ABSTRACT
Recently we reported that feline and canine dental calculus fluoresced pink to red under long wavelength ultraviolet light due to the presence of porphyrin. Here we report the observation of such fluorescence in 30 of 30 cats, 30 of 30 dogs, and 8 of 13 supragingival samples and 5 of 5 subgingival samples of humans. The fluorescence spectra of the calculus dissolved in 9 M HCl show that it is due to three distinct metal-free porphyrins. Similar fluorescence is obtained from bacterial cultures grown from calculus deposits of cats and dogs and bacteria grown on blood agar containing hemin and vitamin K1. The results of the bacterial culture study suggest that the metal-free porphyrin is produced by bacteria in the mouth. The clinical observation of fluorescence can be used for diagnosis.