Which item is used during orthodontic treatment with a removable appliance?

During orthodontic treatment with a removable appliance, a crib is the correct item used. A crib is a specific feature designed into certain types of removable orthodontic appliances, particularly for managing the position of the teeth or dental arches. It helps to maintain space or guide tooth eruption, especially in cases where the patient may have bruxism or thumb-sucking habits.

In contrast, brackets are typically fixed components bonded to the teeth on traditional braces, not applicable to removable appliances. Molar bands are metal bands that are cemented onto the molars and serve as anchors for fixed appliances. Tubes are often used in conjunction with bands or braces for attaching archwire, but again, these are not part of removable appliance setups. Thus, the crib is specifically associated with the function and design of removable orthodontic devices.