My ex once got an emergency tooth bonding at one of the two (count 'em , two!) dental offices at FRA. Saved our vacation, as the next stop was Nairobi. However, this is probably nothing to plan on doing.

I've taken the train to Wiesbaden and back -- nice town to walk around or visit the Bath. But check timing, it strikes me as marginally too far for 4 1/2 hours.