Orthodontic retainers are custom-made devices, usually made of wires or clear plastic, that hold teeth in position after surgery or any method of realigning teeth. Once a phase of orthodontic treatment has been completed to straighten teeth, there remains a lifelong risk of relapse (a tendency for teeth to return to their original position) due to a number of factors: recoil of periodontal fibres, pressure from surrounding soft tissues, the occlusion and patient’s continued growth and development. By using retainers to hold the teeth in their new position for a length of time, the surrounding periodontal fibres are allowed to adapt to changes in the bone which can help minimize any changes to the final tooth position after the completion of orthodontic treatment.
Retainers can be removable or fixed. The four types of retainers typically prescribed by orthodontists and dentists are Hawley, Essix, Zendura, and Bonded (Fixed) retainers. A review of the evidence suggests that removable retainers are only required to be worn part-time (at night) and that overall there is still insufficient evidence to recommend one type of retention procedure over another.