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 160 studies in 53 countries (see map and tables below) and overlooks additional children with chalky 12-year molars and wisdom teeth ("18-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

Main Map
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 kids who have both molar types affected). In the tables, you can also see the variations, both between studies in different countries and among those within the same country, region or city). It is noteworthy that these modern 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 (integers).

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 of Molar Hypomineralisation graph in 6 year olds and 2 year olds

PREVALENCE STUDIES FOR CHALKY 2-YEAR MOLARS

Region/Location	Case Prevalence	Report
Oceania
Australia Melbourne	14%	Owen et al, 2018 Hypomineralized second primary molars: prevalence, defect characteristics and relationship with dental caries in Melbourne preschool children.
Melbourne	8%	Gambetta-Tessini et al, 2018 Carious lesion severity and demarcated hypomineralized lesions of tooth enamel in schoolchildren from Melbourne, Australia.
Melbourne	20%	Silva et al, 2019 Etiology of Hypomineralized Second Primary Molars: A Prospective Twin Study.
Europe
Netherlands Alphen aan de Rijnland, Gouda, Breda and Den Bosch	5%	Elfrink et al, 2008 Hypomineralized second primary molars: prevalence data in Dutch 5-year-olds.
Rotterdam	9%	Elfrink et al, 2012 Deciduous Molar Hypomineralization and Molar Incisor Hypomineralization.
Germany Munich	4%	Kuhnisch et al, 2014 Proportion and extent of manifestation of molar-incisor-hypomineralizations according to different phenotypes.
Jena	2%	Wagner Y, 2017 Developmental defects of enamel in primary teeth - findings of a regional German birth cohort study.
Lahn-Dill, Frankfurt	3%	Amend et al, 2021 Prevalence of molar-incisor-hypomineralisation (MIH) among 6-12-year-old children in Central Hesse (Germany).
Spain Valencia	15%	Negre-Barber et al, 2016 Hypomineralized second primary molars as predictor of Molar Incisor Hypomineralization.
Valencia	3%*	Llena et al, 2018 Risk factors associated with new caries lesions in permanent first molars in children: a 5-year historical cohort follow-up study.
France Bordeaux region	10%	Estivals et al, 2023 The prevalence and characteristics of and the association between MIH and HSPM in South-Western France.
Asia
Iraq Mosul City	7%	Ghanim et al, 2013 Prevalence of demarcated hypomineralisation defects in second primary molars in Iraqi children.
India Guatam Budh Nagar	6%	Mittal & Sharma 2015 Hypomineralised second primary molars: prevalence, defect characteristics and possible association with molar incisor hypomineralisation in Indian children.
Nagpur	5%	Mittal et al, 2016 Assessment of association between molar incisor hypomineralization and hypomineralized second primary molar.
Chandigarh	8%	Goyal et al, 2019 Prevalence, defect characteristics and distribution of other phenotypes in 3- to 6-year-old children affected with Hypomineralised Second Primary Molars.
Singapore All 4 quarters	3%	Ng et al, 2015 Prevalence of molar incisor hypomineralization (MIH) in Singaporean children.
Syria Latakia	41%	Halal & Raslan, 2020 Prevalence of hypomineralised second primary molars (HSPM) in Syrian preschool children.
Israel Tel Aviv	6%	Ajzman et al, 2023 The prevalence of developmental dental defects in Israeli children and its association with perinatal conditions: a cross-sectional study.
Saudi Arabia Southern region	5%	Zakirulla et al, 2020 Prevalence of Hypomineralization in Second Primary Molars (HSPM) in 7 to 10-Year-Old Saudi Children.
Africa
Nigeria Ile-Ife	5%	Temilola et al, 2015 The prevalence and pattern of deciduous molar hypomineralization and molar-incisor hypomineralization in children from a suburban population in Nigeria.
Ile-Ife	6%	Oyedele et al, 2016 Hypomineralised second primary molars: prevalence, pattern and associated co-morbidities in 8- to 10-year-old children in Ile-Ife, Nigeria.
Ile-Ife	2%	Folayan et al 2020 Association between developmental dental anomalies, early childhood caries and oral hygiene status of 3-5-year-old children in Ile-Ife, Nigeria.
Americas
Brazil Botelhos	20%	Costa-Silva et al, 2013 Influence of deciduous molar hypomineralization on the development of molar-incisor hypomineralization.
Paranoa	7%	da Silva Figueiredo Se et al, 2017 Are hypomineralized primary molars and canines associated with molar-incisor hypomineralization?
Curitaba	9%	Lopes-Fatturi et al, 2019 Systemic Exposures Associated with Hypomineralized Primary Second Molars.
Teresina	15%	Lima et al, 2019 Pre-term birth and asthma is associated with hypomineralized second primary molars in pre-schoolers: A population-based study.
Parnaiba	4%	Lira et al, 2021 Prevalence and predispondent factors of molar-incisor hypomineralization in primary dentition.
Chile Talca	5%	Gambetta-Tessini et al, 2019 The impact of MIH/HSPM on the carious lesion severity of schoolchildren from Talca, Chile.
Canada Toronto	4%	Sidhu et al, 2019 Prevalence and presentation patterns of enamel hypomineralisation (MIH and HSPM) among paediatric hospital dental patients in Toronto, Canada: a cross-sectional study.
Venezuela Caracas	20%	Rodriguez-Rodriguez et al, 2021 Prevalence and distribution of Molar-Incisor Hypomineralization in children receiving dental care in Caracas Metropolitan Area, Venezuela.
United States Indiana	6%	Tagelsir Ahmed et al, 2021 Demarcated Primary Second Molar Hypomineralization: Prevalence Data and Associated Sociodemographic Determinants from Indiana.
Average prevalence	9% (for 33 studies from 19 countries)

PREVALENCE STUDIES FOR CHALKY 6-YEAR MOLARS

Region/Location	Case Prevalence	Report
Oceania
Australia Perth	22%	Arrow, 2008 Prevalence of developmental enamel defects of the first permanent molars among school children in Western Australia.
Sydney	44%	Balmer et al, 2005 Prevalence of enamel defects and MIH in non-fluoridated and fluoridated communities.
Melbourne	15%	Gambetta-Tessini et al, 2018 Carious lesion severity and demarcated hypomineralized lesions of tooth enamel in schoolchildren from Melbourne, Australia.
New Zealand Wellington	15%	Mahoney & Morrison, 2009 The prevalence of Molar-Incisor Hypomineralisation (MIH) in Wainuiomata children.
Wellington	19%	Mahoney & Morrison, 2011 Further examination of the prevalence of MIH in the Wellington region.
Europe
Sweden Jönköping	10%	Koch et al, 1987 Epidemiologic study of idiopathic enamel hypomineralization in permanent teeth of Swedish children.
Kållered & Mölndal	18%	Jalevik et al 2001 The prevalence of demarcated opacities in permanent first molars in a group of Swedish children.
Malmo	16%	Brogardh-Roth et al, 2011 Molar-incisor hypomineralization and oral hygiene in 10- to-12-yr-old Swedish children born preterm.
Vastra Gotaland	12%	Jälevik et al, 2018 The prevalence of developmental defects of enamel, a prospective cohort study of adolescents in Western Sweden: a Barn I TAnadvarden (BITA, children in dental care) study.
Finland Helsinki & Kuopio	17%	Alaluusua et al, 1996 Polychlorinated dibenzo-p-dioxins and dibenzofurans via mother’s milk may cause developmental defects in the child’s teeth.
Helsinki	19%	Leppaniemi et al, 2001 Nonfluoride hypomineralizations in the permanent first molars and their impact on the treatment need.
Helsinki	8%	Tseveenjav et al (2020) Estimating molar-incisor-hypomineralization among 8-year-olds based on 15-year public oral health practice-based data.
Vantaa	25%	Alaluusua et al, 1996 Developmental dental defects associated with long breast feeding.
Lammi, Jalasjarvi, Helsinki, Oulu, Lappeenranta	17%	Wuollet et al, 2014 Background factors of molar-incisor hypomineralization in a group of Finnish children.
Lammi, Jalasjarvi	12%	Wuollet et al, 2016 Molar-incisor hypomineralization and the association with childhood illnesses and antibiotics in a group of Finnish children.
Lammi, Jalasjärvi, Lappeenranta	18%	Wuollet et al, 2018 The Association between Molar-Incisor Hypomineralization and Dental Caries with Socioeconomic Status as an Explanatory Variable in a Group of Finnish Children.
Netherlands Alphen aan de Rijnland, Gouda, Breda and Den Bosch	10%	Weerheijm et al, 2001 Prevalence of cheese molars in eleven-year-old Dutch children.
Alphen aan de Rijnland, Gouda, Breda, Den Bosch	14%	Jasulaityte et al, 2008 Prevalence of molar-incisor-hypomineralisation among children participating in the Dutch National Epidemiological Survey (2003).
Rotterdam	9%	Elfrink et al, 2012 Deciduous Molar Hypomineralization and Molar Incisor Hypomineralization.
United Kingdom Leeds	15%	Zagdwon et al, 2002 The prevalence of developmental enamel defects in permanent molars in a group of English school children.
Leeds	40%	Balmer et al, 2005 Prevalence of enamel defects and MIH in non-fluoridated and fluoridated communities.
Northern England	16%	Balmer et al 2012 The prevalence of molar incisor hypomineralisation in Northern England and its relationship to socioeconomic status and water fluoridation.
Germany Dresden	6%	Dietrich et al, 2003 Molar incisor hypomineralisation in a group of children and adolescents living in Dresden (Germany).
Lahn-Dill	6%	Preusser et al, 2007 Prevalence and severity of molar incisor hypomineralization in a region of Germany – a brief communication.
Lahn-Dill, Frankfurt	14%	Amend et al, 2021 Prevalence of molar-incisor-hypomineralisation (MIH) among 6-12-year-old children in Central Hesse (Germany).
Munich	14%	Kohlboeck et al, 2013 Is there a relationship between hyperactivity/inattention symptoms and poor oral health? Results from the GINIplus and LISAplus study.
Munich	17%	Kunisch et al, 2018 Relationship between caries experience and demarcated hypomineralised lesions (including MIH) in the permanent dentition of 15-year-olds.
Greifswald, Heidelberg, Dusseldorf, Hamburg	10%	Petrou et al, 2014 Prevalence of Molar-Incisor-Hypomineralisation among school children in four German cities.
Italy Lissone	14%	Calderara et al, 2005 The prevalence of Molar Incisor Hypomineralisation (MIH) in a group of Italian school children.
Rome	6%*	Condo et al, 2012 MIH: epidemiologic clinic study in paediatric patient.
Rome	18%*	Nissi et al, 2022 Prevalence of molar incisor hypomineralization among school children in Rome, Italy.
Spain Catalonia	18%	Gomez et al, 2011 Prevalence of molar-incisor hypomineralisation observed using transillumination in a group of children from Barcelona (Spain).
Barcelona	18%	Martinez Gomez et al, 2012 Prevalence of molar-incisor hypomineralisation observed using transillumination in a group of children from Barcelona (Spain).
Barcelona province	8%	Hernández et al, 2018 First Permanent Molars and Permanent Incisors Teeth by Tooth Prevalence of Molar-Incisor-Hypomineralisation in a Group of Spanish Schoolchildren.
Valencia	22%	Garcia-Margarit et al, 2013 Epidemiologic study of molar-incisor hypomineralization in 8-year-old Spanish children.
Valencia	24%	Negre-Barber et al, 2016 Hypomineralized second primary molars as predictor of Molar Incisor Hypomineralization.
Valencia	19%	Llena et al, 2020 Risk Factors Associated with Carious Lesions in Permanent First Molars in Children: A Seven-Year Retrospective Cohort Study.
Madrid	13%	Marcianes et al, 2023 Predictive Value of Hypomineralization of Second Primary Molars for Molar Incisor Hypomineralization and Other Relationships between Both Developmental Defects of Dental Enamel.
Madrid region	29%	Ortega-Luengo et al, 2024 Prevalence and clinical presentation of molar incisor hypomineralisation among a population of children in the community of Madrid.
Lithuania Kaunas	10%	Jasulaityte et al 2007 Molar incisor hypomineralization: review and prevalence data from the study of primary school children in Kaunas/Lithuania.
Bosnia & Herzegovina 9 communities	12%	Muratbegovitz et al, 2007 Molar-incisor-hypomineralisation impact on developmental defects of enamel prevalence in a low fluoridated area.
Foca	13%	Jankovic et al, 2014 Distribution and characteristics of molar-incisor hypomineralization.
Kljuc	12%	Mulic et al, 2017 How serious is molar incisor hypomineralisation (MIH) among 8- and 9-year-old children in Bosnia-Herzegovina? A clinical study.
Sarajevo	12%	Arslanagic et al, 2020 Demarcated opacities as predictors of progression of the molar incisor hypomineralisation: a pilot study.
Bulgaria Plovdiv	5%	Kukleva et al, 2008 Molar incisor hypomineralisation in 7-to-14-year old children in Plovdiv, Bulgaria—an epidemiologic study.
Greece Athens	10%	Lygidakis et al, 2008 Molar-incisor-hypomineralisatoin (MIH). Retrospective clinical study in Greek children. I. Prevalence and defect characteristics.
Thessaloniki, Ptolemaida, Ioannina	21%	Kevrekidou et al, 2015 Molar incisor hypomineralization of eight- and 14-year-old children: prevalence, severity, and defect characteristics.
Denmark North Jutland County	38%	Wogelius et al, 2008 Prevalence and distribution of demarcated opacities in permanent 1st molars and incisors in 6 to 8-year-old Danish children.
Aalborg	30%	Wogelius et al, 2020 Use of asthma drugs and prevalence of molar incisor hypomineralization.
Turkey Istanbul	15%	Kusku et al, 2008 The prevalence and aetiology of molar-incisor hypomineralisation in a group of children in Istanbul.
Istanbul	14%	Koruyucu et al, 2018 Prevalence and etiology of molar-incisor hypomineralization (MIH) in the city of Istanbul.
Kocaeli & Canakkale	9%	Kusku et al, 2009 The prevalence of molar incisor hypomineralization (MIH) in a group of children in a highly polluted urban region and a windfarm-green energy island.
Ankara	8%	Sonmez et al, 2013 Putative factors associated with molar incisor hypomineralisation: an epidemiological study.
Izmir	12%	Kılınc et al, 2019 Prevalence, aetiology, and treatment of molar incisor hypomineralization in children living in Izmir City (Turkey).
Slovenia 3 regions	21%	Groselj & Jan, 2013 Molar incisor hypomineralisation and dental caries among children in Slovenia.
Ljubljana	20%	Hocevar et al, 2020 The possible influence of genetic aetiological factors on molar-incisor hypomineralisation.
Poland Wielkopolska	8% *	Opydo-Szymaczek & Gerreth, 2015 Developmental Enamel Defects of the Permanent First Molars and Incisors and Their Association with Dental Caries in the Region of Wielkopolska, Western Poland.
Pomerania	6%	Glodkowska N, Emerich K, 2019 Molar Incisor Hypomineralization: prevalence and severity among children from Nothern Poland.
Norway Tromso, Balsfjord	14%	Schmalfuss et al, 2016 Canines are affected in 16-year-olds with molar-incisor-hypomineralisation (MIH): an epidemiological study based on the Tromso study "Fit Futures".
Oslo, Lillestrom	25%	Sidaly et al, 2016 Five-minute Apgar score ≤ 5 and Molar Incisor Hypomineralisation (MIH) - a case-control study.
Oslo	28%	Afzal et al, 2023 Molar-incisor hypomineralisation in Norwegian children: prevalence and associated factors.
Albania Tirana	14%	Hysi et al 2016 Prevalence and aetiology of Molar-Incisor Hypomineralisation among children aged 8-10 years in Tirana, Albania.
Austria Graz	7%	Buchgraber et al, 2017 Molar incisor hypomineralization: proportion and severity in primary public school children in Graz, Austria.
Switzerland Geneva	7%	Abdelaziz et al, 2022 Prevalence of Molar Incisor Hypomineralization in over 30,000 schoolchildren in Switzerland.
France Bordeaux region	19%	Estivals et al, 2023 The prevalence and characteristics of and the association between MIH and HSPM in South-Western France.
Brittany	9%	Boyer et al, 2023 Prenatal exposure to persistent organic pollutants and molar-incisor hypomineralization among 12-year-old children in the French mother-child cohort PELAGIE.
Romania Bucharest	3%	Stanciu et al, 2012 Epidemiological study on molar-incisor hypomineralisations in schoolchildren from general population.
Bucharest	14%	Ciocan et al, 2023 Real-World Evidence on the Prevalence of Molar Incisor Hypomineralization in School Children from Bucharest, Romania.
Asia
Hong Kong	3%	Cho et al, 2008 Molar incisor hypomineralization in Hong Kong Chinese children.
	6%	Wong et al, 2014 Risk factors of developmental defects of enamel – a prospective cohort study.
Iraq Mosul City	19%	Ghanim et al, 2011 Molar-incisor hypomineralisation: prevalence and defect characteristics in Iraqi children.
Erbil	27%	Ismail & Saleem, 2023 Prevalence of molar incisor hypomineralization (MI) and its association with some risk factors in group of children attending two specialized dental centers in Erbil city.
Jordan Amman, Irbid, Al-Karak	18%	Zawaideh et al, 2011 Molar incisor hypomineralisation: prevalence in Jordanian children and clinical characteristics.
India Gandhinagar, Gujurat	9%	Parikh et al, 2012 Prevalence and characteristics of Molar Incisor Hypomineralisation (MIH) in the child population residing in Gandhinagar, Gujarat, India.
Chandigarh	6%	Mittal et al, 2014 Molar incisor hypomineralisation: prevalence and clinical presentation in school children of the northern region of India.
Chandigarh	12%	Mariam et al, 2022 A case-controlled investigation of risk factors associated with molar incisor hypomineralization (MIH) in 8-12 year-old children living in Chandigarh, India.
Udaipur, Rajasthan	10%	Bhaskar et al, 2014 Molar-incisor hypomineralization: prevalence, severity and clinical characteristics in 8- to 13-year-old children of Udaipur, India.
Guatam Budh Nagar, Uttah Pradesh	7%	Mittal & Sharma 2015 Hypomineralised second primary molars: prevalence, defect characteristics and possible association with molar incisor hypomineralisation in Indian children.
Guatam Budh Nagar, Uttar Pradesh	10%	Mittal & Sharma 2015 Molar Incisor Hypomineralization: prevalence and defect characteristics in Indian schoolchildren.
Guatam Budh Nagar, Uttar Pradesh	10%	Mittal, 2016 Phenotypes of enamel hypomineralization and molar incisor hypomineralization in permanent dentition: Identification, quantification and proposal for classification.
Lucknow, Uttar Pradesh	14%	Mishra & Pandey 2016 Molar incisor hypomineralization: an epidemiological study with prevalence and etiological factors in Indian paediatric population.
Moradabad City, Uttar Pradesh	4%	Khan et al, 2022 Prevalence, pattern, and severity of molar incisor hypomineralization in 8–12-year-old schoolchildren of Moradabad City.
Salem, Tamil Nadu	8%	Krishnan et al, 2015 Prevalence and characteristics of MIH in school children residing in an endemic fluorosis area of India: an epidemiological study.
Chennai, Tamil Nadu	10%	Yannam et al, 2016 Prevalence of molar incisor hypomineralization in school children aged 8-12 years in Chennai.
Chennai, Tamil Nadu	13%	Padavala & Sukumaran, 2018 Molar Incisor Hypomineralization and Its Prevalence.
Tiruchengode, Tamil Nadu	5%	Samuel et al, 2017 Caries status and salivary characteristics of south Indian school children with Molar Incisor Hypomineralization: a cross-sectional study.
Chengalpattu, Tamil Nadu	11%	Jha et al, 2023 Prevalence of Molar Incisal Hypomineralization and its Association with Dental Caries, Oral hygiene Status, and Body Mass Index.
Davangere, Karnataka	9%	Kirthiga et al 2015 Prevalence and severity of molar incisor hypomineralization in children aged 11-16 years of a city in Karnataka, Davangere.
Udupi, Karnataka	27%	Tadikonda et al 2015 Prevalence of Molar Incisor Hypomineralization and its relation with dental caries in school children of Udupi district, South India.
Bangalore, Karnataka	12%	Shakuntala et al, 2016 Molar Incisor Hypomineralization: A study of prevalence and etiology in a group of South Bangalore children.
Bengaluru, Karnataka	2%	Subramaniam et al, 2016 Prevalence of molar incisor hypomineralization in 7–9-year-old children of Bengaluru city, India.
Virajpet, Karnataka	13%	Rai et al 2019 Prevalence of Molar Incisor Hypomineralization among school children aged 9 to 12 years in Virajpet, Karnataka, India.
Nagpur, Maharashtra	7%	Mittal et al, 2016 Assessment of association between molar incisor hypomineralization and hypomineralized second primary molar.
Muradnagar, Ghaziabad	21%	Rai et al, 2018 Molar Incisor Hypomineralization: Prevalence and Risk Factors Among 7-9 Years Old School Children in Muradnagar, Ghaziabad.
Malabar, Kerala	13%*	Peedikayil et al 2019 Molar incisor hypomineralization in North Malabar: An epidemiological study.
Muvattupuzha, Kerala	4%	Emmatty et al 2020 The prevalence of molar incisor hypomineralization of school children in and around Muvattupuzha, Kerala.
Central Delhi, New Delhi	1%	Goswami et al 2019 Molar Incisor Hypomineralization-An Emerging Burden: A Short Study on Prevalence and Clinical Characteristics in Central Delhi, India.
Cuttack, Odisha	4%*	Ray et al 2020 Prevalence and treatment need of molar incisor hypomineralisation in 8-12 year old school going children of Cuttack, Odisha.
Jaipur, Rajasthan	4%*	Emmanuel et al, 2021 Molar Incisor Hypomineralization incidence among 6–11-year-old schoolchildren of two rural community of Jaipur, India.
Krishna, Andhra Pradesh	2%	Tarannum et al, 2021 Molar Incisor Hypomineralization Prevalence in the Schoolchildren of Gannavaram Mandal, Krishna District, Andhra Pradesh, India: A Cross-sectional Study.
Iran Zahedan	13%	Ahmadi et al, 2012 Molar incisor hypomineralization: a study of prevalence and etiology in a group of Iranian children.
Shiraz	20%	Ghanim et al, 2014 Molar-incisor hypomineralisation: a prevalence study amongst primary schoolchildren of Shiraz, Iran.
Guilan	18%	Salem et al, 2016 Prevalence and predictors of molar incisor hypomineralization (MIH) among rural children in northern Iran.
China Wenzhou	26%	Li & Li 2012 Investigation of molar-incisor hypomineralization among children from 6 to 11 years in Lucheng District, Wenzhou City.
Suzhou	4%	Hong et al, 2017 Prevalence study of Molar-Incisor Hypo Mineralisation in primary school children in South China.
Foshan	8%	Pang et al, 2019 Interactions with the aquaporin 5 gene increase the susceptibility to molar-incisor hypomineralization.
Lankao	14%	Zhang et al, 2023 Study on machine learning of molar incisor hypomineralization in an endemic fluorosis region in central China.
Saudi Arabia Jeddah	9%	Allazzam et al, 2014 Molar incisor hypomineralization, prevalence, and etiology.
Riyadh	41%	Al-Hammad et al, 2018 Prevalence and Clinical Characteristics of Molar-Incisor-Hypomineralization in School Children in Riyadh, Saudi Arabia.
Mecca	27%	Sulaimani et al, 2021 The prevalence and etiology of molar-incisor hypomineralization among female school children.
Singapore All 4 quarters	10%	Ng et al, 2015 Prevalence of molar incisor hypomineralization (MIH) in Singaporean children.
Thailand Muang district	28%	Pitiphat et al, 2014 Factors associated with molar incisor hypomineralization in Thai children.
Kranuan district	21%	Pitiphat et al, 2014 Molar incisor hypomineralization and dental caries in six- to seven-year-old Thai children.
Nepal Kavre	14%	Shresthra et al, 2014 Prevalence of molar incisor hypomineralisation among school children in Kavre.
Malaysia Shah Alam	17%	Hussain et al, 2015 Distribution of molar incisor hypomineralization in Malaysian children attending university dental clinic.
United Arab Emirates Dubai	27%	Hussain et al 2018 The Prevalence and Severity of Molar Incisor Hypomineralization and Molar Hypomineralization in Dubai, UAE.
Dubai	8%	Ahmad et al 2019 Prevalence of Molar-Incisor Hypomineralisation in an Emerging Community, and a Possible Correlation with Caries, Fluorosis and Socioeconomic Status.
Ras Al Khaimah	21%	Padmanabhan et al, 2021 Molar Incisor Hypomineralization prevalence in Arab children in UAE and its association with risk factors – a cross sectional study.
Japan 8 regions	20%	Saitoh et al, 2018 Prevalence of molar incisor hypomineralization and regional differences throughout Japan.
Lebanon 5 regions	27%	Elzein et al, 2020 Molar incisor hypomineralisation in Lebanon: prevalence and clinical characteristics.
5 regions	23%	Elzein et al, 2021 Relation between molar-incisor hypomineralization (MIH) occurrence and war pollutants in bombarded regions: Epidemiological pilot study in Lebanon
Israel Tel Aviv	10%	Ajzman et al, 2023 The prevalence of developmental dental defects in Israeli children and its association with perinatal conditions: a cross-sectional study.
Syria Damascus	40%	Al-Nerabieah et al, 2023 Prevalence and clinical characteristics of molar-incisor hypomineralization in Syrian children: a cross-sectional study.
Africa
Libya Benghazi	3%	Fteita et al, 2006 Molar-incisor hypomineralization (MIH) in a group of school-aged children in Benghazi, Libya.
Benghazi	16%	Arheiam et al, 2021 Prevalence, distribution, characteristics and associated factors of molar-incisor hypomineralisation among Libyan schoolchildren: a cross-sectional survey.
Kenya Matungulu & Kangundo	14%	Kemoli, 2008 Prevalence of molar incisor hypomineralisation in six to eight year-olds in two rural divisions in Kenya.
Nigeria Ile-Ife	18%	Oyedele et al, 2015 Prevalence, pattern and severity of molar incisor hypomineralisation in 8- to 10-year-old school children in Ile-Ife, Nigeria.
Ile-Ife	10%	Temilola et al, 2015 The prevalence and pattern of deciduous molar hypomineralization and molar-incisor hypomineralization in children from a suburban population in Nigeria.
Ile-Ife	13%	Oyedele et al, 2015 Co-morbidities associated with molar-incisor hypomineralisation in 8 to 16 year old pupils in Ile-Ife, Nigeria.
Ile-Ife & Ibadan	3%	Folayan et al, 2018 Developmental defects of the enamel and its impact on the oral health quality of life of children resident in Southwest Nigeria.
Egypt Cairo	2%	Saber et al, 2018 Prevalence of molar incisor hypomineralisation in a group of Egyptian children using the short form: a cross-sectional study.
Tunisia Tunis	35%	Sakly et al, 2020 Prevalence of Molar Incisor Hypomineralisation Among School Children aged 7-12 years in Tunis, Tunisia.
Sudan Khartoum state	20%	Abdalla et al, 2021 Molar incisor hypomineralization, prevalence, pattern and distribution in Sudanese children.
Americas
Brazil Rio de Janeiro	40%	Soviero et al, 2009 Prevalence and distribution of demarcated opacities and their sequelae in permanent 1st molars and incisors in 7 to 13-year-old Brazilian children.
Rio de Janeiro	29%	Reis et al, 2021 Prevalence and severity of molar incisor hypomineralization in Brazilian children.
Botelhos	20%	Da Costa-Silva et al, 2010 Molar incisor hypomineralization: prevalence, severity and clinical consequences in Brazilian children.
Botelhos	17%	Costa-Silva et al, 2013 Influence of deciduous molar hypomineralization on the development of molar-incisor hypomineralization.
Botelhos	16%	da Costa Silva et al, 2017 The Impact of Molar-Incisor Hypomineralisation on Dental Caries in Permanent First Molars: A Prospective Cohort Study.
Araraquara	12%	Jeremias et al, 2013 Dental caries experience and Molar-Incisor Hypomineralization
Araraquara	20%	Fragelli et al, 2020 Aesthetic perception in children with molar incisor hypomineralization.
Teresina	18%	de Lima et al, 2015 Epidemiologic study of molar-incisor hypomineralization in schoolchildren in north-eastern Brazil.
Teresina	29%	Teixeira et al, 2018 Exploring the association between genetic and environmental factors and molar incisor hypomineralization: evidence from a twin study.
Lavras	20%	Tourino et al, 2016 Association between molar incisor hypomineralization in schoolchildren and both prenatal and postnatal factors: a population-based study.
Paranoa	15%	da Silva Figueiredo Se et al, 2017 Are hypomineralized primary molars and canines associated with molar-incisor hypomineralization?
Paranoa	16%	Raposo et al, 2019 Prevalence of hypersensitivity in teeth affected by Molar-Incisor Hypomineralization (MIH).
Curitiba	12%	Portella et al, 2019 Impact of molar incisor hypomineralization on quality of life in children with early mixed dentition: A hierarchical approach.
Curitiba	12%*	Fatturi et al, 2020 The relationship between molar incisor hypomineralization, dental caries, socioeconomic factors, and polymorphisms in the vitamin D receptor gene: a population-based study.
Florianopolis	10% *	Santos et al, 2019 Prevalence of self-reported dental pain and associated factors among eight- to ten-year-old Brazilian schoolchildren.
Lagoas	47%	Dourado et al, 2020 Molar-incisor hypomineralization in quilombola children and adolescents: A study of prevalence and associated factors.
Campina Grande	10%	Farias et al, 2021 Prevalence of molar-incisor hypomineralization is associated with dental caries in Brazilian schoolchildren.
Campina Grande	11%	Fernandez et al, 2021 Incisor Molar Hypomineralization and Quality of Life: A Population-Based Study with Brazilian Schoolchildren.
Campina Grande	13%	Fernandes et al, 2024 Impact of Molar Incisor Hypomineralization on Oral Health-Related Quality of Life in Brazilian Schoolchildren Aged 8 to 10 Years.
Manaus	13%	Hanan et al, 2023 Molar Incisor Hypomineralization in adolescents and adults and its association with facial profile and occlusion.
Sao Luis	15%	Franco et al, 2023 Pre- and perinatal exposures associated with molar incisor hypomineralization: Birth cohort, Brazil.
Natal	16%	Soares et al, 2024 The prevalence and characteristics of molar-incisor hypomineralisation in Natal, Brazil.
Argentina Buenos Aires	16%	Biondi et al, 2011 Prevalence of molar incisor hypomineralization in the city of Buenos Aires
Buenos Aires	6%	Biondi et al, 2012 Prevalence of molar-incisor hypomineralization (MIH) in children seeking dental care at the Schools of Dentistry of the University of Buenos Aires (Argentina) and University of la Republica (Uruguay).
Uruguay Montevideo	7%	Biondi et al, 2012 Prevalence of molar-incisor hypomineralization (MIH) in children seeking dental care at the Schools of Dentistry of the University of Buenos Aires (Argentina) and University of la Republica (Uruguay).
Mexico Mexico City	16%	Gurrusquieta et al, 2017 Prevalence of molar incisor hypomineralization in Mexican children.
Mexico City	35%	Villanueva-Gutiérrez et al, 2019 Prevalence and Severity of Molar-Incisor Hypomineralization, Maternal Education, and Dental Caries: A Cross-Sectional Study of Mexican Schoolchildren with Low Socioeconomic Status.
Mexico City	20%, 32%	Irigoyen-Camacho ME et al, 2019 Evaluating the changes in molar incisor hypomineralization prevalence: A comparison of two cross-sectional studies in two elementary schools in Mexico City between 2008 and 2017.
Chile Talca	16%	Gambetta-Tessini et al, 2019 The impact of MIH/HSPM on the carious lesion severity of schoolchildren from Talca, Chile.
Santiago	13%	Harz et al, 2023 Prevalence and severity of molar-incisor hypomineralization, is there an association with socioeconomic status? A cross-sectional study in Chilean schoolchildren.
Columbia Medellin	11%	Mejía et al, 2019 Molar Incisor Hypomineralization in Colombia: Prevalence, Severity And Associated Risk Factors.
Medillin	31%	Farias et al, 2022 Does molar-incisor hypomineralization (MIH) affect only permanent first molars and incisors? New observations on permanent second molars.
United States Milwaukee	10%	Davenport et al, 2019 Prevalence of molar-incisor hypomineralization in Milwaukee, Wisconsin, USA: a pilot study.
Pittsburgh	8% *	Hartsock et al, 2020 A Snapshot of the Prevalence of Molar Incisor Hypomineralization and Fluorosis in Pittsburgh, Pennsylvania, USA.
Indiana	13%	Tagelsir Ahmed et al, 2020 Prevalence of molar-incisor hypomineralization and other enamel defects and associated sociodemographic determinants in Indiana.
New Orleans	14%	Lanford et al, 2021 Prevalence of Molar-Incisor Hypomineralization within an orthodontic department in the United States.
Canada Toronto	17% *	Sidhu et al, 2019 Prevalence and presentation patterns of enamel hypomineralisation (MIH and HSPM) among paediatric hospital dental patients in Toronto, Canada: a cross-sectional study.
Ecuador Guayaquil	9%	Ordonez-Romero et al, 2019 Distribution of Molar Incisor Hypomineralization in Ecuadorian children.
Venezuela Caracas	26%	Rodriguez-Rodriguez et al, 2021 Prevalence and distribution of Molar-Incisor Hypomineralization in children receiving dental care in Caracas Metropolitan Area, Venezuela.
Average prevalence	15% (for 172 studies from 55 countries)

* 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.