Root was unbeaten on a compact 111 - his first significant score of an otherwise wretched tour - while Joe Denly carved out his maiden Test half-century with 69.
Root was repeatedly asked to reveal what Gabriel said on the field but declined each time.
With the highest ever successful run chase in Tests remaining the Windies' 418 against Australia 16 years ago in Antigua, England's lead has already put them as firm favourites to win their first match in the series.
Gabriel, 30, was warned by the umpire for the language he used, though his original comment was not picked up.
The incident took place in the 44th over when England were sailing smoothly at 138 for 2 with Root and Joe Deny at the crease when both players ran into some kind of "interaction".
"That battle was a good contest, he's had a wonderful series and he should be proud".
"You can see that in the way he approaches the game and that's how I feel about it as well".
"The sky is the limit for this side as they continue to grow", said Drakes.
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"It's nice to show some people who've probably doubted me in the past, I've even doubted myself that I can do it, but I wouldn't say I'm out of the woods yet". "I think they can sometimes be caught in the moment and not always say what you want to say or think you're saying. There's nothing wrong with being gay".
Once Stokes was gone, Roach carved through England's lower order.
With Joseph and Gabriel falling soon after, the West Indies were skittled out for 154, which gave England a 123-run lead.
Speaking afterwards, match referee Jeff Crowe said was satisfied the umpires dealt with the matter on the field.
Shannon Gabriel, fastest of West Indies' four-pronged pace attack, set the skids in motion when he bowled Jos Buttler for 67.
"It feels fantastic. All the hard times I've had with injury, and the self-doubt, today I feel like an England", said Wood.
West Indies coach Richard Pybus was unaware of any potential controversy at close of play, but told the BBC: "Nothing has been reported to me but if a comment was made we'll review it and if it was untoward we'll be addressing it".