Possible to close gap while having dental bridges? (Photo)

!About a year ago, I have gotten two 3-tooth dental bridges. However, there has been a gap that has formed in between my two dental bridges. the front teeth area of the two bridges have a tugging-like feeling, occasionally throbbing, though no pain. A dentist said it was due to not having a permanent retainer behind them, which I was not told about right after I got the dental bridges. I’m wondering if there is a way to move just the bridge part to fill the gap back + relieve the tugging feeling