50NL. River: call or fold?

[Alexey]

Full Tilt Poker
$0.25/$0.50 No Limit Hold'em Ring Game
6 Players
LegoPoker Hand Converter (http://www.legopoker.com/hh)

<font color="black">Stack Sizes</font>
BTN: $33.30 stats: 28/1.8/2.5
SB: $34.95
Hero (BB): $49
UTG: $28.10
MP: $22.90
CO: $52.05

<font color="black">Preflop:</font> T/images/graemlins/diamond.gif 9/images/graemlins/heart.gif ($0.75, 6 players)
UTG calls $0.50, MP folds, CO folds, BTN calls $0.50, SB calls $0.25, Hero checks

<font color="black">Flop:</font> 3/images/graemlins/heart.gif 3/images/graemlins/spade.gif 7/images/graemlins/diamond.gif ($2, 4 players)
SB checks, Hero checks, UTG checks, BTN checks

<font color="black">Turn:</font> 3/images/graemlins/heart.gif 3/images/graemlins/spade.gif 7/images/graemlins/diamond.gif [9/images/graemlins/club.gif] ($2, 4 players)
SB checks, <font color="red">Hero bets $0.90</font>, UTG folds, BTN calls $0.90, SB calls $0.90
On turn I tryed to pick up the pot, and by underbetting represent slowplayed 3. Well, I think that was stupid, I had to bet pot for value.

<font color="black">River:</font> 3/images/graemlins/heart.gif 3/images/graemlins/spade.gif 7/images/graemlins/diamond.gif 9/images/graemlins/club.gif [6/images/graemlins/club.gif] ($4.7, 3 players)
SB checks, Hero checks, <font color="red">BTN bets $4.70</font>, SB folds, Hero ...?
I have TPwk , odds are 2 to 1, my small turn bet could provocate him on bluff. Do you call here?

[holyfield5]

bet more on turn, river is close but i lean towards a call given action.