INTRODUCTION: Dentoalveolar surgeries such as piezocision, have been developed with the aim to accelerate the tooth movement and therefore reduce the length of orthodontic treatment. Although this surgical technique seems to present several advantages, such as decreased risk of decalcification or orthodontic relapse, its use as a routine practice is not yet recommended. The main purpose of this study is to determine the duration of orthodontic treatment by using the piezocision. The secondary objectives are to evaluate the effect of this surgical technique on bone density, root resorption, osteoclast activity, inflammatory events and pain assessment. MATERIAL AND METHODS: The investigators will conduct a prospective study. The experimental group will consist of 14 adults, subjects from 18 to 40 years-old (10 women, 4 men). The control group will consist of 30 matched patients, who have been already treated in the orthodontic clinic of the University of Montreal. The reliabilities of Intra and Inter assesors will be measured for each doctor. After completion of the surgical guides from CBCT, the Piezocision will be performed the same day of the bracket indirect placement. The surgical procedure will be standardized and did it by the same surgeon. The appointments will be every 2 weeks for 4 months, then every month. The investigators will make an assessment of pain by using a numerical visual scale, during the first 7 days after surgery. Analysis of inflammatory markers (IL-1) and osteoclast activity (RANKL, OPG) will be evaluated from the gingival sulcus fluid collected at day 0, 1, 3, 5, 8, 12, 16 and 24 weeks. At the end of the treatment, the overall quality evaluation of treatment using the "American Board of Orthodontics' grading system" would be realized by two blind external observers to limit bias.

EXPECTED RESULTS Orthodontic treatment accelerated by piézocicison will be completed within one year and will be 50% faster than a traditional treatment. The ratio benefit / risk of performing the piezocision will be acceptable for the patient and the orthodontist. We expect the following results: low pain, and absence of dental and periodontal deleterious effect (no root resorption, no tooth vitality loss and no bone loss). The same cohort can be used in future studies to assess the long term stability of the treatment.

Inclusion Criteria:

• normal or low skeletal problem;
• dental relationchip without extraction;
• healthy;
• complete adult teeth;
• very cooperative;
• no plaque;
• no active periodontal disease and no bone loss visible radiographically;
• patient wishing a shorter orthodontic treatment.

Exclusion Criteria:

• patient regularly taking analgesic and antidepressants.
• patients with alcool abuse problems.
• patient smoking more than 10 cigarettes per day.
• pregnant patient.
• allergy to non-steroidal anti-inflammatory drugs.
• local or systemic Immunodeficiencies.
• uncontrolled systemic disease (For exaemple diabetes, cardiovascular disease).
• coagulation problems or taking anti-coagulants.
• presence of oral infections and periodontal disease uncontrolled active.
• taking intravenous bisphosphonates or taking oral bisphosphonates for more than 4 years.
• taking a long-term corticosteroids.
• antibiotic necessary before any surgery and taking antibiotics within 6 months before surgery