The purpose of this study was to examine the possibility of the existence of high-risk groups of dental caries and influential factors for the high-risk groups, as there was a possibility that certain people might especially be at risk of suffering from dental caries when decayed, missing, and filled teeth index were analyzed, which were the typical indicators of dental caries. The data of the 4th National Health & Nutrition Survey for 2007, 2008 and 2009 were analyzed. Significant caries index (SiC index) were calculated, which were one of the representative devices to indicate high-risk groups of dental caries, and the SiC index and related factors were analyzed by using c2 (chi-square) test. Besides, logistic regression analysis was utilized to find out influential factors, and a statistical package STATA 11.0 was employed. As a result of analyzing what factors would be linked to high-risk groups of dental caries, it`s found that women were more likely to belong to high-risk groups than men (p＜0.01). How the related factors affected the high-risk groups was analyzed, and it`s found that those who didn`t find themselves to be in good oral health were more likely to be classified into a high-risk group, and that those who brushed their teeth three times a more a day on a regular basis were more likely to belong to a high-risk group than the others who didn`t (p＜0.01). Thus, SiC index were calculated in this study to confirm the existence of dental caries high-risk groups, and what factors impacted on the high-risk groups was ascertained. It`s required to implement efficient national policies to step up the promotion of national oral health based on the findings of the study.