Ireland stay on course for Six Nations Grand Slam after Scotland win
Replacement number eight Jack Conan scored Ireland's third try as they turned up the heat in the second half despite the loss of both hookers to injury, leading to flanker Josh van der Flier throwing in at the line-out and three props in the front row of the scrum.
Scotland were in the game at halftime as they trailed 8-7 having scored a try through centre Huw Jones, which will give them some confidence heading into the Rugby World Cup where they face Ireland and South Africa in their pool with only two teams to advance to the quarter-finals.
Ireland, who have claimed the Triple Crown and have their sights now set on a Grand Slam, lead the Six Nations table with 19 points from four games, four ahead of second-placed France.
They host England in their final game next Saturday while Scotland welcome Italy.
"It was an incredibly tough game," Sexton told the BBC. "That was one of the toughest first halves I've played, the pace it was played at.
"Some good management at halftime, we stuck at it, knew we could get by at scrum-time, we had to find a way at the lineout.
"We've got to get the bodies back together. We'll be playing against an English team that are hurting (after losing to France) and one that we have huge respect for."
Ireland claimed an eighth win in a row against the Scots and spoilt the party for home captain Stuart Hogg in his 100th cap, but there are some concerns for coach Andy Farrell.
Centre Gary Ringrose had to be carried off on a stretcher in the final 10 minutes. That followed early injuries suffered by number eight Caelan Doris, hooker Dan Sheehan, lock Iain Henderson, and then Sheehan’s replacement Ronan Kelleher.
Prop Cian Healy came on in the hooker position and performed admirably in the unfamiliar role, as did Van der Flier at the line-out.
Sexton kicked seven points to equal Ronan O’Gara’s record points haul of 557 in Six Nations matches, a missed conversion in the first half denying him the top position outright.
After a period of concerted pressure in the Irish 22, Jones scored the first try of the game after being put through a gap by centre partner Sione Tuipulotu.
But Ireland hit back with a try from Hansen as he produced a brilliant finish in the corner under pressure.
The visitors increased the tempo in the second period, with Hansen taking an excellent high ball to heap pressure on the Scottish line and the ball was worked out wide for Lowe to dot down in the corner.
If that was a blow for Scotland, then a minute later the hammer came down on their chances as Conan ran in his score.
"That first half we lacked a clinical edge," Scotland captain Jamie Ritchie said. "We created opportunities that we did not put away.
"Credit to Ireland in the second half, we could not get continuity. They are a very good side, number one in the world for a reason.
"We knew we could apply pressure if we slowed the ball down. You saw that in the first half but there were a couple of times in the second half we allowed them to get momentum and were therefore on the wrong side of the scoreline."