There are several candida species such as candida tropicalis, candida albicans, glabrata, crusei and others wherein candida albicans is the most common species in the human mouth. Newborn are often infected by species located during birth by species located in the vaginal canal.
 
Candida is classified as diploid fungus that grows either as yeast or filamentous. Candida albicans has some natural enemies in the oral cavity which are the epithelium itself which acts as a barrier, natural competition in the oral cavity and as well Iga antibodies which prevent the adhesion of fungi to the oral epithelium and enzymes such as lysozyme, lactoperoxidase and antileukoprotease.