Prevalence and characteristics of Molar Incisor Hypomineralisation (MIH) in the child population residing in Gandhinagar, Gujarat, India.
Abstract: Most prevalence studies on Molar Incisor Hypomineralisation (MIH) have been carried out in European countries and data from Asia especially south Asian populations are lacking. AIM: To investigate the prevalence and clinical characteristics of MIH in children residing in a western region of India. METHOD: A cross-sectional survey including 1,366 children from 5 age cohorts, 8-12 years, studying in primary schools or attending the University Department, was carried out in the area of Gandhinagar, Gujarat, India. The dental examination was performed by a single well-trained and calibrated examiner in day light conditions. Full mouth inspection of wet teeth was conducted using the EAPD 2003 criteria for diagnosis of MIH. Results were recorded and statistically analysed using Chi-square test, independent sample t-test and Pearson correlations. RESULTS: Prevalence of MIH was 9.2% in the examined population. Males and females were equally affected. Among 12 index teeth involved in the examination, the most commonly affected were in descending order 46, 36, 16, 11 [FDI] and the least 42, 32, and 22. 17.4% of the cases revealed only molars involved, the remaining 72.6% having both molars and incisors affected; all four first permanent molars showed in 23% of the cases while no cases of only affected incisors were found. Of the MIH teeth 77.3% revealed mild defects and 22.7% severe defects. All incisors were mildly affected, as compared with only 67.1% of the molars, the remaining 32.9% being severely affected. As age increased, a statistically significant larger total number and severity level of affected teeth were recorded. CONCLUSION: Prevalence of MIH using EAPD 2003 criteria was found to be similar to other studies evaluating children in different geographic locations such as Europe, South America etc. Using the EAPD standardised criteria, more studies should be conducted in other Indian regions, in order to further evaluate prevalence, characteristics and treatment needs for this clinically demanding condition.

Key words: MIH prevalence, MIH severity, Clinical characteristics.
Article Type: Report
Subject: Epidemiology (Research)
Diagnosis (Standards)
Tooth diseases (Diagnosis)
Tooth diseases (Care and treatment)
Children (Diseases)
Children (Care and treatment)
Authors: Parikh, D.R.
Ganesh, M.
Bhaskar, V.
Pub Date: 02/01/2012
Publication: Name: European Archives of Paediatric Dentistry Publisher: European Academy of Paediatric Dentistry Audience: Academic Format: Magazine/Journal Subject: Health Copyright: COPYRIGHT 2012 European Academy of Paediatric Dentistry ISSN: 1818-6300
Issue: Date: Feb, 2012 Source Volume: 13 Source Issue: 1
Topic: Event Code: 310 Science & research; 350 Product standards, safety, & recalls
Product: Product Code: 8000420 Diagnostic Procedures NAICS Code: 6215 Medical and Diagnostic Laboratories
Geographic: Geographic Scope: Sweden; India Geographic Code: 4EUSW Sweden; 9INDI India
Accession Number: 279612745
Full Text: Introduction

Molar-Incisor Hypomineralisation (MIH) has been suggested as firstly noted as early as the 17th and 18th century following an examination of archaeological sub-adult samples of a London cemetery [Odgen et al., 2008]. One of the first epidemiological studies evaluating this condition was conducted in Sweden in the 1970s and reported 15% prevalence in children born between 1966-1974 [Koch et al., 1987]. That study described this condition as 'idiopathic enamel hypomineralisation'. Subsequently, many different terms for the same condition have been suggested, such as cheese molars [van Amerongen and Kreulen, 1995] and non-fluoride hypomineralisation [Leppaniemi et al., 2001]. In 2001 the term Molar-Incisor Hypomineralisation (MIH) was introduced following a meeting during the 5th Congress of the European Academy of Paediatric Dentistry [Weerheijm et al., 2001a]. According to these authors, 'the definition of MIH would be hypomineralisation of systemic origin that affects one to four first permanent molars, frequently associated with affected permanent incisors". The subsequent EAPD seminar in Athens 2003 established the judgment criteria for MIH in epidemiological studies (Table 1) [Weerheijm et al., 2003]. Many prevalence studies were conducted since then using the EAPD criteria with a reported prevalence of 2.4-40.2% [Jalevik, 2010].

MIH can create serious problems for clinicians in terms of management as well as for children due to sensitivity of mainly the affected posterior teeth. Children often report shooting pain when they are brushing their teeth or even breathing cold air, shortly after the eruption of the affected teeth. Severely affected posterior teeth are soon in need of restoration as a result of enamel disintegration and subsequent caries, while anteriors teeth frequently present demanding aesthetic management [Mathu-Muju and Wright, 2006].

The high prevalence of MIH indicates the need for further research clarifying the aetiological factors [Alaluusua, 2010] and improving the durability of the various restorations indicated for this demanding condition [Lygidakis, 2010]. Among all reported studies, most prevalence studies have been performed in the European continent and there are only few reports from Asia and specifically none from India [Jalevik, 2010]. The aim therefore of the present cross sectional study was to evaluate the prevalence and clinical characteristics of MIH in children residing in a western region of India.

Materials and methods

Ethical approval: Study protocol and informed consent had been approved by the Ethical Committee at Ahmedabad Dental College and Hospital, Gandhinagar, Gujarat.

Study design: The study was a cross-sectional survey which included 1,366 children in five different cohorts, 8-12 years, attending the seven primary schools of the rural area of Gandhinagar district (through school-based dental health care programmes) and also children who attended a departmental clinic.

Subject selection: After getting permission from the Government and school authorities of selected schools, informed consent forms were given to all students. Children present on the day of examination, with approved parental informed consent forms, were included in the study. In addition children who reported for examination, during the same study period, in the Ahmedabad department with parents willing to participate in the study.

Study setting and data collection: A single well-trained calibrated examiner performed the dental examinations in day light conditions. A full mouth inspection of wet teeth was performed for all the examined children using the EAPD 2003 criteria (Table 1). The severity of MIH was determined by the criteria used initially by Jasulaityte et al. [2007] and recently included in the EAPD recommendations [Lygidakis et al., 2010]. According to these criteria mild cases are recorded as demarcated enamel opacities without enamel breakdown, occasional sensitivity to external stimuli e.g. air/water but not brushing and only mild aesthetic concerns of discolouration of the incisors. In severe cases there are demarcated enamel opacities with breakdown, caries, persistent/spontaneous hypersensitivity affecting function e.g. during brushing and strong aesthetic concerns that may have socio-psychological impact.

Prior to the examinations, a calibration exercise was conducted for the examiner in the clinic, using clinical photographs of 30 patients (15 cases of MIH and 15 cases with other enamel defects). The validity of using clinical photographs to study enamel defects has been established previously [Sabieha and Rock, 1998]. All cases of MIH and the teeth being affected were correctly diagnosed by the examiner, who was very familiar with the diagnosis and management of children with MIH. The same procedure was repeated one month later and the reproducibility index calculated using Cohen's Kappa coefficient which was 100%.

Statistical analysis: Data were collected, recorded, tabulated and evaluated using the Statistical Package for Social Sciences (SPSS) 17.0 for Windows. Percentage arithmetic mean value, standard deviation, independent sample t-test, Chi-square test and Pearson correlations were used while a p-value of <0.05 was considered statistically significant.

Results

In total, 1366 of 8-12 year old children were available for examination following the selection criteria described above; 230 children were examined in our Department and the remaining 1,136 in their schools.

Distribution of the subjects by age and gender: The age range of the children examined having all index teeth present (4 FPM and 8 incisors) was 8-12 yrs. The mean age of the total sample was 10.4 years (SD [+ or -] 1.2). Of the study sample 612 (44.80%) were females and 754 (55.20%) males.

Prevalence of MIH: Out of the total number of children examined (n = 1,366), 126 were diagnosed with MIH, revealing a prevalence of 9.22% in the rural areas of Gandhinagar. There was no statistically significant difference (p<0.001) regarding the gender, as males (68) and females (58) were almost equally affected. Regarding the age distribution, 10-year-old age children had a statistically significantly (p=0.042) higher MIH prevalence (12.1%), as compared with the rest of the age groups where the prevalence was similar ranging from 8-9% (Figure 1). Finally the overall prevalence of MIH in the 1,136 school children (9.24%) and in the 230 examined in the Department (9.13%) did not show any significant differences.

[FIGURE 3 OMITTED]

Tooth types affected by MIH: The 126 children having MIH revealed 546 affected teeth, 370 molars and 176 incisors. In the molar group the most commonly affected tooth was the mandibular right first permanent molar (85.7% of the cases), followed in descending order by the mandibular left (84.1%), the maxillary right (66.7%) and left first permanent molars (57.1%), revealing that mandibular molars were statistically significantly (p<0.001) more frequently affected than maxillary molars (Figure 2). In the incisor group the most commonly affected tooth was the maxillary right permanent central incisor (66.7%) followed by the left permanent central incisor (42.9%). The remaining permanent incisors revealed much lower frequencies ranging from 3.2% to 9.5% (Figure 2). Overall affected teeth were statistically significantly (p=0.008) more frequently found in the maxilla (56.7%) as compared to the mandible (43.2%), while the right side revealed more affected teeth than the left (p=0.013). All four first permanent molars were affected in 23% of 126 MIH cases, with the remaining 77% having 1-3 molars affected. Twenty-two (17.46%) of the children had only molars affected (MH) while 104 (82.53%) of them revealed both incisors and molars affected (MIH). Finally it appeared that the total number of affected teeth were statistically significant (p=0.027) increasing with age. The 22 children with MIH at the age of 8 years had 18.1% affected teeth and this frequency increased with age until 12 years of age where the 24 MIH children had 53.8% of their teeth affected (Figure 3).

Severity level of affected teeth: All 176 affected incisors revealed mild defects, as compared to only 67.1% (248) of the molars being mildly affected, with the remaining 32.9% (122) revealing severe defects (Figure 3). Overall, mild defects were found in 424/546 (77.7%) of affected teeth and severe defects in 122/546 (22.3%). Regarding severely affected molars statistically significant (p=0.049) differences were observed. The most frequently involved tooth was the mandibular right first permanent molar (45.9% of the severely affected teeth), followed in descending order by the maxillary right (22.9%), the mandibular left (21.3%) and the maxillary left first permanent molars (9.8%) (Figure 4). More severely affected molars were recorded in the mandibular, but this difference was not statistically significant (p=0.497).

The clinical severity of affected teeth was statistically significant (p=0.031) increasing as the age increased (Figure 4). Children aged 8 years revealed 5.3% severely affected molars and this frequency increased at the age of 9 and 10 years to 5.8% at the age of 11 years to 11.1% and finally at the age of 12 years to 12.8%. In addition severity levels appear to be statistically significant (p=0.026) influenced by the total number of affected teeth. As shown in Figure 4 the total number of affected teeth and the percentage of severely affected teeth increased with increasing age of the children.

Discussion

The aim of the present study was to determine the prevalence and severity of MIH in an Indian child population residing in the rural area of Gandhinagar, Gujarat. The findings of this study indicate that MIH is common among children in this area, revealing approximately one in ten children being affected by the defect.

India, with a population of 1.21 billion people is the second most populous country in the world. More than 50% of India's current population is below the age of 25 years and over 35% below the age of 15 years [Census of India, 2011]. The majority of international studies of MIH have been conducted on children of European descent and unfortunately there are no reports on MIH from India. Therefore prevalence studies on MIH are of great importance for the public health authorities of India since MIH appears to be a demanding developmental disturbance of permanent teeth in the country. Gandhinagar is the capital of the state of Gujarat in Western India and has a population of approximately 208,000 [Census of India, 2011]. Therefore the number of children examined is representative of the child population of the area, considering additionally that 65% of the population resides in the rural areas where the examined schools were located. In addition, regarding the selection criteria and the different age cohorts examined in the present study the study design followed to a certain degree the recent recommendations of the EAPD regarding MIH prevalence studies [Jalevik, 2010; Lygidakis

et al., 2010].

Diagnostic criteria: Following the study and the criteria used for the description of idiopathic enamel defects in Sweden by Koch et al. [1987], various criteria have been used for the diagnosis by different authors before the establishment of the EAPD criteria in 2003; these include the modified DDE index proposed by FDI [1992] and used by Jalevik et al. [2001] and Weerheijm et al. [2001b] and the one proposed by Alalausua et al. [1996] and used by Leppaniemi et al. [2001].

According to the reports following the 6th Interim seminar and workshop of the European Academy of Paediatric Dentistry on MIH [Jalevik, 2010; Lygidakis et al., 2010] the large variation in prevalence and severity data appearing in the various studies worldwide was partly attributed to the different criteria used in the past for diagnosis of MIH. Therefore in our study, the criteria used for the assessment of MIH were the ones recommended by the EAPD and used in the majority of the published studies since 2003. Finally in order to have the best possible consistency and reproducibility for the dental examinations in this study, a single investigator was involved whose reproducibility was determined twice prior to commencement of the study.

Prevalence of MIH: When we compared our prevalence result (9.2%) with other studies using the same diagnostic criteria, similar rates with the studies from Greece (10.2%), Lithuania (9.7%), Bosnia and Herzegovina (12.3%) and Turkey (9.2%) were obtained [Lygidakis et al., 2008a; Jasulaityte et al., 2007; Muratbegovic et al., 2007; Kuscu et al., 2009]. However the same criteria used in other countries revealed a greater variation of MIH prevalence, ranging from 2.8% in Hong-Kong to 40.2% in Brazil [Jalevik, 2010]. In addition three more recent studies in other Asian regions revealed prevalence rates of 2.8% in Hong-Kong, 17.6% in Jordan and 18.6% in Iraq [Cho et al., 2008; Zawaideh et al., 2011; Ghanim et al., 2011].

Many studies in the past excluded restored or carious teeth from their assessment, whereas others incorrectly classified post-eruption breakdown as hypoplasia. In addition severely affected molars sometimes require extensive restorations or extraction that could have superimposed the developmental defects, particularly in studies including children over 10 years old. All these previous problems may have led to an underestimation of MIH, while limited children cohorts as in some recent studies following the EAPD criteria may also have led to underestimation of the MIH prevalence. The inclusion of children up to the age of 12 years in the present study and the large number of examined children increased the confidence that this study gives a 'true' reflection of the MIH prevalence in our area.

Clinical characteristics of MIH: Evaluating the results concerning the type of teeth affected, it appears that only 17.4% of the affected children had MH, while 82.6% revealed the full MIH spectrum. This percentage is much lower than in all previous reports, where MIH children having only molars affected varied from 22.6-35% [Jasulaityte et al., 2007; Chawla et al., 2008; Lygidakis et al., 2008a; Zawaideh et al., 2011].

Although in the present study more maxillary teeth in total were affected compared to the mandibular, when molars were evaluated, mandibular teeth were much more affected than maxillary teeth. This finding is in agreement with previous reports [Jalevik et al., 2001; Jasulaityte et al., 2007; Zawaideh et al., 2011], but differs from studies reporting negligible differences between the upper and lower teeth [Weerheijm et al., 2001b; Cho et al., 2008; Chawla et al., 2008] and others reported more maxillary as compared to mandibular affected molars [Leppaniemi et al., 2001; Preusser et al., 2007; Muratbegovic et al., 2007; Lygidakis et al., 2008a]. With regard to incisors, similar discrepancies were found; in agreement with all previous reports maxillary incisors in total were much more frequently affected than mandibular, but when considered separately, maxillary central and lateral incisors were more frequently affected. This is in agreement with some studies [Preusser et al., 2007; Lygidakis et al., 2008a], but contradicting others [Jasulaityte et al., 2007; Zawaideh et al., 2011].

Although several explanations in the past have been given for these contradictory results it is still difficult to explain these discrepancies, as in all recent studies similar examination and evaluation criteria were used and evaluation was conducted by experienced examiners. Further studies on larger populations are required to determine if there are real differences between maxillary and mandibular teeth and what the reason is.

Severity of the defects: The great majority (77.3%) of the affected teeth in the present study revealed mild defects, using the classification adopted by the EAPD in 2010 that defines only mild and severe defects, a proposal that seems to enhance the reproducibility of the results [Jasulaityte et al., 2007; Jalevik, 2010; Lygidakis et al., 2010]. This finding is in agreement with previous reports [Jalevik et al., 2001; Lygidakis et al., 2008a]. The association of the increasing severity as the total number of affected teeth per child increases has also been reported before [Jalevik et al., 2001; Leppaniemi et al., 2001; Jasulaityte et al., 2007; Lygidakis et al., 2008a; Zawaideh et al., 2011] and may be the result of the variation in timing, duration and severity of single or multiple aetiological 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 periods may result in a greater number and more severely affected teeth [Jalevik and Noren, 2000; Lygidakis et al., 2008b]. Finally the present study revealed that the degree of severity of affected molars increased with age. Again this finding has been reported before [Leppaniemi et al., 2001; Jasulaityte et al., 2007; Lygidakis et al., 2008a] 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.

Recent research supports the assumption that MIH is a widespread problem in Western Europe. In our study one out of ten children were suffering from MIH and it appears that this condition is becoming a concerning developmental dental disturbance also in our region. Following the results of the present study, there is definitely a need to determine the occurrence of MIH through out India. Until the exact causes are known and prevention of the defect could be an option [Alaluusua, 2010], children with MIH frequently require extensive treatment soon after tooth eruption. Considering the population of India, the costs involved and the demanding nature of the dental treatment clearly indicate the urgent need for further investigations into this problem.

A carefully managed recall program for children who are affected is essential and this would certainly help the development of better preventive and therapeutic measures for dealing with this developmental disturbance of permanent teeth. MIH is also an extremely important topic for public health authorities because of the importance of early diagnosis and the necessary dissemination of information.

Conclusions

MIH prevalence is 9.2% in the child population residing in Gandhinagar, Gujarat, India and males and females are equally affected with 17.4% of the cases revealed only molars affected and 72.6% had both molars and incisors affected. All four first permanent molars were affected in 23% of the cases while no cases of only affected incisors were found and 77.3% of the affected teeth revealed mild defects and 22.7% severe defects. All incisors were mildly affected, as compared to only 67.1% of the molars, the remaining 32.9% being severely affected. The severity and total number of affected teeth increased with age.

Recommendations

More prevalence studies following a prospective study design in different age cohorts and using the standardised EAPD diagnostic criteria should be conducted in other regions of India in order to further establish the prevalence and clinical characteristics of MIH in the country.

Acknowledgments:

The authors wish to thank the Statistician Mr. Ghanshaym C. Patel for his contributions in the statistical analysis of this study.

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D.R. Parikh, M. Ganesh, V. Bhaskar

Dept of Paedodontics and Preventive Dentistry, Ahmedabad Dental College, Gujarat, India.

Postal address: Dr. D.R. Parikh, Dept of Pedodontics & Preventive Dentistry, Ahmedabad Dental College, Ranchodpura, Santej, Ta:Kalol, Gandhinagar, Gujarat, India.

Email: drdhaval.pedodontist@gmail.com
Table 1: Diagnostic Criteria for MIH (Weerheijm 2003)

Each tooth should be examined for:

1   Absence or presence of demarcated
    opacities (defect altering the
    translucency of the enamel)

2   Posteruptive enamel breakdown (loss of
    surface enamel after tooth eruption,
    usually associated with a pre-existing
    opacity)

3   Atypical restorations (frequently
    extended to the buccal or palatal smooth
    surfaces reflecting the distribution of
    hypoplastic enamel)

4   Extracted molars due to MIH.

5   Failure of eruption of a molar or
    incisor.

Permanent first molars and incisors (12 index teeth) should be
examined and therefore the age of 8 years upwards is the best
time for examination.

Examination for MIH should be performed on wet teeth after
cleaning and clearly visible opacities regardless of size
should be recorded.

Figure 1. Number and percentage of Gujarati
children having MIH by age group.

                          Age (Years)

                   8     9    10    11    12

Percentage (%)   8,8   8,3   12,1  8,2   9,2
Number (n)        22    26    30    24    24

Figure 2. Number and percentage of affected teeth
in Gujarati children with MIH.

                  11    12    16    21    22    26    31    32

Percentage (%)    67    10    67    43     3    57     6     3
Number (n)        84    12    84    54     4    72     8     4

                  32    36    41    42    46

Percentage (%)     3    84     5     3    86
Number (n)         4   106     6     4   108

Figure 4. Percentage of affected and severely affected teeth in
Gujarati with MIH by age.

                               8      9     10     11     12

% of Teeth with Severe MIH    5,3    5,8    5,8   11,1   12,8
% of Teeth with MIH          18,1   29,1   26,6   54,1   53,8
& of Children with MIH        8,8    8,3   12,1    8,2    9,2
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