Why is contention necessary?
First of all, the periodontal and gum tissue around the tooth need time to reorganize around the new positions of the teeth. During the orthodontic treatment, under the orthodontic forces, the periodontal space enlarges and the collagen fibers around the teeth are torn. The teeth gain a certain mobility and that is part of how the movement of teeth becomes possible. After removing the braces it is necessary to keep the teeth into position until the periodontal ligament and the collagen fibers reorganize, which usually lasts between 4 to 6 months, but it can take up to 12 months
The second reason is related to the mobility and instability of the teeth position at the end of the treatment and the fact that a lot of forces act on them (soft tissues around them such as: lips, cheeks and tongue) and endanger the stability of the treatment result.
How long is contention necessary?
The contention period depends on many factors, such as the initial malocclusion type, the periodontal status of the teeth, the growth and development left and the occlusion stability at the end of the orthodontic treatment. That is why the duration differs from patient to patient and it is established by the orthodontist and the team of specialists which take care of the case.
Which are the contention devices?
There are many types of contention devices but they can be split into two major groups: fixed and mobile. The mobile ones are preferred for the upper jaw and the fixed ones for the lower one. As for the duration of contention, it is chosen by the orthodontist according to the stability of the final result.
Fig 1: Mobile contention on upper jaw, Hawley appliance
Fig. 2: Fixed contention on lower jaw, retainer