Molar incisor hypomineralization: a study of aetiological factors in a group of UK children

Objectives. The objectives were to investigate the aetiology of molar incisor hypomineralization (MIH), and to discuss previously published studies. Subjects and methods. One hundred and nine children attending the Department of Paediatric Dentistry at the Royal London Hospital were included in the study: 57 children with MIH and 52 controls. Their mothers completed a medical history interview. Results. No significant associations were found with MIH and delivery and birth complications, breastfeeding, immunization history, other illnesses and allergies, general anaesthetics, fluoride history, and trauma or abscesses affecting the primary predecessors. A family history of enamel defects was more commonly reported for MIH children, but the association was not statistically significant. However, MIH was significantly more common among those whose mothers had experienced problems during pregnancy (P = 0.025), those who had chickenpox between the ages of 3 and 3.99 (P = 0.047), and those for whom amoxycillin was the only antibiotic they had received (P = 0.028). Conclusions. The aetiology of MIH remains unclear, and this study questions whether it is because of a lone aetiological insult. This study recommends further research looking at the links with chickenpox occurring around the third year of life and amoxycillin.     

Background factors of molar-incisor hypomineralization in a group of Finnish children

Objective. Molar-Incisor Hypomineralization (MIH) is a common developmental enamel defect characterized by demarcated opacities in permanent molars and incisors. Its etiology still remains unclear. The aim of this retrospective cohort study was to assess if the socioeconomic environment of the child is associated with MIH. Materials and methods. The study was located in two rural towns and three urban cities in Finland. A total of 818 children, between 7–13 years old, were examined for MIH using the evaluation criteria in line with those of the European Academy of Paediatric Dentistry, but excluding opacities smaller than 2 mm in diameter. The mothers filled in a questionnaire which included questions related to the family’s way of living (e.g. area of residency, farming, day care attendance) and socioeconomic status (family income, number of mother’s school years, level of maternal education). Results. The prevalence of MIH in the study population was 17.1%. Family income, urban residency and day care attendance were associated with MIH in the univariate analysis. In the multivariate analysis using binary logistic regression, only urban residency during a child’s first 2 years of life remained associated with MIH. The prevalence of MIH in urban areas was 21.3% and in rural areas 11.5% (OR = 2.18, CI = 1.35–3.53, p = 0.001). Conclusions. The prevalence of MIH was related to urban residency and could not be explained by any other factor included in the study.     

Molar incisor hypomineralization in Hong Kong Chinese children

Background.   Most prevalence studies on molar incisor hypomineralization (MIH) were carried out in European countries, and data from the East-Asian populations were lacking.
Aim.   This study aimed to investigate the prevalence of MIH in Hong Kong Chinese children.
Design.   Since 2006, charting of teeth with MIH was included into the routine dental examination in a school dental clinic. The dental records of grade 6 primary school children who attended annual check-up in this clinic in 2006 were subsequently reviewed retrospectively. The records were selected for this study if the charting indicated that the children were affected by MIH.
Results.   A total of 2635 records were reviewed and 73 cases of MIH were identified. The prevalence of MIH in this group of children was 2.8%. Their mean age was 12, and the male-to-female ratio was 1 : 1.2. The mean decayed, missing, or filled permanent teeth value of those affected was 1.5, which was higher than that of the general Hong Kong Chinese children aged 12 years old (0.8). A total of 192 teeth were affected. The most commonly affected teeth were permanent maxillary first molars, followed by mandibular first molars and maxillary central incisors. Dental fillings and fissure sealants were found in 52 (38%) and 65 (47%) permanent first molars with hypomineralization, respectively. Medical histories were unremarkable in 60 children, whereas early childhood diseases were reported in 13 cases.
Conclusions.   The prevalence of MIH in the permanent dentition of Hong Kong Chinese children was 2.8%. Children with MIH showed higher caries experience in the permanent dentition than the general population of similar age.     

Molar incisor hypomineralization in HIV‐infected children and adolescents

The objective was to determine the prevalence of molar incisor hypomineralization (MIH) among individuals between 7 and 15 years old infected or noninfected with human immunodeficiency virus (HIV). The study was conducted with 33 HIV‐infected individuals (study group; SG) and 66 non‐HIV‐infected schoolchildren (control group; CG), paired by gender and age. Data collection was based on medical records (SG), a questionnaire for caregivers and oral examination for diagnosis of MIH (European Academy of Pediatric Dentistry criteria) and caries (DMFT index and ICDAS). Data were analyzed with Mann‐Whitney, chi‐square, and Fisher's exact tests and logistic regression. In SG, MIH (45.5%) and caries (87.9%) had higher prevalence. MIH was associated with use of protease inhibitors in SG (OR: 2.14; 95% CI: 1.21 to 3.77) and incubator need in CG (OR: 2.80; 95% CI: 1.71 to 9.10). HIV‐infected patients had a higher prevalence of MIH and dental caries in the permanent dentition.     

Factors associated with molar incisor hypomineralization in Thai children

Molar incisor hypomineralization (MIH) is a qualitative developmental enamel defect that affects one to four permanent first molars, with or without involvement of permanent incisors. Its etiology is of systemic origin, but is not well understood. Therefore, we conducted this cross‐sectional study to examine pre‐, peri‐, and postnatal risk factors for MIH among children, 7–8 yr of age, in urban areas of Khon Kaen, Thailand. Molar incisor hypomineralization defects were diagnosed using the European Academy of Pediatric Dentistry criteria. Mothers or primary caregivers were interviewed on maternal medical history and habits during pregnancy, pregnancy and delivery complications, and the child's medical history. Molar incisor hypomineralization defects were observed in 78 (27.7%) of 282 children. Multiple logistic regression analysis showed a statistically significant association between the development of MIH and Cesarean section (adjusted OR = 2.0, 95% CI = 1.1–3.7), complications during vaginal delivery (adjusted OR = 4.5, 95% CI = 1.9–11.0), and severe/chronic illness when under 3 yr of age (adjusted OR = 2.9, 95% CI = 1.6–5.0). There was no association of preterm birth and low birth weight with MIH. The results suggest that Cesarean section, complications during vaginal delivery, and poor health during the first 3 yr of life are independent risk factors for MIH.     

Aetiology of molar–incisor hypomineralization: a critical review

Objective.  The objective of this study was to assess the strength of evidence for the aetiology of molar–incisor hypomineralization (MIH), often as approximated by demarcated defects.
Method.  A systematic search of online medical databases was conducted with assessment of titles, abstracts, and finally full articles for selection purposes. The level and quality of evidence were then assessed for each article according to Australian national guidelines.
Results.  Of 1123 articles identified by the database search, 53 were selected for review. These covered a variety of potential aetiological factors, some of which were grouped together for convenience. The level of evidence provided by the majority of papers was low and most did not specifically investigate MIH. There was moderate evidence that polychlorinated biphenyl/dioxin exposure is involved in the aetiology of MIH; weak evidence for the role of nutrition, birth and neonatal factors, and acute or chronic childhood illness/treatment; and very weak evidence to implicate fluoride or breastfeeding.
Conclusion.  There is currently insufficient evidence in the literature to establish aetiological factor/s relevant for MIH. Improvements in study design, as well as standardization of diagnostic and examination protocols, would improve the level and strength of evidence.     

The prevalence of molar incisor hypomineralization (MIH) in a group of children in a highly polluted urban region and a windfarm-green energy island

Backround.  Children's developing teeth may be sensitive to environmental pollutants such as polychlorinated dibenzo- p -dioxins (PCDDs) and polychlorinated dibenzofurans. The term molar incisor hypomineralization (MIH) was introduced to describe the clinical appearance of enamel hypomineralization of systemic origin affecting one or more permanent first molars (PFMs) that are associated frequently with affected incisors.
Aim.  The aim of this study was to determine the prevalance of MIH in children from the most industrialized and polluted region and the most green-energy island of Turkey.
Design.  In September 2007, a retrospective study was initiated in two elementary schools: one, a group of children ( N  = 153) who fitted the criteria from Tavsancil, Kocaeli ( N  = 109) and the other from Bozcaada island, Canakkale ( N  = 44). The soil samples were collected from selected regions in order to determine the contamination levels in a heavily industrialized area and a non-industrialized area.
Results.  Prevalance of MIH in children in Bozcaada island was 9.1%, while prevalance of MIH was 9.2% in Tavsancil. The PCDD/F levels in soil samples collected from Bozcaada and Tavsancil were determined as 1,12 and 8,4 I-TEQ ng/kg dry soil, respectively ( P  < 0.001).
Conclusions.  In this preliminary study with a small study population, prevalence of MIH did not seem to be associated with the levels of PCDD/Fs in the environment.     

Molar incisor hypomineralization: prevalence,severity and clinical consequences in Brazilian children

International Journal of Paediatric Dentistry 2010; 20: 426–434 Background. The prevalence of molar incisor hypomineralization (MIH) varies considerably around the world; however, few studies have examined MIH in South American countries. Objective. To evaluate the prevalence, severity, and clinical consequences of MIH in Brazilian children residing in rural and urban areas of the municipality of Botelhos, Minas Gerais, Brazil. Methods. Children aged 6 to 12 years (n = 918) with all four‐first permanent molars erupted had these teeth evaluated according to the European Academy of Paediatric Dentistry (EAPD) criteria. The examinations were conducted by two previously trained examiners, and the dental impact caused by MIH was evaluated with the Decayed, Missing and Filled Teeth (DMFT) index (WHO). Results. Molar incisor hypomineralization was present in 19.8% of the 918 children, with a higher prevalence in rural areas. The majority of the defects presented were demarcated opacities without post‐eruptive structural loss, which has been considered as mild defects. Children with MIH had higher DMFT values. Conclusion. Despite the high prevalence of MIH, the severity of the defects was mild. The results indicate a positive association between MIH and the presence of dental caries.     

Linking the clinical presentation of molar‐incisor hypomineralisation to its mineral density

International Journal of Paediatric Dentistry 2010; 20: 353–360 Background. The in vitro methods used for the assessment of the severity of molar‐incisor hypomineralisation (MIH) are not available for clinicians faced with questions regarding the severity in clinical cases, and the best management approach. Aim. To assess whether there is a relation between the severity of the defects in MIH enamel (represented by reduction in the mineral density) and the clinical presentation (represented by the colour of the defect and its laser fluorescence). Design. The colour of enamel was recorded (normal, white, yellow or brown) in specific areas for ten extracted first permanent molars with MIH defects and ten extracted sound teeth. Laser fluorescence (LF) and mineral density (MD) were measured for the same areas. A mixed model, using sample/tooth as a random effect, was used to estimate the relationship between the MD and the colour‐coding, and between the MD and LF readings. Results. The between‐samples correlation coefficient for the colour coding and the MD was 0.99 (P < 0.001), and 0.83 (P < 0.001) for the LF and MD. Conclusions. The degree of staining of MIH enamel, as assessed visually or by LF, may be used clinically to reflect the severity of the defect.     

Molar incisor hypomineralization: a questionnaire inventory of its occurrence in member countries of the European Academy of Paediatric Dentistry (EAPD)

Objectives. The objectives were to find out whether hypomineralized permanent first molars and incisors, known as Molar Incisor Hypomineralization (MIH), occurs all over Europe, whether its prevalence in each country is known and whether or not it is considered to be a clinical problem. Sample and methods. Clinical photos of MIH and a five‐item questionnaire were sent to members of the European Academy of Paediatric Dentistry (EAPD). A total of 59 questionnaires were sent to members in 31 countries. After one month a reminder was sent to non‐responders. Results. Fifty‐four dentists (92%) in 30 countries (97%) returned the questionnaire. MIH was stated to occur in all but one country (the Czech Republic). Nearly all the responders (97%) stated that they were familiar with the clinical appearance of MIH and a majority saw it as a clinical problem. Furthermore, a large majority of the responders (90%) considered it important to map the prevalence of MIH in European countries as such data are available to only a limited extent. Conclusion. Paediatric dentists in Europe are aware of MIH and the majority consider it to be a clinical problem. Only limited data are available on the prevalence of MIH. Comparable and representative prevalence studies are therefore urgently needed to gain more knowledge about the magnitude of MIH and related clinical problems.     

Prevalence and severity of molar incisor hypomineralization in a region of Germany -- a brief communication

OBJECTIVES: Molar incisor hypomineralization (MIH) is a developmental disturbance concerning permanent incisors and first permanent molars. The aim of this study was to ascertain the frequency of MIH in the region of central Hesse, Germany. METHODS: 1,022 children aged 6 to 12 years were surveyed during routine school-based dental examinations, which were conducted by the regional public health department. Symptoms of MIH were recorded and a DMF-T evaluation was carried out. RESULTS: Approximately 6 percent (5.9 percent) of all examined children showed at least one ill-structured first permanent molar in terms of MIH. Furthermore, 57.9 percent of these children with hypomineralized first molars also showed changes in the enamel structure of the permanent incisors. Altogether, children with MIH showed a significantly higher DMF-T value for permanent teeth than children without MIH. CONCLUSIONS: A carefully managed recall program for children affected by MIH is essential with regard to the increasing importance of preventive and restorative measures.