Journal of Indian Society of Pedodontics and Preventive Dentistry
Journal of Indian Society of Pedodontics and Preventive Dentistry
                                                   Official journal of the Indian Society of Pedodontics and Preventive Dentistry                           
Year : 2014  |  Volume : 32  |  Issue : 4  |  Page : 322--329

Molar-incisor hypomineralization: Prevalence, severity and clinical characteristics in 8- to 13-year-old children of Udaipur, India


Shubha Arehalli Bhaskar, Sapna Hegde 
 Department of Paediatric Dentistry, Pacific Dental College and Hospital, Udaipur, Rajasthan, India

Correspondence Address:
Shubha Arehalli Bhaskar
Department of Paediatric Dentistry, Pacific Dental College and Hospital, Debari, Udaipur - 313 024, Rajasthan
India

Abstract

Background: The last couple of decades has seen an increasing interest in molar-incisor hypomineralization (MIH). Although the reported prevalence of MIH ranges from 2.4% to 40.2% worldwide, very little data is available from India. Objective: To assess the prevalence, clinical characteristics, distribution, severity and association with caries of MIH defects in children aged 8-13 years of Udaipur, Rajasthan. Study design: This cross-sectional descriptive study consisted of 1173 children aged 8-13 years selected by random sampling procedure. The European Academy of Pediatric Dentistry criteria were followed for MIH diagnosis. The presence of dental caries and treatment need for MIH-affected teeth were recorded as per the WHO criteria. Results: The prevalence of MIH in the children examined was 9.46%. Severity of the defects increased with the age of the children. Involvement of incisors increased when more First permanent molars (FPMs) were affected. An average of 3.65 teeth was involved per MIH-affected individual. Significantly larger numbers of mandibular FPMs and maxillary central incisors were diagnosed with MIH. The association of dental caries was significantly higher with MIH-affected FPMs. Primary molars and permanent canines and premolars were also showed MIH like lesions in some of the MIH-affected children. Conclusion: MIH was observed in about 10% of the children examined. MIH-affected FPMs appear to be more vulnerable to early caries and subsequent pulp involvement with need for extensive dental treatment.



How to cite this article:
Bhaskar SA, Hegde S. Molar-incisor hypomineralization: Prevalence, severity and clinical characteristics in 8- to 13-year-old children of Udaipur, India .J Indian Soc Pedod Prev Dent 2014;32:322-329


How to cite this URL:
Bhaskar SA, Hegde S. Molar-incisor hypomineralization: Prevalence, severity and clinical characteristics in 8- to 13-year-old children of Udaipur, India . J Indian Soc Pedod Prev Dent [serial online] 2014 [cited 2020 Aug 10 ];32:322-329
Available from: http://www.jisppd.com/text.asp?2014/32/4/322/140960


Full Text

 Introduction



The decline of dental caries worldwide has encouraged researchers and clinicians to observe and recognize other problems that were often overlooked in the past. [1],[2] The last couple of decades has seen the recognition and acknowledgement of non-fluoride-associated developmental dental defects as an increasing clinical problem. [2] These defects, characterized by discolored opacities or a total absence of enamel, are observed to most commonly affect the first permanent molars (FPMs) with or without involvement of the permanent incisors and have been varyingly referred to in the literature as hypomineralized FPMs, idiopathic enamel hypomineralization, dysmineralized FPMs, non-fluoride hypomineralization, cheese molars, internal enamel hypoplasia, non-endemic mottling of enamel, opaque spots and enamel opacities. [1],[2],[3],[4] During the last decade, the term "Molar-Incisor Hypomineralization (MIH)" has gained increasing popularity and is used to describe hypomineralization of systemic origin affecting one or more permanent first molars and frequently associated with hypomineralized permanent incisors. [1],[2],[3],[4] For a patient to be diagnosed as suffering from MIH, at least one permanent first molar must be affected with or without involvement of the incisors. [5] The term "Molar Hypomineralization (MH)" has been used, sometimes, to distinguish children in whom the incisors are not affected. [6]

MIH does not appear to be a new phenomenon; it was first noted in Sweden in the late 1970s. [7] However, it is likely that the condition has been frequently overlooked, especially in extensively carious teeth where the dental caries may take precedence over the developmental defect responsible for initiation of the cavity. [1],[8],[9]

Reports of the prevalence of MIH vary considerably throughout the world and rates range from 2.4% to 40.2% [9],[10] with the highest prevalence reported in children of Rio de Janeiro, Brazil. [11] 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. [2],[9],[10],[11],[12]

A majority of MIH prevalence studies have been conducted in Europe. [2],[9] Results of a questionnaire survey mapping the occurrence of MIH throughout Europe have suggested that MIH had been observed in all the responding European countries, apart from the Czech Republic. [12] However, there exists a paucity of data pertaining to MIH in Indian populations.

Hence, the present study attempted to determine the prevalence of MIH in a young, Indian population of Udaipur, Rajasthan, and to define the clinical features, severity and distribution of defects and their association with dental caries in affected individuals.

 Material and Methods



The present cross-sectional descriptive study was carried out after obtaining ethical clearance from the institutional Ethical Committee.

Study population

The study population comprised of 8- to 13-year-old schoolchildren belonging to Udaipur city, who visited the pediatric dental service of our dental hospital as part of a school health programme during a one-year period starting October 2011 and ending September 2012. Children having fully erupted index teeth for MIH (all permanent first molars and incisors), were included in the study. Children with other defects of enamel such as amelogenesis imperfecta, dentinogenesis imperfecta, hypoplasia, diffuse opacities, white spot lesions, tetracycline staining, erosion, fluorosis, white cuspal and marginal ridges, or any disability or systemic disease that would compromise routine oral care were excluded.

Sample selection

The study sample was selected by random sampling procedure. Informed consent was obtained from the parents of the children selected to participate in the study.

Training and calibration

Prior to the examinations, the investigator was trained to diagnose and differentiate MIH and other enamel defects by a calibration exercise employing clinical photographs of 30 patients (15 cases of MIH and 15 with other enamel defects). [13],[14] The same procedure was repeated 20 days later and the reproducibility index calculated using Cohen's Kappa coefficient. The intra-examiner agreement was found to be 0.96 (excellent).

Method of data collection

Clinical examination and diagnosis of MIH

The children were seated on the dental chair and subjected to dental examination. Hypomineralized molars and incisors were diagnosed clinically based on the European Academy Pediatric Dentistry (EAPD) criteria recommended in 2003 [5] and revised at an Interim Seminar and Workshop concerning MIH organized by the EAPD in 2009 [10] [Table 1] and [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5].{Table 1}{Figure 1}{Figure 2}{Figure 3}{Figure 4}{Figure 5}

Following thorough oral prophylaxis, the index teeth (four FPMs and eight permanent incisors) were kept wet for examination to distinguish opacities from incipient carious lesions. [5],[10] All clearly visible opacities measuring more than 1 mm were recorded. [9],[10] All examinations were carried out by one investigator.

Recording of hypomineralization in teeth other than index teeth

MIH-like defects on teeth other than index teeth (primary molars and permanent canines and premolars) in MIH-affected children [Figure 6] were also recorded. {Figure 6}

Assessment of dental caries in MIH-affected teeth

All permanent first molar teeth affected by MIH in the study population were assessed for the presence of dental caries as per the criteria established by the World Health Organization in 1997. [15]

Statistical analysis

The data was 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 correlations. For all tests a P-value of 0.05 or less was considered to be of statistical significance.

 Results



Prevalence of molar-incisor hypomineralization

Of the 1173 children examined, 111 were diagnosed as having teeth affected by MIH, giving a prevalence rate of 9.46%. MIH was more frequently observed in boys than in girls, but the difference was not statistically significant (P > 0.05, [Table 2]. Of the affected children, 79 (71%) had hypomineralized molars (MH) only, while 32 (29%) had both molars and incisors affected. The prevalence of MIH was found to be increasing as the age increases (P > 0.05, [Table 2] and [Table 3].{Table 2}{Table 3}

Nearly 50% children had all four FPMs involved (35 with MH and 20 with MIH). Of the affected individuals, only one had all the index teeth hypomineralized. The four FPM-two incisor combination (31%) of affected teeth was the most frequently observed association followed by the four FPM-one incisor combination (19%) [Table 4].{Table 4}

A significant correlation (P < 0.001) was observed between hypomineralization of molars and that of incisors with the involvement of incisors appearing to increase when more FPMs were affected [Table 5], [Graph 1].{Table 5}

Distribution of affected teeth in children with MIH

In the 111 MIH-affected children, 415 teeth (344 FPMs and 71 permanent incisors) were involved, with an average of 3.74 teeth (3.1 FPMs and 0.64 incisors) per individual. Of 344 hypomineralized molars, 167 were mildly and 177 moderate-severely affected. Mandibular left FPMs (98) were most frequently affected, followed by mandibular right (91), maxillary left (80) and maxillary right first molars (75). Of 344 affected molars, 2 molars in one child were extracted and 2 molars in another child were restored by stainless steel crowns (included under moderate-severe category).

A higher number of FPMs was affected in children aged above 10 years than below 10 years (P > 0.05) with significantly higher number of severely affected FPMs in the older children (P < 0.05, [Table 6], [Graph 2]. {Table 6}

Significantly larger numbers of mandibular FPMs were not only diagnosed with MIH (P < 0.001), but also showed hypomineralization of the severe variety (P < 0.05) when compared to the maxillary FPMs. A significantly higher number of maxillary FPMs were mildly hypomineralized (P < 0.001). No significant difference (P > 0.05) was observed between the left and right sides of the arches in the number and severity of FPM hypomineralization.

Prevalence of caries in FPMs of MIH and non-MIH children

Dental caries was significantly more frequent in the hypomineralized FPMs of MIH-affected children (P < 0.001) when compared to the FPMs of the non-MIH children [Table 7]. {Table 7}

The association of dental caries was significantly higher (P < 0.001) with MIH-affected FPMs, especially mandibular (38.7%) when compared to maxillary (18.8%) FPMs (P < 0.001). Nearly equal numbers of MIH-affected molars were involved by caries on the right and left sides of the arch.

Distribution of hypomineralized incisors in MIH-affected children

Of the incisors, the maxillary left central incisors (n = 21) were the most commonly hypomineralized followed by the maxillary right central incisors (n = 17). All severely involved incisors belonged to the maxillary arch. Hypomineralized maxillary permanent incisors were significantly more in number in total as well as in the mildly and severely affected categories when compared to the mandibular incisors (P < 0.05). Also, significantly more maxillary than mandibular central incisors were involved (P < 0.05).

Hypomineralization of teeth other than index teeth

Another observation was the presence of hypomineralized primary molars in 16 out of 67 (23.8%) MIH-affected children in the mixed dentition group and12 children out of 44 (27.3%) in the permanent dentition group had hypomineralized canines and premolars.

 Discussion



The present study assessed the clinical features, severity and distribution of MIH defects and their association with dental caries in a group of 8- to 13-year-old children. Eight years and above is considered the best time for examination for MIH because, at this age, most children will have erupted all four permanent first molars as also the most of the incisor teeth. [5],[10]

Diagnostic criteria

Dental examination was carried out of cleaned and wet teeth to detect the presence of enamel defects and to allow distinction between diffuse opacities, demarcated opacities and white spot carious lesions. [5],[9],[10] Various researchers have used different criteria for recording the presence of MIH such as the DDE index or the modified DDE index, [6],[16],[17] the diagnostic criteria of Alalausua [18] and the criteria recommended by European Academy of Pediatric Dentistry in 2003. [13],[14],[19],[20],[21],[22] In the present study, the EAPD criteria established in 2003 [5] and further revised in 2009 [10] was employed.

Suckling et al. [23] found that reproducibility of small enamel opacities (less than 2 mm) was low, and many studies [24],[25] have ignored defects measuring less than 2 mm in order to avoid the possibility of misdiagnosing white spot lesions, white cuspal ridges or a patchy appearance of amelogenesis imperfecta/fluorosis. In the present study defects smaller than 1 mm were not considered, as recommended by the EAPD in 2009, [10] in order to define a "truer" prevalence of MIH in the study group.

Recording of severity

The severity of defects was determined using the criteria recommended by the EAPD in 2009. [10] Earlier studies have classified MIH into mild, moderate and severe defects. [18],[24],[25] Recently, the moderate and severe groups have been combined into one group i.e. disintegrated or severe in order to improve reproducibility. [9],[10]

Prevalence of MIH

The prevalence of MIH in the present study group was observed to be 9.46%. This finding was comparable to that of a previous Indian study of 8- to 12-year-old schoolchildren from Gujarat. [14] The large variations in the prevalence rates of MIH may reflect real differences between regions and countries, differences in sample sizes, recording methods, indices and diagnostic criteria used and age groups/special groups investigated may also be contributory. [2],[3],[4],[9],[12] Often, the presence of dental caries may mask the true prevalence of MIH. When older children are studied, occlusal wear and restorations could have superimposed the developmental defects. [2],[4],[9]

Similar to the findings of the present study researchers who studied MIH in German, [26] Brazilian, [11],[13] Iraqi [27] Gujarati Indian [14] and Spanish [28] populations also found slightly higher prevalence in boys. Studies on Australian [29] and Jordanian [22] children, however, have reported a higher prevalence in girls.

A majority of the children diagnosed as having MIH in the present study had hypomineralized molars (MH) only, a finding similar to those of studies on Lithuanian, [19] Greece [21] and Jordanian [22] populations. Other studies, however, have reported MIH to be more frequent than MH in their populations. [14],[26],[28],[29] These variations may be due to differences in recording methods including the setting for clinical examination (e.g., in schools where examination may be carried out under poor light or without thorough oral prophylaxis), indices and diagnostic criteria used. Frequently, the presence of dental caries, occlusal wear and restorations may mask the presence of developmental defects in FPMs. [2],[4],[9]

The increased prevalence reported in older children may be due to easier recognition and diagnosis once post-eruptive discoloration and breakdown has occurred in mild defects that might otherwise go unnoticed in younger children. [21],[29]

Distribution/clinical characteristics

In the present study an average 3.74 teeth (3.1 molars and 0.64 incisors) were hypomineralized per individual affected by MIH. Other reported average hypomineralized teeth per individual affected were of 3.2 teeth and 2.4 FPMs in Swedish, [24] 3.4 FPMs and 2.2 incisors in Greek, 5.59 teeth and 3.16 FPMs in Bosnian, [17] 1.98 FPMs in Brazilian [11] and 3.5 teeth (2.4 FPMs and 1.1 incisors) in Spanish [28] children.

Distribution of MIH-affected FPMs

In the present study group, a wide spectrum of clinical characteristics of MIH was observed which ranged from a single hypomineralized molar to four hypomineralized molars to all eight index teeth hypomineralized. The older children had significantly more number of severely affected FPMs than the younger children. These findings are comparable with those of studies on Lithuanian, [19] Greek, [21] Brazilian, [13] Jordanian [22] and Gujarati Indian [14] populations. This suggests the dynamic nature of hypomineralized lesions. With increasing age and exposure to challenges in the oral environment, mild defects worsen, resulting in clinically detectable loss of structure or its consequences such as atypical restorations. [13]

Some authors have suggested that differences in examination conditions may make it difficult to view maxillary molars as clearly as mandibular molars. [22] Also, the early eruption of mandibular molars with resultant early post-eruptive enamel breakdown or caries makes them more obviously affected than maxillary molars. In the present study mandibular FPMs were affected more. This is in agreement with the observations of studies on Swedish, [21] Lithuanian, [19] Jordanian [22] and Gujarati Indian [14] populations, but contradicts the observations of studies on Dutch, [8] Chinese [20] and Australian [29] populations that found a similar distribution of hypomineralized molars between arches, and studies on German, [26] Bosnian, [17] Greek [21] and Iraqi [27] populations which found more maxillary molars affected than mandibular.

Distribution of MIH-affected incisors

Involvement of incisors appeared to increase when more FPMs were affected. Similar conclusions were drawn from studies on German, [26] Australian, [29] Brazilian [11],[13] and Iraqi [27] populations. This presumably indicates that when the etiological insult is severe, it concurrently affects molars and incisors. [27]

A larger number of maxillary incisors was affected than mandibular, a finding in accordance with those of most studies on different populations. [14],[19],[20],[21],[26],[27] Most defects on incisors were of the mild variety, probably owing to no or minimal masticatory forces on the affected surfaces. All severely affected incisors belonged to the maxillary arch. The loss of tooth structure in these teeth may be a consequence of the abrasive force of tooth brushing. [13]

Prevalence of caries in FPMs of MIH and non-MIH children

MIH has long been associated with an increased incidence of dental caries, which has been attributed to the characteristics of hypomineralized enamel, such as higher porosity and lower mechanical resistance. [3],[13],[30] There is also a higher relative concentration of carbon in the hypomineralized enamel which could be the cause for increased acid solubility of the enamel. [30] The resultant hypersensitivity may compromise oral hygiene procedures further increasing the caries risk. [30],[31] MIH is considered a dental caries risk factor in populations with a low prevalence of dental caries. [8],[24],[28],[32],[33] In populations with high caries activity, the hypomineralized lesions could be disguised by carious lesions. [2],[9],[13]

In the present study, dental caries was a more frequent finding in FPMs in children with MIH than in those without. MIH-affected mandibular FPMs were more frequently decayed than maxillary FPMs. Most studies have reported higher prevalence of caries in MIH-affected than in unaffected individuals. [13],[20],[24],[26],[28],[32]

Hypomineralization of teeth other than index teeth

To broaden the knowledge of the nature of MIH, it is of great importance to know the extent to which teeth other than FPMs and incisors are affected. [9] Weerheijm et al. [5] reported that MIH-like defects are also seen on second primary molars and permanent cuspids. In the present study, 27% of MIH-affected children who were in the permanent dentition stage also had one or more hypomineralized canines and premolars. It has been suggested that systemic etiological factors acting for longer periods during enamel mineralization and maturation tend to produce more affected teeth with more severe defects. [9],[21]

Hypomineralization of primary molars has been reported by a few researchers. [34],[35] The development of the second primary molars starts at around the same time as that of the FPMs and permanent incisors, but the duration is longer for permanent molars. [36] These MIH-like defects in the primary molars are described as deciduous molar hypomineralization (DMH). [34] Elfrink et al. [34] have reported a 9% prevalence of hypomineralized primary molars and a 8.7% prevalence of MIH in the same Dutch population. In the present study, it was noted that 24% of the MIH-affected children who were in the mixed dentition stage also had one or more hypomineralized primary molars.

 Conclusion



Recent research supports the assumption that MIH is a widespread problem all over the world. In the present study MIH was found to affect one out of every ten children examined as was observed in another study on Indian children. Hence, it appears that this condition is more prevalent than was recognized until recently. 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.

References

1Weerheijm KL. Molar-incisor hypomineralization (MIH): Clinical presentation, aetiology and management. Dent Update 2004;31:9-12.
2Willmott N. Molar incisor hypomineralization. Dent Nurs 2011;7:132-7.
3William V, Messer LB, Burrow MF. Molar-incisor hypomineralization: Review and recommendations for clinical management. Pediatr Dent 2006;28:224-32.
4Crombie F, Manton D, Kilpatrick N. Aetiology of molar-incisor hypomineralization: A critical review. Int J Paediatr Dent 2009;19:73-83.
5Weerheijm KL, Duggal M, Mejàre I, Papagiannoulis L, Koch G, Martens LC, et al. Judgement criteria for molar-incisor hypomineralization (MIH) in epidemiologic studies: A summary of the European meeting on MIH held in Athens, 2003. Eur J Paediatr Dent 2003;4:110-3.
6Mahoney EK, Morrison DG. The prevalence of Molar-Incisor Hypomineralization (MIH) in Wainuiomata children. N Z Dent J 2009;105:121-7.
7Koch G, Hallonsten AL, Ludvigsson N, Hansson BO, Holst A, Ullbro C. Epidemiologic study of idiopathic enamel hypomineralization in permanent teeth of Swedish children. Community Dent Oral Epidimiol 1987;15:279-85.
8Weerheijm L, Jalevik B, Alaluusua S. Molar-incisor hypomineralization. Caries Res 2001;35:390-1.
9Jalevik B. Prevalence and diagnosis of Molar-Incisor Hypomineralization (MIH): A systematic review. Eur Arch Paediatr Dent 2010;11:59-64.
10Lygidakis NA, Wong F, Jälevik B, Vierrou AM, Alaluusua S, Espelid I. Best clinical practice guidance for clinicians dealing with children presenting with Molar-Incisor Hypomineralization (MIH): An EAPD Policy Document. Eur Arch Paediatr Dent 2010;11:75-81.
11Soviero V, Haubek D, Trindade C, Matta TD, Poulsen S. Prevalence and distribution of demarcated opacities and their sequelae in permanent 1 st molars and incisors in 7 to 13-year-old Brazilian children. Acta Odontol Scand 2009;67:170-5.
12Weerheijm KL, Mejàre I. Molar-incisor hypomineralization: A questionnaire inventory of its occurrence in member countries of the European Academy of Paediatric Dentistry (EAPD). Int J Paediatr Dent 2003;13:411-6.
13da Costa-Silva CM, Jeremias F, de Souza JF, Cordeiro Rde C, Santos-Pinto L, Zuanon AC. Molar-incisor hypomineralization: Prevalence, severity and clinical consequences in Brazilian children. Int J Paediatr Dent 2010;20:426-34.
14Parikh DR, Ganesh M, Bhaskar V. Prevalence and characteristics of Molar-Incisor Hypomineralization (MIH) in the child population residing in Gandhinagar, Gujarat, India. Eur Arch Paediatr Dent 2012;13:21-6.
15World Health Organization. Oral health surveys. Basic methods. 4 th ed. Geneva: WHO; 1997. p. 39-46.
16Weerheijm KL, Groen HJ, Beentjes VE, Poorterman JH. Prevalence of cheese molars in 11-year-old Dutch children. J Dent Child 2001;68:259-6.
17Muratbegovic A, Markovic N, Ganibegovic Selimovic M. Molar-Incisor Hypomineralization in Bosnia and Herzegovina: Aetiology and clinical consequences in medium caries activity population. Eur Arch Paediatr Dent 2007;8:189-94.
18Alaluusua S, Lukinmaa PL, Vartiainen T, Partanen M, Torppa J, Tuomisto J. Polychlorinated dibenzo-p-dioxins and dibenzofurans via mother's milk may cause developmental defects in the child's teeth. Environ Toxicol Pharmacol 1996;1:193-7.
19Jasulaityte l, Veerkamp JS, Weerheijm KL. Molar-incisor hypomineralization: Review and prevalence data from a study of primary school children in Kaunas/Lithuania. Eur Arch Paediatr Dent 2007;8:87-94.
20Cho SY, Ki Y, Chu V. Molar incisor hypomineralization in Hong Kong Chinese children. Int J Paed Dent 2008;18:348-52.
21Lygidakis NA, Dimou G, Briseniou E. Molar-incisor hypomineralization (MIH). Retrospective clinical study in Greek children. I. Prevalence and defect characteristics. Eur Arch Paediatr Dent 2008;9:200-6.
22Zawaideh FI, Al-Jundi SH, Al-Jaljoli MH. Molar-Incisor Hypomineralization: Prevalence in Jordanian children and clinical characteristics. Eur Arch Paediatr Dent 2011;12:31-6.
23Suckling GW, Brown RH, Herbison GP. The prevalence of developmental defects of enamel in 696 nine-year-old New Zealand children participating in a health and development study. Community Dent Health 1985;2:303-13.
24Jälevik B, Klingberg G, Barregård L, Noren JG. The prevalence of demarcated opacities in permanent first molars in a group of Swedish children. Acta Odontol Scand 2001;59:255-60.
25Calderara PC, Gerthoux PM, Mocarelli P, Lukinmaa PL, Tramacere PL, Alaluusua S. The prevalence of Molar-Incisor Hypomineralization (MIH) in a group of Italian school children. Eur J Paediatr Dent 2005;6:79-83.
26Preusser SE, Ferring V, Wleklinski C, Wetzel WE. Prevalence and severity of molar-incisor hypomineralization in a region of Germany - a brief communication. J Public Health Dent 2007;67:148-50.
27Ghanim A, Morgan M, Mariño R, Bailey D, Manton D. Molar-incisor hypomineralization: Prevalence and defect characteristics in Iraqi Children. Int J Paediatr Dent 2011;21:413-21.
28Garcia-Margarit M, Catalá-Pizarro M, Montiel-Company JM, Almerich-Silla JM. Epidemiologic study of molar-incisor hypomineralization in 8-year-old Spanish children. Int J Paediatr Dent 2014;24:14-22.
29Chawla N, Messer LB, Silva M. Clinical Studies on Molar-Incisor Hypomineralization. Part 1: Distribution and Putative Associations. Eur Arch Paediatr Dent 2008;9:180-90.
30Fagrell TG, Dietz W, Jälevik B, Norén JG. Chemical, mechanical and morphological properties of hypomineralized enamel of permanent first molars. Acta Odontol Scand 2010;68:215-22.
31Rodd HD, Boissonade FM, Day PF. Pulpal status of hypomineralized permanent molars. Pediatr Dent 2007;29:514-20.
32Jeremias F, Souza JF, Costa Silva CM, Cordeiro RD, Zuanon AC, Santos-Pinto L. Dental caries experience and Molar-Incisor Hypomineralization. Acta Odontol Scand 2013;71:870-6.
33Jalevik B. Klingberg GA. Dental treatment, dental fear and behaviour management problems in children with severe enamel hypomineralization of their permanent first molars. Int J Paediatr Dent 2002;12:24-32.
34Elfrink ME, Ten Cate JM, Jaddoe VW, Hofman A, Moll HA, Veerkamp JS. Deciduous molar hypomineralization and molar incisor hypomineralization. J Dent Res 2012;91:551-5.
35Ghanim A, Manton D, Mariño R, Morgan M, Bailey D. Prevalence of demarcated hypomineralization defects in second primary molars in Iraqi children. Int J Paediatr Dent 2013;23:48-55.
36Butler PM. Comparison of the development of the second deciduous molar and first permanent molar in man. Arch Oral Biol. 1967;12:1245-60.