Open margin on new bridge

[rchapa1234]

Hello I recently discovered what I belive to be an open margin on my new bridge I got 3 weeks ago. My question here is how long before decay/or damage occurs to the underlying tooth or margin. I'm willing to go back in to dentist to get this resolved but I'll be out of town for a couple of weeks.

 

[Dr M]

How do you know there is an open margin? Do you have an x-ray to confirm this? Or are you perhaps just feeling the connection between the crown and the tooth?