Two weeks ago I replaced my 6 front veneers of 15 years with 6 porcelain veneers. After a week, a gap appeared in between my front two teeth. It looks like my front teeth are further out past the side incisors. My Dentist wants me to use a retainer to close the gap. My questions, what would cause the gap to appear and other than ortho, what other options do I have to close this gap?