Is 75 percent of dental caries really found in 25 percent of the population?

OBJECTIVES

Dental caries prevalence is used to quantify inequalities and to target high-risk populations for interventions. Prevalence can be described via measures of centrality; however, some have used cumulative frequency distribution curves (Lorenz curves). This investigation provides dental caries Lorenz curves for the primary and permanent dentitions at selected ages. Results provide accurate age-specific and dentition-specific X values for the general statement, "75 percent of dental caries is found in X percent of the population."

METHODS

Data were derived from the Third National Health and Nutrition Examination Survey, a cross-sectional study conducted between 1988 and 1994. Cumulative frequency distributions for total dfs or DMFS were plotted against cumulative frequency distributions for the total population.

RESULTS

X values varied substantially between dentitions and across ages. Total dental caries experience in the permanent dentition was more dispersed than it was in the primary dentition, and the total dental caries experience in older persons was more dispersed than it was in younger persons. For those aged 2-5 years, 75 percent of dental caries (primary dention) was found in 8.1 percent of the population. For those aged 6 years or older, 75 percent of dental caries (permanent dentition) was found in 33.0 percent of the population.

CONCLUSIONS

For accuracy and relevancy, the statement, "75 percent of dental caries is found in X percent of the population" must be applied to a particular dentition or age group, and must account for appropriate severity and prevalence reference points.