After Arter had put the Cherries ahead, the O’s restored parity through Dean Cox before finding themselves down to 10 men when when defender Scott Cuthbert was sent off after 55 minutes for a reckless challenge. The one-man disadvantage proved too much to overcome as Bournemouth dominated thereafter to emerge victorious.
The teams had started the match occupying the bottom two places in League One and it was the visitors who opened the scoring from the penalty spot on 20 minutes when Orient skipper Ben Chorley was adjudged to have pulled down Thomas and Arter made no mistake with the spot-kick.
However, within three minutes, the Os levelled when a powerful drive by Cox from 15 yards struck Cherries defender Mathieu Baudry and was deflected past goalkeeper Darryl Flahavan.
The dismissal of Cuthbert proved defining as the Cherries capitalised with the extra man. The visitors went ahead on 74 minutes when a Shaun Cooper drive from 20 yards struck the crossbar and Thomas stabbed the rebound home from close range.
The Cherries put the game out of the reach of their hosts when the lively Thomas caused problems for the home defence before laying the ball off for Pugh to drill home from close range.