Maynard sent Edgar to the canvas early in the fight with a heavy left and had the champion in trouble throughout the first round, but Edgar overcame the damage and fought back in the next three rounds.
One judge scored it 48-46 for Maynard, another had it 48-46 for Edgar and the third called it even.
All three judges scored the first round 10-8 for Maynard.
Edgar defeated B.J. Penn for the belt in April and retained the title in an immediate rematch.
Edgar was asked it he would fight Maynard again.
