Asked if he would consider recalling the 32-year-old, Dunga told TV Cultura in an interview: "If he can be the same Ronaldo he was before."
Ronaldo has scored a record 15 goals at three World Cups, including eight in 2002 when he helped Brazil win a record fifth title.
He scored an injury-time equaliser for Corinthians in their derby with Palmeiras on Sunday in only his second game after returning from a knee injury 13 months ago.
Two weeks ago, many Brazilians were questioning whether he had the appetite for a comeback after he was fined for returning late to the team hotel after a day off.
"If we look at what was being said about Ronaldo two weeks ago and what is being said today....," said Dunga.
"It's good for football because it's the pitch which tells the truth. All the talk off the pitch counts for little."
Dunga praised Ronaldo's determination to bounce back after rupturing a tendon in his left knee in a match for AC Milan in February last year, the third such injury of his career.
"I saw his determination to come back, to be the great player that he always was, his quality, his pleasure in playing football," said Dunga.
"It was very good for Brazilian football, we were hoping he could play again, score goals and bring happiness.
He warned that Ronaldo still had a lot of work to do.
"He's been out of action for 18 months, at the moment he's only playing for 25 minutes, the life of an idol is tough."
Ronaldo has not played for Brazil since his much-criticised performance at the 2006 World Cup.
Ronaldo said in a separate interview with TV Globo: "I've always dreamed of wearing the Brazilian shirt again, I was always happiest playing at the World Cup.
"I'm sure that if I can find my best form, I can be useful for Brazil."
