Dene is by far the best player ever to emerge from New Zealand and although he never made the top sixteen, spent nine seasons in the top 32. He won his national amateur title in 1980 at the age of 17 and the following year was invited to play in Junior Pot Black and he reached the final losing out to Dean Reynolds.

He turned pro in 1984 and reached the quarter final of the British Open in his debut season and reached the Crucible stage of the World Championship. Things did not go so well over the following two seasons until the end of the 1986/7 season when he got to the Crucible again where he beat Cliff Thorburn and Doug Mountjoy to reach the last eight. In 1987/8 he reached the British Open quarter final again as well as the last 16 of the UK Championship and this was enough to put him into the top 32 in the world rankings at the end of the season – at number 23.

He failed to progress beyond the last 32 in any ranking event in 1988/9 and his ranking slipped back five places but he began the following season in fine form reaching his first world ranking final in the Hong Kong Open. He lost to Mike Hallett in the deciding frame but was a quarter finalist in the Mercantile Credit Classic later that season and in the season after he made it to the last eight of the European Open which helped him to his best ranking of 18^th for the 1991/2 season.