Evaluation of the Effect of Electrical Stimulation on the Rate of Orthodontic Tooth Movement and the Dental Arches

Thirty-eight 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: electrical group and control group. In each group, en-masse retraction will be initiated after completion of the leveling and alignment phase via closed nickel-titanium coil springs applying 250 g of force per side, Mini-implants will be used as an anchor unit.

The dental changes will be detected using dental casts and to evaluate the rate of teeth retraction.

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 canines will be inserted.

A removable device containing a small electrical circuit will be applied to each patient to supply the required electric current.

Each patient in the electrical group will be asked to wear the device for five hours a day until the completion of the retraction of the upper anterior.

(250-300) g force will be applied on each side 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. Retraction will be stopped when a class I canine relationship will be achieved and a good incisor relationship will be obtained.

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. Photographs of the upper casts will be taken with a central vertical projection on the occlusal plane and with a millimeter scale at the same level used to standardize and calibrate the conditions to match the casts when photographing them. Reference points will be used for upper casts study and the measurements will be calculated using the Image J computer program. To evaluate the movement of the anterior teeth: we will project the incisive edge on the median line and measure the distance from this point to the projected position of the medial end of the third palatine wrinkle on the median line.

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 to the projected position of the medial end of the third palatine wrinkle on the median line.

Eligibility Criteria:
Inclusion Criteria:

1. Adult healthy patients, Male and female, Age range: 15-27 years.
2. Class II Division 1 malocclusion:

   * Mild / moderate skeletal Class II (sagittal discrepancy angle ≤7)
   * Overjet ≤10
   * Normal or excessive facial height (Clinically and then cephalometrically assessed using these three angles: mandibular/cranial base angle, maxillary/mandibular plane angle and facial axis angle)
   * Mild to moderate crowding ≤ 4
3. Permanent occlusion.
4. Existence of all the upper teeth (except third molars).
5. Good oral and periodontal health:

   * Probing depth \< 4 mm
   * No radiographic evidence of bone loss.
   * Gingival index ≤ 1
   * Plaque index ≤ 1

Exclusion Criteria:

1. Medical problems that affect tooth movement (corticosteroid, nonsteroidal anti-inflammatory drugs (NSAIDs), ...)
2. Presence of primary teeth in the maxillary arch
3. Missing permanent maxillary teeth (except third molars).
4. Poor oral hygiene or Current periodontal disease:

   * Probing depth ≥ 4 mm
   * radiographic evidence of bone loss
   * Gingival index \> 1
   * Plaque index \> 1
5. Patient had previous orthodontic treatment