Abstract
Objectives
Molar Incisor Hypomineralisation (MIH) and Hypomineralised Second Primary Molars (HSPM) involve qualitative structural developmental anomalies of tooth enamel affecting the first permanent molars (and often incisors) and the second primary molars, respectively. A putative relationship between HSPM and MIH has been reported in the scientific literature. The aim was to determine whether children with HSPM are more likely to develop MIH.
Source
A systematic search using PubMed/Medline, Embase and Cochrane Library electronic databases for publications from 2001 to August 2017 investigating the link between MIH and HSPM was undertaken.
Study selection
Four reviewers selected the studies independently, extracted the data according to PRISMA statement, and assessed the bias risk with the Newcastle–Ottawa Scale (NOS) criteria.
Results
From 645 potentially eligible studies, 14 were selected for full text analysis and 5 were included in the meta-analysis. Cross-sectional and cohort studies were reported and 4662 participants were included. The meta-analyses were performed with a random model calculated an OR total of 4.66 (95% CI 2.11–10.26; P < 0.001). The weighted mean of the co-occurrence of HSPM and MIH prevalence was 19.94%.
Discussion
The high heterogeneity (I 2 = 88%) can be explained by the great variation present in number of participants and variable caries risk. Despite the limitations of the study, the presence of HSPM is predictive for MIH, with greater MIH prevalence in the presence of mild HSPM.
Clinical significance
Early detection and preventive intervention could reduce MIH complications.
1
Introduction
Developmental Defects of Enamel (DDE) include hereditary enamel defects, dental fluorosis, enamel opacities, hypoplasia, and discoloured enamel [ ]. Opacity is defined as a qualitative defect in enamel leading to abnormality in translucency of enamel [ ]. Demarcated opacities can be divided into two subgroups: white-cream and yellow-brown [ ]. In 2001, Molar Incisor Hypomineralisation (MIH) was defined as a qualitative demarcated enamel hypomineralisation defect of tooth enamel affecting at least one first permanent molar (FPM), often affecting permanent incisors [ ]. A systematic review highlighted a MIH global prevalence of 14.2% [ ]. More recently, the term Hypomineralised Second Primary Molar (HSPM) was used to describe similar enamel defects affecting second primary molars [ ]. To date, the aetiology is still unclear, but authors agree that it is multifactorial [ ]. MIH constitutes a public health problem, with consequences that are not only health-related but also economic. MIH may impact on the well-being of young patients in a crucial period of infant development [ ]. Difficulties involved in treating MIH-affected teeth are numerous due to hypersensitivity, anxiety, difficulties with anaesthesia, poor aesthetics, carious lesions with fast progression and failure of restorations [ ]. Currently, in the absence of identified cause(s), no risk prevention actions can be adopted. Periods of mineralisation of second primary molars and first permanent molars overlap, so risk factors arising during this period could affect the second primary molars and the first permanent molars simultaneously [ ]. Some authors hypothesised that HSPM could be predictive for MIH, but results are contradictory [ ] and no systematic review has been performed. If this association could be confirmed a preventive program to minimise posteruptive enamel breakdown (PEB) and hypersensitivity could be implemented.
The aim of the present study is to assess the relationship between HSPM and MIH by mean of a systematic review of literature. In other words: are children affected by HSPM more likely to develop MIH?
2
Materials and methods
A detailed search of literature published from 2001 to August 2017 was conducted. The MIH definition was first published in 2001 [ ]. This systematic review was conducted and reported following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA Statement) checklist. The selection and quality assessment were performed by authors who have not published papers on the topic of this manuscript.
2.1
Search strategy and selection criteria
Studies that involved participants of any age with MIH were included. Studies which assessed the association between MIH and HSPM were included as primary outcomes. The last search date was August 2017. Three online databases were used to identify relevant references: Medline via PubMed, Embase and Cochrane Library. In addition, hand searching in the reference lists of selected studies was performed. The terms ((hypomineralized AND second AND primary AND molars) OR (deciduous AND molar AND hypomineralization) OR HSPM) OR ((molar AND incisor AND hypomineralization) OR (demarcated AND opacities) OR MIH) were entered into the search fields. The search was limited to English and French language articles. The title and abstract of identified studies were screened by three reviewers (AD, EG and YD) for eligibility. Consensus was obtained by discussion or consultation with one other reviewer (PR). Studies that did not include recording of demarcated enamel hypomineralisation on primary and permanent molars were excluded. Studies that were literature reviews or case reports were excluded. If there were multiple articles based on the same population, only the study which reported the most detailed data was included. Redundant studies that were identified in more than one database were removed. Four reviewers (AD, EG, PR and YD) then independently read the studies in entirety. In addition, the reference sections of the included studies were hand searched to identify additional publications not found in the databases.
2.2
Data extraction
Data extraction was performed using spreadsheets (Excel 2007, Microsoft © , CA, USA) by two reviewers (AD and EG) and checked by two other reviewers (YD and PR). Disagreements were discussed and consensus reached. The aim, country, study design, patient characteristics (country of residence and age), and sample size of each eligible study were collected.
2.3
Assessment of risk of bias
The risk of bias assessment was conducted by two reviewers (EG and PR). The methodological quality of the included studies was scored according to the Newcastle–Ottawa Scale (NOS) [ ]. The NOS is a star rating system that allocates a maximum of nine stars across three categories: participant selection (four stars), comparability (two stars) and measurement of outcome in cohort (three stars). Regarding the cross-sectional studies, NOS criteria were adapted, thus, the last point on “adequacy of follow up of cohorts” were deleted, so for measurement of outcome in cohort the maximum number of stars is two. Cohort studies with fewer than six stars and cross-sectional studies with fewer than five stars were considered to be at high risk of bias; subsequently no studies were excluded.
2.4
Statistical analysis
The odds ratio (OR) with 95% confidence interval (CI) was used to test the association between HSPM and MIH. Review Manager (RevMan) version 5.3. was used to perform the heterogeneity calculation and meta-analysis using random-effects models [ ]. A P value ≤ 0.05 was considered statistically significant (Z-test). The significance of any discrepancies in the estimates from different studies was assessed by mean of the I 2 statistic, which describes the percentage total variation across studies that is due to heterogeneity rather than change. Due to the small number of studies included, a formal test of publication bias (such as a funnel plot) could not be performed.
2
Materials and methods
A detailed search of literature published from 2001 to August 2017 was conducted. The MIH definition was first published in 2001 [ ]. This systematic review was conducted and reported following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA Statement) checklist. The selection and quality assessment were performed by authors who have not published papers on the topic of this manuscript.
2.1
Search strategy and selection criteria
Studies that involved participants of any age with MIH were included. Studies which assessed the association between MIH and HSPM were included as primary outcomes. The last search date was August 2017. Three online databases were used to identify relevant references: Medline via PubMed, Embase and Cochrane Library. In addition, hand searching in the reference lists of selected studies was performed. The terms ((hypomineralized AND second AND primary AND molars) OR (deciduous AND molar AND hypomineralization) OR HSPM) OR ((molar AND incisor AND hypomineralization) OR (demarcated AND opacities) OR MIH) were entered into the search fields. The search was limited to English and French language articles. The title and abstract of identified studies were screened by three reviewers (AD, EG and YD) for eligibility. Consensus was obtained by discussion or consultation with one other reviewer (PR). Studies that did not include recording of demarcated enamel hypomineralisation on primary and permanent molars were excluded. Studies that were literature reviews or case reports were excluded. If there were multiple articles based on the same population, only the study which reported the most detailed data was included. Redundant studies that were identified in more than one database were removed. Four reviewers (AD, EG, PR and YD) then independently read the studies in entirety. In addition, the reference sections of the included studies were hand searched to identify additional publications not found in the databases.
2.2
Data extraction
Data extraction was performed using spreadsheets (Excel 2007, Microsoft © , CA, USA) by two reviewers (AD and EG) and checked by two other reviewers (YD and PR). Disagreements were discussed and consensus reached. The aim, country, study design, patient characteristics (country of residence and age), and sample size of each eligible study were collected.
2.3
Assessment of risk of bias
The risk of bias assessment was conducted by two reviewers (EG and PR). The methodological quality of the included studies was scored according to the Newcastle–Ottawa Scale (NOS) [ ]. The NOS is a star rating system that allocates a maximum of nine stars across three categories: participant selection (four stars), comparability (two stars) and measurement of outcome in cohort (three stars). Regarding the cross-sectional studies, NOS criteria were adapted, thus, the last point on “adequacy of follow up of cohorts” were deleted, so for measurement of outcome in cohort the maximum number of stars is two. Cohort studies with fewer than six stars and cross-sectional studies with fewer than five stars were considered to be at high risk of bias; subsequently no studies were excluded.
2.4
Statistical analysis
The odds ratio (OR) with 95% confidence interval (CI) was used to test the association between HSPM and MIH. Review Manager (RevMan) version 5.3. was used to perform the heterogeneity calculation and meta-analysis using random-effects models [ ]. A P value ≤ 0.05 was considered statistically significant (Z-test). The significance of any discrepancies in the estimates from different studies was assessed by mean of the I 2 statistic, which describes the percentage total variation across studies that is due to heterogeneity rather than change. Due to the small number of studies included, a formal test of publication bias (such as a funnel plot) could not be performed.
3
Results
3.1
Study selection
The details of the literature search and the process of article selection are summarized in Fig. 1 . The search resulted in 644 publications from PubMed, 1 from manual search, and no study from Cochrane and Embase databases. From a total of 645 citations, 631 were excluded according to the selection criteria. The reference lists of the 13 articles were manually searched to identify publications not identified in previous screenings; subsequently one study was included [ ]. After full-text reading of the remaining 14 articles, a further 9 were excluded due to lack of prevalence figures for MIH or HSPM, unclear diagnostic criteria for MIH (for example, diffuse opacities recording), studies did not include clinical data or contained a duplicate population. The total number of excluded articles were 640, with five articles remaining for qualitative analysis [ ].
3.2
Study characteristics
The sample size of the included studies ranged from 134 to 2327 participants, a total of 4662 included children. Descriptive characteristics of the five studies are shown in Table 1 . Articles were published between 2012 and 2016. Three studies were conducted in schools and the others in medical centres. European Academy of Paediatric Dentistry (EAPD) diagnostic criteria for MIH were used in all studies. EAPD criteria include absence or presence of demarcated opacities; posteruptive enamel breakdown; atypical restorations; extraction of molars due to MIH; failure of eruption of a molar or an incisor [ ] (supplementary Table S1). Four studies performed intra-examiner reliability tests which ranged from 0.8 to 0.95, highlighting almost perfect agreement [ ]. Table 1 shows the characterization of the studies in relation to their country of publication, type of study design, and age of the subjects. The studies were performed on three continents: Asia, South America and Europe. Studies were either cohort [ ] or cross-sectional [ ] in nature.
