Occlusal Bite Force Changes After Surgical Correction of the Increased Vertical Dimension
Condition: Orthodontic Appliance
MeSH terms: Prognathism
Study type: Interventional

Summary: 
      The aim of this study was to record the OBF changes after surgical correction of mandibular
      prognathism in patients with or without increased vertical skeletal dimensions at different
      time intervals (T0: before surgery; T1: at debond; T2: 3 months post-retention).
    

Detailed description: 
      Forty-two patients who presented to orthodontic clinics with severe Class III skeletal
      malocclusion and were already into orthodontic preparation for orthognathic surgery were
      selected to participate in thestudy.

      Patients were allocated into one of 2 groups as follows: - Group 1: - Class III patients with
      increased vertical relationship Included 22 patients (8 males, 14 females).These patients
      were scheduled for bimaxillary surgical procedures (Maxillary advancement and mandibular
      setback with posterior maxillary impaction) to correct the antero-posterior and vertical
      skeletal discrepancies.

      Group 2: - Class III subjects with normal vertical relationship Included 20 patients (8
      males, 12 females).These patients were scheduled for mandibular setback surgical procedure
      (with no posterior maxillary impaction) to correct the antero-posterior skeletal discrepancy.

      Diagnostic records (orthopantomogram, lateral cephalogram, study casts, clinical photographs)
      were taken for all subjects before surgery. The same records were taken post surgery just
      before fixed orthodontic appliance debond.

      The included patients were treated by orthodontic teaching staff and postgraduate residents
      at orthodontic clinics/JUST using pre-adjusted edgewise fixed appliance (3M Gemini Uniteks,
      0.022" MBT prescription brackets).

      Bite force was measured bilaterally in the first molar region using a portable occlusal force
      gauge (GM10, Nagano Keiki, Tokyo, Japan), that consisted of a hydraulic pressure gauge and a
      biting element made of a vinyl material encased in a polyethylene tube. 3 OBF measurements
      were recorded on each side and incisally with a 15 second rest between each bite, the average
      of the three readings was used. Three OBF measurements were considered in the analysis: the
      maximum OBF (MOBF) achieved by the subject, the averaged OBF on molars (AOBF), and the OBF at
      the incisal region (IOBF).

      Number of teeth in contact was measured using double-sided articulation paper strips that was
      smeared with a thin layer of petroleum jelly prior to its' use so as to improve the
      visualization of the markings of the contact points that existed in a subject's intercuspal
      position.
    

Intervention name(s): Mandibular Setback with maxillary impaction; Mandibular setback only
Intervention type(s): Procedure; Procedure
Intervention description(s): Occlusal bite force will be measured after surgery to correct vertical disproportions; Occlusal bite force will be measured after surgery without changing vertical disproportions.
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Intervention model description: Patients were allocated into one of 2 groups as follows: - Group 1: - Class III patients with increased vertical relationship Group 2: - Class III subjects with normal vertical relationship
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: bite force; mandibular prognathism; increased vertical dimension; surgical correction