The dodge on use from the trinket pushes block of the combattable so you end up with something like this. (should include miss as well but we'll go with your example, crit block is always block chance-20% btw)
Normal: 20% dodge 20% parry 36% normal blocks 24% crit blocks (60% block with 40% crit block)
With trinket use: 25% dodge 20% parry 33% normal blocks 22% crit blocks (55% block with 40% crit block and 5% additional block over the CTC cap)
Basicly you replace 5% block with 5% dodge while every block has the same crit block chance as before.
One thing to keep in mind that shieldblock gives CTC-75 critblock% buff so while at 105% CTC you get a 30% critblock bonus from shieldblock instead of the regular 25% at 100% CTC. But outside of shieldblock there aren't any changes to critical block chance cause of the extra dodge. Most optimal use of the buff is 1 second after shieldblock ends so you use the next shieldblock on the last second of the buff and get a free 5% extra crit block for that shieldblock.