Original Paper Received: January 20, 2014 Accepted after revision: February 10, 2015 Published online: May 13, 2015
Caries Res 2015;49:378–383 DOI: 10.1159/000380858
Longitudinal Evaluation of the Structural Integrity of Teeth Affected by Molar Incisor Hypomineralisation Camila Maria Bullio Fragelli a Fabiano Jeremias a Juliana Feltrin de Souza b Marco Aurélio Paschoal c Rita de Cássia Loiola Cordeiro a Lourdes Santos-Pinto a
a
Department of Pediatric Dentistry and Orthodontics, Araraquara School of Dentistry, UNESP, Universidade Estadual Paulista, São Paulo, b Department of Pediatric Dentistry, Universidade Positivo, Curitiba, and c Department of Pediatric Dentistry, Universidade CEUMA, Maranhão, Brazil
Key Words Child studies · Longitudinal studies · Tooth demineralization
Abstract The aim of this prospective cohort study was to evaluate the risk of posteruptive breakdown and the development of caries lesions in teeth with molar incisor hypomineralisation (MIH). A total of 367 permanent incisors and first molars, affected and not affected by MIH lesions, of 45 children with MIH from Araraquara, São Paulo, Brazil, were evaluated at intervals from 6 to 12 months by assessing the severity of MIH, the presence of tooth caries lesions and the treatment needed. During the study period, all patients received preventive care. The data were analysed using Fisher’s exact test and actuarial method survival analysis. Significant associations were also found in teeth between the presence of MIH and a DMFT index >0 in all periods and also between the need for treatment and the presence of MIH. The teeth affected by MIH opacities were healthy in 99% of incisors and 93% of molars at the end of the 12-month period. Due to the high likelihood of maintaining the tooth structure in opacities, the complete or premature removal of the affected area is not justified. © 2015 S. Karger AG, Basel
© 2015 S. Karger AG, Basel 0008–6568/15/0494–0378$39.50/0 E-Mail [email protected] www.karger.com/cre
Molar incisor hypomineralisation (MIH), defined in 2001 as a qualitative enamel defect of systemic origin, affects from 1 to 4 of the first permanent molars and can also be associated with the permanent incisors [Weerheijm et al., 2003]. The world prevalence of MIH ranges from 2.4 to 40% [Jalevik, 2010], and according to 2 recent systematic reviews [Crombie et al., 2009; Alaluusua, 2010], the aetiology of MIH remains unknown. Clinically, the hypomineralised enamel presents as a white to yellow or brown porous opacity [Weerheijm, 2003], with borders that are clear and distinct from the healthy enamel [Jalevik and Noren, 2000]. At times, the opacity is so porous that immediately after eruption, it may break, leaving the dentin exposed and enabling dental caries lesions to develop [Jalevik et al., 2001; Weerheijm et al., 2003; Weerheijm, 2004]. Cross-sectional studies [Leppaniemi et al., 2001; Da Costa-Silva et al., 2011] have highlighted the occurrence of posteruptive breakdown in teeth affected by MIH due to the reduced mechanical properties of the affected enamel structure [Mahoney et al., 2004a, b; Xie et al., 2008]. The yellow and brown opacities are more porous [Jalevik and Noren, 2001], with a clinically higher risk of breakdown than the white opacities [Da Costa-Silva et al., 2011]. The unprotected dentin favours the development of carious lesions [Jalevik et al., 2001; Weerheijm et al., Lourdes Santos-Pinto Faculdade de Odontologia de Araraquara – UNESP Rua Humaitá, 1680 Araraquara, SP 14801-903 (Brazil) E-Mail lspinto @ foar.unesp.br
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Methodology Approval for this study was obtained from the Ethics and Research Committee of the Araraquara Dental School, São Paulo, Brazil (protocol No. 41/09) and performed after the parents or guardians of the children had signed the written, free and clarified consent. Study Design This prospective cohort study included 3 clinical examinations performed at 6-month intervals in children aged from 6 to 9 years who attended the Paediatric Dentistry Clinic of the Araraquara Dental School in São Paulo, Brazil. Subjects At baseline, the 45 children included in the study had been previously diagnosed with MIH. The participants were selected from the previous epidemiological survey, attended by 1,157 children, with an MIH prevalence of 12.3% [Jeremias et al., 2013]. Children diagnosed with MIH and presenting inclusion criteria were invited to participate. The inclusion criteria were children born and living in Araraquara. The exclusion criteria were enamel tooth malformation linked to syndromes, dental fluorosis, imperfect amelogenesis and the presence of fixed orthodontic appliances. Teeth with restoration, posteruptive breakdown or need for treatment at baseline were excluded. At baseline, the number of teeth examined (incisors and first molars, permanent teeth) was 367: 185 with MIH (affected group) and 182 without (control group). Follow-up evaluations were performed at 6 and 12 months. Calibration and Reproducibility A single examiner was calibrated according to the DMFT index criteria for tooth decay [World Health Organisation, 1997]. The ‘Treatment needs for individual teeth’ scores [World Health Organisation, 1997] were employed to determine the necessity of treatment. The diagnosis of MIH was based on criteria proposed by the European Academy of Paediatric Dentistry [Weerheijm et al., 2003]. The examiner evaluated 32 clinical photographs of patients from the Clinic of Paediatric Dentistry of the Araraquara Dental School in São Paulo, Brazil, followed by a discussion with the MIH research team of all the indices, codes and criteria to be used. After agreement had been reached, patients presenting with enamel alterations (17 of them with MIH) were evaluated. After 2 weeks, the patients were evaluated again, and the kappa index was used to verify the agreement between the evaluations. The intra-administrator values for tooth decay and for MIH were greater than 0.89.
Structural Integrity of Molar Incisor Hypomineralisation
Evaluation of MIH Severity and Treatment The three clinical examinations (baseline, 6 and 12 months) were performed in a clinical environment according to examinations approved by the World Health Organisation [1997] under artificial lights and after cleaning and drying the teeth with sterile gauze. The severity of MIH in each affected tooth at baseline was graded based on the severest defect on its surface. Enamel opacities were divided according to their colouring into white, yellow and brown groups. The structural losses were classified as mild, i.e. teeth with small enamel losses involving more than one surface but without involving cusps, or severe, i.e. with crown degradation involving the cusp. Teeth not affected by MIH were considered unchanged. The severity of MIH for each patient was graded at baseline based on the most severely affected tooth. Patients with teeth affected in only opacity were classified as having mild MIH, and patients with structural losses or atypical restorations were classified as having severe MIH. The DMFT and dmft indexes were determined according to the World Health Organisation criteria at baseline [World Health Organisation, 1997]. The presence or absence of glass ionomer cement restorations was observed at baseline. The patients monitored in this research received, over 1 month, weekly 5% fluoride varnish applications (Duraphat® Colgate, New York, USA) to all teeth, as well as oral hygiene instructions. Evaluation of the Aggravation of MIH Severity and the Incidence of Tooth Caries At baseline, the teeth, permanent incisors and first molars, were divided into two groups: affected by MIH (MIH group) and sound (control group). All first molars and permanent incisors were photographed to document and compare the integrity of the dental enamel in subsequent evaluations. Follow-up examinations were performed at 6 and 12 months under the same conditions as the initial examination. To ensure high-quality descriptions of the clinical findings, photographs were taken of the affected teeth in all dental examinations for later comparisons. For all patients, the existence of tooth caries was determined by the presence of decayed tooth surfaces and restored or lost elements (DMFT index). A DMFT index >0 was considered positive and indicated the need for treatment such as restorations, endodontic treatment or extractions. Sealant treatments and preventive care were not considered. Increases in the severity of MIH in the group of teeth affected by opacities were determined during the clinical examination by verifying the presence of mild or severe posteruptive breakdown. The teeth that were not affected by MIH, i.e. the control group, were similarly followed longitudinally. The MIH criteria were not applied to this group. Statistical Analysis The data were analysed using the Statistical Package for Social Sciences computer program, version 16.0 for Windows (SPSS Inc., Chicago, Ill., USA). Descriptive statistics were used to present the results. Associations between the categorical variables were assessed using Fisher’s exact test at a significance level of 5% and relative risk (with 95% confidence intervals). The actuarial method was used to evaluate the survival of MIH opacities, considering the different periods of analysis and information on patients while they took part in the study [Szklo and Nieto, 2000].
Caries Res 2015;49:378–383 DOI: 10.1159/000380858
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2003]. This point suggests an association between the presence of these defects and dental caries, as reported by several authors [Leppaniemi et al., 2001; Muratbegovic et al., 2007; Da Costa-Silva et al., 2010]. Based on the above considerations, the objective of this longitudinal study was to evaluate the clinical characteristics of teeth presenting with MIH and to assess the risk of posteruptive breakdown and the development of tooth caries lesions.
c
b
e
d
Color version available online
a
f
Fig. 1. From left to right: white, yellow and brown opacities on permanent incisors at baseline (a), 6 months (b) and 12 months (c); white, yellow and brown opacities on permanent incisors at baseline (d), 6 months (e) and posteruptive breakdown on permanent incisor at 12 months (f).
Table 1. Increase in the severity of MIH by opacity group after 6
Results
and 12 months of observation
380
Caries Res 2015;49:378–383 DOI: 10.1159/000380858
Severity of MIH
Baseline
Follow-up: 6 months PEB
Follow-up: 12 months PEB
White opacity Yellow opacity Brown opacity
116 (62.7) 41 (22.2) 28 (15.1)
1 (0.86) 1 (2.4) 4 (14.3)
– – 1 (3.5)
Data are numbers with percentages in parentheses. PEB = Posteruptive enamel breakdown.
sociation was also found at 12 months between the presence of MIH and a DMFT index >0, indicating a close correlation of MIH and the experience of tooth caries (table 3). Of the 45 patients treated, 5 had posteruptive fractures. Three of the 7 posteruptive breakdowns occurred in the same patient, 2 at 6 months and 1 at 12 months. For statistical analyses considering the patient characteristics (table 4), only the interval of 0–6 months was considered as there were no new patients with fractures at 12 months. There were no statistically significant differences among posteruptive breakdowns, DMFT index, dmft index, gender and glass ionomer cement restorations at the baseline analysis (table 4). There was a statistically significant difference between only posteruptive breakdown and MIH severity (p = 0.032; table 4). Fragelli et al.
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The permanent first molars and incisors of 45 children were followed, and only 7 children were lost to the followup examinations; however, their data were included while they participated in the research. The average participant age was 8.11 years old, with a median of 8.2 years (6.37– 9.54), and 57.7% of the sample was male. The average participant age after lost participants was 8.12 years old, with a median of 8.5 years (6.42–9.54), and 57.8% was male. At baseline, the number of teeth presenting MIH opacities was 185 (50.5%), and 182 (49.5%) had no signs of MIH. The severity of MIH changed during the study period (table 1) due to posteruptive breakdown in teeth with MIH opacities (fig. 1). Posteruptive breakdown occurred in 7 teeth affected by MIH, and 6 broke down after the 6-month follow-up. Brown opacities were associated with enamel breakdown in 5 teeth. There was only 1 case of incisor breakdown, and 3 of the 7 posteruptive breakdowns occurred in the same patient. Five of 6 molars exhibited cup envelopment with enamel breakdown and were classified as severe posteruptive breakdown. At the end of 12 months, the likelihood of an opacity remaining unchanged in a molar with MIH was 93%, compared to 99% in an incisor with MIH (table 2). The need for treatment and the presence of MIH demonstrated a statistically significant association at 6 months, as verified by the greater need for treatment in teeth affected by MIH than in non-affected teeth (table 3). An as-
Table 2. Actuarial methods for the affected group Interval, months (x)
Subjects Subjects withdrawn Subjects at living at start during the risk during of interval (lx) interval (wx) the interval (rx)
Deaths during the interval (dx)
Death rate during the interval (qx)
Survival rate during the interval (px)
Cumulative survival rate to end of interval S(tx)
Molars
0–6 6–12
83 72
6 10
80 67
5 1
0.062 0.014
0.938 0.986
0.938 0.948
Incisors
0–6 6–12
102 99
2 11
101 93.5
1 0
0.009 –
0.991 –
0.991 0.991
Where: rx = lx – wx/2, qx = dx/rx and px = 1 – qx.
Table 3. Numbers and percentages (in parentheses) of teeth according to the presence (affected group) and absence (control group) of MIH associated with DMFT >0 and positive TN MIH
DMFT >0
p
RR
Positive TN
p
RR
Baseline Positive (n = 185) Negative (n = 182)
0 (0.0) 0 (0.0)
–
–
0 (0.0) 0 (0.0)
–
–
6 months Positive (n = 177) Negative (n = 168)
6 (3.3) 2 (1.1)
0.159
2.84 [0.58–13.9]
7 (3.9) 1 (0.5)
0.038
6.72 [0.83–54.0]
12 months Positive (n = 156) Negative (n = 147)
8 (5.1) 1 (0.6)
0.022
7.53 [0.95–59.5]
3 (1.9) 0 (0)
0.135
–
RR = Relative risk; 95% confidence intervals are given in square brackets; TN = treatment need. p values were assessed by Fisher’s exact test, a = 5%. Italics indicate statistically significant p values.
Table 4. Associations between posteruptive breakdown and MIH severity, DMFT index, dmft index, gender and GIC presence of patients
affected by MIH Variable
Patients with PEB
Patients without PEB
p
RR
MIH severity Mild Severe
4 (28.6) 1 (3.5)
10 (71.4) 28 (96.5)
0.032
8.28 [1.01–67.42]
DMFT index 0 >0
3 (25.0) 2 (6.5)
9 (75.0) 29 (93.5)
0.123
3.87 [0.73–20.39]
dmft index 0 >0
3 (18.7) 2 (7.4)
13 (81.3) 25 (92.6)
0.259
2.53 [0.47–13.56]
Gender Female Male
2 (11.1) 3 (12.0)
16 (88.9) 22 (88.0)
0.657
0.92 [0.17–4.98]
GIC restoration presence Presence Absence
1 (4.8) 4 (18.2)
20 (95.2) 18 (81.8)
0.186
0.26 [0.03–2.15]
Structural Integrity of Molar Incisor Hypomineralisation
Caries Res 2015;49:378–383 DOI: 10.1159/000380858
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PEB = Posteruptive breakdown; figures in parentheses are percentages; RR = relative risk; 95% confidence intervals are given in square brackets; GIC = glass ionomer cement. p values were assessed by Fisher’s exact test, a = 5%. Italics indicate statistically significant p values.
The enamel alteration termed MIH presents a great challenge to all dentists, and longitudinal studies that have evaluated the clinical behaviour of affected teeth have been extremely important in supporting treatment decisions. This work is, however, the first prospective longitudinal study that has followed MIH opacities and demonstrated that the risk of enamel breakdown increases over time. Over 12 months, 7 patients deferred treatment, and the main reason for drop-outs was a lack of interest in the follow-up treatment. Thus, it was important to maintain continuous reinforcement with the families, focusing on the importance of periodic follow-up in patients with MIH. Statistically significant relationships among MIH, tooth caries and the need for treatment were observed in this study. The MIH opacities are hypomineralised areas with porosities that may cause plaque retention. Additionally, the usual sensitivity of such teeth causes children to avoid dental hygiene, increasing the stagnation of food. In addition, enamel breakdown leading to unprotected dentin and caries can develop easily [Weerheijm et al., 2003]. MIH patients’ susceptibility to tooth decay and follow-up needs have been cited by other authors [Mejare et al., 2005; Muratbegovic et al., 2007; Da Costa-Silva et al., 2010, 2011]. These findings indicate that patients who are affected by MIH require early and periodical clinical examinations to avoid damage to oral health. In 2002, Jalevik and Klingberg [2002] reported that patients with MIH require up to 10 times more treatments than patients not affected by MIH. Furthermore, Leppaniemi et al. [2001] concluded that MIH has a relevant impact on the need for treatment, even in patients with few tooth caries lesions. The treatment indications in teeth affected by MIH vary according to the degree of severity. Treatments include prevention, conservative or invasive restorations with the removal of all affected areas and the extraction of the first molar affected, followed by orthodontic treatment or spontaneous closure of the space [Lygidakis et al., 2010]. In this study, it was observed that even under frequent clinical observation and with preventive care, including fluoride varnish application, new breakdowns occurred, especially in areas with yellow and brown opacities, corroborating previous findings about the increased risk of enamel breakdown in teeth with yellow and brown MIH opacities [Da Costa-Silva et al., 2011]. Among the 185 teeth with MIH opacities, only 7 break382
Caries Res 2015;49:378–383 DOI: 10.1159/000380858
downs occurred. This low rate leads us to infer that complete or premature removal of the affected area is not justified [Lygidakis et al., 2003; Zagdwon et al., 2003; Takahashi et al., 2009]. The breakdowns of opacities occurred predominantly in molars, most likely due to the influence of masticatory efforts on the compromised structures [Weerheijm et al., 2003; Weerheijm, 2004; Da Costa-Silva et al., 2011]. Clinically, it is challenging to predict the risk of breakdown of MIH enamel opacities. This study considers only 2 factors, the colour of the MIH opacity and the type of tooth. The yellow and brown enamel opacities and molar teeth increased the risk of enamel breakdown, suggesting that these areas are defective enamel with low resistance and greater susceptibility to breakdown and dental caries. This finding could help clinicians make decisions on child treatment.
Conclusions
The risk of posteruptive breakdown in molars was 7%, and in incisors it was 1%. However, the teeth affected by MIH were at greater risk of developing tooth decay and exhibited a greater need for treatment than unaffected teeth.
Acknowledgements We thank the Research Foundation of the State of São Paulo (FAPESP) and the National Council for Scientific and Technological Development (CNPq) for financial support.
Disclosure Statement There are no conflicts of interest in this paper.
References
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Discussion
Structural Integrity of Molar Incisor Hypomineralisation
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Caries Res 2015;49:378–383 DOI: 10.1159/000380858
Longitudinal Evaluation of the Structural Integrity of Teeth Affected by Molar Incisor Hypomineralisation Camila Maria Bullio Fragelli a Fabiano Jeremias a Juliana Feltrin de Souza b Marco Aurélio Paschoal c Rita de Cássia Loiola Cordeiro a Lourdes Santos-Pinto a
a
Department of Pediatric Dentistry and Orthodontics, Araraquara School of Dentistry, UNESP, Universidade Estadual Paulista, São Paulo, b Department of Pediatric Dentistry, Universidade Positivo, Curitiba, and c Department of Pediatric Dentistry, Universidade CEUMA, Maranhão, Brazil
Key Words Child studies · Longitudinal studies · Tooth demineralization
Abstract The aim of this prospective cohort study was to evaluate the risk of posteruptive breakdown and the development of caries lesions in teeth with molar incisor hypomineralisation (MIH). A total of 367 permanent incisors and first molars, affected and not affected by MIH lesions, of 45 children with MIH from Araraquara, São Paulo, Brazil, were evaluated at intervals from 6 to 12 months by assessing the severity of MIH, the presence of tooth caries lesions and the treatment needed. During the study period, all patients received preventive care. The data were analysed using Fisher’s exact test and actuarial method survival analysis. Significant associations were also found in teeth between the presence of MIH and a DMFT index >0 in all periods and also between the need for treatment and the presence of MIH. The teeth affected by MIH opacities were healthy in 99% of incisors and 93% of molars at the end of the 12-month period. Due to the high likelihood of maintaining the tooth structure in opacities, the complete or premature removal of the affected area is not justified. © 2015 S. Karger AG, Basel
© 2015 S. Karger AG, Basel 0008–6568/15/0494–0378$39.50/0 E-Mail [email protected] www.karger.com/cre
Molar incisor hypomineralisation (MIH), defined in 2001 as a qualitative enamel defect of systemic origin, affects from 1 to 4 of the first permanent molars and can also be associated with the permanent incisors [Weerheijm et al., 2003]. The world prevalence of MIH ranges from 2.4 to 40% [Jalevik, 2010], and according to 2 recent systematic reviews [Crombie et al., 2009; Alaluusua, 2010], the aetiology of MIH remains unknown. Clinically, the hypomineralised enamel presents as a white to yellow or brown porous opacity [Weerheijm, 2003], with borders that are clear and distinct from the healthy enamel [Jalevik and Noren, 2000]. At times, the opacity is so porous that immediately after eruption, it may break, leaving the dentin exposed and enabling dental caries lesions to develop [Jalevik et al., 2001; Weerheijm et al., 2003; Weerheijm, 2004]. Cross-sectional studies [Leppaniemi et al., 2001; Da Costa-Silva et al., 2011] have highlighted the occurrence of posteruptive breakdown in teeth affected by MIH due to the reduced mechanical properties of the affected enamel structure [Mahoney et al., 2004a, b; Xie et al., 2008]. The yellow and brown opacities are more porous [Jalevik and Noren, 2001], with a clinically higher risk of breakdown than the white opacities [Da Costa-Silva et al., 2011]. The unprotected dentin favours the development of carious lesions [Jalevik et al., 2001; Weerheijm et al., Lourdes Santos-Pinto Faculdade de Odontologia de Araraquara – UNESP Rua Humaitá, 1680 Araraquara, SP 14801-903 (Brazil) E-Mail lspinto @ foar.unesp.br
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Methodology Approval for this study was obtained from the Ethics and Research Committee of the Araraquara Dental School, São Paulo, Brazil (protocol No. 41/09) and performed after the parents or guardians of the children had signed the written, free and clarified consent. Study Design This prospective cohort study included 3 clinical examinations performed at 6-month intervals in children aged from 6 to 9 years who attended the Paediatric Dentistry Clinic of the Araraquara Dental School in São Paulo, Brazil. Subjects At baseline, the 45 children included in the study had been previously diagnosed with MIH. The participants were selected from the previous epidemiological survey, attended by 1,157 children, with an MIH prevalence of 12.3% [Jeremias et al., 2013]. Children diagnosed with MIH and presenting inclusion criteria were invited to participate. The inclusion criteria were children born and living in Araraquara. The exclusion criteria were enamel tooth malformation linked to syndromes, dental fluorosis, imperfect amelogenesis and the presence of fixed orthodontic appliances. Teeth with restoration, posteruptive breakdown or need for treatment at baseline were excluded. At baseline, the number of teeth examined (incisors and first molars, permanent teeth) was 367: 185 with MIH (affected group) and 182 without (control group). Follow-up evaluations were performed at 6 and 12 months. Calibration and Reproducibility A single examiner was calibrated according to the DMFT index criteria for tooth decay [World Health Organisation, 1997]. The ‘Treatment needs for individual teeth’ scores [World Health Organisation, 1997] were employed to determine the necessity of treatment. The diagnosis of MIH was based on criteria proposed by the European Academy of Paediatric Dentistry [Weerheijm et al., 2003]. The examiner evaluated 32 clinical photographs of patients from the Clinic of Paediatric Dentistry of the Araraquara Dental School in São Paulo, Brazil, followed by a discussion with the MIH research team of all the indices, codes and criteria to be used. After agreement had been reached, patients presenting with enamel alterations (17 of them with MIH) were evaluated. After 2 weeks, the patients were evaluated again, and the kappa index was used to verify the agreement between the evaluations. The intra-administrator values for tooth decay and for MIH were greater than 0.89.
Structural Integrity of Molar Incisor Hypomineralisation
Evaluation of MIH Severity and Treatment The three clinical examinations (baseline, 6 and 12 months) were performed in a clinical environment according to examinations approved by the World Health Organisation [1997] under artificial lights and after cleaning and drying the teeth with sterile gauze. The severity of MIH in each affected tooth at baseline was graded based on the severest defect on its surface. Enamel opacities were divided according to their colouring into white, yellow and brown groups. The structural losses were classified as mild, i.e. teeth with small enamel losses involving more than one surface but without involving cusps, or severe, i.e. with crown degradation involving the cusp. Teeth not affected by MIH were considered unchanged. The severity of MIH for each patient was graded at baseline based on the most severely affected tooth. Patients with teeth affected in only opacity were classified as having mild MIH, and patients with structural losses or atypical restorations were classified as having severe MIH. The DMFT and dmft indexes were determined according to the World Health Organisation criteria at baseline [World Health Organisation, 1997]. The presence or absence of glass ionomer cement restorations was observed at baseline. The patients monitored in this research received, over 1 month, weekly 5% fluoride varnish applications (Duraphat® Colgate, New York, USA) to all teeth, as well as oral hygiene instructions. Evaluation of the Aggravation of MIH Severity and the Incidence of Tooth Caries At baseline, the teeth, permanent incisors and first molars, were divided into two groups: affected by MIH (MIH group) and sound (control group). All first molars and permanent incisors were photographed to document and compare the integrity of the dental enamel in subsequent evaluations. Follow-up examinations were performed at 6 and 12 months under the same conditions as the initial examination. To ensure high-quality descriptions of the clinical findings, photographs were taken of the affected teeth in all dental examinations for later comparisons. For all patients, the existence of tooth caries was determined by the presence of decayed tooth surfaces and restored or lost elements (DMFT index). A DMFT index >0 was considered positive and indicated the need for treatment such as restorations, endodontic treatment or extractions. Sealant treatments and preventive care were not considered. Increases in the severity of MIH in the group of teeth affected by opacities were determined during the clinical examination by verifying the presence of mild or severe posteruptive breakdown. The teeth that were not affected by MIH, i.e. the control group, were similarly followed longitudinally. The MIH criteria were not applied to this group. Statistical Analysis The data were analysed using the Statistical Package for Social Sciences computer program, version 16.0 for Windows (SPSS Inc., Chicago, Ill., USA). Descriptive statistics were used to present the results. Associations between the categorical variables were assessed using Fisher’s exact test at a significance level of 5% and relative risk (with 95% confidence intervals). The actuarial method was used to evaluate the survival of MIH opacities, considering the different periods of analysis and information on patients while they took part in the study [Szklo and Nieto, 2000].
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2003]. This point suggests an association between the presence of these defects and dental caries, as reported by several authors [Leppaniemi et al., 2001; Muratbegovic et al., 2007; Da Costa-Silva et al., 2010]. Based on the above considerations, the objective of this longitudinal study was to evaluate the clinical characteristics of teeth presenting with MIH and to assess the risk of posteruptive breakdown and the development of tooth caries lesions.
c
b
e
d
Color version available online
a
f
Fig. 1. From left to right: white, yellow and brown opacities on permanent incisors at baseline (a), 6 months (b) and 12 months (c); white, yellow and brown opacities on permanent incisors at baseline (d), 6 months (e) and posteruptive breakdown on permanent incisor at 12 months (f).
Table 1. Increase in the severity of MIH by opacity group after 6
Results
and 12 months of observation
380
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Severity of MIH
Baseline
Follow-up: 6 months PEB
Follow-up: 12 months PEB
White opacity Yellow opacity Brown opacity
116 (62.7) 41 (22.2) 28 (15.1)
1 (0.86) 1 (2.4) 4 (14.3)
– – 1 (3.5)
Data are numbers with percentages in parentheses. PEB = Posteruptive enamel breakdown.
sociation was also found at 12 months between the presence of MIH and a DMFT index >0, indicating a close correlation of MIH and the experience of tooth caries (table 3). Of the 45 patients treated, 5 had posteruptive fractures. Three of the 7 posteruptive breakdowns occurred in the same patient, 2 at 6 months and 1 at 12 months. For statistical analyses considering the patient characteristics (table 4), only the interval of 0–6 months was considered as there were no new patients with fractures at 12 months. There were no statistically significant differences among posteruptive breakdowns, DMFT index, dmft index, gender and glass ionomer cement restorations at the baseline analysis (table 4). There was a statistically significant difference between only posteruptive breakdown and MIH severity (p = 0.032; table 4). Fragelli et al.
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The permanent first molars and incisors of 45 children were followed, and only 7 children were lost to the followup examinations; however, their data were included while they participated in the research. The average participant age was 8.11 years old, with a median of 8.2 years (6.37– 9.54), and 57.7% of the sample was male. The average participant age after lost participants was 8.12 years old, with a median of 8.5 years (6.42–9.54), and 57.8% was male. At baseline, the number of teeth presenting MIH opacities was 185 (50.5%), and 182 (49.5%) had no signs of MIH. The severity of MIH changed during the study period (table 1) due to posteruptive breakdown in teeth with MIH opacities (fig. 1). Posteruptive breakdown occurred in 7 teeth affected by MIH, and 6 broke down after the 6-month follow-up. Brown opacities were associated with enamel breakdown in 5 teeth. There was only 1 case of incisor breakdown, and 3 of the 7 posteruptive breakdowns occurred in the same patient. Five of 6 molars exhibited cup envelopment with enamel breakdown and were classified as severe posteruptive breakdown. At the end of 12 months, the likelihood of an opacity remaining unchanged in a molar with MIH was 93%, compared to 99% in an incisor with MIH (table 2). The need for treatment and the presence of MIH demonstrated a statistically significant association at 6 months, as verified by the greater need for treatment in teeth affected by MIH than in non-affected teeth (table 3). An as-
Table 2. Actuarial methods for the affected group Interval, months (x)
Subjects Subjects withdrawn Subjects at living at start during the risk during of interval (lx) interval (wx) the interval (rx)
Deaths during the interval (dx)
Death rate during the interval (qx)
Survival rate during the interval (px)
Cumulative survival rate to end of interval S(tx)
Molars
0–6 6–12
83 72
6 10
80 67
5 1
0.062 0.014
0.938 0.986
0.938 0.948
Incisors
0–6 6–12
102 99
2 11
101 93.5
1 0
0.009 –
0.991 –
0.991 0.991
Where: rx = lx – wx/2, qx = dx/rx and px = 1 – qx.
Table 3. Numbers and percentages (in parentheses) of teeth according to the presence (affected group) and absence (control group) of MIH associated with DMFT >0 and positive TN MIH
DMFT >0
p
RR
Positive TN
p
RR
Baseline Positive (n = 185) Negative (n = 182)
0 (0.0) 0 (0.0)
–
–
0 (0.0) 0 (0.0)
–
–
6 months Positive (n = 177) Negative (n = 168)
6 (3.3) 2 (1.1)
0.159
2.84 [0.58–13.9]
7 (3.9) 1 (0.5)
0.038
6.72 [0.83–54.0]
12 months Positive (n = 156) Negative (n = 147)
8 (5.1) 1 (0.6)
0.022
7.53 [0.95–59.5]
3 (1.9) 0 (0)
0.135
–
RR = Relative risk; 95% confidence intervals are given in square brackets; TN = treatment need. p values were assessed by Fisher’s exact test, a = 5%. Italics indicate statistically significant p values.
Table 4. Associations between posteruptive breakdown and MIH severity, DMFT index, dmft index, gender and GIC presence of patients
affected by MIH Variable
Patients with PEB
Patients without PEB
p
RR
MIH severity Mild Severe
4 (28.6) 1 (3.5)
10 (71.4) 28 (96.5)
0.032
8.28 [1.01–67.42]
DMFT index 0 >0
3 (25.0) 2 (6.5)
9 (75.0) 29 (93.5)
0.123
3.87 [0.73–20.39]
dmft index 0 >0
3 (18.7) 2 (7.4)
13 (81.3) 25 (92.6)
0.259
2.53 [0.47–13.56]
Gender Female Male
2 (11.1) 3 (12.0)
16 (88.9) 22 (88.0)
0.657
0.92 [0.17–4.98]
GIC restoration presence Presence Absence
1 (4.8) 4 (18.2)
20 (95.2) 18 (81.8)
0.186
0.26 [0.03–2.15]
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PEB = Posteruptive breakdown; figures in parentheses are percentages; RR = relative risk; 95% confidence intervals are given in square brackets; GIC = glass ionomer cement. p values were assessed by Fisher’s exact test, a = 5%. Italics indicate statistically significant p values.
The enamel alteration termed MIH presents a great challenge to all dentists, and longitudinal studies that have evaluated the clinical behaviour of affected teeth have been extremely important in supporting treatment decisions. This work is, however, the first prospective longitudinal study that has followed MIH opacities and demonstrated that the risk of enamel breakdown increases over time. Over 12 months, 7 patients deferred treatment, and the main reason for drop-outs was a lack of interest in the follow-up treatment. Thus, it was important to maintain continuous reinforcement with the families, focusing on the importance of periodic follow-up in patients with MIH. Statistically significant relationships among MIH, tooth caries and the need for treatment were observed in this study. The MIH opacities are hypomineralised areas with porosities that may cause plaque retention. Additionally, the usual sensitivity of such teeth causes children to avoid dental hygiene, increasing the stagnation of food. In addition, enamel breakdown leading to unprotected dentin and caries can develop easily [Weerheijm et al., 2003]. MIH patients’ susceptibility to tooth decay and follow-up needs have been cited by other authors [Mejare et al., 2005; Muratbegovic et al., 2007; Da Costa-Silva et al., 2010, 2011]. These findings indicate that patients who are affected by MIH require early and periodical clinical examinations to avoid damage to oral health. In 2002, Jalevik and Klingberg [2002] reported that patients with MIH require up to 10 times more treatments than patients not affected by MIH. Furthermore, Leppaniemi et al. [2001] concluded that MIH has a relevant impact on the need for treatment, even in patients with few tooth caries lesions. The treatment indications in teeth affected by MIH vary according to the degree of severity. Treatments include prevention, conservative or invasive restorations with the removal of all affected areas and the extraction of the first molar affected, followed by orthodontic treatment or spontaneous closure of the space [Lygidakis et al., 2010]. In this study, it was observed that even under frequent clinical observation and with preventive care, including fluoride varnish application, new breakdowns occurred, especially in areas with yellow and brown opacities, corroborating previous findings about the increased risk of enamel breakdown in teeth with yellow and brown MIH opacities [Da Costa-Silva et al., 2011]. Among the 185 teeth with MIH opacities, only 7 break382
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downs occurred. This low rate leads us to infer that complete or premature removal of the affected area is not justified [Lygidakis et al., 2003; Zagdwon et al., 2003; Takahashi et al., 2009]. The breakdowns of opacities occurred predominantly in molars, most likely due to the influence of masticatory efforts on the compromised structures [Weerheijm et al., 2003; Weerheijm, 2004; Da Costa-Silva et al., 2011]. Clinically, it is challenging to predict the risk of breakdown of MIH enamel opacities. This study considers only 2 factors, the colour of the MIH opacity and the type of tooth. The yellow and brown enamel opacities and molar teeth increased the risk of enamel breakdown, suggesting that these areas are defective enamel with low resistance and greater susceptibility to breakdown and dental caries. This finding could help clinicians make decisions on child treatment.
Conclusions
The risk of posteruptive breakdown in molars was 7%, and in incisors it was 1%. However, the teeth affected by MIH were at greater risk of developing tooth decay and exhibited a greater need for treatment than unaffected teeth.
Acknowledgements We thank the Research Foundation of the State of São Paulo (FAPESP) and the National Council for Scientific and Technological Development (CNPq) for financial support.
Disclosure Statement There are no conflicts of interest in this paper.
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Discussion
Structural Integrity of Molar Incisor Hypomineralisation
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