Orthodontic spacer

[1] Spacers are either circular rubber bands about a centimeter in diameter placed between top and bottom molars;[citation needed] there may be 1-12 spacers applied or small metal spring clips (spring separators) that push the molars apart.

The spacers stay between the teeth for one week and move the teeth apart slowly until they are far apart enough so that orthodontists can fit a tooth brace or molar band in between them or fit an expander with rubber rings or other appliances.

Spacers can also cause toothache and gum pain because of the constant pressure against the patient's teeth.

One very primitive, model is a metal bar that has a key used to tighten.

Secondly, and more contemporary, there is an expander that is two L-shaped metal rods, attached at the molars.