“…Since then, several studies on caries prevention have been published due to the development of several types of lasers, such as CO 2 , (Stern & Sognnaes, 1972;Featherstone, et al, 1998;Hsu, et al, 2000;Tisai, et al, 2002;Kato, et al, 2003;Klein, et al, 2005;Steiner-Oliveira, et al, 2006), argon (Westerman, et al, 2002;Nammour, et al, 2005), Nd:YAG (Bahar & Tagomori, 1994;Hossain, et al, 2001a), and Diodo (Kato, et al, 2006) and more recently with the group of erbium lasers: Er, Cr:YSGG and Er:YAG (Kayano, et al, 1989;Fried, et al, 1996;Hossain, et al, 2001b;Apel, et al, 2004). There are various theories to explain the reduced acid solubility of dental enamel after heating.…”