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Year : 2019  |  Volume : 10  |  Issue : 3  |  Page : 65-69

Distribution of Molar Incisor Hypomineralization in Ecuadorian Children

1 Department of Pediatric Dentistry, University of Guayaquil, Guayaquil, Ecuador
2 Department of Periodontology, University of Guayaquil, Guayaquil, Ecuador
3 Department of Orthodontics, University of Guayaquil, Guayaquil, Ecuador

Date of Web Publication28-Nov-2019

Correspondence Address:
Ingrid Ordonez-Romero
Specialist in Pediatric Dentistry, Department of Pediatric Dentistry, School of Dentistry, University of Guayaquil
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/denthyp.denthyp_26_19

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Introduction: In Latin America, the molar–incisor hypomineralization (MIH) prevalence is between 7% and 40%, making this pathology an oral health problem in this region. MIH affects the development of tooth enamel exclusively of first molars and permanent incisors. The objective of this investigation was to establish the distribution of MIH in Ecuadorian children between 7 and 12 years of age who attend two schools in the city of Guayaquil, Ecuador. Materials and Methods: Two hundred forty-nine children from 7 to 12 years of age were clinically evaluated and diagnosed using the criteria of the European Academy of Pediatric Dentistry 2003. Data were analyzed statistically by descriptive analysis and Chi-square test. Results: There were 23 children affected with MIH (9.24%), with greater representation in girls (6.8%), statistically significant difference between genders. There is a greater frequency of MIH in permanent first molars (74.4%) than permanent incisors (P = 0.002). In relation to dental arches, small differences were observed between them. In the group of affected molars, atypical restorations were observed only in the lower arch. About the characteristics of the MIH, the demarcated opacities were the most frequent (P = 0.001). The white–yellow color of the demarcated opacities was the most frequent (52.3%). Conclusions: The MIH has a considerable presence in the Ecuadorian children evaluated and, therefore, it could have repercussions on the oral health of this population. The need for further studies in the country is evident.

Keywords: Distribution, molar–incisor hypomineralization, prevalence

How to cite this article:
Ordonez-Romero I, Jijon-Granja Y, Ubilla-Mazzini W, Porro-Porro L, Alvarez-Giler G. Distribution of Molar Incisor Hypomineralization in Ecuadorian Children. Dent Hypotheses 2019;10:65-9

How to cite this URL:
Ordonez-Romero I, Jijon-Granja Y, Ubilla-Mazzini W, Porro-Porro L, Alvarez-Giler G. Distribution of Molar Incisor Hypomineralization in Ecuadorian Children. Dent Hypotheses [serial online] 2019 [cited 2023 Jun 2];10:65-9. Available from:

  Introduction Top

Molar–incisor hypomineralization (MIH) is described as a defect in the development of tooth enamel that affects the first molars and permanent incisors. In 2001, Weerheijm et al.[1] warned for the first time about the presence of this pathology in children, exposing their research to the assembly of the European Academy of Pediatric Dentistry (EAPD), who in 2003 recognized it and established the diagnostic criteria for the development of epidemiological studies.

Currently, there are many investigations that analyze the clinical characteristics, the possible etiological factors, and the effectiveness of various treatments, contributing to the understanding of this condition.[2],[3]

Prevalence rates are high, which shows the presence of MIH in all countries that conducted epidemiological studies, so it could become a public health problem.[4],[5],[6] In Latin America, a survey was applied to pediatric dentistry in the region, which gathered information on the presence of pathology in the nations and concluded that oral health professionals recognize MIH as a problem in the area of ​​residence. The prevalence rates in this area are Brazil (18%),[6] Argentina (16%),[7] Uruguay (7%),[7] and Mexico (16%).[8]

In general, MIH affects the first permanent molars more than the permanent incisors, both in the number of affected parts and in the severity of the enamel alteration.[1] Being the first permanent teeth, key parts of the occlusion dental, its early alteration leads to complications for chewing, phonation, and aesthetic of human beings.[4]

The posteruptive rupture of tooth enamel (posteruptive enamel breakdown, PEB) is one of the characteristics of MIH, leading a risk of hypersensitivity during tooth brushing, presence of caries, complete destruction of the crown, and esthetic problems.[9] From a PEB, a restoration is made that is atypical for its cavity design that tries to respect the apparently healthy remnant tissue.[10],[11]

In 2015, the Faculty of Dentistry of the University of Guayaquil conducted a pilot study on MIH in children attending the pediatric dentistry clinic, observing a 16.3% prevalence, influencing the development of this research, which had the objective to establish the distribution of MIH in Ecuadorian children between 7 and 12 years of age who attend two study schools in the city of Guayaquil.

  Materials and Methods Top

This observational, descriptive, and cross-sectional study was conducted in two schools in the city of Guayaquil, Ecuador, which are part of the local area of care services of the University of Guayaquil with a population of 420 students, obtaining a sample of 249 children with 95% confidence interval were estimated, which also fulfilled the inclusion and exclusion criteria. The parents or legal representatives of the children were informed about the objectives and procedure of the investigation. The signed consents were collected as acceptance of the participation of the children in the study.

Inclusion criteria were children between 7 and 12 years of age, with at least one first permanent molar erupted (teeth with more than half of the crown erupted). The exclusion criteria were children with amelogenesis imperfecta, dental fluorosis, opacities in permanent incisors without affectation of the permanent first molar, and defects in the permanent incisors associated with the history of trauma or infection in the primary dentition. The study was carried out in accordance with the principles of the Declaration of Helsinki and was approved by the Committee of Scientist and Ethics of the Faculty of Dentistry of the University of Guayaquil.

Before the clinical examination, the calibration was carried out with a trained examiner, based on a group of clinical photographs of MIH and other developmental defects of the enamel (DDE), obtaining a kappa intraexaminer agreement of 0.80 and an interexaminer of 0.72. The children were examined in the school facilities, in the best-lit classroom, with a mouth mirror, a blunt tip probe, and a headlamp. The cases of MIH were recorded with a digital camera (Nikon D7000 with lens Tokina macro 100mm F2.8D AT-X PRO).

The teeth were examined after tooth brushing. The dental surfaces were observed looking for MIH tests using the criteria of the EAPD 2003, which refer to at least one permanent first molar that must be affected with or without accompanying permanent incisors; also, they present demarcated opacities (DOs), posteruptive enamel loss (PEB), atypical restoration (AR), molar extracted due to MIH (E-MIH), and teeth without exit (UT). The DOs with less than 1-mm extension were excluded.

The judgment criteria MIH (EAPD 2003) were as follows:
  1. DO: A demarcated defect involving an alteration in the translucency of the enamel, variable in degree. The defective enamel is of normal thickness with a smooth surface and can be white, yellow, or brown in color.[1]
  2. PEB: A defect that indicates deficiency of the surface after eruption of the tooth. Loss of initially formed surface enamel after tooth eruption. The loss is often associated with a preexisting DO.[1]
  3. AR: The size and shape of restorations are not conforming to the temporary caries picture. In most cases, in molars, there will be restorations extended to the buccal or palatal smooth surface. At the border of the restorations frequently an opacity can be noticed. In incisors, a buccal restoration can be noticed not related to trauma.[1]
  4. Extracted molar due to MIH: Absence of a first permanent molar should be related to the other teeth of the dentition. Suspected for extraction due to MIH are opacities or ARs in the other first permanent molars combined with absence of a first permanent molar. Also, the absence of first permanent molars in a sound dentition in combination with DOs on the incisors is suspected for MIH. It is not likely that incisors will be extracted due to MIH.[1]
  5. Unerupted: The first permanent molar or the incisor to be examined are not yet erupted.[1]

Notes: In cases of a large caries lesion with DOs at the border of the cavity or on the noncaries surfaces, these teeth should be judged as MIH. Other changes in dental enamel such as amelogenesis imperfecta, hypoplasia, diffuse opacities, white spot lesions, tetracycline staining, erosion, fluorosis, and white cuspal and marginal ridges should be excluded from the types of enamel defects outlined as above.[1]

A clinical file was designed to record the total number of children affected by gender and age, the distribution of MIH by the type of affected tooth (first molars or permanent incisors), the characteristic clinical signs (OD, PEB, and AR) according to the affected maxilla, and the classification of the detected opacities depending on whether they are white creamy, yellow, and yellow brown.

The data for each patient were entered according to the preprinted clinical records that contained the MIH characteristics organized by sex, age, tooth type, clinical sign, and opacity color. The prevalence and distribution of MIH were expressed by descriptive statistics. The statistical significance of the differences between the proportions was evaluated by the Chi-square test. The P value of less 0.05 was considered statistically significant. The Chi-squared tests determined the differences between the variables: children with MIH according to gender, teeth with MIH according to their type (molars and incisors), clinical signs according to the affected maxilla, and DOs according to the color change. All information was analyzed using the statistical package version 24.0 (SPSS Inc., Chicago, IL, USA).

  Results Top

This study included 249 children, with the participation of 57.8% of girls and 42.2% of boys. Of the total of individuals, 155 and 94 belonged to the "Rita Lecumberri" and the "Edizon Mendoza" School, respectively. The average age of the children examined was 9.14 (standard deviation ± 1.68) [Table 1].
Table 1 Distribution of the participants by gender and age groups

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The majority of the children had sufficiently erupted the 12 teeth that had to be examined (incisors and permanent first molars); the teeth that presented half of the crown were reported as not erupted. The MIH prevalence was 9.24%, with the highest representation in girls (6.8%) than boys (2.4%). The data analysis demonstrated that there is a statistically significant difference between both the genders (χ2 = 5.261, P = 0.021) [Table 2].
Table 2 Prevalence of MIH defect by gender

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According to the results obtained, MIH affected 23 children and 78 teeth, of which 58 were molars (74.4%) and 20 were incisors (25.6%). The greatest affectation in molars shows a statistically significant difference (χ2 = 18.513, P = 0.002) [Table 3].
Table 3 Prevalence MIH according to affected teeth

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The frequency of MIH according to the maxillary or mandibular dental arch demonstrates that in the molars of the lower arch, ARs are recorded unlike the molars of the upper arch that do not register this type of affectation characteristic of MIH. The DOs and posteruptive ruptures showed similar frequencies between arches. As for the incisors, the upper and lower centrals were similarly affected. The results obtained indicate that opacities were more common than posteruptive ruptures and ARs (χ2 = 75.297, P = 0.001) [Figure 1].
Figure 1 Prevalence of molar–incisor hypomineralization (MIH) in maxillary and mandibular permanent index teeth.

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In the total surfaces with DOs, the white–yellow color was the most frequent (52.3%), followed by the white with 32.3% and the yellow–brown with 15.5% (χ2 = 31.496, P = 0.001). The changes of white–yellow color appeared more in molars than incisors (χ2 = 75.69, P = 0.001). On the other hand, the most prevalent color change was white in the incisors, showing a statistically significant difference compared to molars with white opacities (χ2 = 9.68, P = 0.001) [Table 4].
Table 4 Prevalence of color in changes

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  Discussion Top

This study was carried out in two schools in a suburban area of ​​low socioeconomic status. The prevalence observed in this population was similar to that reported in other countries of the region such as Uruguay and Argentina.[7] However, the prevalence is lower than that reported in Mexico[8] and Brazil,[6] and this could be due to the diversity of age ranges or the population studied.

The predilection for the gender was evident, with the female being the most representative (73.9% vs. 26.1%); this differs from that observed by other studies that revealed statistically insignificant differences between the two.[12],[13]

Like other studies, the first permanent molars were affected more frequently than the permanent incisors. Both the molars and the incisors were affected mostly in the girls,[6] unlike the study by Glodkowska and Emerich in 2019, which were the children most affected than the girls.[2]

Assessing the dental arches, no significant differences were observed between the two. MIH clinical defects affected 49.5% of upper jaw teeth and 50.5% lower jaw teeth. The lower molars were slightly more affected than the upper molars. In the central and lateral incisors, there were no differences between the upper and lower incisors, in agreement with other studies.[2]In the global distribution of clinical signs, we found that the DOs were the most frequent type in molars and incisors than the other defects, presenting similar percentages in both the jaws, in agreement with Buchgraber et al. (2018).[5] On the other hand, ARs were observed only in the lower molars, in 17.4% of the total number of children with MIH. The posteruptive rupture was more prevalent in the molars, only 7.1% of the incisors were affected.

The different color distribution of the opacities was evidenced, and in the molars, the yellowish-white opacities prevailed. On the contrary, in the incisors, the most relevant opacities were those of white color. In total, yellowish-white opacities represented the highest percentage followed by white and finally yellow–brown opacities; however, this difference is not statistically significant, in agreement with the other studies.[3]

The present study revealed that MIH is an existing problem in the city of Guayaquil, Ecuador. However, the findings are not representative of the country as a whole. To better understand the national condition, future investigations of a broader scope that may involve different regions of the country should be carried out. This study can provide reference information due to the scarcity of data on this subject in Ecuador.

  Conclusion Top

Children from 7 to 12 years of age living in Guayaquil, Ecuador, who were evaluated in this study, presented a considerable prevalence of MIH (9.24%), with a predilection for girls. Similar affectation in the teeth was observed in maxilla and mandible. The most common defect was DO with a greater percentage of white-yellowish color changes. The ARs are presented only in lower molars.

The population affected with MIH must be intervened in a timely manner, avoiding the possible repercussions on their oral health. In addition, more studies are needed in the country, as part of the follow-up to determine the pattern of the growth figures of this pathology.

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There are no conflicts of interest.

  Uncited references Top


  References Top

Weerheijm K, Duggal M, Mejáre I, Papagiannoulis L, Koch G, Martens L et al. Judgement criteria for molar incisor hypomineralisation (MIH) in epidemiologic studies: a summary of the European meeting on MIH held in Athens, 2003. Eur J Paeditr Dent 2003;3:110-3.  Back to cited text no. 1
Glodkowska N, Emerich K. Molar incisor hypomineralization: prevalence and severity among children from Northern Poland. Eur J Paediatr Dent 2019;20:59-66.  Back to cited text no. 2
Elhennawy K, Schwendicke F. Managing molar-incisor hypomineralization: a systematic review. J Dent 2016;55:16-24.  Back to cited text no. 3
Koruyucu M, Özel S, Tuna EB. Prevalence and etiology of molar-incisor hypomineralization (MIH) in the city of Istanbul. J Dent Sci 2018;13:318-28.  Back to cited text no. 4
Buchgraber B, KqiKu L, Ebeleseder KA. Molar incisor hypomineralization: proportion and severity in primary public school children in Graz, Austria. Clin Oral Investig 2018; 22:757–62.  Back to cited text no. 5
De Lima Mde D, Andrade MJ, Dantas-Neta NB, Andrade NS, Teixeira RJ, de Moura MS et al. Epidemiologic study of molar-incisor hypomineralization in schoolchildren in North-eastern Brazil. Pediatr Dent 2015;37:513-9.  Back to cited text no. 6
Biondi AM, Lopez Jordi Mdel C, Cortese SG, Alvarez L, Salveraglio I, Ortolani AM. 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). Acta Odontol Latinoam 2012;25:224-30.  Back to cited text no. 7
Gurrusquieta BJ, Nuñez VM, Lopez ML. Prevalence of molar incisor hypomineralization in Mexican children. J Clin Pediatr Dent 2017;41:18-21.  Back to cited text no. 8
Lygidakis N, Wong F, Jälevik B, Vierrou A, Alaluusua S, Espelid I. Best clinical practice guidance for clinicians dealing with children presenting with molar-incisor-hypomineralisation (MIH): an EAPD policy document. Eur Arch Paediatr Dent 2010;11:75-81.  Back to cited text no. 9
Tourino LF, Corrêa-Faria P, Ferreira RC, Bendo CB, Zarzar PM, Vale MP. Association between molar incisor hypomineralization in schoolchildren and both prenatal and postnatal factors: a population-based study. PLoS One 2016;11:e0156332.  Back to cited text no. 10
Temilola OD, Folayan MO, Oyedele T. The prevalence and pattern of deciduous molar hypomineralization and molar-incisor hypomineralization in children from a suburban population in Nigeria. BMC Oral Health 2015;15:73.  Back to cited text no. 11
Hussein AS, Faisal M, Haron M, Ghanim AM, Abu-Hassan MI. Distribution of molar incisor hypomineralization in Malaysian children attending University Dental Clinic. J Clin Pediatr Dent 2015;39:219-23.  Back to cited text no. 12
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.  Back to cited text no. 13
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