carried out after the institutional approval obtained from the ethical
      committee.

      SOURCE OF DATA The sample size consists of 20 subjects selected from the patients attending
      the regular Out Patient Department at the Department of Orthodontics and Dentofacial
      Orthopaedics for orthodontic treatment.

      TARGET SAMPLE SIZE A sample size of 17 for the present study was calculated at 90% power.To
      compensate for 10% dropouts the final sample size was calculated to be 20.

      INTERVENTION AND DESIGN OF STUDY The main intervention in this clinical trial is surgical
      placement of zygomatic miniplates after initial leveling and alignment of maxillary dental
      arch. After selection of subjects (patients meeting selection criteria), treatment with
      0.022" MBT preadjusted edgewise appliance was started. Maxillary arch will be stabilized with
      the help of 0.019" × 0.025" stainless steel wire. Pre-treatment diagnostic records and Cone
      Beam Computed Tomography will be taken before placing miniplates . Maxillary 3rd molars will
      be extracted, if present . L shaped 2mm titanium miniplates (OrthoMax,Vadodara , India) will
      be surgically placed under local anaesthesia in aseptic conditions at zygomatic region
      bilaterally. Hooks will be soldered on archwire used for stabilizing dentition. Ni-Ti closed
      coil spring/Elastomeric chain will be used to apply a force on both sides (calibrated using
      Dontrix Gauge ) from miniplates to soldered hooks. Patient will be recalled at 4 weeks
      interval. Records including Cone Beam Computed Tomography will be taken on achievement of
      Class I molar relation bilaterally. Lateral cephalograms and CBCT will be taken 2 years post
      retention.

      DATA COLLECTION AND CONE BEAM COMPUTED TOMOGRAPHY ANALYSIS The investigator will record the
      patients' name, address, contact number and other relevant case history records will be
      taken. Cephalometric radiographs and Cone Beam Computed Tomography and will be recorded
      before placement of zygomatic miniplates, on achievement of Class I molar relation
      bilaterally and 2 years post retention for assessment of distalization. These records will be
      analyzed. The relevant values will be entered in a predesigned format. Soft tissue profile
      changes between pretreatment and post treatment will be assessed on lateral cephalogram and
      the raters- orthodontist, laypersons,patients,parents and general dentists will assess
      changes in facial appearance on a visual analog scale with profile photographs. Patient
      perception will be assessed using questionnaire rating by patient regarding various
      parameters at 1 week, 2 weeks, 1 month and 6 months after the placement of miniplate in
      zygomatic region. Changes in the upper-airway size will be measured by using lateral
      cephalometric radiographs taken before and after distalization.

      INFORMED CONSENT OF THE PATIENT A valid, informed written consent of the patient or parent/
      guardian will be obtained from the patient before registering the patient in this clinical
      study . Patient will be informed about all the theoretical risks and benefits of the
      intervention under test .Risks and hazards of radiation during CBCT will also be explained to
      the patient. The patient will be given 72 hours to discuss the study with his/her family and
      take the decision regarding participation in the study
    

Intervention name(s): Class II correction using miniplates in zygomatic region
Intervention type(s): Device
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Treatment