Effectiveness of Two Corticotomy Techniques in Retracting the Upper Anterior Teeth by Using Miniscrews
Condition: Class II Div 1 Malocclusion; Protrusion, Incisor
MeSH terms: Malocclusion; Overbite
Study type: Interventional

Summary: 
      This study aims to evaluate and compare the skeletal, dental and soft tissue changes, the
      levels of pain and discomfort and the effect on periodontal health and teeth vitality
      associated to traditional corticotomy and flapless corticotomy in the retraction of upper
      anterior teeth.

      40 patients requiring extraction of maxillary first premolars and maximum anchorage to
      retract the upper anterior teeth will participate in the study. They will be divided randomly
      into two groups : flapless corticotomy (20 patients) and traditional corticotomy (20
      patients). Pre-retraction, corticotomy will be performed in the maxillary anterior segment.
      The skeletal, dental and soft tissue changes will be performed using lateral cephalometric
      radiographs which will be obtained pretreatment, pre and post en-masse retraction of the
      anterior teeth and we will also use the dental casts to evaluate the dental changes.
    

Detailed description: 
      A corticotomy is cutting of the bone involves cortical bone only, leaving intact the
      medullary vessels and periosteum It offers an advantage to adult patients in reduction the
      orthodontic treatment time. The definition of traditional corticotomy is: elevating
      full-thickness periodontal flaps from a coronal approach, and vertical corticotomies are made
      between the teeth extending from 2-3 mm apical of the alveolar crest to 2 mm beyond the tooth
      apices and connected by a horizontal corticotomy; this process is done on both the labial and
      palatal aspects.

      The definition of flapless corticotomy is: a minimally invasive version of corticotomy, using
      a piezotome in order to inflict bone injury. This technique entails labial and palatal
      interproximal piezoelectric microincisions into the cortical bone, without reflecting
      periodontal flaps.

      Prior to enrollment of each subject into the study, they will be examined completely to
      determine the orthodontic treatment plan. The operator will inform them about the aim of the
      study and ask them to provide a written informed consent.

      Self-drilling titanium mini-implants (1.6mm diameter and 8mm length) will be used. they will
      be inserted between the maxillary second premolar and first molar at approximately 8-10mm
      above the archwires at the mucogingival junction and will be checked for primary stability
      (mechanical retention). Then the maxillary first premolar will be extracted. The maxillary
      arch will be levelled and aligned. The rectangular stainless steel archwires (0.019" ×
      0.025") with anterior 8mm height soldered hooks distal to the lateral incisors will be
      inserted.

      The surgery will be carried out under local anesthesia. The traditional corticotomy will be
      handled by the same maxillofacial surgeon and the flapless corticotomy will be handled by the
      same orthodontist.

      For traditional corticotomy, sulcular incisions the mesial aspect of one second premolar to
      the mesial surface of the contralateral second premolar will be placed, and full thickness
      flap will be elevated, 3 mm above the apical region of the tooth. piezoelectric under copious
      irrigation will be used for making vertical and horizontal cuts (only cortical surface). The
      vertical cuts will be between the dental roots in the interdental cortical surfaces ,stopping
      2 mm short of the alveolar crest, occlusally. Horizontal cut will connect the vertical cuts 2
      mm beyond root apex. These cuts will be performed from the mesial aspect of one second
      premolar to the mesial surface of the contralateral second premolar involving the anteriors.
      Similarly, a palatal flap incision will be raised immediately for doing the same vertical and
      horizontal cuts in the superficial surface of the palatal bone.

      For the flapless corticotomy, The depth of gingival tissue will be determined through bone
      sounding using a periodontal probe. A scalpel will be used to make the incisions through the
      gingiva, 4mm below the interdental papilla to preserve the coronal attached gingiva. These
      vertical incisions will be placed from the mesial aspect of one second premolar to the mesial
      surface of the contralateral second premolar on the labial and palatal aspects of the maxilla
      through the gingiva and the underlying bone. A piezosurgery knife will be used to create the
      cortical alveolar incisions to a depth of 1 mm within the cortical bone.

      Postoperatively, all patients will be advised to rinse with chlorhexidine mouthwash twice a
      day for one week. All patients will be contacted the day after the procedure to ensure no
      complications with surgery and will be followed up one month post-surgery to assess for signs
      of infection and ensure normal healing. We will assess patients' acceptance and the levels of
      pain and discomfort of traditional corticotomy and flapless corticotomy by asking all
      patients to fill out 4 questionnaires during the first month after the surgical procedure
      using a VAS.

      The surgical procedure will be performed and (250-300) g force will be applied on each side
      (3-4 days) after corticotomy using two NiTi springs attached between the mini-implants and
      the soldered hooks in a direction approximately parallel to the occlusal plane for conducting
      an en-masse retraction. The force level will be measured every 2 weeks after the corticotomy
      . Retraction will be stopped when a class I canine relationship will be achieved and a good
      incisor relationship will be obtained.

      Periodontal health will be assessed at the beginning of orthodontic treatment, before and
      after corticotomy by evaluating the following parameters: plaque index, gingival index,
      bleeding index, and gingival recession.

      Dental casts will be used for the quantification of the anteroposterior movement of the
      anterior teeth and the first molars every 30 days until class I canine relationship will be
      achieved and a good incisor relationship will be obtained.

      To evaluate the movement of the anterior teeth: we will project the canine cusp on the median
      line and measure the distance from this point to the projected position of a distinct medial
      ruga point.

      To evaluate the movement of the first molars: we will project the mesial contact point of the
      first molar on the median line and measure the distance from this point to the projected
      position of a distinct medial ruga point. These measurements will be made with sliding
      calipers.
    

Intervention name(s): Flapless corticotomy surgical intervention will be conducted; Traditional corticotomy
Intervention type(s): Procedure; Procedure
Intervention description(s): Piezocision will be used to perform the procedure; Here the surgery involves elevation of flaps and then conducting the surgical intervention using piezo-surgery cutting saws.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Treatment
Keywords: En masse retraction; Corticotomy; Acceleration of tooth movement; Piezocision; Flapless corticotomy; Class II division 1 malocclusion; Protrusion of upper incisors; Sliding mechanics; mini-implant based anchorage; temporary anchorage devices