Journal of Indian Association of Public Health Dentistry

: 2017  |  Volume : 15  |  Issue : 2  |  Page : 135--139

Caries status and salivary characteristics of South Indian school children with molar incisor hypomineralization: A cross-sectional study

Allwyn Samuel, Sharath Asokan, PR Geethapriya 
 Department of Pedodontics and Preventive Dentistry, KSR Institute of Dental Science and Research, Tiruchengode, Tamil Nadu, India

Correspondence Address:
Sharath Asokan
Department of Pedodontics and Preventive Dentistry, KSR Institute of Dental Science and Research, Tiruchengode - 637 215, Tamil Nadu


Introduction: Molar incisor hypomineralization (MIH) is a common developmental condition resulting in enamel defects in first permanent molars and permanent incisors. Aims: This study aims to determine the prevalence of MIH in school children aged 8–12 years in Tiruchengode, Tamil Nadu, South India. The caries status and the salivary characteristics of children with and without MIH were compared. Materials and Methods: In this cross-sectional study, a total of 4495 children were screened. Children with hypomineralized permanent molars and incisors were diagnosed using the European Academy of Pediatric Dentistry criteria. The caries severity was assessed using the International Caries Detection Assessment System II scoring criteria. The saliva and plaque samples of 50 children with MIH and 50 children with molar hypomineralization (MH) children were collected in a sterile container. Similarly, saliva and plaque sample of the 100 children with no caries and no MIH (control group) were collected and compared with the MIH/MH children. Salivary pH, buffering capacity, and plaque pH were estimated. The data were subjected to statistical analysis using the SPSS software version 17.0. Pearson and Student's t-test were used to compare the data. P =0.05 or less was considered to be of statistical significance. Results: The prevalence of MIH/MH was 5.25% (n = 236) in Tiruchengode district. Among the children, 3.33% (n = 150) boys and 1.91% (n = 86) girls had MIH/MH. The prevalence of dental caries in children with MIH/MH was 52.1% (n = 123 children). Conclusion: MIH is an important clinical problem that often concerns both the general dentists and pediatric dentists. Creating awareness about this condition, early diagnosis, and prompt treatment among the dentists, and population is obligatory, especially in countries like India.

How to cite this article:
Samuel A, Asokan S, Geethapriya P R. Caries status and salivary characteristics of South Indian school children with molar incisor hypomineralization: A cross-sectional study.J Indian Assoc Public Health Dent 2017;15:135-139

How to cite this URL:
Samuel A, Asokan S, Geethapriya P R. Caries status and salivary characteristics of South Indian school children with molar incisor hypomineralization: A cross-sectional study. J Indian Assoc Public Health Dent [serial online] 2017 [cited 2022 Dec 2 ];15:135-139
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Tooth enamel is unique among the mineralized tissues due to its high mineral content. Enamel is made up of highly organized, tightly packed crystallites that comprise 87% of its volume and 95 of its weight. Developmental enamel defects are still an enigma in scientific aspects as well as in clinical practice. In 1992, a working group of the World Dental Federation (Fédération dentaire internationale [FDI]) presented an epidemiological index of Developmental Defects of the Dental Enamel which allows recording of a broad range of defects, categorized as demarcated opacities, diffuse opacities, or hypoplasia.[1] According to the FDI Commission on Oral Health, Research and Epidemiology (1992), these defects are precisely been classified into two distinct categories: hypomineralized enamel or enamel opacities and enamel hypoplasia.[1] While opacity is defined as a qualitative defect of the enamel, hypoplasia is defined as a quantitative defect of the enamel (Suckling, 1989).[2]

A developmental defect which is of great clinical importance is molar incisor hypomineralization (MIH). It was first acknowledged in Sweden in late 1970s; however, this term was introduced by Weerheijm et al. in 2001.[3] MIH describes the clinical picture of hypomineralization of systemic origin of one or more permanent molars as well as any associated incisors. The term MIH was defined as the clinical appearance of morphological enamel defects involving the occlusal and/or incisal third of one or more permanent molars or incisors as result as hypomineralization of systemic origin.[4] The first permanent molar enamel is commonly affected to an extent ranging from mild-to-severe, as well as in many cases; the incisor enamel is also affected. Furthermore, this specific form of developmental defects of enamel shows opacities often asymmetrically distributed with a marked variation in severity within an individual ranging from small demarcated white yellow or brown opacities.[5] Weerheijm suggested that more severe cases are characterized with postenamel breakdown (PEB) with soft porous enamel which looks like discolored chalk or old Dutch cheese.[4]

The MIH porous enamel can easily break down, especially under the influence of masticatory forces, leaving unprotected dentin, and favoring the development of carious lesions. Although MIH is an asymmetrical defect, when a severe injury exists in a tooth, it is common for the contralateral tooth to be also affected. Weerheijm et al. stated a term molar hypomineralization (MH) as a qualitative defect of enamel with a decreased amount of mineralized, inorganic substance resulting in alterations of translucency of enamel. The term MH includes only the first four permanent molars excluding the incisors.[3] Reports of the prevalence of MIH vary considerably throughout the world and ranges from 2.4% to 40.2%.[6] While these large variations may reflect real differences between regions and countries, differences in recording methods, indices used and populations investigated may also be contributory.

Saliva plays a vital role in oral health. It is effective in promoting remineralization over demineralization which is associated with calcium and phosphate content, viscosity, pH, flow rate, and acid buffering capacity. The properties of individual's saliva might also have an effect on the integrity of defective enamel.[7] Hence, this study attempted to study the prevalence of MIH in Tiruchengode, Tamil Nadu and also study the salivary and plaque characteristics of children with and without MIH.

 Materials and Methods

The present cross-sectional study was planned and conducted at various schools in Tiruchengode, Western Tamil Nadu, South India, from October 2016 to December 2016. The study design and protocol were analyzed and approved by the Institutional Review Board and Institutional Ethics Committee.

The study used convenience sampling method and 8052 children aged 8–12 years belonging to 7 private and 7 government schools of Tiruchengode were screened. Children with fully erupted index teeth (all first permanent molars and incisors) were included in the study. Children with special health-care needs; dental defects such as amelogenesis imperfecta, fluorosis; medical illness at the time of examination since medications alter the salivary flow; uncooperative children were excluded from the study.

Clinical examination was done in school premises by a single investigator. The children were seated on the chair and subjected to dental examination under natural sunlight. Hypomineralized permanent molars and incisors were diagnosed clinically based on the European Academy Pediatric Dentistry (EAPD) criteria recommended in 2003 and revised at an Interim Seminar and Workshop concerning MIH organized by the EAPD in 2009.[8],[9] The index teeth were kept wet for examination to distinguish opacities from incipient carious lesions. All clearly visible opacities were measured and recorded. The children with MIH and MH were recorded separately for the comparison.

A full-mouth caries assessment was performed for all MIH children using The International Caries Detection and Assessment System (ICDAS II) scoring criteria to assess the caries severity. A visual tactile caries assessment of four permanent molars and eight permanent incisors was performed. Cotton rolls were used to wet and dry the teeth surfaces. The Shepherd hook explorer was used to remove any remaining plaque or debris and detect surface contour, enamel or dentine cavitation, the presence or absence of sealants, or restorations. Data were recorded for all permanent molars and incisors.

Whole saliva was stimulated by asking the children to chew a piece of modeling wax which is made in the form of pellets for 3 min. To alleviate potential inconvenience in chewing modeling wax, a demonstration was done. Participants were assured that the procedure was not invasive to eliminate the dental treatment-related anxiety that may affect saliva production. The stimulated salivary specimens were collected from children in a sterile container for determination of pH and buffering capacity. The saliva from 100 normal children (without caries) and 50 children with MIH and 50 children with MH of same age and sex were collected by convenience sampling method and analyzed. Plaque samples were collected with sterile toothpicks from the same 200 children and stored in a sterile container. The collected plaque was diluted in 20 ml of distilled water, and the pH was measured using Hanna pH meter. The collected samples were then tested, within 1 h of time.[10]

Using a standard protocol, the pH meter was standardized with pH calibration solutions ranging from pH 4, 7, and 10. The head of the pH bulb was immersed in the calibration solution until the pH of the solution was determined correctly in all the three ranges. Once the values displayed digitally stops to fluctuate, the final readings were recorded.

For determination of salivary buffering capacity, the classical Ericson's test (1959) was used. They recommended to use 0.005 mol per L of HCl for stimulated saliva. The desired HCl was calculated using Solcalc software (solution calculator Inc.). To prepare 1000 ml of a 0.005 mol per L of HCl, 0.14 ml of 37.2% HCl was added with distilled water. For buffering capacity, 1.0 ml of the saliva is transferred to 3.0 ml of 0.005 mol per LHCl. One drop of Octanol was added to prevent the foaming reaction, and the sample was mixed for 20 min to remove carbon dioxide. Finally, the buffering capacity was evaluated electrometrically using Hanna pH meter.

The data were analyzed using the Statistical Package for Social Sciences software version 17.0 for Windows (SPSS Inc., Chicago, IL, USA). A descriptive analysis of the prevalence and distribution of the clinical recordings was performed. A comparison between groups was carried out using the Chi-square test and Pearson's correlations. For all tests, P ≤ 0.05 was considered to be statistically significant.


In the present study, only 55.8% (n = 4495) children aged 8–12 years were included in the study. Among the study population, 51.9% (n = 2333) were boys and 48% (n = 2162) were girls. Total enamel defects including MH and MIH was seen in 5.25% (n = 236) of children, of which 63.5% (n = 150) were boys and 36.4% (n = 86) were girls. The prevalence of MH was about 1.62% (n = 73), in which 1.06% (n = 48) were boys and 0.55% (n = 25) were girls. The prevalence of MIH was 3.62% (n = 163) children, in which 62.5% (n = 102) were boys and 37.4% (n = 61) were girls.

[Table 1] shows the comparison of prevalence of MH and MIH in boys and girls. There was a significant difference between the genders. Boys (n = 150; [6.4%]) had significantly more hypomineralization (MH/MIH) when compared to girls (n = 86; [3.9%]). [Table 2] shows the comparison of mean plaque pH, salivary pH, and salivary buffer capacity between the MH/MIH affected children and control group. The mean plaque pH of children with MH and MIH scored relatively higher than the control group. A significant difference (P = 0.001) was observed between the study group and control group. The mean salivary pH of children with MH and MIH scored significantly lower (P = 0.001) than the control group. No significant difference was seen between the MH/MIH and control group in salivary buffering capacity.{Table 1}{Table 2}

[Table 3] shows the comparison of dental caries status between MH and MIH children. Among 236 children with MH and MIH, 123 children had dental caries. There was no difference in the caries status between the genders. Among those teeth with dental caries (n = 140), 65.7% of teeth were limited to opacity, and 34.2% of teeth had PEB.{Table 3}


In epidemiological surveys on caries prevalence, children are normally not screened for the presence of MIH. Since MIH is widespread and the majority of clinicians perceive MIH to be a huge clinical problem, it is worthy of further investigation. This cross-sectional study attempted to provide information on the prevalence, distribution, caries severity, and salivary characteristics of MIH in South Indian children. The study sample included children from randomly chosen 14 schools around Tiruchengode district. Children aged 8–12 years were selected for this study and are considered the best time for examination for MIH because most children have all four permanent first molars and most of the incisor teeth erupted at this age.[9],[11]

MIH is recognized as a global dental problem, and epidemiologic reports from worldwide are continuously published.[12] The prevalence varies considerably from a few percent in China to almost 40% in Denmark and Brazil.[13],[14] The large variations in the prevalence rates of MIH may reflect real differences between regions and countries, differences in sample sizes, differences in recording methods, indices, and diagnostic criteria used and the age groups studied.

The prevalence of MIH and MH in the present study group was observed to be 5.25%. Parikh et al.[15] and Bhaskar and Hegde [7] stated a prevalence rate of 9.2% and 9.46% among 8–12 years old children in Gujarat and Udaipur, India, respectively. Among the 236 children with MIH and MH, 63.5% of them were boys and 36.5% of them were girls. Preusser et al.,[16] Soviero et al.,[14] da Costa-Silva et al.,[17] Ghanim et al.,[18] and Parikh et al.[15] also found slightly higher prevalence among boys in Germany, Brazil, Iraq, Gujarat, respectively. However, Chawla et al.[19] and Zawaideh et al.[20] have reported a higher prevalence among girls in Australian and Jordanian children, respectively.

The whole saliva collected from the mouth is a complex mixture. Saliva has a pH normal range of 6.2–7.6 with 6.7 being the average pH. In the oral cavity, the pH is maintained near neutrality (6.7–7.3) by saliva. The buffering capacity of saliva is a significant property affecting the dental caries process with the salivary bicarbonate system being the main mechanism for buffering. The bicarbonate concentration is very low in resting saliva that has limited acid-buffering capacity. Therefore, stimulated saliva was collected in the present study for measuring the buffering capacity. The children were given a modeling wax to stimulate saliva as done in the study by Hebbal et al.[21] A significant difference in salivary pH and plaque pH was found between the study group and control group. The reason behind the differences in salivary and plaque pH properties between the groups is not clear. One possible explanation given by Ghanim et al. (2013) is that children with hypomineralization may be those with higher predisposition to salivary changes because of medical conditions.[22] On the other hand, it is well recognized that salivary composition shows considerable inter-subject variation, particularly in young individuals whose saliva properties are known to be still immature. In this study, we also compared the salivary characteristics between the MH group and MIH. There was a significant difference in salivary pH, plaque pH, and buffer capacity. The reason behind the difference between these two groups is unknown. More studies should be carried out on these criteria to relate the difference between MH and MIH. The salivary-buffering capacity between the groups showed no significant difference. Only few of the children examined in our study had a low buffering capacity, possibly explaining the lack of correlation observed between hypomineralization severity and buffering capacity of saliva.

MIH is considered as a risk factor of dental caries in populations with a low prevalence of dental caries.[23] In populations with high caries activity, the hypomineralized lesions could be disguised by carious lesions.[3],[24] In the present study, among the children with MH and MIH, 123 children had dental caries which shows a higher prevalence rate of dental caries among study group. The presence of dental caries was about 57% in boys and 43% in girls with no statistical difference between both the genders. Jälevik et al.,[24] Preusser et al.,[16] Cho et al.,[13] da Costa-Silva et al.,[17] Jeremias, and Garcia-Margarit et al. 2014[23] also stated a higher prevalence of dental caries in MIH affected than in unaffected individuals.

In the present study, ICDAS II criteria were used to deliver a more accurate picture of the enamel defect–caries relationship. Only three tooth surfaces (buccal, occlusal, and lingual/palatal) were considered in the analysis to achieve a better assessment of this lesion-site-specific association. Among 236 children with MH and MIH, 123 children had dental caries which shows a higher prevalence rate of dental caries among MIH and MH group. MIH threatens to become a concerning developmental enamel defect. Considering the low awareness of this condition among the dentists and general population of India, the demanding nature and the costs involved, the urgent need for further investigations into this problem becomes clearly evident. A diligent follow-up and recall program for children who are affected is essential for developing preventive and therapeutic measures and formulating public awareness and prevention programs. A nationwide survey to find the prevalence of MIH is recommended.

This study compared the caries severity between MIH and MH subjects but did not compare the severity with the control group. More studies with larger sample size and age range can be considered to establish a cause and effect relationship between the risk factors and the occurrence of MIH.


In the present study, MIH and MH were found in 5.25% of children examined with 3.33% of boys and 1.91% of girls affected. Considering the low awareness of this condition among the general dentists and population of India, the demanding nature and the costs involved, the urgent need for further investigations into this problem becomes clearly evident. A diligent follow-up and recall program for children who are affected is essential for developing preventive and therapeutic measures and formulating public awareness and prevention programs.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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