Victoria reached 4-210 at stumps, still trailing Tasmania by 145 runs at the midway point of the match.
Dean notched up his eighth first-class century in the second last over of the day to be unbeaten on 103.
Dean struck 13 boundaries in his 201-ball innings, but Tasmania wicketkeeper Jake Doran missed a catch on the shot which saw the opener bring up his ton.
In concert with wicketkeeper Sam Harper, Dean helped the unbeaten home side revive from a parlous 4-110.
No.6 Harper was unbeaten on 42 at the close.
There were, however, rare failures for the Vics' leading run-getters, Peter Handscomb and Nic Maddinson.
Maddinson made just one as debutant Ben Manenti (1-50) picked up the dangerman with a caught and bowled.
Captain Handscomb looked confident during his 22 but was caught at first slip after driving at a delivery from former Victorian teammate Peter Siddle.
Earlier in the day, Tasmania's tail proved there are few demons in the Junction Oval pitch by adding a quickfire 105 at nearly a run a ball in a wild 90-minute start to the day.
Spinner Tom Andrews struck 39 from 44 balls, while Jackson Bird cracked 26 off just 18 deliveries, including two sixes in three balls off fellow paceman James Pattinson.
After resuming at 5-250, Tom Rogers was dismissed from just the third ball of the day meaning the Tigers had lost 3-5 following a mini-collapse late on day one.
Right-arm spinner Todd Murphy impressed in just his second first-class outing for the Vics by returning figures of 4-98, while Jon Holland wrapped up the tail for 4-82Â
With a draw between NSW and Western Australia the most likely scenario, the winner of this match is set to head into the final round at the top of the Shield standings.
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