It took 41 minutes for Leo Cullen's men to register the bonus point, but a sloppy final half an hour will have frustrated the Leinster management as the men of Gwent closed out the scoring with tries from Pat Howard and replacement Sarel Pretorius.

Peter Dooley and Ross Molony both crossed for their first Leinster tries in the first half, with man-of-the-match Jack Conan's effort on the half-hour making it 21-3 for half-time.

Joey Carbery's withdrawal after his 41st-minute try may be a sign as to who will fill the fly-half position in next Friday's Champions Cup clash with Northampton. There are ongoing concerns over Jonathan Sexton's hamstring strain.

Leinster captain Isa Nacewa landed all four conversions and they were needed in the end as the Dragons outplayed the home side for the remainder of the game. However, the visitors' challenge for a losing bonus point fell short.

The lineout was an early concern for Leinster, with five balls lost by the break, but they opened the scoring with Dooley's 11th-minute score which saw him wriggle free of two defenders and stretch over near the left corner.

Nacewa converted and also added the extras to Molony's try barely three minutes later. Luke McGrath and Hayden Triggs sparked a lively attack and with Rhys Ruddock straightening up from a half-blocked pass, he linked with Noel Reid whose offload sent Molony over.

Angus O'Brien responded with a penalty but the Dragons' efforts to hang on to Leinster's coattails were not helped by an injury to full-back Carl Meyer in an accidental knee-to-head collision with Adam Byrne.

The Leinster pack lost possession at a third successive maul opportunity just as they were poised to strike for another try, while Byrne also threatened from a couple of kick chases.

The hosts continued to create chances and Conan brilliantly burst onto McGrath's flat pass to break two attempted tackles and charge in under the posts, with Nacewa converting.

What would have been a classy team try, finished by Rory O'Loughlin, was ruled out for a forward pass from Byrne.

However, there was nothing wrong with Carbery's almost immediate try on the resumption, the young number 10 trailing a powerful break by O'Loughlin from halfway to gather the scoring pass.

Lewis Evans did just enough to prevent Nacewa from collecting Dan Leavy's offload for a probable fifth try for Leinster.

Whereas the hosts allowed their intensity to drop, the Dragons bench had the desired impact, particularly Pretorius and Cory Hill.

Another of the replacements Geraint Rhys Jones floated an excellent one-handed pass behind him for the onrushing Howard to cross the whitewash in the 54th minute.

The deficit was down to 13 points after Pretorius threw a smart dummy from a 69th-minute close-in ruck and reached over wide on the left, giving his side a deserved seven points following a prolonged bout of pressure.

For all the Dragons' energy and momentum, Leinster held them at arm's length during the closing 10 minutes as the Welsh region fell to their 17th straight away defeat in the PRO12.