1. S. O. Griffin, P. M. Griffin, J. L. Swann, and N. Zlobin, J. Dent. Res. 83, 634 (2004).
2. H. Keltjens, T. Schaeken, and H. van der Hoeven, Int. Dent. J. 43, 143 (1993).
3. J. S. Wefel, Am. J. Dent. 7, 261 (1994).
4. J. D. B. Featherstone, Am. J. Dent. 7, 271 (1994).
5. O. Fejerskov and B. Nyvad, in Textbook of Geriatric Dentistry, Ed. by P. Holm-Pedersen and H. Löe (Munksgaard, Copenhagen, 1996), p. 584.