Effect of Corticotomy on the Orthodontic Tooth Movement

Orthodontic therapy allows for the treatment of dental malpositions in order to produce an adequate relationship between teeth during occlusion. Conventional orthodontic therapy applies slight forces and moves teeth slowly. It is generally performed during a 2 year minimum of time. Recent studies seem to suggest that orthodontic therapy time can be shortened by surgical assistance (corticotomy). This investigation is aimed to determine the velocity of tooth movement and changes in periodontal clinical parameters between corticotomy-assisted orthodontic therapy and conventional orthodontic therapy.

The use of surgical techniques to accelerate orthodontic tooth movement has been developed. By means of surgical burs, vertical grooves in the cortical plate (corticotomy) are produced mesial and distal to the roots of teeth that are being moved 3 mm below the marginal crest and extending beyond the apex. Animal studies showed that the rapid orthodontic tooth movement was due to increased cellular activity in the surrounding periodontal tissues, a regional acceleratory phenomenon (RAP). A high osteoclastic activity is observed in the compression side although is also observed in the tension side to a less degree. Histological analysis indicates that at day 21 the remodeling tissues are replaced by a fibrous tissue and later (60 days) by bone. Furthermore, the tissues immediately adjacent to the corticotomy are characterized by an increased width of the periodontal ligament, less calcified spongiosa bone surface and higher counts of osteoclasts. But not only the catabolic activity is increased (osteoclasts) but also the anabolic activity (osteoblasts) is increased 3-fold as well. This balances the rate of bone resorption and bone apposition. An interesting finding was the reduced rate of hyalinization at the compression site, which may be due to increased width of the periodontal ligament and thus facilitating tooth movement.

As opposed to conventional osteotomy used in alveolar distraction, the preservation of the medullar vasculature during a corticotomy procedure provides and adequate blood supply and nutrition. This accelerates the rate of tissue healing and remodeling and hence orthodontic movement can start immediately after surgery. It has been calculated that the rate of tooth movement is doubled (2.5mm to 3mm at day 25) in comparison to standard orthodontics without any detrimental effects on periodontal tissues. This surgically assisted approach for improved tooth movement is beneficial for molar intrusion, space closure, de-crowding and open bite management.

This investigation is aimed to determine the velocity of tooth movement and changes in periodontal clinical parameters between corticotomy-assisted orthodontic therapy and conventional orthodontic therapy. Periodontally and systemically healthy subjects in need of orthodontic therapy for the treatment of teeth crowding in the anterior segment. The rate of tooth movement will be assessed by radiographs and cast models and periodontal clinical parameters will be recorded at each visit during the 4 month follow-up.

Eligibility Criteria:
Inclusion Criteria:

* Voluntary participation
* Legally adult age (\>18 years old)
* Full permanent dentition (28 teeth excluding third molars)
* Severe anterior teeth crowding
* Thick periodontal biotype

Exclusion Criteria:

* Systemic diseases (i.e. diabetes, HIV)
* cigarette smoking
* Under medications: bisphosphonates, anti-epileptic drugs, contraceptives, corticosteroids, estrogen, antihistamine drugs, calcitonin, vitamin D
* Previous orthodontic treatment
* Periodontal disease
* Severe gingival recessions
* Pregnancy
* Previous root resorption