With a compliant patient, space closure with clear aligners is quite successful. Aligners need to be worn for at least 20-22 hours daily for sufficient forces to be applied on to the teeth for space closure.
Below is a case with spacing in the lower front teeth that is being treated with Invisalign.
Invisalign has additional features such as attachments that can help upright teeth (such as the 2 lower central incisors below) as the space is being closed.
The reason for the spacing needs to be assessed so that the appropriate treatment can be selected. Space closure may not be beneficial for someone who has very narrow teeth (the final result may not be very aesthetic) or if you have a buried tooth/teeth that is the cause of the spacing. If your teeth are not ideally proportioned, you may benefit from veneers or composite bonding to correct the shape and size of your teeth while simultaneously closing the spaces.
Some patients with a prominent labial frenum may also need this removed to prevent re-opening of the space after treatment has been completed.
Long term retention is a must, preferably with fixed wire retainers and clear retainers worn over that to ensure that the spaces stay closed.