PREVALENCE OF D3s

Some D3s are surprisingly common and others rare – but obviously still of potential importance to those suffering them – hence prevalence information is significant for researchers and healthcare providers as well as the at-risk public. Comparison of studies done in different places might yield clues about causation (aetiology), and how individuals or population groups vary in their vulnerability (e.g. geographic and racial risk factors). Prevalences of the 4 major D3s, and resulting impacts on affected individuals and society, are compared here.

Prevalence of Molar HYPOMINERALISATION

Popularly termed 'chalky molars', Molar Hypomineralisation is both a worldwide problem and the commonest type of D3. The 6-year molars (i.e. first "adult" or "permanent" back teeth) are affected most often, followed by the "baby" 2-year and adult 12-year molars. Although later replaced by adult teeth (second premolars), chalky 2-year molars remain a concern because of their potential to decay rapidly and cause orthodontic issues if extracted prematurely. A combined average case prevalence of 19% (i.e. about 1-in-5 kids) has been determined for chalky 2-year and 6-year molars in otherwise healthy children – this finding comes from over 141 studies in 47 countries (see map and tables below) and overlooks additional children with chalky 12-year molars. While the bulk of studies originate in Europe, other countries around the globe are increasingly investigating this problem – including the USA which in 2019 reported its first study (at long last!!).

Most data are for 6-year molars in 7–12 year old children who will carry the liabilities of Molar Hypomineralisation for the rest of their lives. Given this high prevalence and life-long burden, Molar Hypomineralisation clearly merits increased attention as a global concern for public health (read more). See also the projected global incidence of Molar Hypomineralisation, which strongly reinforces our concerns.

Map showing countries with 'chalky 6-year molar' studies

TOUCH PINS TO SEE COUNTRY NAMES

For further reference, the prevalence studies for chalky 6-year molars and equivalent data for chalky 2-year molars are graphed and tabulated below. In the graphs you can readily see the range and distribution of case prevalence values for both types of molar. Notably, hypomineralised (chalky) 6-year molars are roughly twice as common as hypomineralised 2-year molars – hence these two types of chalky molar together affect about 1-in-5 schoolchildren when allowing for overlap (i.e. those who have both molar types affected). In the tables, you can also see the variations, both between studies in different countries and between those within the same country. It is noteworthy that the reports for chalky 6-year molars extend back to 1987, at which time the prevalence reported for Jönköping, a historic city in Sweden, was similar to today's global average (10% & 15%, respectively). Caution should be applied when making detailed comparisons because not all studies were conducted equivalently – e.g. some involve much larger datasets than others, and variations exist for the diagnostic criteria used and the population types studied. Given such imprecision, we have rounded the reported prevalence values to whole numbers.

These online data are updated periodically. The latest information is available to D3G members on request. To join D3G and support our social-good venture, go here.

PREVALENCE STUDIES FOR CHALKY 2-YEAR MOLARS

PREVALENCE STUDIES FOR CHALKY 6-YEAR MOLARS

* for technical reasons (e.g. to better match the widely accepted definition of MH/MIH), indicated prevalence values have been sourced from data within the article, not the abstract – validation has been achieved through personal communication with the authors in most instances (contact us for details)

NB: Authors – please advise us of new studies suitable for inclusion here.