Prevalence of molar incisor hypomineralization and demands for treatment according to the severity of its clinical manifestation.

doi:10.21203/rs.3.rs-4279100/v1

Aim

Assess the prevalence and severity of molar incisor hypomineralization (MIH) in children 6- to 12-year-old and correlate MIH severity with the complexity of treatment demands.

Materials and methods

Between March and October 2023, 2,136 children were screened for MIH by two calibrated examiners. MIH severity was categorized in mild, moderate, severe, and very severe. Treatment requirements were categorized in basic, intermediate, and complex.

Results

The prevalence of MIH was 15.5% (n = 331). Among the 126 children with atypical caries/restoration, cusp involvement was observed in 60.3%, endodontic treatment was necessary in 24.6%, only 15% needed restorations limited to two tooth surfaces with no cusp involvement. Extraction due to MIH was observed in 2.7%.

Conclusion

The prevalence of MIH was in accordance with previous literature. Whenever a restorative treatment was necessary, it often involved multiple tooth surfaces and cusps. The complexity of treatment demands increased with age. It is necessary that oral health policymakers pay special attention to children with MIH to ensure appropriate treatment.

Molar incisor hypomineralization

Prevalence

Treatment need

Molar incisor hypomineralization (MIH) has been extensively studied since its first description in 2001[1]. Characterized as a qualitative defect of enamel mineralization, MIH presents clinically as demarcated opacities ranging in color from white-creamy to yellow-brownish affecting at least one first permanent molar often affecting also permanent incisors [2].

The estimate overall prevalence of MIH is 13.5%, showing no significant geographical difference between continents, with 36.3% of cases classified as moderate to severe[3]. The asymmetric characteristic of MIH was confirmed by variations in the number of affected FPM and permanent incisors[3].

The defective enamel has a lower mineral content, is highly porous, and prone to breakdown as soon as it emerges in the oral cavity and is exposed to functional forces[4, 5]. The severity of the hypomineralization correlates with the clinical features of the enamel. Yellow-brownish opacities have a higher protein content and decreased mechanical properties than the white-creamy ones[6]. Therefore, darker opacities are at higher risk of breakdown and progression to the more severe levels of the condition[7]. MIH has been associated with higher caries prevalence and increased caries index in children[8, 9]. The less mineralized enamel and areas where the enamel disintegrates favor caries progression, resulting in atypical caries lesions affecting multiple tooth surfaces. Moreover, tooth surfaces usually not affected by caries, such as free smooth surfaces and cusps, are often carious or filled in the presence of MIH[10]. Hence, besides the higher caries index, children with MIH might also require more complex restorative treatment.

MIH has been shown to significantly increase the global burden of dental treatment needs. In 2015/2016, it was estimated that the proportion of patients in need of care (those with tooth pain, hypersensitivity, or post-eruptive breakdown) was 27.4% or 5 million new treatment cases each year. Much of the burden of MIH relies on low- and middle-income countries, where the access to dental treatment is limited [11]. Providing oral care for all the affected individuals is highly challenging. Therefore, aside from assessing the prevalence of MIH, it is necessary to provide data about the demands and complexity of the treatment needs, so that oral health policymakers are substantiated to appropriately plan the oral health care strategies.

The aim of the present study was to assess the prevalence and severity of MIH in a group of children 6- to 12-year-old and correlate the MIH severity with the complexity of treatment demands.

Study design, setting, and participants

This was a cross-sectional observational study conducted in the city of Petrópolis, Brazil. Ten public schools were visited to screen patients for a randomized controlled trial (RCT) that will evaluate the clinical performance of restorative treatment for severe MIH molars (registered in REBEC RBR-4mtq8d9). These ten public schools were chosen because the dentists participating in the RCT as operators are affiliated with the local public oral care system, and the schools are situated within the coverage of this system. Hence, the children selected for the RCT can easily be referred to the nearest oral health unit. Petrópolis is situated in the southeast region of Brazil, in the state of Rio de Janeiro, has a population of slightly over 300,000 inhabitants. The Human Development Index is 0.745 and the population has access to artificially fluoridated water according to Brazilian regulations.

All children from the 1st to the 7th grades at school were considered eligible and were invited to participate in the study. The study was approved by the Research Ethics Committee of the Pedro Ernesto University Hospital – Rio de Janeiro State University (5.763.553). Participation was voluntary and an informed consent was sent to children’s caregivers. The inclusion criterion was the presence of at least one FPM erupted. Children presenting other developmental enamel defect than MIH (e.g., amelogenesis imperfecta, severe fluorosis), chronic health conditions, unable to cooperate with the dental examination, or with orthodontic appliances were excluded. Children who were absent on the day the school was visited were considered as dropouts.

MIH detection and severity at the tooth level

Between March 2023 and October 2023, two trained and calibrated examiners performed the clinical examinations. First, a screening was conducted in the classrooms with the children seated at their desks and the dentist positioned in front each child. Using a head lamp and wood sticks to gently retract cheeks and tongue, the dentist searched for any signs of suspicious opacities, enamel breakdown, or restorations indicative of MIH according to EAPD criteria[12]. Children who presented any indicative sign of MIH were referred for a detailed examination in a separate room. Supervised toothbrushing was done prior to the detailed examination. Then, children were seated on regular chairs with a small pillow supporting their heads against the chair back. The dentist was positioned behind the child for a better view of the whole mouth. In addition to the head lamp, the dentist used dental mirror, probe, and cotton rolls if it was necessary to control moisture. The comprehensive mouth examination followed Ghanim[13] criteria for MIH, differentiating between white-creamy and yellow-brownish opacities (Table 1). Other enamel defects besides MIH, i.e. fluorosis and hypoplasia, were also registered but will not be considered in the present study. MIH was registered at the tooth surface level. Trained assistants registered the collected data in datasheets.

Table 1

MIH severity classification at the tooth level.
Score	Description
0	No visible enamel defects.
21	White-creamy opacity (W-OP)
22	Yellow-brownish opacity (Y-OP)
3	Post-eruptive breakdown (PEB)
4	Atypical restoration (AR)
5	Atypical caries (AC)
6	Extracted due to MIH (EXT)*
*Teeth extensive coronary disintegration, clearly indicated for extraction were also considered as EXT.

MIH severity at the individual level

Patients were categorized based on the severity of MIH, determined by the most severe score assigned to at least one tooth. In this classification, scores for AR and AC were combined as AR/AC to indicate both past and present restorative needs. AR/AC was further divided into three categories from the mildest to the most severe conditions: AR/AC involving up to 2 tooth surfaces without cusp or pulp involvement (AR/AC-2surfaces), AR/AC involving cusp and/or 3 or more tooth surfaces with no pulp involvement (AR/AC-cusp), and AR/AC with pulp involvement (AR/AC-pulp). Pulp involvement was assessed according to PUFA criteria[14]. These severity categories of MIH were then correlated with treatment demands, considering the clinical findings (Table 2). The recommendations regarding treatment were based on EAPD guidelines [12].

Table 2

MIH severity and corresponding treatment recommendation.
MIH		Treatment
Description	Severity	Modalities	Complexity
W-OP*	Mild	Monitoring	Basic
Y-OP*	Mild/Moderate	Monitoring or Topical fluoride or remineralizing agents or Sealants	Basic
PEB (restricted to enamel or exposing hard dentine)	Moderate	Monitoring or Topical fluoride or remineralizing agents or Sealants or Direct restoration	Basic/Intermediate
AR/AC (extending up to two tooth surfaces, not involving cups, with no pulp involvement).	Severe	Direct restoration	Intermediate
AR/AC cusp (extending to three or more tooth surfaces, involving cusps).	Very severe	Indirect restoration	Complex
AR/AC pulp (with pulp involvement).	Very severe	Endodontic treatment and indirect restoration	Complex
EXT (extensive coronary disintegration, with pulp involvement, indicated for extraction or extracted due to MIH).	Very severe	Extraction and/or orthodontic monitoring/orthodontic treatment	Complex
* W-OP or Y-OP in anterior teeth might be indicative for aesthetic treatment if aesthetics is a concern for the patient. For any of the severity levels, report of hypersensitivity by the patient may increase the level of the treatment demand.

Training and calibration

The examiners received theoretical and practical training on how to diagnose MIH and to assess pulp involvement by an experienced examiner. The distinction between MIH and other developmental defects of enamel was emphasized during the training process. Calibration exercises were done with a set of 40 clinical photographs to assess the level of intra- and inter-examiner agreement in MIH diagnosis and 25 clinical photographs for pulp involvement assessment. After 2 weeks interval, the photographs were re-analyzed. The agreement was analyzed using the kappa coefficient test. Considering MIH diagnosis at the tooth level (no/yes), the intra-examiner agreement achieved kappa 0.95 for the examiner 1 and 1.0 for the examiner 2. Considering MIH severity at the tooth level (no/mild/severe), the weighted kappa was 0.97 for the examiner 1 and 0.97 for the examiner 2. The inter-examiner agreement was 0.95 and 1.0 for diagnosis and 0.94 and 0.97 for severity assessment, respectively. For pulp involvement, the intra-examiner agreement was 1.0 for both examiners, and inter-examiners was 0.92 and 1.0, for examiners 1 and 2, respectively). The assessment of pulp involvement was dichotomized in yes/no.

Statistical Analysis

Data were organized in a excel sheet (Microsoft Excel for Mac version 18.80) and then analyzed in SPSS (IMB SPSS Statistics version 29.0.1.0). Exploratory analysis included calculation of proportions of categorical variables and medians, means, and standard deviation of numerical variables. The severity of MIH, considered as an dependent variable, was firstly categorized in 5 levels (W-OP, Y-OP, PEB, AR/AC, and EXT). Then, for some of the associations, it was categorized in 2 levels (W-OP/Y-OP or PEB/AR/AC/EXT) defining the threshold based on enamel disintegration. For the association between MIH severity and treatment demands, children were classified according to the presence of the most complex condition in at least one tooth., according to the following hierarchical sequence: EXT > AR/AC with pulp involvement > AR/AC involving cusp with no pulp involvement > AR/AC involving up to 2 tooth surfaces without cusp or pulp involved > PEB > Y-OP > W-OP. Dependent variables were tested for normality using the Kolmogorov-Smirnov test where p-values < 0.05 indicated non-normal distribution. Therefore, non-parametric tests were used to test the association between dependent and independent variables. Kruskal-Wallis or Mann-Whitney tests were used for numerical variables and Chi-square was used for categorical variables.

From the 2,352 children enrolled in the 1st to the 7th grades at schools, 2,308 (98,1%) returned the informed consent. Eighty-eight children were absent on the day the examinations, 76 were excluded because did not present any FPM, and 11 children were excluded due neurological condition or orthodontic appliance. The final sample comprised 2,136 children, 6- to 12-year-old, 1,040 (48.7%) girls and 1,096 (51.3%) boys.

The prevalence of MIH was 15.5%, affecting 331 children, who were 170 (51.4%) girls and 161 (48.6%) boys with a mean age of 9.0 (SD = 1.80) years. From the 331 children with MIH, 105 (31.7%) presented only W-OP, 53 (16.0%) presented at least one tooth with Y-OP, 38 (11.5%) presented at least one tooth with PEB, 126 (38.1%) presented at least one tooth with AR or AC, and 9 (2.7%) had at least one missing FPM due to MIH. A significant increase in severity was seen in the older children (p = 0.03). These data are displayed in Table 3. As the severity of MIH increased, the average number of affected FPM and PI also tended to increase (p < 0.05) (Table 4).

Table 3: Distribution of the sample according to MIH severity and its association with age.
MIH severity	All children with MIH		Age (years)
	All children with MIH		6 - 9		10 - 12		p-value*
	n	%	n	%	n	%	p-value*
W-OP	105	31.7	64	33.9	41	28.9	0.03
Y-OP	53	16.0	33	17.5	20	14.1
PEB	38	11.5	26	13.3	12	8.5
AR/AC	126	38.1	65	34.4	61	43.0
EXT	9	2.7	1	0.5	8	5.6
Total	331	100	189	100	142	100
* Chi-square test

Table 4

Mean number of first permanent molars (FPM) and permanent incisors (PI) affected per child according to the MIH severity (n = 331).
MIH severity	Affected teeth
	FPM			PI
	Mean	SD	Median	Mean	SD	Median
W-OP	1.7^a	0.93	2.0	0.57^a	1.06	0
Y-OP	1.89^a	0.80	2.0	0.66^a.c	0.90	0
PEB	2.26^a,b	0.98	2.0	1.32^b	1.17	1
AR/AC	2.72^b,c	0.95	3.0	1.01^b.c	1.29	1
EXT	3.44^c	0.88	4.0	0.56^a,b	0.73	0
Total	2.26	1.03	2.0	0.84	1.16	0
Note: Different superscript letters indicate statistical significance (Kruskal-Wallis test adjusted by Bonferroni correction; p < 0.05).

Regarding the distribution within the dentition, 162 (48.9%) children presented only FPM affected, 132 (39.9%) presented both PI and FPM affected, 20 (6.0%) had other permanent teeth (OPT) affected combined with PI and FPM, and 17 (5.1%) had only OPT and FPM affected. The more severe the MIH, the greater the variety of affected teeth. Both PI and OPT were significantly more affected in the more severe forms of MIH (Table 5).

Table 5

Proportion of children presenting only first permanent molars (FPM) affected, both permanent incisors (PI) and FPM affected, or any other permanent teeth (OPT) affected with or without PI also affected according to the severity of molar incisor hypomineralization (MIH).
MIH severity	FMP		FPM + PI		FPM + OPT w/ or wo/ PI		Total	p-value*
MIH severity	n	%	n	%	n	%	n	p-value*
Mild (W-OP/Y-OP)	95	60.1	50	31.6	13	8.2	158	< 0.001
Severe (PEB/AR/AC/ EXT	67	38.7	82	47.4	24	13.9	173	< 0.001
Total	162	48.9	132	39.9	37	11.2	331
*Chi-square test

Table 6 shows the prevalence of enamel hypomineralization at the tooth level among the 331 children with MIH. The upper FPM were the most affected teeth followed by the lower FPM, and upper central PI. In terms of proportions, the second permanent molars were more frequently affected than the lateral PI. Figure 1 illustrates the distribution of enamel defect within the dentition based on severity. The FPM showed the highest frequency with the more severe scores (PEB/AR/AC/EXT), being the only teeth missing due to MIH. Y-OP, PEB, AR, and AC were more commonly found among the second permanent molars than in the PI.

Table 6

Prevalence of enamel hypomineralization at the tooth level among the 331 children with MIH. Superscript numbers indicate the sequence from the most to the least affected group of teeth.
Upper right side			Upper left side
%	n/N	Tooth	Tooth	n/N	%
13.2	5/38	³17	27³	3/41	7.3
60.4	197/326	¹16	26¹	185/318	58.2
7.3	7/96	⁶15	25⁶	4/97	4.1
3.7	5/136	⁶14	24⁶	0/137	0
3.3	3/90	⁵13	23⁵	5/85	5.9
6.0	15/252	⁴12	22⁴	16/255	6.3
21.9	65/297	²11	21²	67/299	22.4
Lower right side			Lower left side
%	n/N	Tooth	Tooth	n/N	%
9.5	31/325	²41	31²	39/325	12.0
7.8	23/293	⁴42	32⁴	21/293	7.2
4.5	6/134	⁵43	33⁵	4/134	3.0
3.3	4/122	⁶44	34⁶	5/131	3.8
3.1	3/98	⁶45	35⁶	6/99	6.1
55.5	183/330	¹46	36¹	183/328	55.8
17.1	7/41	³47	37³	9/47	19.1
¹ First Permanent Molars; ² Central Permanent Incisors; ³ Second Permanent Molars; ⁴ Lateral Permanent Incisors; ⁵ Permanent Canines; ⁶ Premolars.

Table 7 illustrates the distribution of children based on MIH severity and its correlation with the complexity of the treatment demand for posterior teeth at the individual level. Children exhibiting the mild form of MIH, characterized by W-OP (105; 31.7%) and Y-OP (53; 16.0%), were categorized as those requiring basic treatment. Basic to intermediate treatment was considered recommended for children with PEB (38; 11.5%) or AR/AC involving up to 2 tooth surfaces with no cusps or pulp involvement (19; 5.7%). The more severe forms of MIH, AR/AC involving cusps (76; 23.0%), AR/AC with pulp involvement (31; 9.4%) and EXT (9; 2.7%) were considered as those requiring complex treatments. Regarding the anterior teeth, 158 (47.7%) children has at least one anterior tooth affected, mostly with W-OP (118; 36.1%). Y-OP affected at least one anterior tooth in 30 (9.2%) children, PEB was seen in 5 (1.5%) children and 1 (0.3%) had an anterior tooth with a AR. The complexity of the treatment demand was significantly associated with age as it can be seen in Fig. 2.

Table 7

Complexity of the treatments demands for posterior and anterior teeth according to MIH severity at the individual level.
Treatment demands		MIH severity	n	%
Posterior teeth
Basic	Monitoring	W-OP	105	31.7
	Monitoring or Topical fluoride or Remineralizing agents or Sealants	Y-OP	53	16.0
Basic/Intermediate	Monitoring or Topical fluoride or Remineralizing agents or Sealants or Direct restoration	PEB	38	11.5
Intermediate	Direct restoration	AR/AC − 2 surfaces	19	5.7
Complex	Indirect restoration	AR/AC - cusp	76	23.0
	Endodontic treatment and Indirect restoration	AR/AC - pulp	31	9.4
	Extraction and orthodontic monitoring/treatment	EXT	9	2.7
Anterior teeth
Basic/Intermediate	Monitoring	W-OP	118	36.1
	Aesthetica treatment*:	Y-OP	30	9.2
	microabrasion resin
	infiltration or direct
	restoration
Intermediate	Direct restoration	PEB	5	1.5
		AR	1	0.3
* Aesthetic treatment is indicated when aesthetics is a concern for the patient.

The prevalence of MIH observed in the present study, 15.5%, was similar to the estimated prevalence worldwide observed in the most recent meta-analysis which reported an overall prevalence of 13.5% [3]. The proportion of children with severe MIH, presenting at least one tooth with PEB/AR/AC/EXT, was 52.3%, being higher than the estimated proportion of severe cases reported by the meta-analysis which was 36.3% [3]. However, some of the studies included in the meta-analysis [15–20] and a more recent study with a quite large sample carried out in Norway [21], reported similar or even higher proportion of severe cases. In the present study, we speculate whether very mild cases might have been underdiagnosed during the initial screening phase, where children were examined without a dental mirror, using only a head lamp and wood sticks to retract cheeks and tongue. This could explain the difference between our findings and those from a previous study conducted in the same city in 2018, where there was no prior screening stage and all eligible children were comprehensively examined, and the prevalence of MIH was 28.7%, but the severe cases comprised only 24.8% [22]. Another possible explanation for the higher proportion of severe cases might be the age of the participants. In 2018, only 8-year-old children were included [22], while in the present study children between 6 and 12 years-old were examined. Previous studies have noted that MIH tend to worsen with age, as the demarcated opacities may progress to PEB over time [7, 23–25]. The association between age and MIH severity was also found in our study, with the most severe forms of MIH being more prevalent among older children.

In line with previous publications [17, 21, 22, 26, 27], a higher severity of MIH was associated with a greater number of affected teeth. This trend was observed not only for FPM and PI, but also for other permanent teeth, referred to as HOPT, in agreement with findings from other studies [28, 29]. Given the age range of the participants, most of them did not present other permanent teeth besides FPM and PI yet. Despite this, a relatively high number of affected second permanent molars was observed. Proportionally, only FPM and central upper permanent incisors exhibited higher rates of affection than second permanent molars. Furthermore, in terms of severity, second permanent molars were the second group of teeth most severely affected after FPM. High frequency and severity of affection in second permanent molars have been reported in studies involving adolescents and adults [28–30].

Regarding the correlation between MIH severity and treatment requirements, almost half of the children presented only demarcated opacities. At this severity level, children require preventive approach, mostly clinical monitoring, fluorides, and sealants [12]. Monitoring might be enough for white opacities that are at lower risk of breakdown, while extra protective care might be necessary for yellow opacities that are at higher risk of breakdown [7]. However, when dealing with anterior teeth, patient’s expectations and self-perception about teeth appearance are mandatory in terms of indication for aesthetic treatment.

In general, severe MIH comprises all cases with PEB or atypical caries/restoration regardless its extension. However, treatment decision may differ depending on the size, location, and number of tooth surfaces affected by the defect [12]. It has been shown that children with MIH present higher caries indices [8, 9]. Additionally, they present not only more carious or filled teeth, but also a higher number of carious or filled tooth surfaces per tooth. Moreover, smooth free surfaces usually not affected by typical caries lesions are often affected by PEB or atypical caries/restorations [10]. In the present study, we categorized the atypical caries/restorations considering the complexity of the treatment required. Cusp involvement and pulp complication were the two major concerns. It was observed that most of the atypical caries/restorations had widespread extension, involving multiple tooth surfaces and cusps. Among the 126 children with at least one tooth with atypical caries/restorations, cusp involvement was observed in slightly more than 60% of cases, and endodontic treatment was necessary in 24%. Only 15% of the children needed only restorations limited to two tooth surfaces with no cusp involvement.

Most of the clinical studies assessing the survival rate of direct restorations in MIH molars do not provide details about their extension and whether the fillings involved cusps [31–35]. Direct restorations would be inappropriate in cases where multiple tooth surfaces and cusps are involved [12] because it extrapolates the indication for direct restorative materials. The inadequate indication of the restorative materials, rather than the hypomineralized enamel itself, might be one of the main reasons for the higher failure rate of direct restorations compared to indirect restorations in patients with MIH. Over a period of 24 months, cusp involvement was the most significant factor related to failure of composite resin restorations in MIH molars [36]. In another study, after 12 months, more than one third of the composite restorations involving cusps had failed comparing with less than 15% failure of those without cusp involvement [37].

Hence, whenever a restorative treatment is being planned for a hypomineralized molar, it is advisable to evaluate if the restoration will extend to cusp areas before deciding about which technique and material should be used. Nevertheless, conventional indirect restorative procedures may be more time-consuming and require more cooperation from the patients. General anesthesia or nitrous oxide sedation have been recommended for the comfort of patients [32, 38], but these facilities are not always available on a regular basis, particularly in low-income countries. Moreover, conventional preparation for indirect restoration is more invasive and require substantially more dental tissue removal than conservative selective tissue removal usually practiced for direct fillings. Nonetheless, survival rates over 90% after 3 years have been reported for indirect ceramic, resin, and metal onlays [32, 38, 39].

Attempting to maximize success rate of restorations and minimize discomfort for the patients during the clinical procedure, stainless steel crowns (SSC) have been used with no tooth preparation in severely affected molars [36, 40, 41]. This approach is based on an adaptation of the Hall Technique concept originally recommended for carious primary molars [42]. Although randomized trials and longer follow up are necessary to support its recommendation, it seems that SSC according to the Hall Technique might be a promising strategy for molars with widespread PEB and/or atypical caries involving cusps. The technique is practical, fast and may be used as an interim restoration or at longer-term with the advantage of being minimally invasive.

The frequency of pulp involvement and MIH has not been widely explored, but at least two studies reported that pulp complications were significantly more frequent in children with enamel defects, mainly MIH [43, 44]. Atypical caries with pulp complication in FPM were observed in almost 10% of the children in the present study. Additionally, indication for extraction or already a missing FPM due to MIH were observed in the sample, but in slightly less than 3% of the children. These cases represent the most severe clinical conditions related to MIH, requiring even more complex treatment. The scenario depicts a group of children with MIH, all under 12 years-old, where for every 10 children, one has at least one FPM requiring endodontic treatment or extraction. The significant association between age the complexity of the treatment demands reflects the worsening of MIH over time.

One strength of the present study is its relatively large sample compared to most previous studies [3]. However, given the non-probability sampling method used, its external validity is reduced. Another limitation was that the assessment of treatment demands according to MIH severity relied solely on clinical data collected during oral examinations by dentists. Patients-report symptoms, such as hypersensitivity and tooth pain, along with aesthetic perceptions, may influence the need for treatment.

Nevertheless, based on the findings of the present study, we conclude that children with MIH may present a wide range of treatment demands. When restorative treatment is necessary, it often involves multiple tooth surfaces and cusps, making the choice of technique and restorative material challenging. More complex treatment needs, such as endodontic treatment and extraction, are not uncommon and tend to increase with age. Therefore, it is urgently necessary that oral health policymakers to pay special attention to children with MIH and support oral healthcare to ensure appropriate treatment, aiming to reduce the burden of the disease.

Author Contribution

VMS and TKSF contributed to the conception and design of the study. BMSG, RCJ, PPGR, and GFM collected the clinical data and inserted the data in a database. VMS analyzed the data. All authors made substantial contribution to drafting, writing, and critically revising the manuscript.

Acknowledgement

We acknowledge Fundação de Amparo a Pesquisa do Estado do Rio de Janeiro (FAPERJ) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES). This study was conducted as part of the Master thesis of the first author (BMSG) at Rio de Janeiro State University.

Data Availability

The data that support the findings of this study are not openly available due to reasons of sensitivity and are available from the corresponding author upon reasonable request.

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No competing interests reported.

Prevalence of molar incisor hypomineralization and demands for treatment according to the severity of its clinical manifestation.

Status:

Version 1

Abstract

Figures

Introduction

Methods

Study design, setting, and participants

MIH detection and severity at the tooth level

MIH severity at the individual level

Training and calibration

Statistical Analysis

Results

Discussion

Declarations

Author Contribution

Acknowledgement

Data Availability

References

Additional Declarations

Status:

Version 1