Coghlan makes his first start since suffering a hand injury on his return from making his Wales debut in the autumn.
Talisman Wainwright, lock Ben Carter, full-back Angus O’Brien, centres Aneurin Owen and Fine Inisi and scrum-half Che Hope are back in the starting line-up.
Ryan Woodman, who moves to lock from blind-side flanker, fly-half Tinus de Beer and wings Rio Dyer and David Richards are the only survivors in the XV from Treviso.
“We want to make the last 16 and we know when we’re at home we need to front up for the fans – all the players wearing the jersey all know the expectations,” said Tiatia.
“We need to do justice to the jersey and then try and wear it for another week. That is earned, not given.
“I can’t wait for the players to get amongst it. After the disappointment against Benetton, it’s good to get back on the horse and get stuck in.”
Dragons have won their last three games on home soil after a comeback Challenge Cup success against Lyon and comprehensive United Rugby Championship victories against Connacht and Scarlets.
They last won four successive Rodney Parade fixtures in 2019-20 when Dean Ryan’s side enjoyed five victories on the spin before the Covid pandemic.
“We love playing at home, but it’s only an advantage if we turn up,” said Tiatia.
“We’re excited get back and our fans are awesome and great supporters of the team.
“We have lots to prove from last week, in terms of where we can get to, and we can’t be defined by one performance.”
Newcastle, who have former Wales and Scarlets fly-half Stephen Jones on their coaching team, make just three changes to the line-up that beat Perpignan 26-19.
Number eight Freddie Lockwood is back from a broken hand, lock Jamie Hodgson has served a one-game suspension and centre Cameron Hutchison replaces Oli Spencer, who suffered a head injury last week.
“The fact that we already have a home tie in the round of 16 is irrelevant, because we know that home advantage in the later rounds is huge if we are able to go deeper into the competition,” said Jones.
“Securing a higher seeding from the group stage gives us the best possible chance of achieving that, but it’s also about maintaining our momentum.
“The Challenge Cup has been a great driver for us and I see it as a really important tournament, so we’re fully committed to it.”
