Abstract
Objectives
To determine the prevalence and presentation patterns of molar-incisor hypomineralisation (MIH) in Brazilian children.
Methods
A cross-sectional study was carried out with 715 individuals aged 8–17 years. MIH was diagnosed according to European Academy of Paediatric Dentistry (EAPD) criteria, using intraoral photographs. Data were analysed using Chi Square and Pearson’s Correlation tests at α = 0.05.
Results
The prevalence of MIH was 15.66 %. Mild defects represented by demarcated yellow and brown opacities comprised 83.5 % of the total MIH lesions and the severity of MIH lesions increased significantly as age increased. The average number of first molars affected by MIH per child was 2.26, and 36 children (32.14 %) had at least one affected incisor. With the increase of affected molars, the number of incisors with opacities showed an obvious increasing. The maxillary left first molar was the most affected tooth, and the maxillary central incisors were the anterior teeth most frequently affected by MIH.
Conclusion
The prevalence of MIH was within the range of published studies and the severity of the defects was mostly mild.
Highlights
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The prevalence of MIH was 15.66 %.
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The mild form of the defect comprised the majority of cases.
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The severity of defects increased with age.
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Maxillary molars and incisors were significantly more affected with MIH in comparison to the mandibular teeth.
1
Introduction
Molar-incisor hypomineralisation is an enamel defect of systemic origin that affects one to four permanent first molars and is frequently associated with affected incisors [ , ]. Clinically, hypomineralised enamel lesions manifest as white–creamy to yellow–brown opacities that are clearly demarcated from the normal enamel [ ]. The enamel of affected teeth is more porous, with lower density and mineral content, and has lower mechanical properties compared to healthy teeth. In severe MIH cases, affected molars are more likely to post‐eruptive breakdown (PEB), due to the sub-surface porous structure and the detrimental effect of occlusal stresses [ ].
Despite intensive efforts to understand the aetiology of MIH, it has not been fully elucidated. Some systemic factors such as fever, childhood diseases, and respiratory problems that occur during the prenatal, perinatal, and post-natal periods have been associated with MIH [ ]. Besides, a multifactorial pathogenesis with a possible genetic component has been hypothesized [ ].
Dental management of MIH represents a challenge for the patients, paediatric dentists and caregivers, due to the variation in clinical appearance and the broad spectrum of treatment modalities, ranging from prevention of PEB and dental caries, management of hypersensitivity and pain, through restorative treatment or extraction with or without subsequent orthodontic approach [ , ]. The decision on the choice of treatment must be made considering the child’s age, severity of MIH, orthodontic issues, presence of dental anomalies, symptomatology of the affected tooth and the aesthetic expectations of the patient [ ].
There is a wide variation in the proportion of MIH throughout the world [ , ]. Previous studies have reported the prevalence and clinical characteristics of MIH in children in different countries [ ], as the early diagnosis of enamel defects allows the dentist to establish preventive measures, for the preservation of the tooth, and greater engagement of caregivers in the longitudinal follow-up of the treatment [ ].
Our study aimed at determining MIH prevalence in Natal, Brazil , exploring the characteristics and distribution of hypomineralised lesions on permanent first molars and incisors.
2
Material and methods
This study was designed following the guidelines of the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE).
2.1
Study design
Ethical approval was obtained from the Ethics Committee of the State University of Rio Grande do Norte (No 4.397.488). The study followed the guidelines related to the use of clinical records for research by the Council for International Organizations of Medical Sciences (CIOMS).
2.2
Settings and participants
Clinical records of 1021 patients seeking treatment at the State University of Rio Grande do Norte that provides services to children and up to middle adolescence were evaluated. Data were collected from March 2020 to December 2022.
Patients aged between 8 and 17 years and with at least one of the first permanent molars erupted and completely visible were included. The exclusion criteria were as follows: patients with amelogenesis imperfecta or tetracycline staining and those who were undergoing orthodontic treatment. Individuals with blurred, dark, pixelated photographs or when it was not possible to visualise all tooth surfaces were also excluded.
2.3
Variables
The primary variable was the presence of MIH. The type of permanent tooth, severity, arch, age, and gender were considered as independent variables.
2.4
Measurements and control of bias
For the diagnosis of MIH, the judgement criteria established and modified by the EAPD [ , ] were used ( Fig. 1 ). The occlusal, facial, and palatal as well as lingual surfaces of permanent first molars and incisors (index teeth) were examined for the presence of demarcated opacities.
The severity of MIH was classified according to Lygidakis et al. (2010) [ ] as follows: mild, when there were demarcated opacities without PEB, or as severe, when post-eruptive breakdown, atypical patterns of dental carious lesions, atypical restoration, or extraction due to MIH had occurred. The patient was graded as having a mild or a severe MIH according to the most affected MIH molar.
The intraoral photographs were evaluated by a single paediatric dentist, with clinical experience who was calibrated following the recommendations of the specific training manual for this index, previously published by Ghanim et al. [ ]. Intra-examiner reproducibility was performed by re-examining 20 % of the records (143 children). The reproducibility scoring was excellent (Cohen’s Kappa coefficient = 0.95).
2.5
Statistical analysis
The data were tabulated and analysed in the Jamovi software (The Jamovi Project, 2021; version 1.6). Descriptive statistics were used to describe some characteristics (age and gender) of the children, stratified by groups according to the presence or absence of MIH. To test for statistically significant differences of these measures between groups according to the presence or absence of MIH, the Chi-square test was used. Pearson’s correlation was used to correlate the number of affected molars and incisors. Statistical significance was set at a level of p < 0.05.
3
Results
Out of 1021 clinical records analysed, 306 were excluded: 235 (76.80 %) due to age; 23 (7.52 %) because of the presence of orthodontic appliances and 48 (15.68 %) because of photograph’s low quality. The final sample consisted of 715 patients of which 358 (50.07 %) were females and 357 (49.93 %) males. The mean age was 12.52 (SD = 2.55) years.
The prevalence of MIH was 15.66 % (112 patients). The characteristics of the study participants are represented in Table 1 . There was no significant difference between the presence of MIH between the investigated genders ( p = 0.756) and ages ( p = 0.902).
| Variable | MIH-AFFECTED n (%) | NON-MIH-AFFECTED n (%) | p -value # | TOTAL N = 715 |
|---|---|---|---|---|
| Sex | ||||
| Female | 54 (48.21 %) | 304 (50.37 %) | 0.756 | 358 (50.07 %) |
| Male | 58 (51.79 %) | 299 (49.63 %) | 357 (49.93 %) | |
| Age | ||||
| 8 | 8 (7.15 %) | 35 (5.81 %) | 0.902 | 43 (6.01 %) |
| 9 | 8 (7.15 %) | 51 (8.46 %) | 59 (8.25 %) | |
| 10 | 9 (8.03 %) | 71 (11.77 %) | 80 (11.19 %) | |
| 11 | 16 (14.28 %) | 70 (11.6 %) | 86 (12.02 %) | |
| 12 | 16 (14.28 %) | 70 (11.6 %) | 86 (12.02 %) | |
| 13 | 13 (11.61 %) | 70 (11.6 %) | 83 (11.62 %) | |
| 14 | 12 (10.71 %) | 93 (15.42 %) | 105 (14.69 %) | |
| 15 | 13 (11.61 %) | 53 (8.78 %) | 66 (9.23 %) | |
| 16 | 10 (8.93 %) | 53 (8.78 %) | 63 (8.81 %) | |
| 17 | 7 (6.25 %) | 37 (6.13 %) | 44 (6.16 %) | |
Among the 112 children with MIH, 84 children (75 %) had mild lesions and 28 children (25 %) had severe MIH. The proportion of mild and severe MIH in each age group is shown in Table 2 . There was statistical difference in the proportions of mild and severe MIH in each age group (χ2 = 18.4, p = 0.040).
| Age (years) | Mild n (%) | Severe n (%) | Total n (%) | p -value # |
|---|---|---|---|---|
| 8 | 7 (87.5) | 1 (12.5) | 8 (100) | 0.040 X 2 = 18.4 |
| 9 | 8 (100) | 0 (0) | 8 (100) | |
| 10 | 7 (77.77) | 2 (22.22) | 9 (100) | |
| 11 | 13 (81.25) | 3 (18.75) | 16 (100) | |
| 12 | 12 (75) | 4 (25) | 16 (100) | |
| 13 | 10 (76.92) | 3 (23.07) | 13 (100) | |
| 14 | 8 (66.66) | 4 (33.34) | 12 (100) | |
| 15 | 8 (61.53) | 5 (38.46) | 13 (100) | |
| 16 | 3 (30) | 7 (70) | 10 (100) | |
| 17 | 6 (85.71) | 1 (14.29) | 7 (100) |
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