The CPO-D index is the universally used index for dental studies in the population, quantified by the WHO (World Health Organization). It was developed by Klein, It is essential to study the prevalence of dental caries in different countries.

The index is the result of the sum of carious, lost and clogged permanent parts:

A decayed tooth is one that has the enamel undermined, a softening floor or wall; those with temporary fillings are also considered.

A crowded tooth is one where one or more surfaces are found with permanent restorations and no evidence of decay. Crowned teeth due to anterior caries are taken into account.

A tooth lost due to cavities, which has been extracted as a result.

Indicated extraction, a tooth is considered as indicated for extraction for reasons of caries if it presents a very extensive or total destruction of the dental crown, associated with the loss of pulp vitality.

Healthy tooth, if there is no evidence of clinically treated tooth decay.

In 1944, Gruebbel proposed the ceo index (decayed, extraction indicated, obturation), where “e” means “indicated for extraction” and missing teeth are omitted. The index is obtained by adding the decayed, lost and filled permanent teeth, including the indicated extractions, to the total number of individuals examined, making it an average. Only 28 teeth are considered. It should be obtained by age, those recommended by WHO are: 5-6, 12, 15, 18, 35-44, 60-74 years. The CPO-D index at age 12 is used to compare the oral health status of different countries. This strategic age is the intermediate point in life with the highest incidence of caries and the epidemiological indicator that reflects the oral state of the child and adolescent population. The index for the permanent dentition is always written in capital letters and for the primary dentition in lowercase letters.

Geographic, historical and cultural factors are determining factors in caries rates. Gender, male or female, indicates the higher incidence in girls than in boys due to the earlier appearance of teeth in girls.

The Eastern Mediterranean region (Saudi Arabia, Syria, Morocco, Kuwait, Jordan, Lebanon and Morocco) has higher rates of cavities than the industrialized countries, linked to the increase in sugar consumption due to the drop in price.

The WHO (2007) in its action plan for the promotion and prevention of oral health recommends the incorporation of strategies and approaches comparable to those for the treatment of chronic diseases. This concern was discussed at the United Nations General Assembly (UN, 2001) on the prevention and control of non-communicable diseases, which established increased attention to the rising levels of non-communicable diseases such as dental health.