When Emma's new dentist-boyfriend Carl makes an appointment for Brittany so he can treat her 68 cavities, she quips: "This room looks like the one on that spaceship where I got probed."

And when the glee clubbers push Will to let them perform Britney Spears' music, a straight-faced Brittany says forlornly that she's lived her life in the pop star's shadow.

"I hope you will all respect that I want glee club to remain a place where I, Brittany S. Pierce, can escape the torment of Britney Spears,” she says.

Will ultimately relents, but not before Kurt tells him to "stop being so fricken uptight" and gets sent to the principal's office. And only after Brittany gets anesthetized by Dr. Carl and gets in touch with her pop sensation alter ego performing a hazy rendition of Spears' Slave 4U.

But as more of the glee kids visit the dentist, (played by the snackalicious John Stamos) and reenact more of Spears' famous videos, I began thinking that the music industry had co-opted Ryan Murphy's show from the performers and their storylines.

What saved this episode from being a total bad trip? Watching Will wrestle to be less "fricken uptight,'' buying the same Corvette as his opponent Carl, and getting a visit from his crazy ex-wife.

Less amusing was the conflict between Rachel and Finn over his return to football: both Lea Michele and Cory Monteith seem thinner and more self-conscious than they were last season.

But back to the show: To prove to Emma that he can let loose, Will signs off on a performance of Britney's Toxic at a homecoming pep rally. The sizzling performance sets off howls of sexual heat in an auditorium filled with hormonal kids. Disgusted, Sue Sylvester sets off the fire alarm and provokes a "Britney Spears sex riot."

The genius of Glee has been the fantastical storylines that require viewers to suspend belief while visiting a mythical high school in Lima, Ohio. But real-life celebrity now encroaches on the fun.

I'm hoping that Murphy can shake off these hangers-on before the show's critical success stampedes out the door.