The Dynamos lost two early wickets in the first four overs, with Gordon Muchall caught by Keith Barker off Neil Carter for 1 and Phil Mustard run out by Barker for 15 after a decision from the third umpires fell in the favour of the hosts.
The Dynamos fell to 33-3 after Ian Blackwell (6) was caught and bowled by Steffan Piolet in his first over.
David Miller added 11 before he was run out by Chris Woakes off the final delivery of the 8th over.
An impressive one handed catch on the boundary from Rikki Clarke, off Barker, saw Paul Collingwood dismissed for 24 with the Dynamos 80-5 in the 14th over.
An unbroken partnership of 65 in the final six overs saw Durham’s total boosted to 145-5 by the end of the innings thanks to a determined and quick scoring Dale Benkenstein (50*) and Gareth Breese (31*).
Liam Plunkett broke the opening partnership when Varun Chopra was caught by Mitchell Claydon off the seamer’s fourth delivery for 9. Neil Carter and Darren Maddy put on 73 to put the Bears in a strong position early on in their innings and by the time Carter (38) was out lbw to Scott Borthwick the game did look out of the Dynamos hands.
But, the Dynamos fought back with Gareth Breese claiming the scalp of Maddy (40) after a cracking catch by Miller.
The Bears were 124-4 when the same pair combined to dismiss Clarke for 10 with the hosts requiring 21 off 15 deliveries.
With five runs required from the final over, Scott Borthwick claimed a wicket with the first and fifth delivery, Muchall catching both Troughton (28) and Borthwick (1), resulting in the Bears requiring two runs from the final ball.
Despite the fightback the Dynamos were denied the points after Carter swept the last delivery for four securing the win for the Bears.
The Dynamos are still in with a chance of qualifying for the quarter finals providing they win their final Friends Provident t20 fixture, which is against Northamptonshire Steelbacks at Emirates Durham ICG on Thursday (14 July, 5.30pm start).
Tickets are available to purchase priced at £13 for adults and £5 for juniors in advance (£17.50 for adults and £6 for juniors on the day) by calling the Box Office on 0844 499 4466 or by booking online at www.durhamccc.co.uk