Canine Retraction With Temporary Anchorage Devices

In orthodontic patients who require overjet correction, increased facial convexity, or relief of severe crowding, dental extraction followed by canine retraction is indicated. In conventional orthodontic treatment, the molars are used for anchorage and reinforced with intra-oral or extra-oral appliances. Although effective, this produces unwanted side effects where the molars move mesially and rotate, taking up some of the extraction space. As the canines move into the extraction space they tip backward requiring further uprighting. Power arms are vertical metal extensions placed in the canine brackets. They direct the force to the center of resistance of the tooth to allow bodily movement and prevent canine tipping. Temporary anchorage devices (TADs) are minimally invasive, small screws, inserted in the jaw bones to act as anchorage units instead of the molars.

This study aims to evaluate the effect of the TADs and power arms on the efficiency of canine retraction including the rate of canine retraction and canine tipping as well as mesial molar drift and rotation.

The null hypothesis is that the use of the power arm and the TADs have no effect on the canine retraction rate.

This study is a single-arm, single-center study. Twenty quadrants in 10 adult patients will be selected from the Orthodontic Outpatient Clinic at the Future University in Egypt.

Orthodontic records will be collected including study models, intra- and extra-oral photographs and cone beam computed tomograms.

Molars will be banded and Roth 0.22" brackets will be bonded to the canine and second premolars. Power arms, 8mmin length, will be inserted in the vertical slots of the canine brackets.

The dental arches will be leveled and aligned using consecutive archwires. TADs will be inserted between the second premolars and first molars. The first premolars will then be extracted and canines will be retracted within a week. Canines will be retracted along 0.016" X 0.22" stainless steel archwires using 150 g of force applied by an elastomeric chain. The elastic chain will be replaced every 4 weeks.

After 6 months of canine retraction, the orthodontic records will be collected for comparison.

Inclusion criteria

• Adult orthodontic patient
• Any malocclusion requiring the extraction of the first premolar and canine retraction
• Full permanent dentition with the exception of the wisdom teeth.

Exclusion criteria

• Any missing permanent tooth
• Previous orthodontic treatment
• Periodontal disease; pregnancy
• Systemic disease or medication that affects bone metabolism