The dentures were made especially for Amitabh"s character Auro in the film. The shape and size of the dentures transform Amitabh"s voice and give him a lisp. The dentures were worn by Amitabh throughout the film"s shooting and also while dubbing. According to director Balki, they changed Amitabh"s personality completely.
Meanwhile, the title song that is sang by Amitabh was sent to them by Ilaiyaraja, who had recorded it in his own voice. Amitabh then sung it himself and sent back to Ilaiyaraja who then mixed it.
Amitabh Bachchan accomplished the feat of talking and singing in a 12-year-old child"s voice, thanks to the specially designed dentures he used for his role in Paa.