It was almost exactly 15 years ago that the teen-age Stephanie Mills opened at the Majestic Theater on Broadway as Dorothy in ''The Wiz'' and introduced what has since become her signature song, Charlie Smalls' ballad ''Home.'' On Tuesday evening, Miss Mills, now 32 years old, returned to Broadway, this time to the Brooks Atkinson Theater (256 West 47th Street) for six nights in what has been billed as a triumphant coming-home-to-Broadway engagement.
The singer recently re-recorded her signature song, which is also the title of her newest album. In her grown-up rendition of ''Home'' she attempts to turn a rather humble ballad into a pop-gospel answer to ''Over the Rainbow,'' with vocal embellishments, twists and belted passages that are so elaborate the tune becomes virtually unrecognizable.
Miss Mills's new grandiose version of ''Home,'' which she performed near the end of her opening-night show, is typical of her larger-than-life approach to all pop singing. Again and again on Tuesday, the singer seemed intent on showing that she could sing louder and be sexier and more boldly dramatic than any other pop-soul diva.
The singer's extraordinary voice, which mixes the kittenish and the ferocious, has always suggested what Diana Ross might sound like had she three times as much power and a solid gospel background. Throughout the concert, one had the sense of Miss Mills not simply singing songs but grabbing and attacking them with an avidity that was sometimes thrilling but just as often overbearing. During her interpretation of the Gladys Knight hit ''If I Were Your Woman,'' she kicked a chair across the stage to emphasize a point. Thus overdramatized, a song that offers loyalty and devotion to a potential lover seemed instead to assert a fanatical, frightening possessiveness.
Such gestures might have made more dramatic sense had Miss Mills's concert included some significant emotional changes of pace. But instead of tenderness or soul-searching, her show hammered home a single theme: loud, if virtuosic, self-aggrandizement.