How to Get a Wider, Broader Smile? (photo)

The photo you attached must not be you or you were treated really young because you appear to still have a right primary cuspid,  The teeth don't look like they have ever had full braces, possibly a short term expander of some type only.

If you had a full treatment you should have been wearing at least an upper  retainer and it does not look like that was being done.from the look of the left lateral incisor.  This his looks like about a 12 year old untreated patient that  should be a good candidate for some modest slow arch expansion such as I would do using Damon system braces.  After treatment it will be essential to wear retainers as recommended by your orthodontist.  If you question the stability of the expansion and want to keep track of and measure the amount of expansion achieved during and retained after treatment a cone beam CT scan is a good way to do that.

In the picture uploaded there are still baby teeth present and permanent teeth coming in. That means that the final orthodontic treatment has not been done yet. When full treatment is implemented it will help to create a broader smile.

Based on this one photo, your arch seems very narrow and would most likely require expansion with not just braces but an expander appliance that expands slowly.  The main reason for most post-orthodontic expansion relapses is that expansion is being done too rapidly to allow the bone to actually grow so that the expansion will hold.  All that's happening is the teeth are being flared out giving the appearance of expansion but then they tip back in after a while. A slow expander will give bone time to grow and in the end, the result will be much more stable.

I am going to guess that your initial treatment broadened your smile and arches.  Unfortunately, you might just have been born with a narrow facial structure and this will tend to return if the arches were expanded beyond what your body could tolerate.  You could certainly get retreated and do some expansion but, the more you expand the more unstable the final result will be.  Wear your retainers every night for the rest of your life and the correction will hold.  Be so-so about retainer wear and you'll need ortho a third time