^(u p. h. keyes and h. v. jordan 



Host and Teeth 



Although factors in the host and teeth are known to contribute 

 importantly to caries activity, these are undoubtedly the most dif- 

 ficult to determine in a way that can be considered definitive. There 

 are many factors in the oral cavity and in the teeth themselves which 

 are thought to be either conducive or nonconducive to caries activity. 

 Some of these are obviously related to the inherent nature of the 

 host and to his over-all constitutional make-up. Of great importance 

 and particular interest are those nonconducive factors which grad- 

 ually develop within the host himself despite an inherent tendency 

 toward susceptibility. For example, the older host, both animal and 

 human, seems to be more refractory to this disease. In part this 

 has been attributed to maturation factors in the teeth and to the 

 presence of fluoride in the enamel. More information is becoming 

 available as to what these properties may be in terms of chemical 

 composition and physical properties (Brudevold, 1962rt; Johansen, 

 1962; Zipkine^flL, 1962). 



Dietary Substrate 



The substrate formed by the ingesta and saliva provides a source 

 of nutrient both to the macroorganism (host) and to the many 

 microorganisms of the mouth and alimentary canal. If some of the 

 bacteria ( parasites ) have a cariogenic potential, and if the food sub- 

 strates are of the proper quality and quantity, colonization and 

 plaque formation occur on certain coronal surfaces of the teeth. See 

 Fig. 2. The microflora associated with caries does not induce lesions 

 unless carbohydrates are present, but the cariogenic potential of 

 carbohydrates in both animals and humans is related to such factors 

 as quality, quantity, and physical consistency ( Stephan, 1948; Haldi 

 et al, 1953; Gustafsson et al, 1954; Shaw and Griffiths, 1960; Volker, 

 1962), and the carbohydrates must also be present in the mouth a 

 certain length of time (Kite et al., 1950; Larson et al., 1962). These 

 same conditions probably appl\' to other essential nutrients and not 

 to carbohydrates alone. 



