A space or gaps between the middle two teeth at the front of the upper jaw is known as a midline diastema/spacing. This spacing is more frequent in those who have had fixed appliance treatment (permanent clip) in the previous few years. It's also a sign of ageing, and it's more common in persons over the age of 45. https://www.kristelleklearaligners.com/midline-teeth-correction-aligners.php