Celtics win 18th NBA championship with 106-88 Game 5 victory over Dallas Mavericks [Video]

Jayson Tatum put his hands behind his head, with TD Garden fans standing on their feet cheering around him, and took it all in.Walking to the bench, he wrapped both arms around Celtics coach Joe Mazzulla.The journey was complete.The Boston Celtics again stand alone among NBA champions.Video above: Celtics title merchandise goes on sale moments after Game 5 victory Tatum had 31 points, 11 assists and eight rebounds, and the Celtics topped the Dallas Mavericks 106-88 on Monday night to win the franchise’s 18th championship, breaking a tie with the Los Angeles Lakers for the most in league history.Boston earned its latest title on the 16th anniversary of hoisting its last Larry O’Brien Trophy in 2008. It marks the 13th championship won this century by one of the city’s Big 4 professional sports franchises.“It means the world,” Tatum said on stage after the team received the trophy from NBA Commissioner …