Sometimes teeth are artificially moved by orthodontics to new positions that fall outside of their natural equilibrium ideal. Once the forces that moved teeth are removed, these teeth have a natural tendency to return to their natural equilibration position, and thus may again become “crooked”.
Thus most orthodontists will use “orthodontic retainers” to help teeth remain in their new position. This allows you then to remove the original orthodontic brackets and wires that originally moved and aligned the teeth to their new positions.
The art of good orthodontics is to predict where teeth can be orthodontically moved and remain stable, and without the need for prolonged retention devices.
After all, retention devices are a form of braces anyway. Removable retainers are cumbersome to wear, and also to chew with. Some orthodontists prefer using “fixed” retainers, which are wires that are glued to the bakcs of teeth, and hold front teeth together. Teh wires prevent the teeth from drifting apart or together, or becoming crooked again.
“Fixed” orthodontic appliances are difficult to clean around, and can more easily collect stagnant plaque and calculus leading to gum disease.
Remember, that teeth that are moved into natural positions, are also naturally stable, and do not require long periods of “retainer” wear.