When is a Retainer Used Rather Than Braces?

The first question would be whether you are actually referring to a retainer or if you are thinking of a clear aligner system like Invisalign (the materials composition is very similar!). Invisalign or any other clear aligner system will gradually move your teeth with a series of retainer-like clear aligners. The aligner trays are changed every two weeks until the teeth are finally straight. The amount of trays needed may range from 5 sets (2 weeks each) to 30 sets (again, 2 weeks each), depending on the difficulty of the case. This type of Orthodontic treatment is a great option for certain patients. Your Orthodontist should decide whether Invisalign or braces will give you the best outcome. A regular retainer is designed to maintain your teeth in the position that they are currently in. Sometimes a retainer may be able to make very minor movements of the teeth. So, if you are looking for more than minor correction, you should ask your Orthodontist about braces or Invisalign. 

Retainers can be used for minor tooth movement such as slight crowding or small spacing, however they are not effective to correct major crowding. Invisalign is a good alternative to traditional retainers  to fix more complex dental malocclusions.

Thank you for your question. If you are asking about "classic" active retainers with wires, they can do only limited movement. In case you have a minor crowding or spacing AND your overbite is not deep, there is a certain success using these appliances.If you are refering to plastic tray systems like Invisalign, a lot more can be accomplished. There are certain cases, which should be done with braces, but most can be sussessfully be treated with Invisalign.

Hi there,
Retainers keep teeth in the position they were put in with braces.  The word "retain" means to keep something in position.  Retainers come in various shapes and sizes, from those that are clear and plastic, to the ones that seat into your palate with a bar across the front teeth, to ones made entirely out of metal (Cobalt-chrome retainers).  Retainers are ineffective in moving the teeth and are used for a period determined by the orthodontist AFTER the teeth have been straightened using braces.
As for braces, these are active appliances which straighten the teeth by application of forces.  Braces can either be fixed or removable and can be either visible or almost invisible.  There are types of braces, called clear aligners, such as invisalign, which look like retainers that are worn after braces.  Invisalign moves the teeth by changing aligners every week so that each new aligner has a slightly different tooth position, thus moving the teeth gradually with each change.  Other types of removable brace includes simple removable appliances with an acrylic plate.  Fixed appliances are fixed onto the teeth, they usually have brackets that are mounted onto the teeth on the inside (lingually) or outside (buccally) of the teeth and effect their action by the use of wires which are changed according to the prescription of the treating dentist. 
Hope this helps!
Best,
MJ x

Retainers are designed to retain the final position of your teeth at the end of your orthodontic treatment. In order to move your teeth into new position/alignment you would need a series of "retainers" where the tooth position is altered in between each aligners. An example of such treatment would be Invisalign, or ClearCorrect. Talk to an orthodontist and he or she can tell you how many trays you would need. Good luck!