Attachments are auxilliaries to aid in the movement of teeth by providing a larger surface area for your Invisalign to grip onto. They are temporarily bonded to your teeth with the help of aligner templates using a white filling material to match the shade of your teeth.
They can serve as anchors for certain segements of your teeth so that some can move, while others do not. They may also be required to help keep aligners in palce while wearing elastics.
There are many different shaped attachments, with some of the larger ones being 4mmX2mmX1mm. Most attachments are now of a square or rectangular shape and bevelled to make them less visible and allow aligners to be more easily removed. They also allow more tolerance for incorrectly fitting aligners.
Buttons on the other hand are generally a clear or metal auxillary bonded to a tooth to allow an elastic to be attached to it. It is similar to a brace. Often times, your aligner must be trimmed so that the button can be bonded to your tooth while allowing aligner seating.
Judicious use of attachments and buttons are some of the most important aspects of proper Invisalign treatment. See an experienced local provider who can help determine if attachments are required for your treatment.