The pair have been included in the 24-man squad for the World Cup qualifier in Porto on 16 October.
Bruce, who has an Irish grandmother, had originally decided against playing for Northern Ireland under 21s when selected and went to the Republic team instead.
He made his senior debut with the Republic in a friendly against Ecuador in 2007 and played against Poland a year later but decided to change his allegiance last year after holding talks with Nigel Worthington.
Northern Ireland manager Michael O'Neill told UTV: "It's not really a case of having him back because he was never really ours to begin with."
"His initial decision was to be with the Republic of Ireland. He was only involved with them at friendly level so he was never really committed to them.
"It was a case of proving his eligibility to play for Northern Ireland which he did before I took over and that wasn't a factor for me selecting or not selecting him up until now."
With Gareth McAuley suspended O'Neill felt it was the right time to bring the Hull defenders in, despite both carrying recent injuries.
Bruce tore his groin against Blackpool on Tuesday night and Dudgeon has been recovering from a knee injury.
O'Neill said: "The players were informed before Tuesday so it was disappointing to see Alex coming off on Tuesday but we've been in contact with Hull and it sounds like he's going to be ok for this Saturday's game against Sheffield Wednesday.
"Both are playing regularly in the Championship. I've watched them personally against Blackpool on Tuesday night and we've had them watched on a number of occasions since the start of the season."
Neither player was having a great time at their respective clubs when I took over but we've been monitoring them and feel they deserve their chance.
"The left back is a position we have three very young options for that if you include Ryan McGivern and Daniel Lafferty, and Joe deserves the opportunity as well. Alex can play in a number of positions across the back four and that versatility is really important to us."
As well as the new faces some older ones will return for Portugal.
David Healy and Grant McCann are back in favour and Paddy McCourt, Niall McGinn and Martin Paterson return from injury.
There is however no place for goalkeeper Lee Camp, who pulled out of the squad before the Luxembourg game due to personal reasons.
"Lee indicated to me when he left before the Luxembourg game that being involved at international level wasn't the best for his club career at this minute in time along with personal reasons.
"I understood but was disappointed at the timing of the decision. But if Lee feels he wants to be involved again we can revisit that in the future."
We need a squad that's fully committed to what we're trying to do and Lee admitted he wasn't.
If he plays, Healy will win his 94th cap for his country.
"David was injured for the last three games and his club situation was difficult, but he resolved that by signing for Bury," added O'Neill.
"His fitness has improved in recent weeks with game time. He's a player we'd be foolish to overlook with the experience he gives us.
"He's a very important person to have in the squad, he has a very positive influence the younger players and I believe he can still affect things on the pitch.
"With regards to Grant he was never really out of the squad, I left him on standby for the Finland and Russia games."
O' Neill said that the player was on the transfer list and was unsure if that would be resolved.
"He's now off it at Peterborough and is a lot more settled.
"The conversation we had was very clear that he was very keen and focused and wanted to be involved again at international level. He's been playing regularly for Peterborough and gives us that experience and balance on the left hand side."
Chris Brunt, Jamie Ward and Andrew Little are unavailable due to injuries.
Roy Carroll, Alan Mannus, Michael McGovern, Aaron Hughes, Ryan McGivern, Jonathan Evans, Craig Cathcart, Alex Bruce, James McPake, Joe Dudgeon, Chris Baird, Steven Davis, Grant McCann, Oliver Norwood, Corry Evans, Niall McGinn, Shane Ferguson, Pat McCourt, Josh Carson, Martin Paterson, David Healy, Dean Shiels, Kyle Lafferty, Will Grigg.