The use of corticotomy surgery in addition to orthodontic standard treatment could accelerate the treatment. Corticotomy involves vertical interdental incisions of the gingiva and the bone with a very low thickness. Orthodontic appliances are placed immediately after the surgery.

This study aims to compare the tooth movement when correcting mandibular dental crowding in two groups of patients:

Test group: orthodontic treatment and minimally invasive corticotomy surgery. Control group: standard orthodontic treatment without surgery.

Dental crowding in children, adolescents or adults is the most common reason to undergo orthodontic treatment. This malocclusion, characterized by the overlapping of teeth, is caused by a lack of space. In the mandibular anterior region, it is a predisposing factor for a periodontal disease. Good oral hygiene is difficult to maintain because the dental crowding promotes plaque retention in narrow interdental spaces and complicates the passage of brushes and dental floss. The standard orthodontic treatment lasts approximately 18-30 months. If the mandibular tooth space is less than 6 mm, it can be generally treated by orthodontics without therapeutic extractions.

Corticotomy has been a proven surgical technique for many years. It involves vertical interdental incisions of the gingiva and the bone with a very low thickness. It is mainly used to facilitate the movements of teeth. Dental movements associated with corticotomy may be twice as fast as those achieved with standard non-surgical treatment.

The study focuses on the correction of mandibular dental crowding. Its purpose is to compare the tooth movement obtained with orthodontic treatment and minimally invasive corticotomy surgery with that obtained with standard orthodontic treatment without surgery.

Patients requesting an orthodontic treatment to correct a dental crowding less than 12 mm are randomized to benefit from corticotomy surgery and orthodontic treatment (test group) or from only orthodontic treatment (control group). It is planned the inclusion of 22 patients, 11 in the test group and 11 in the control group.

After two visits necessary for the recruitment phase, treatment starts for the test group with the surgery and the appliance with brackets and arches, and, for the control group, with the appliance with brackets and arches.

The surgery of corticotomy is performed with a personalized surgical guide just before the placement of orthodontic appliance. The initial impressions of the patient's dental arch as well as its three-dimensional radiography (CBCT) make it possible to create a perfectly adapted guide. The incisions are made with a piezoelectric device between the roots of teeth, from the mandibular second premolar to the contralateral second mandibular premolar.

The study lasts 12 months after the placement of orthodontic material. During this 12 months, periodical controls (1 week, 2 weeks and 1-12 months) are carried out. After these 12 months, all patients undergo treatment with controls specific to standard orthodontic procedure.

Inclusion Criteria:

• The patient is over 18 years old,
• The dental crowding of the patient does not exceed 12 mm. The crowding, measured from the right mandibular canine to the left mandibular canine, doesn't require extraction or orthognathic surgery.
• The patient has no active periodontal disease and no history of treated periodontal disease.
• The patient has good dental hygiene.
• The patient has no untreated decay.
• The patient accepts the wear of metallic orthodontic materials.

Exclusion Criteria:

The patient :

• is not able to understand the information given by the practitioner for legal, psychological or linguistic reasons.
• will have predictable follow-up difficulties.
• is pregnant.
• has a high risk of endocarditis.
• has severe or acquired immune deficiency.
• has a malignant condition, an history of radiotherapy in the mandibular region.
• has severe hematology, hemophilia, chronic renal failure, autoimmune disease, a condition requiring organ transplantation, poorly controlled diabetes, osteoporosis, rheumatoid arthritis or psychiatric illness.
• is under antimitotic, immunosuppressive or high dose corticosteroid treatment.
• smokes more than 10 cigarettes per day.
• has a systemic disease that affects bone, such as osteoporosis, hyperparathyroidism, or vitamin D deficiency.