Answer based on context:

Coming off their road win over the Browns, the Titans flew to Heinz Field for a Week 5 intraconference duel with the Pittsburgh Steelers.  Tennessee threw the game's opening punch in the first quarter with a 29-yard field goal from kicker Rob Bironas, but the Steelers answered with quarterback Ben Roethlisberger completing an 8-yard touchdown pass to tight end Heath Miller.  Pittsburgh added onto their lead in the second with Roethlisberger completing a 7-yard touchdown pass to wide receiver Hines Ward and a 1-yard touchdown pass to fullback David Johnson. The Steelers continued their dominating performance in the third quarter with Roethlisberger completing a 5-yard touchdown pass to Ward.  The Titans would respond with a 1-yard touchdown run from running back Chris Johnson, yet Pittsburgh came right back in the fourth quarter with kicker Shaun Suisham getting a 19-yard field goal.  Tennessee tried to rally as quarterback Matt Hasselbeck found wide receiver Damian Williams on a 19-yard touchdown pass, but the Steelers closed out the game with Roethlisberger completing a 40-yard touchdown pass to wide receiver Mike Wallace.

How many touchdown passes did Roethlisberger throw?
4