Mid line diastema
in most of the cases reverses back. You are not clear in what exactly was done with dental lasers.
can fix any gap between the teeth using lasers. What i feel is that the gap was fixed with composite resin restoration which requires a light cure gun at the end, and you are confused with the light cure gun as dental lasers.
Coming back to your query, if the resin restoration has come out then one can easily redo it in a single sitting.
Thanks and Regards