|Year : 2016 | Volume
| Issue : 2 | Page : 134-138
Prevalence of molar incisor hypomineralization in school children aged 8-12 years in Chennai
Savitha Deepthi Yannam1, Deepti Amarlal2, Chamarthi Vishnu Rekha3
1 Department of Pediatric and Preventive Dentistry, GSL Dental College and Hospital, Rajamundry, Andhra Pradesh, India
2 Department of Pediatric and Preventive Dentistry, Sri Sai Dental College, Vikarabad, Telangana, India
3 Department of Pediatric Dentistry, Meenakshi Ammal Dental College, Chennai, Tamil Nadu, India
|Date of Web Publication||14-Apr-2016|
Dr. Savitha Deepthi Yannam
Department of Pedodontics and Preventive Dentistry, GSL Dental College and Hospital, Rajamundry - 533 296, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Objective: To investigate the prevalence and severity of molar incisor hypomineralization (MIH). Materials and Methods: A sample of 2,864 students aged 8-12 years were selected from government and private schools in Chennai. MIH was diagnosed clinically based on the diagnostic criteria established by the European Academy of Pediatric Dentistry (EAPD) 2003. Results: A total of 277 children (9.7%) had MIH. There was statistically significant difference in prevalence related to age but there was no statistical difference in prevalence with respect to gender. Conclusion: Prevalence of MIH was 9.7% in the child population residing in Chennai. Males and females were equally affected. The rate of occurrence and severity of MIH are more in the right mandibular first molar. The severity of MIH is more in molars compared to incisors (P < 0.001) and is more in government schools compared to private schools (P = 0.002).
Keywords: Hypomineralization, molar incisor hypomineralization (MIH), prevalence, white spot lesion
|How to cite this article:|
Yannam SD, Amarlal D, Rekha CV. Prevalence of molar incisor hypomineralization in school children aged 8-12 years in Chennai. J Indian Soc Pedod Prev Dent 2016;34:134-8
|How to cite this URL:|
Yannam SD, Amarlal D, Rekha CV. Prevalence of molar incisor hypomineralization in school children aged 8-12 years in Chennai. J Indian Soc Pedod Prev Dent [serial online] 2016 [cited 2019 Dec 13];34:134-8. Available from: http://www.jisppd.com/text.asp?2016/34/2/134/180438
| Introduction|| |
The developmental defects of enamel are one of the most frequently observed developmental abnormalities of the human dentition that are a frequent finding in primary and permanent dentition. These defects are generally classified as enamel hypoplasia and enamel hypomineralization. Enamel hypoplasia is a quantitative defect of enamel, resulting from a disturbance to the ameloblasts during matrix formation,  whereas enamel hypomineralization is a qualitative defect of enamel because of the disturbance during initial calcification and/or during maturation characterized by abnormal enamel translucency and therefore it is known as enamel opacity. ,
Molar incisor hypomineralization (MIH) appears to have been first recognized in the late 1970s by Swedish dentists working within the public health services.  It existed long before it was first identified. MIH is defined by Weerheijm et al. (2001), as "a hypomineralization of systemic origin of one to four permanent first molars frequently associated with affected incisors."  MIH is also named as idiopathic enamel hypomineralization,  nonfluoride hypomineralization in first permanent molars,  and cheese molars. 
MIH is frequent in many populations throughout the world. However, a wide variation of 2.4-40.2% has been reported. Most prevalence studies have been carried out in Northern Europe and the rates between 3.6% and 25% were reported.  The reported prevalence of MIH varies from 2.4% in Germany and Bulgaria, , to 40% in Leeds, and to 44% in Sydney.  The only Indian study that was conducted at Gandhi Nagar, Gujarat, showed a prevalence of 9.2%.  There is a wide variability in the prevalence rates because of the use of different indices and criteria, examination variability, methods of recording, and different age groups. The various indices used are Alaluusua et al. criteria (1996),  mDDE, ,, Kemoli criteria (2008),  Koch et al. criteria (1987),  and the European Academy of Pediatric Dentistry (EAPD) 2003 criteria.  The EAPD criteria was given after the discussions on MIH at the EAPD Dublin congress, Athens, March 2003, and it seems to establish the judgment criteria for MIH in epidemiological studies. In this study, the children were examined for MIH according to the description given by the EAPD 2003. The aim of the study therefore was to assess the prevalence of MIH in school children residing in Chennai.
| Materials and Methods|| |
The study was approved by the Institutional Review Board of the Meenakshi Academy of Higher Education and Research.
The nature and purpose of the study was explained to the heads of the schools (Correspondent, Principal, Head master, Headmistress, etc.), and prior permission was obtained to conduct the survey in their schools. The study was conducted in June-July 2012.
The survey was aimed to include both the government and private schools from different parts of Chennai. Random sampling methodology was used to select the schools from the government and private category from different parts of Chennai. From the selected schools, 2,864 students within the age group of 8-12 years were included in the study.
All examinations took place in the nursing room of the school. Teeth were inspected visually in daylight with a torch, while the child is seated in an ordinary chair. To examine, sterilized mouth mirror and probe that were individually wrapped were used. The probe was occasionally used to remove plaque. Teeth were not dried before inspection. One examiner performed the dental examination. The examination chart contains a section of demographic variables such as name, age, gender, school, and a chart for entry of the diagnosis and severity of MIH. Only permanent eight incisors and first four molars were examined. MIH was diagnosed clinically based on the diagnostic criteria established by the EAPD 2003.
EAPD criteria 2003
2-Posteruptive enamel breakdown
4-Extracted molar due to MIH
5-Unerupted molar due to MIH
Exclusion criteria for MIH
If the authoritative head of the schools were not interested or not willing to be a part of the survey, those schools were excluded from the study. The schools in areas with ground water fluoride concentration exceeding 2 ppm were also excluded. The children with amelogenesis imperfecta, dentinogenesis imperfecta, hypoplasia, diffuse opacities, white spot lesions, tetracycline stains, erosion, fluorosis, and Turner's tooth were excluded. The children with defects smaller than 2 mm were excluded. Demarcated opacities in second molar and premolars were excluded. The children whose first permanent molars are not fully erupted were excluded. The children with appliances, such as brackets and bands, were excluded. Children who were uncooperative were excluded from the survey.
Statistical analysis was performed using the Statistical package for the Social Sciences (SPSS) (SPSS Inc, Version 16 Chicago, IL, USA) to analyze the data. Karl Pearson Chi-square test is used to compare the proportions. Differences were considered statistically significant if P ≤ 0.05.
| Results|| |
A total of 2,864 students were evaluated. Among them 1,499 were boys and 1,365 were girls. The prevalence of MIH was 9.7%. There was statistically significant difference in prevalence related to age (P < 0.0001), but there was no statistical difference in prevalence with respect to gender.
[Table 1] shows age-wise distribution of MIH. [Figure 1] shows the distribution of sample according to age. This table shows that the prevalence of MIH was highest among 10-year-old children (12.95%). The least prevalence of MIH (7.41%) was seen in 12-year-old children. [Figure 1] shows the distribution of MIH according to age. There is statistical significance in the prevalence of MIH among the observed age groups.
[Table 2] shows the prevalence of MIH in molars and incisors individually. The severity of MIH was more in molars (19.4%) when compared to incisors (4.4%) and the difference between the two is statistically significant. Mild MIH was more in incisors (95.6%) when compared to molars (80.6%) and the difference between the two is statistically significant (P < 0.001).
[Table 3] shows the prevalence of MIH for each indexed tooth. The severity of MIH was more in mandibular left first permanent molar (22.55%). Mandibular right central incisor showed the least severity of MIH (2.56%). Mandibular right central incisor showed the highest prevalence (97.44%) in terms of mildness and mandibular left first permanent molar showed the least prevalence and was statistically significant (P < 0.001).
[Table 4] shows prevalence of MIH in private and government schools. The severity was more in government schools (20.6%) when compared to private schools. The mild defects was more in private schools (86.4%) when compared to government schools and the difference between the two is statistically significant (P = 0.002).
[Table 5] shows the prevalence of MIH in the right and left halves of the jaw. The severity of MIH was more on the left side (16.5%) when compared to the right side. The mild defects was more in the right side (84.5%) when compared to the left side but the difference between the two was not statistically significant.
[Table 6] shows the distribution of MIH in the maxilla and mandible. The severity of MIH was more in mandible (18%) when compared to maxilla, whereas mild MIH was more in maxilla (86%) when compared to mandible, but the difference between the two was not statistically significant.
| Discussion|| |
Of 2,864 children examined, 9.27% children from private school and 10.52% from government school had MIH. Of the 1,122 children examined for teeth with MIH, 86.4% presented with mild lesions and 13.6% presented with severe lesions among the students from private college, and 79.4% presented with mild lesions, 20.6% presented with severe lesions among the students from government schools. The difference in severity is statistically significant (P = 0.002).
The age range chosen in the study was 8-12 years (EAPD 2003). At this age, in most children, all four first permanent molars and majority of incisors would have erupted. In addition, the risks that enamel hypomineralization would be masked by caries would be minimal. In order to assure consistency in sample examination, a single investigator was used after calibration prior to the commencement of the study and whose reliability was tested prior to and during the study.
The study was done based on the recommendations given by the EAPD.  Children with atleast one affected molar were included and in subjects with all first permanent molars extracted, not due to orthodontic reasons, with MIH signs in one other indexed tooth (four permanent first molars, eight permanent incisors), were diagnosed as MIH.
Of the schools examined based on the socio-economic decile, 179 children in private schools and 98 children in government schools had MIH. There is no statistical difference based on socioeconomic status, which was in agreement with Erin Mahoney (2011). 
Evaluating the results concerning the type of teeth affected, it appears that only 9.6% of the children had MIH, out of which 59.56% revealed the full MIH spectrum (all four molars affected). This percentage is much higher than in all previous reports, where children having full MIH spectrum varied from 22.6% to 35%. ,,,
In the present study, there is no statistical difference in the prevalence between the maxillary teeth compared to the mandibular teeth, which was in agreement with the study done by Jalevik et al.  The findings of this study differ from the previous reports. , Further studies on larger populations are required to determine if there are real differences between maxillary and mandibular teeth and the reasons behind. Several authors ,,,,,,, reported that maxillary first permanent molars are more affected as compared to mandibular molars. With regard to incisors, maxillary incisors were mostly affected in comparison to mandibular incisors in this study and among the maxillary incisors, central incisors were more frequently affected. This is in agreement with other studies. ,
A great majority (77.3%) of the affected teeth in the present study revealed mild defects. This finding is in agreement with that of the previous studies. , The association of increase in severity of MIH with increases in total number of teeth affected has also been reported ,,, and may be the result of the variation in timing, duration, and severity of single or multiple etiological factors. As it has been shown before in clinical and laboratory studies, an insult or combination of insults acting for a longer time during prenatal/perinatal/postnatal period may result in a greater number and more severely affected teeth. , Finally the present study revealed that the degree of severity of affected molars increased with age as was reported earlier, ,, and can be attributed to the presence of the affected teeth for longer periods in the mouth of older children, that leads to an increased risk of enamel breakdown in teeth involved in mastication.
| Conclusion|| |
Of 2,864 children examined,
- 9.7% presented molar incisor hypomineralization defects.
- Distribution of MIH was more in 10 years of age, while the least affected age group was 12 years.
- Distribution of MIH was more in males than females.
- The occurrence and severity of MIH is more in the right mandibular first molar.
- Severity of MIH is more in molars compared to incisors.
- Distribution of MIH is more in mandible than maxilla and severity is also more in mandible.
- Distribution of MIH in the right side of the jaw is more affected than that in the left side, and left side is more severely affected than the right side.
- Distribution of MIH is more in government schools compared to private schools, and the severity of MIH is more in government schools compared to private schools.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]