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David Tennant Added a Line to His Latest Doctor Who Regeneration

When you get to be the Doctor twice, you're allowed to make a little throwback.

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All of Doctor Who’s post-regeneration scenes are brief little windows in what to possibly expect from a new Doctor—but when you’re David Tennant and getting the chance to play not one, but two Doctors, you’re going to want to have a little callback to the last time you did this.

Tennant’s debut as the 14th Doctor in the climax of “The Power of the Doctor” is brief, but of course touches upon the confusion of both the Doctor and the audience that they suddenly look like one of their past selves again. Gazing out of new-old eyes after regenerating, the Doctor stops gasping for breath and runs their tongue over their mouth, tumbling out the 14th Doctor’s first words: “I know these teeth.”


It’s a line that was apparently suggested by none other than Tennant himself. “It wasn’t exactly the longest day at the keyboard,” incoming/returning showrunner Russell T. Davies told Doctor Who Magazine about writing his part of the regeneration scene. “They’re obvious first lines. But David added the bit about teeth. That’s his line. So it’s written by the two of us.”

Ninth Doctor Regenerates | Christopher Eccleston to David Tennant | Doctor Who | BBC

It’s a callback, of course, to the climax of “The Parting of the Ways,” when Christopher Eccleston’s Ninth Doctor transformed into Tennant’s Tenth, heralding his new body with a comment “New teeth. That’s weird. So where was I?” It’s a cute moment, and one Davies appreciated the addition of. “That’s rather nice, isn’t it?,” the writer continued. “I like that. I was really chuffed.”


Tennant and Davies return to Doctor Who in a series of three specials in November 2023, to celebrate the series’ 60th anniversary.

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