Baekgue Choi, Sunkyu Park, Jongsam Nam

Title: Mandibular Total Distalization of Class III Patients with Mini-screw Anchorage in Lingual Orthodontics

Class III patients generally need total distalization of their lower teeth. Therefore, orthodontists use mini-screws for absolute anchorage at the lower arch. The mandible is preferred over the maxilla for these implants, as the mandible’s cortical bone is thicker and its soft tissue is thinner. There are also fewer anatomic structures for orthodontists to consider, including the maxillary sinus and greater palatine artery. However, the lingual side of the mandible is not the best place to implant mini-screws. Though full of attached gingiva, approaching the mandible’s lingual side with a screw driver cannot be well performed beside the tongue, which moves without ceasing. Thus, mini-screws are placed at the buccal side.

Although braces are bonded on the lingual surface of teeth, buccally located mini-screws must bond with another attachment. In lieu of buccal attachment, the second molar should be considered. Generally, attaching lingual braces to the second molars of the lower arch is problematic. Short clinical crown height, for example, is usually present. Even when orthodontists successfully bond braces at the second molar, the tongue is surrounded by lingual braces that easily cause wounds and inflammation.

Moreover, this procedure calls for an arched wire, which tends to roam around the mouth. This is another reason to avoid attaching second molar braces. When the braces of the second molar are absent at the lingual side, the first and second molars must be attached via buccal braces. In this situation, orthodontists must consider braces on the first and second molars as buccal attachments for total distalization.

We will now discuss cases of total distalization in Class III patients where a buccal approach to lingual orthodontics was applied.