Final answer:
Once the arch wire has been positioned in the brackets during orthodontic treatment, it is ligated (option 2) in place using either elastic or metal ties. This securement allows for the necessary pressure to move teeth into the correct position.
Step-by-step explanation:
Once the arch wire has been positioned in the brackets, it is ligated in place. The process of ligation involves using either elastic or metal ties to hold the arch wire within the brackets affixed to the teeth. This is part of the orthodontic treatment that adjusts the positions of teeth.
Ligation is essential because it allows the arch wire to apply the correct amount of pressure on the teeth to move them into the desired position. If this process were not done properly, the effectiveness of the orthodontic treatment could be compromised. Regular adjustments and changing of these ligatures may be needed as the teeth move and the treatment progresses.