Applying flapless piezocision corticotomies on the alveolar bone and separating anterior mandibular teeth using a piezosurgery device (i.e. ultrasonic waves that perform very accurate incisions without any sutures following this procedure) may improve the speed of tooth alignment during orthodontic treatment. This study consists of two groups, patients will be randomly assigned to one of these two groups. The efficacy of this procedure on 18 patients (experimental group) will be evaluated,whereas the second group (control group) will receive a traditional orthodontic therapy. The time required to achieve complete alignment of crowded mandibular anterior teeth (from canine to canine) will be compared between the two groups.

According to the American Association of Orthodontists (AAO), the length of comprehensive orthodontic treatment ranges between 18-30 months, depending on treatment options and individual characteristics. In addition, orthodontic treatment time ranges between 25-35 months for extraction therapies, respectively. Reducing orthodontic treatment time is one of the main goals for orthodontists, due to problems such as root resorption, periodontal disease and caries that are associated with prolonged treatment time.

Many techniques have been introduced to accelerate orthodontic tooth movement; surgical and non-surgical. The surgical approach is the most clinically applied and most tested with known predictions and stable results. Surgical approaches usually vary from total block osteotomies to flapless partial corticotomies .In spite of corticotomy-assisted orthodontic treatment efficiency, the invasiveness of these procedures (i.e. requiring full mucoperiosteal flaps elevation) might have limited their widespread acceptance among orthodontists and patients. Therefore, more conservative flapless corticotomy techniques have recently been proposed. These procedures can be accomplished in a reasonably short periods that might produce less pain and discomfort, so we will gain better patient acceptance. Although various techniques of flapless corticotomy have been reported to be successful in practice, scientific evidence for their effectiveness so far has been limited to case series and a few clinical trials, generally with small groups. This study aims to provide some evidence about the efficacy of piezosurgery in a flapless technique to align crowded lower anterior teeth using a parallel-group randomized controlled trial study design.

Inclusion Criteria:

1. Adult healthy patients , Male and female, Age range: 15-27 years.

2. Severe crowding ≤ 7 (Little's irregularity index)

3. Permanent occlusion.

4. Exist all the Mandibular 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, NSAIDs, …)

2. Patients have anti indication for oral surgery ( medical - social - psycho)

3. Presence of primary teeth in the mandibular arch

4. Missing permanent mandibular teeth (except third molars).

5. Poor oral hygiene or Current periodontal disease:

   • Probing depth ≥ 4 mm
   • radiographic evidence of bone loss
   • Gingival index > 1
   • Plaque index > 1

6. Patient had previous orthodontic treatment