Prevalence and diagnosis of Molar-Incisor-Hypomineralisation (MIH): a systematic review.
Abstract: AIM: This was to review the literature published, to point out shortcomings and to suggest areas in need of improvement concerning the diagnosis and prevalence of MIH. METHODs: A broad search of the PubMed database was conducted. Relevant papers published in English were identified after a review of their titles, abstracts or full reading of the papers. Papers were selected if the number of children with at least one first permanent molar affected by demarcated opacities could be deciphered. Targeted publications were critically assessed by the author concerning examination criteria, selection and character of the study groups, examiners' calibration and result presentation. RESULTS: The initial search revealed 414 papers of which 24 met the inclusion criteria. A wide variation in defect prevalence (2.4 -40.2 %) was reported. Cross comparison of the results of the various studies were difficult because of use of different indices and criteria, examination variability, methods of recording and different age groups. CONCLUSIONS: Further standardization of study design and methods is needed to make the results comparable.

Key words: prevalence, diagnosis, MIH, review
Article Type: Report
Subject: Prevalence studies (Epidemiology) (Usage)
Amelogenesis imperfecta (Diagnosis)
Amelogenesis imperfecta (Care and treatment)
Amelogenesis imperfecta (Patient outcomes)
Author: Jalevik, B.
Pub Date: 04/01/2010
Publication: Name: European Archives of Paediatric Dentistry Publisher: European Academy of Paediatric Dentistry Audience: Academic Format: Magazine/Journal Subject: Health Copyright: COPYRIGHT 2010 European Academy of Paediatric Dentistry ISSN: 1818-6300
Issue: Date: April, 2010 Source Volume: 11 Source Issue: 2
Geographic: Geographic Scope: Sweden Geographic Code: 4EUSW Sweden
Accession Number: 277106730
Full Text: Introduction

Since the late 1970s, first permanent molars (FPM) with creamy-white to yellow-brown enamel opacities, in severe cases in combination with disintegration, have been observed frequently [Koch et al., 1987]. One to four molars, and often also the incisors, could be affected. Since first recognised, the condition has been puzzling and interpreted as a distinct phenomenon unlike other enamel disturbances e.g. amelogenesis imperfecta, fluorosis or chronological hypoplastic disturbances.

Diagnostic terms. Historically, a wide variety of terms and definitions have been used to describe various developmental defects of the enamel (DDE). Some are simply descriptive terms while others are linked to the causative agent e.g. fluoride. To remedy this confusion a FDI working group was established, and in 1982 the DDE index was published. This original index turned out to be too complicated to use in practice and a modified DDE index (mDDE) was presented in by FDI [1992].

Briefly, DDE are classified as demarcated opacities, diffuse opacities and hypoplasia. Opacity is defined as a qualitative defect of the enamel, whereas hypoplasia is defined as a quantitative defect of the enamel. Tooth surfaces are inspected visually, and defective areas tactilely explored with a probe. Natural or artificial light is used during examination, defects less than 1mm are not recorded, the teeth are not dried but large debris should be removed with help of a cotton roll. When the results are reported, the number of subjects with one or more teeth affected, the mean number of teeth per child affected by any defect, and by different types of defects are the standard data.

Koch et al. [1987] published a prevalence study in 1987 concerning malformed FPM. They did not use the DDE index but described the enamel defects in terms of colour and surface changes. The condition was named 'enamel hypomineralisation in FPMs'. Alaluusua and coworkers [1996a, b] published two studies concerning mineralisation defects in FPM with prevalence figures. They registered enamel defects in FPM and excluded hypoplasia, fluorosis, and defects related to major disturbances in general health. The degree of severity and size of the defects were also registered as: severe (loss of enamel with need for restoration, atypical restoration), moderate (loss of enamel), mild (colour change). Size was recorded as: large ([greater than or equal to] 4.5 mm), moderate ([approximately equal to] 3.5mm), small ([approximately equal to] 2mm).

In 2001 three studies were published reporting the prevalence of FPM with enamel defects. Leppaniemi et al. [2001] used the 'Alaluusua criteria'. Weerheijm et al. [2001b] and Jalevik et al. [2001] used the mDDE index further adapted to be able to point out the phenomenon 'hypomineralized permanent first molars'. The authors of those papers met at the EAPD congress in Bergen 2000, and concluded that they described the same phenomenon and agreed on a definition and the nomenclature molar-incisor-hypomineralisation (MIH) [Weerheijm et al., 2001a].

The subsequent EAPD seminar in Athens 2003 strove to establish the judgment criteria for MIH in epidemiological studies. The mDDE index was considered to be too time consuming and not adequate for MIH studies. Post-eruptive breakdown (PEB) is prominent feature in MIH and the mDDE index does not clearly differentiate PEB from hypoplasia.

The EAPD seminar in 2003 agreed and published the following conditions [Weerheijm et al., 2003b]:

* Permanent first molars and incisors (12 index teeth) should be examined,

* Examination for MIH should be performed on wet teeth after cleaning,

* Eight years of age was the best time for examination,

* Each tooth should be recorded for:

** absence or presence of demarcated opacities,

** posteruptive enamel breakdown,

** atypical restoration,

** extraction due to MIH,

** failure of eruption of a molar or incisor.

A number of prevalence studies of MIH have now been published from different parts of the world and a wide variation in defect prevalence has been reported. In spite of the EAPD criteria from 2003, comparison of the results of these various studies remains difficult because of the use of different indices and criteria, examination variability, methods of recording and different age groups. The aim of this paper is to review the literature concerning the diagnosis and prevalence of MIH to point out shortcomings and suggest areas in need of improvement.

Materials and Methods

A broad search of PubMed data was conducted using:

* developmental defects of the enamel (enamel developmental defects), prevalence AND developmental defects of the enamel defects (enamel developmental defects),

* molar-incisor-hypomineraliz(s)ation, prevalence AND molar-incisor-hypomineraliz(s)ation, prevalence AND MIH,

* non-fluoride hypomineraliz(s)ations in the first molars, cheese molars and hypomineraliz(s)ed permanent first molars as index terms.

To be considered for this review, the paper had to have been written in English and it must have been possible to decipher the number of children with at least one FPM affected by demarcated opacities. Of the 414 references initially found, 54 were targeted on the basis of their abstracts. After a full reading of the targeted papers, only 24 fulfilled the review criteria.

Results

All studies but one were cross sectional, observational studies. Cho et al. [2008] performed a retrospective study of records. According to the SIGN criteria, the quality of evidence of all studies was low (C-D) [Sign 50]. Only one third of the studies had study groups reflecting the background population (Table 1). Consequently, the majority of studies report the frequency of MIH in a specific group rather than as prevalence. In nearly half of the studies investigation for MIH was the main purpose. However, it could also be a part of a general dental health survey or combined with an ordinary dental examination.

The sample sizes have varied considerably. Descriptions of the study groups were generally sparse or missing. Almost half of the study groups were mixed age groups, three of them [Koch et al., 1987; Dietrich et al., 2003; Kukleva et al., 2008] reported prevalence figures for each age group separately which showed a considerable variation between the groups (Fig1).

[FIGURE 1 OMITTED]

Prior to the publication of judgment criteria for MIH compiled by the EAPD meeting in 2003, the authors had to invent their own examination criteria as in Koch et al. [1987], Alaluusua et al. [1996a, b] and Leppaniemi et al. [2001] while Jalevik et al. [2001], Weerheijm et al. [2001] and Zagdwon et al. [2002] used the mDDE criteria further modified to the entity later on denominated MIH. The condition is thoroughly described in these papers and there is no doubt that MIH is concerned. After publication of the EAPD judgment criteria in 2003, some papers refer to the mDDE criteria, some to the EAPD criteria and some to both of them (Table1). Nevertheless, a recent study [Arrow, 2008], using the mDDE criteria, does not separate posteruptive enamel breakdown from hypoplasia.

Approximately half of the investigations were performed by 1-3 examiners and in most cases they were reported to have been calibrated. One third of the papers did not report the number of investigators. The calibration procedure varied from paper to paper; sometimes it was not described at all. The reported reproducibility was always reported as satisfactory. It was reported as Kappa values, percent of agreement or just as good.

The prerequisites for the examinations differed. Some were performed as ordinary examinations in the dental chair, while others were more or less primitive field surveys. Ten studies did not report if the teeth were examined dry or wet, one reported drying teeth with air syringe and the others examined wet teeth. One fourth did not report demarcated opacities less than 2 mm, the remaining studies did not report any lower limit.

When reporting the prevalence of MIH, all papers refer to the portion of children having at least one FPM affected by MIH. Besides that, the ways in presenting results are probably as many as there are papers, such as tooth, jaw and/or gender distribution, severity and number of affected teeth.

The reported prevalence of MIH varies from 2.4% in Germany and Bulgaria [Dietrich et al., 2003; Kukleva et al., 2008] to 40.2% in Rio de Janeiro [Soveiro et al., 2009]. Actually, one study [Balmer et al., 2005] reported that 40% of children in Leeds and 44% of children in Sydney had demarcated opacities in at least one FPM. However, the study groups only consist of 25 children each, the age span was large and this study was not focusing on MIH. Therefore these results should be considered with caution.

Traditionally, there have been more studies from northern Europe, and MIH has appeared to be more common in those countries. However, lately studies have been published from other parts of the world. A very recent study from Brazil [Soviero et al., 2009] showed a prevalence of 40.2% and a study from Kenya 13.7% [Kemoli, 2008].

Discussion

Agreement on examination criteria and good, comparable studies is of utmost importance in trying to elucidate the phenomenon MIH. The criteria of the EAPD meeting in 2003 are referred to in most of the latter studies and seem to be well established among dentists with special interest in enamel disturbances. In spite of that, the methodology differs markedly from study to study making comparison difficult. Recruitment, representation, sample size and age of the examined children, wet or dry examination, minimum size of the defects, calibration of the examiners, and how to report the results are questions to be discussed.

Recruitment, representation of the study group. Only one third of the investigations were performed on whole age cohorts or randomly selected children in the target population. The other study groups could consist of patients in certain clinics, children insured by an insurance company or just schoolchildren from a selected school. How they were recruited was generally sparsely described. The ability of generalizing the results to the background population was never discussed. Information on socioeconomic and ethnic backgrounds factors was sparse and lacking discussion as to how those factors possibly could have affected the results. In those studies the frequency of MIH in a group of children is described rather than the prevalence. In all studies, descriptions of the children who dropped out were frequently missing.

Sample size and age. It is hard to give advice concerning the optimal sample size in cross sectional, observational studies. In view of the reported prevalence, the more the better is probably a good answer. Regarding the reported variation between age groups [Koch et al., 1987; Dietrich et al., 2003; Kukleva et al., 2009] a recommendation is that the frequency of MIH should be reported for each age cohort separately. The 2003 EAPD meeting recommended 8 years of age as the best age for examination. At that age, in most children, all 4 FPM should be erupted, as will the majority of incisors. At a later age, there is a greater risk that tooth coloured fillings, especially, could be masking defects. An objection would be that all FPM and incisors are not erupted.

A conceivable study design would be to examine a group of children blind every second year from 8 until 14 or 16 years of age. Then a researcher could record and study variation over time. If new cohorts were started every second year it would also be possible to elucidate variation between age cohorts in the same population. A Dutch study has shown MIH on the second primary molars [Elfrink et al,. 2008]. A clinical observation is that the tips of canines quite frequently and also maybe second permanent molars and premolars could be affected. Therefore, all erupted teeth, not only FPM:s and incisors, ought to be examined for demarcated opacities.

Wet or dry teeth examination, minimum size of defects and calibration. When establishing the mDDE criteria, wet examination was proposed by the FDI Working group [1992]. Wet examination has also been used in many MIH studies. It is important that there should be congruenceon this criteria as a higher prevalence is reported from dry examinations compared to wet.

The essential decision as to whether a defect is present or not can be difficult. Trying to help ameliorate this problem it has been proposed not to record any defects smaller than 1 mm [Clarkson and O'Mullane, 1989]. Suckling et al. [1985] found that reproducibility of small opacities (less than 2mm) was low. Six of the reviewed studies have not reported opacities smaller than 2 mm. The others had no lower limit that leads to increased risks of mis-diagnosis of e.g. white spot lesions, white cuspal ridges or a patchy appearance of amelogenesis imperfecta or fluorosis.

Training and calibration of the examiners according to validated methods should be mandatory. An important task is to work out a well-defined method that future examiners could use. When performing vigorous studies more examiners would be needed. This emphasises the need for precise and validated examination criteria as well as well defined calibration procedures.

Reporting of the results. To facilitate comparisons of results from different prevalence studies it is advocated to reach a consensus for some basic results to be reported. Besides reporting how many children have at least one FPM affected it would be useful to report the number of index teeth affected in each child with MIH. Eruption stages influence this result; therefore it is useful to report the number affected for a subgroup with all index teeth erupted [Wogelius et al., 2008, Lygidakis et al., 2008, Soviero et al., 2009].

The degree of disturbance seems to co-vary with the number of affected teeth [Jalevik et al., 2001, Jasulaityte et al., 2007], but not with the prevalence of MIH [Soviero et al,. 2009]. Therefore it is also important to report the severity of the defects in a comparable manner. Earlier studies have classified MIH into mild, moderate and severe defects [Alaluusua et al,. 1996 a,b; Jalevik et al,. 2001, Calderara et al,. 2005]. Lately, the moderate and severe groups have been combined into one group, named disintegrated or severe [Jasulaityte et al,. 2007; Lygidakis et al,. 2008]. This classification seems to involve reproducibility. To broaden the knowledge of the nature of MIH, it is of great importance to know to what extend other teeth than PFM and incisors are affected.

Conclusions

In order to reach the goal of comparable studies with good quality of evidence it is necessary to have well defined study groups representing the background population. Recruitment procedure as well as the rate of dropouts has to be very well described. Each age group ought to be reported on separately and considering the up to now reported prevalence each group ought to consist of at least 100 children. The age of 8 years, when all FPM are usually erupted is the best time for examination. An agreement on procedure and criteria of examination, as wet or dry teeth and minimum size of recorded defect, is needed. Preparing a well defined method for training and calibration of future examiners is of utmost importance. When reporting on MIH it is recommended to report the percentage of children with at least one FPM affected by MIH, the mean number of affected teeth, and the percentage of children with at least one FPM with severe defects. Information on other teeth affected than FPMs and incisors is also desirable.

Aknowledgements.

This invited paper was presented at the 6th Interim Seminar and Workshop of the European Academy of Paediatric Dentistry in Helsinki, Finland, 2009

References

Alaluusua S, Alaluusua S, Lukinmaa P-L, et al. Polychloroinated dibenzo-p-dioxins and dibenzofurans via mother's milk cause development defects in child's teeth. Environ Toxicol Pharmacol 1996a; 1: 193-197.

Alaluusua S, Lukinamaa P-L, Koskimies M, et al. Development dental defects associated with long breast feeding. Eur J Oral Sci 1996b; 104: 439-497.

Arrow P. Prevalence of developmental enamel defects of the permanent molars among school children in Western Australia. Aus Dent J 2008; 53: 250-259.

Balmer RC, Laskey D, Mahoney E, Toumba KJ. Prevalence of enamel defects and MIH in non-fluoridated and fluoridated communities. Eur J Paediatic Dent 2005; 5: 209-212.

Calderara PC, Gerthoux PM, Mocarelli P, et al. The prevalence of Molar Incisor Hypomineralisation (MIH) in a group of Italian school children. Eur J Paed Dent 2005; 6: 79-83.

Clarkson J, O'Mullane D: A modified DDE Index for use in epidemiological studies of enamel defects. J Dent Res 1989; 68: 445-450.

Cho SY, Ki Y, Chu V. Molar incisor hypomineralisation in Hong Kong Chinese children. Int J Paediatr Dent. 2008; 18: 348-352.

Dietrich G, Sperling S, Hetzer G. Molar Incisor Hypomineralisation in a group of children and adolescents living in Dresden (Germany). Eur J Paed Dent 2003; 4: 133-137.

Elfrink ME, Schuller AA, Weerheijm KL, Veerkamp JS. Hypomineralized second primary molars: prevalence data in Dutch 5-year-olds. Caries Res. 2008; 42: 282-285.

FDI Commision on Oral Health, Research and Epidemiology. A review of the development defects of enamel index (DDE Index) Int Dent J 1992; 42: 411-426.

Fleita D, Ali A, Alaluusua S. Molar-incisor hypomineralisation (MIH) in a group of school-aged children in Benghazi, Libya. European Archives of Paediatric Dentistry. 2006: 7; 92-95.

Jasulaityte L, Veerkamp KL, Weerheijm KL. Molar incisor hypomineralisation: review and prevalence data from a study of primary school children in Kaunas (Lithuania). Eur Arch Paed Dent 2007; 8: 87-94.

Jasulaityte L, Weerheijm KL, Veerkamp JS. Prevalence of Molar-Incisor-Hypomineralisation among children participating in the Dutch National Epidemiological Survey (2003). Eur Arch Paediatr Dent 2008; 218-223.

Jalevik B, Klingberg G, Barregard L, Noren JG. The prevalence of demarcated opacities in permanent first molars in a group of Swedish children. Acta Odontol Scand 2001; 59: 255-260.

Kemoli A. Prevalence of Molar Incisor Hypominalisation in six to eight year-olds in two rural divisions in Kenya. East African Med J 2008; 85: 514-519.

Koch G, Hallonsten A-L, Ludvigsson N, et al. Epidemiology study of idiopathic enamel hypomineralisation in permanent teeth of Swedish children. Community Dent Oral Epidemiology 1987; 15: 279-285.

Kukleva MP, Petrova SG, Kondeva VK, Nihtyanova TI. Molar incisor hypomineralisation in 7-to-14year old children in Plovdiv, Bulgaria-an epidemiologic study. Folia Med (Plovdiv) 2008; 50: 71-75.

Kuscu OO, Caglar E, Sandalli N. The prevalence and aetiology of molar-incisor hypomineralisation in a group of children in Istanbul. Eur J Paediatr Dent. 2008; 9: 139-44.

Kuscu OO, Caglar E, Aslan S, et al. The prevalence of molar incisor hypomineralisation (MIH) in a group of children in a highly polluted urban region and a windfarm-green energy island. Int J Paediatr Dent. 2009; 19: 176-185.

Leppaniemi A, Lukinmaa PL, Alaluusua S. Nonluoride hypomineralisations in the first molars and their impact on the treatment need. Caries Res 2001; 35: 36-40.

Lygidakis NA, Dimou G, Briseniou E. Molar-Incisor-Hypomineralisation (MIH). Retrospective clinical study in Greek children. I. Prevalence and defect characteristics. Eur Arch Paediatr Dent 2008; 200-206.

Muratbegovic A, Marcovic M, Ganibegovic Selmovic M. Molar Incisor Hypomineralisation in Bosnia and Herzegovina: Prevalence, Aetiology and Clinical Consequences in Medium Caries Activity Population. Eur Arch Paed Dent 2007; 8: 189-194.

Preusser SE, Ferring V, Wleklinski WE. Prevalence and severity of molar incisor hypomineralisation in a region of Germany--a brief communication. J Public Health Dent 2007; 67: 148-150.

Sign 50. A guideline developer's handbook. http://www.sign.ac.uk/pdf/sign50.pdf

Soviero V, Haubek D, Trindade C, Matta TD, Poulsen S. Prevalence and distribution of demarcated opacities and their sequelae in permanent 1st molars and incisors in 7 to 13-year-old Brazilian children. Acta Odontol Scand. 2009; 67: 170-175.

Weerheijm KL, Jalevik B, Alaluusua S. Molar-Incisor Hypomineralisation. Caries Res 2001a; 35: 390-391.

Weerheim KL, Groen HJ, Beentjes VE, Poorterman JH. Prevalence of cheese molars in eleven-year-old Duch children. J Dent Child 2001b; 68: 259-264.

Weerheijm KL, Mejare I. Molar incisor hypomineralisation: a questionnaire inventory of its occurence in member countries of the European Academy of Paediatric Dentistry (EAPD). Int J Paediatr Dent 2003a; 13: 411-416.

Weerheijm KL, Duggal M, Mejare I, et al. Judgement criteria for Molar-Incisor-Hypomineralisation (MIH) in epidemiologic studies: a summary of the European meeting on MIH held in Athens, 2003. Eur Archs Paediatr Dent 2003b; 3: 110-113.

Wogelius P, Haubek D, Poulsen S. Prevalence and distribution of demarcated opacities in permanent 1st molars and incisors in 6 to 8-years-old Danish children. Acta Odontol Scand 2008; 66: 58-64.

Zagdwon AM, Toumba KJ, Curzon ME. The prevalence of developmental enamel defects in permanent molars in a group of English school children. Eur J Paed Dent 2002;3: 91-96.

B. Jalevik

Centre of Orthodontics and Paediatric Dentistry, Linkoping, Sweden

Postal address: Dr B. Jalevik. Centre of Orthodontics and Paediatric Dentistry, Torkelbergsgatan 11 S-581 85 Linkoping, Sweden Email: birgitta.jalevik@lio.se
Table 1: Summary of epidemiological studies
for molar-insicor hypomineralisation

Study        Coun-         Criteria          Study group       Popu-
             try                                               lation
                                                               based
                                                               ?

Alaluusua    Finland       Dental defects,   Prospective       No
et al.                     fluorosis or      cohort
1996a                      major             examined for
                           disturbances      dioxin in
                           related to        breast milk
                           general health
                           excluded.

Alaluusua    Finland       Alaluusua et      Prospective       No
et al.                     al. 1996 a        cohort
1996b                                        examined for
                                             dioxin in
                                             breast milk

Arrow 2008   Australia     mDDE              Age cohort        Yes *
                                             examined for
                                             MIH

Balmer et    UK            mDDE              Consecutive       No
al. 2005                                     patients in
                                             orthodontic
                                             practice
             Australia

Calderara    Italy         mDDE, MIH krit    Age cohort        Yes
et al.                     2001              examined for
2005                                         MIH

Cho et al    Hong Kong     EAPD 2003         Study of          No
2008                                         records

Dietrich     Germany       mDDE              Patients at       No
et al.                                       annual
2003                                         dental
                                             screening

Fleita et    Libya         mDDE, MIH krit    School            No
al 2006                    2001              cohorts

Jasulait-    Lithuania     EAPD 2003         School            Yes
yte et al.                                   cohort,
2008                                         randomly
                                             selected
                                             schools

Jasulait-    Netherlands   MIH krit 2001     Age cohort        No
yte et al.                                   insured by
2007                                         DNHIF

Jalevik      Sweden        mDDE              Age cohort        Yes
et al.
2001

Kemoli       Kenya         Demarcatef        School            Yes
2008                       opacities,        cohort,
                           posteruptive      randomly
                           defects,          selected
                           extensive         schools
                           restoorations

Koch et      Sweden        Colour and        Age cohorts       Yes
al.1987                    surface
                           changes. AI,
                           fluorosis or
                           hypomin of
                           known origin
                           excluded.

Kukleva et   Bulgaria      EAPD 2003         Randomly          Yes
al. 2008                                     selected.
                                             Stratified
                                             age groups.

Kuscu et     Turkey        EAPD 2003         Patients          No
al 2008

Kuscu et     Turkey        EAPD 2003         Two school        No
al 2009                                      cohorts,
                                             Industrialized-
                                             non-
                                             industrialized
                                             area

Lep-         Finland       Alalausua et al   Two school        No
paniemi et                 1996              cohorts
al. 2001

Lygidakis    Greece        EAPD 2003         Consecutive       No
et al.                                       patients in
2008                                         Community
                                             Paediatric
                                             Dental Center

Muratbe-     Bosnia        EAPD 2003         Randomly          Yes
govic et     Herzegovina                     selected
al. 2007                                     Stratified
                                             school groups

Preusser     Germany       Koch et al.       Schoolchildren    No
et al.                     1987
2007

Soviero et   Brazil        EAPD 2003         School cohort     No
al. 2009

Weer-        Netherlands   mDDE              Age cohort        No
heijm et                                     insured by
al. 2001b                                    DNHIF

Wogelius     Denmark       MIH 2003          Age cohorts       Yes
et al.
2008

Zagdwon et   UK            m DDE             School cohorts.   No
al, 2002                                     Selected with
                                             account of
                                             ethnicity and
                                             socio-economy

Study        Coun-         Age          Sam-      Drop-   Cali-   Wet=W
             try                        ple       outs    bra-    Dry=D
                                        size              tion

Alaluusua    Finland       6-7 yr       102       NR      NR      NR
et al.
1996a

Alaluusua    Finland       12 yr        97        NR      NR      NR
et al.
1996b

Arrow 2008   Australia     7 yr         511       R       Yes     D

Balmer et    UK            8-16 yr      25        NR      Yes     NR
al. 2005
             Australia                  25

Calderara    Italy         7-8 yr       227       R       Yes     W
et al.
2005

Cho et al    Hong Kong     11-14 yr     2,635     NR      Yes     W
2008

Dietrich     Germany       8 age        2,408     R       Yes     NR
et al.                     cohorts,
2003                       10-17 yr

Fleita et    Libya         7-9yr        378       NR      Yes     W
al 2006

Jasulait-    Lithuania     6.5-8.5 yr   1,277     NR      Yes     W
yte et al.
2008

Jasulait-    Netherlands   9 yr         442       R       Yes     D
yte et al.
2007

Jalevik      Sweden        8 yr         519       R       Yes,    W
et al.
2001

Kemoli       Kenya         6-8 yr       3,591     NR      Yes     W
2008

Koch et      Sweden        6 age        2,252,    NR      Yes     NR
al.1987                    cohorts,     343-
                           8-13yr       423
                                        in the
                                        cohorts

Kukleva et   Bulgaria      Eight age    2970,     NR      NR      W
al. 2008                   cohort,      370 in
                           7-14 yr      each
                                        age
                                        cohort

Kuscu et     Turkey        7-9 yr       147       NR      Yes     W
al 2008

Kuscu et     Turkey        7-10 yr      109       NR      Yes     W
al 2009                                 and 44

Lep-         Finland       7-13yr       488       NR      NR      NR
paniemi et
al. 2001

Lygidakis    Greece        5.5-12 yr    3518      NR      Yes     NR
et al.
2008

Muratbe-     Bosnia        12 yr        560       NR      NR      NR
govic et     Herzegovina
al. 2007

Preusser     Germany       6-12yr       1002      NR      Yes     W
et al.
2007

Soviero et   Brazil        7-13 yr      249       R       Yes     W
al. 2009

Weer-        Netherlands   11 yr        497       NR      NR      NR
heijm et
al. 2001b

Wogelius     Denmark       6-8 yr       647       R       Yes     W
et al.
2008

Zagdwon et   UK            7 yr         307       R       Yes     W
al, 2002

Study        Coun-         Size        Degr-    Fre-
             try                       ees of   quency
                                       Sev-
                                       erity

Alaluusua    Finland       [greater    3        17%
et al.                     than or
1996a                      equal to]
                           2mm

Alaluusua    Finland       [greater    3        25%
et al.                     than or
1996b                      equal to]
                           2mm

Arrow 2008   Australia     NR          NR       22%

Balmer et    UK            NR          NR       40%
al. 2005
             Australia                          44%

Calderara    Italy         [greater    3        13.7 %
et al.                     than or
2005                       equal to]
                           2mm

Cho et al    Hong Kong     NR          NR       2.8%
2008

Dietrich     Germany       NR          3        2.4-
et al.                                          11%,
2003                                            mean
                                                5.60%

Fleita et    Libya         [greater    3        2.9%
al 2006                    than or
                           equal to]
                           2mm

Jasulait-    Lithuania     NR          2        9.7%
yte et al.
2008

Jasulait-    Netherlands   NR          NR       14.3%
yte et al.
2007

Jalevik      Sweden        [greater    3        18.4%
et al.                     than or
2001                       equal to]
                           2mm

Kemoli       Kenya         NR          1        13,70%
2008

Koch et      Sweden        [greater    3        3.6%-
al.1987                    than or              15.40%
                           equal to]
                           1/3 of a
                           tooth
                           unit

Kukleva et   Bulgaria      NR          NR       2.4%-
al. 2008                                        7.8%,
                                                mean
                                                3.60%

Kuscu et     Turkey        NR          2        14.9%
al 2008

Kuscu et     Turkey        NR          NR       9.1%;
al 2009                                         9.20%

Lep-         Finland       [greater    3        19.3%
paniemi et                 than or
al. 2001                   equal to]
                           2mm

Lygidakis    Greece        Clearly     2        10.2%
et al.                     visible
2008

Muratbe-     Bosnia        [greater    NR       12.3%
govic et     Herzegovina   than or
al. 2007                   equal to]
                           2mm

Preusser     Germany       NR          3        5.9%
et al.
2007

Soviero et   Brazil        NR          2        40.2%
al. 2009

Weer-        Netherlands   NR          NR       9.7%
heijm et
al. 2001b

Wogelius     Denmark       Clearly     2        37,50%
et al.                     visible
2008

Zagdwon et   UK            NR          NR       14.6 %
al, 2002

NR = Not reported, R = Reported,
* particpation 45%
Gale Copyright: Copyright 2010 Gale, Cengage Learning. All rights reserved.