Elastics

What they do

Brackets and archwires align teeth within each arch. They cannot change how the upper arch sits relative to the lower one, because there is no connection between the two. Elastics make that connection. Stretched from a hook on the upper braces to one on the lower, they pull the arches into a corrected relationship over months.

Common configurations: Class II elastics, running from upper canine back to lower molar, used where the lower jaw sits behind the upper; Class III elastics running the other direction; vertical or box elastics to close an open bite; and cross elastics to correct a single tooth in crossbite.

The wear rule

Twenty to twenty-two hours a day, removed only for eating and brushing, changed for a fresh pair three to four times daily because they lose force as they stretch. Both sides unless you are told otherwise.

Elastics worn twelve hours a day do not achieve half the correction. The teeth move under tension and settle back during the hours the elastics are off, so the net movement approaches nothing while the treatment clock keeps running.

This is the honest reason a case can drift from eighteen months to twenty-six. It is also why fixed appliances are so often recommended for teenagers — brackets work regardless, and only the elastic portion depends on memory.

Making them workable

• Keep bags in three places: school bag, bedside, and pocket or car. The main cause of missed wear is simply not having any to hand.
• Put a fresh pair in immediately after every meal, before doing anything else.
• Expect soreness for the first two to three days of a new elastic prescription. It settles, and it means they are working.
• Never double up to compensate for missed wear. Heavier force does not accelerate movement and it risks the roots.
• If one snaps repeatedly or a hook breaks, call rather than going without for weeks.