Treatment modalities in children with teeth affected by molar-incisor enamel

Treatment modalities in children with
teeth affected by molar-incisor enamel
hypomineralisation (MIH): A systematic review
N.A. Lygidakis
Dept of Paediatric Dentistry, Community Dental Centre for Children, Athens, Greece.
AIM: This was to review the literature concerning the treatment of permanent teeth with molar-incisor hypomineralised
enamel (MIH), comment about possible shortcomings and
propose areas of future research. METHODS: A search of
MedLine, Scopus, ResearchGate, Isis and Google Scholar
databases was conducted using all terms relevant to the
subject. Relevant papers published in English were identified after a review of their titles, abstracts or full reading of
the papers. RESULTS: Of 189 references initially found, 66
papers were included; 34 directly relevant to the subject.
From the latter, only 14 concerned laboratory or clinical studies dealing with treatment for MIH. Since 2000 11 reviews
evaluated, to a certain extent, treatment options for affected
teeth. Analysis of the proposed treatment modalities indicated options for prevention, restorations, and adhesion to
hypomineralised enamel, full coronal coverage and extraction followed by orthodontics. Based on these findings, a
treatment decision plan is proposed. CONCLUSIONS:
Although treatment approaches for MIH have started to be
clearer, long-term clinical trials, supported by laboratory
studies, should be conducted to further facilitate the clinical
management of this dental defect.
Molar incisor hypomineralisation (MIH) is defined as the
developmentally-derived dental defect that involves
hypomineralisation of 1 to 4 permanent first molars (FPM),
frequently associated with similarly affected permanent
incisors [Weerheijm et al., 2003; Mathu-Muju and Wright
2006]. The defect is the result of a variety of environmental factors acting systemically, including prenatal, perinatal
and childhood medical conditions that affect the developing
enamel, while an underlying genetic predisposition could
not be excluded [Lygidakis et al., 2008b, Alaluusua, 2010].
MIH presents as demarcated enamel opacities of different
colour in the affected teeth that occasionally undergo posteruptive breakdown due to soft and porous enamel, resulting
in atypical cavities or even to complete coronal distortion
[Weerheijm et al., 2003]. Accordingly the defect reveals serious clinical management problems attracting the attention of
the dental profession the last decade [Lygidakis et al., 2003;
Mathu-Muju and Wright 2006].
Following the establishment of the presently used diagnostic
criteria for MIH [Weerheijm et al., 2003], a number of welldocumented studies have reported on the prevalence of
the disorder and were reviewed by Jälevik [2010]. Previous
studies recorded a prevalence of 5.9-14.3% in Europe, while
there are few studies concerning America and other parts of
the world [Fleita et al, 2006; Willmott et al., 2008]. Additionally MIH prevalence has a strong positive correlation with
the overall prevalence of developmental defects of enamel.
Muratbegovic et al. [2008] showed that prevalence of DDE
fell after exclusion of MIH patients from 32.8% to 21.4%.
Accordingly it is clear that MIH is an important clinical problem often concerning both general dentists and specialist
paediatric dentists. As caries rates have declined in western countries, paediatric dental defects have become more
apparent, requiring more complex and long-term treatment.
As a result over the last few years a limited number of papers
have appeared dealing with the treatment of MIH. The aim of
this paper was to review the literature concerning the treatment of MIH, comment about possible shortcomings and
propose areas of future research.
A broad search of MedLine, Scopus, ResearchGate, Isis
and Google Scholar databases was conducted for the years
1980 until 2009, using as index terms ‘treatment or management or therapy or clinical approach’ AND ‘dental enamel
defects’, ‘developmental enamel defects’, ‘chronological
enamel defects’, ‘molar-incisor-hypomineralisation’, ‘non
fluoride hypomineralisation of permanent teeth’, ‘idiopathic
hypomineralisation of permanent teeth’, ‘cheese molars’,
‘hypomineralised permanent molars’ and ‘hypomineralised
permanent incisors’. Papers other than in English were
excluded. All abstracts were read and the full text of relevant
ones were then read. The reference list of each of these
papers was additionally examined in order to locate any further references that may not have been found in the search
engines previously mentioned.
Of the 189 initial references, 93 were selected based on their
abstracts, the remaining papers dealing with inherited enamel
defects. After a reading of each paper, 66 papers were chosen for inclusion, 32 supportive to the review and 34 relevant
to the subject. From these 66, those dealing exclusively with
Key words: molar, incisor, enamel hypomineralisation, MIH, treatment, review.
Postal address: Dr N. A. Lygidakis, 2 Papadiamantopoulou Street, Athens 11528, Greece.
Email: [email protected]
European Archives of Paediatric Dentistry // 11 (Issue 2). 2010
N.A. Lygidakis
treatment options and outcomes to MIH, either laboratory
or clinical comprised only 14 for final evaluation. An additional 9 publications dealt with structural properties of MIH
enamel, dentine and pulp, relevant to treatment. Since 2000,
11 reviews evaluated and described, to a certain extent,
the treatment options of such defective teeth. The following
reviews were used in the present paper: Croll, [2000]; Wray
and Welbury, [2001]; Mahoney, [2001]; Fayle, [2003]; Williams and Gowans [2003]; Mathu-Muju and Wright, [2006];
William et al. [2006a]; Sapir and Shapira, [2007]; Fitzpatrick
and O'Connell, [2007]; Willmott et al. [2008]; Daly and Waldron, [2009].
rom this limited number of studies, even though they had
shortcomings, it was evident that a 'treatment guidelines
flow-diagram', based on SIGN methodology, is presently
impossible to be made for MIH. According to the SIGN
criteria, the grade of recommendation from all studies was
moderate (C-D) [Sign, 50].
Clinical problems in MIH. Patient and parents concerns
related to MIH include aesthetics, rapid wear and enamel
loss, increased susceptibility to caries, sensitivity, and finally
tooth loss [Leppaniemi et al., 2001; Jälevik and Klingberg,
2002; Willmott et al., 2008]. When post-eruptive breakdown
occurs in MIH teeth, the porous sub-surface enamel and
even the dentine are exposed, resulting in teeth sensitive to
cold air, warm water and food and tooth brushing [Jälevik and
Klingberg, 2002]. Poor oral hygiene favours plaque retention
and promotes rapid caries development [Leppaniemi et al.,
2001; Mahoney, 2001].
Children with MIH receive much more dental treatment than
unaffected children [Kotsanos et al., 2005; Chawla et al,
2008]. Affected molars usually require extensive treatment
and might create serious problems for both patient and clinician, as they can frequently be difficult to anaesthetise and to
restore adequately. The porous exposed subsurface enamel
and the dentine may promote bacteria penetration into the
dentine resulting to chronic inflammation of the pulp, complicating the use of local analgesia [Rodd et al., 2007; Fargell
et al., 2008]. Research has shown that by the age of 9-years,
children affected with MIH teeth had undergone dental treatment on their FPM nearly 10 times more frequently than
unaffected controls and that each affected tooth had been
treated on average twice [Jälevik and Klingberg, 2002]. A
considerable proportion of treatment needs for MIH patients
was the treatment of affected FPM [Leppaniemi et al., 2001;
Muratbegovic et al., 2007]. In addition, it was found that the
actual treatment needs were probably underestimated by
evaluating only carious, restored and extracted teeth; these
patients would also require further restorative, orthodontic
and preventive care [Leppaniemi et al., 2001]. Finally for
the 18-year-olds there was an additional treatment need in
almost half of the patients who had had their FPM restored
previously [Mejare et al., 2005].
European Archives of Paediatric Dentistry // 11 (Issue 2). 2010
Apart from the restorative difficulties faced by clinicians,
children with MIH have considerable behaviour management
problems; dental fear and anxiety are more commonly found
in these children. Behaviour problems can be related to
pain experienced by the patients during multiple treatment
appointments, as many of them were either inadequately
anesthetised or even had treatment without local analgesia
[Jäalevik and Klingberg, 2002].
A clinical approach for treating MIH. A very useful 6-step
management approach for MIH has been proposed recently
by William et al. [2006a]:
l Risk
l Early
l Remineralisation
(a better term may be mineralisation;
the tooth was never ‘completely’ mineralised during
development although there may also be an element of
demineralisation from enamel caries, superimposed upon
the hypomineralised areas) and desensitisation,
l Prevention
of dental caries and post eruptive enamel
l Restorations
or extractions,
l Maintenance.
Additionally a valuable treatment decision tree was created
by Mathu-Muju and Wright [2006] who proposed a treatment approach according to the level of defect severity
(mild, moderate, severe) and to the length of treatment time
needed (short and long term). According to those authors
the following clinical criteria should be considered in order to
divide the defects in the 3 different severity levels:
l Mild
MIH: Demarcated opacities are in non-stress-bearing
areas of FPM, there are isolated opacities, no enamel
loss from fracturing is present in opaque areas, there is
no history of dental hypersensitivity, there are no caries
associated with the affected enamel, and incisor involvement is usually mild if present.
l Moderate
MIH: Intact atypical restorations can be
present, demarcated opacities are present on occlusal/
incisal third of teeth without posteruptive enamel breakdown, posteruptive enamel breakdown/caries are limited
to 1 or 2 surfaces without cuspal involvement, dental
sensitivity is generally reported as normal, aesthetic concerns are frequently expressed by the patient or parent
l Severe
MIH: Posteruptive enamel breakdown is present
and frequently occurs as the tooth is emerging, there is
a history of dental sensitivity, often widespread caries is
associated with the affected enamel, crown destruction
can readily advance to involve the dental pulp, defective
atypical restoration is present, aesthetic concerns are
expressed by the patient or parent.
Treatment in molar-incisor-hypomineralisation
In assessing the review of William et al. [2006a], although it
is very informative and suggestive, the clear cut treatment
decision tree proposed by Mathu-Muju and Wright [2006]
gives a better way of dealing with MIH clinically and for
the long term. The division, however of the severity of the
defects into 3 categories is complicated and might not help
the clinician. Another way of categorizing the defect should
be investigated, evaluated and agreed upon.
technique [Lygidakis et al., 2009]. FS in the former case
recorded 70.2% full retention compared with 25.5% in the
later (Table 1a). Finally, for partially erupted FPM with MIH,
glass ionomer cements (GIC) can be used as FS, providing
temporarily, caries and sensitivity protection and minimizing
break-downs; as retention of such materials is poor, these
should be replaced as soon as the tooth is fully erupted with
resin-based sealants [William et al., 2006a].
Overall preventive approach and advice. It is very important
to start approaching the affected children and their parents
with the appropriate dietary and preventive advice. As it has
been proposed in a recent extensive review by Willmott et al
[2008], if a child is still using a low-fluoride children’s toothpaste then the parents should be encouraged to change
to one with a higher fluoride level of at least 1,000 ppm F
[EAPD, 2009]. Other topical fluorides may also be useful;
amongst these are topical fluoride varnishes, e.g. Duraphat®
22,600ppm F (Colgate Oral Care) and Gelkam® 1,000ppm F
(Colgate Oral Care). Although there is no research at present
to evaluate their efficacy in MIH patients, all these products
may help to reduce sensitivity and enhance mineralisation of
the hypomineralised areas.
Comments on prevention. The reviews by William et al.
[2006a] and Willmott et al. [2008] deal with the subject of
MIH prevention extensively and adequately providing sensible suggestions. However, the information provided is
empirical and anecdotal as there are no clinical or laboratory
studies on MIH teeth and suggestions are mainly based on
studies of ‘normal’ teeth. Prospective clinical trials will help
to evaluate the use of fluoride products to minimize hypersensitivity. Any CCP-ACP effect on MIH teeth should be
especially evaluated, as the clinical outcome on this promising product is still controversial [Azarpazhooh and Limeback,
2008]. In addition, although stannous fluoride gel has been
demonstrated to reduce dentine sensitivity [Thrash et al.,
1994], this effect has yet to be confirmed by clinical trials in
hypomineralised teeth.
Another product that might be also useful for MIH patients
and requires further research [William et al., 2006a; Willmott
et al., 2008] is Casein (Phosphopepetide-Amorphous Calcium Phosphate, CPP-ACP). This product has been shown
to create and stabilise a super saturated solution of calcium
and phosphate followed by deposition at the enamel surface.
CPP-ACP has been incorporated into sugar-free chewing
gum and encourages remineralisation of the sub-surface
carious lesions [Shen et al., 2001]. Following these findings
it has been empirically suggested that home application of
a CPP-ACP containing cream will help seal, desensitise and
act as a source of bio-available calcium and phosphate for
an erupting tooth with MIH [Willmott et al., 2008; Chawla et
al, 2008]. Finally the use of 0.4% stannous fluoride gels on a
daily basis have also been proposed to be helpful for reducing sensitivity in defective teeth [Fayle, 2003].
Fissure sealants (FS) may also be useful for FPM with mild
defects, not sensitive and without breakdown, particularly
when they are regularly monitored and replaced when lost
[Fayle, 2003; Mathu-Muju and Wright 2006; William et al.,
2006a]. Mathu and Wright [2006] suggested that if the fissures appeared opaque or yellow-brown then a 60 second
pre-treatment with 5% sodium hypochlorite might be beneficial in that it might remove intrinsic enamel proteins. Limited
clinical information on using FS in affected teeth comes from
the study by Kotsanos et al. [2005] who reported that FS
in 35 MIH molars had to be retreated after a shorter period
of time than FS in a control group. However, a recent long
term clinical study in 54 children with MIH and defective
molars with occlusal opacities, reported that FS appeared
to have greater retention when applied using 5th generation adhesive prior to FS, compared with the conventional
Concerning FS, Mathu-Muju and Wright [2006] repeated
a possibly valuable suggestion for pre-treatment that has
been noted previously for defective enamel in amelogenesis
imperfecta cases by Venezie et al. [1994]; however at the
time of that report, modern adhesives did not exist, therefore
the use of 5% sodium hypochlorite might not be as useful nowadays. The only available research for FS is a recent
prospective clinical study [Lygidakis et al., 2009] indicating
that in MIH molars with occlusal opacities, FS appear to
have greater retention when applied using adhesive prior to
Restoring one or more surfaces of hypomineralised permanent molars. Having solved the difficulties in achieving local
analgesia and managing a child’s behaviour, restoration of
the affected FPM can be further complicated by difficulties in defining the cavity margins and the choice of the
suitable replacement material. Concerning the former, two
empirical approaches have been proposed: removal of all
defective enamel until sound surfaces are reached [William
et al., 2006a; Mathu-Maju and Wright, 2006] or removal of
the porous enamel only, until resistance to the bur or to the
probe is felt [Lygidakis et al., 2003; Fayle, 2003]. The first
approach means that a lot of tooth material is lost but is better if an adhesive material is to rely upon bonding to enamel.
The second approach is less invasive, but it can mean that
the defective enamel may continue to chip away.
There are many restorative materials/options available to the
dental surgeon treating these patients: GIC, Resin Modified
Glass Ionomer Cements (RMGIC), Polyacid modified composite resins (PMCR), Composite resins (CR), and amalgam.
European Archives of Paediatric Dentistry // 11 (Issue 2). 2010
N.A. Lygidakis
Table 1a: Papers/studies reported on clinical modalities in hypomineralised molars (MIH).
No of
No of
MIH teeth
Koch and
41 molars; 25
with opacities
12 enamel
hypoplasia, 4
hypomineralised AI
29 gold crowns
4 composite
8 ceramic
100% retention
Excellent (39) or acceptable (2) in:
Marginal Adaptation
Supragingival Margins
At the end of the study: all teeth vital, no
secondary caries
Zagdwon et
al [2003]
42 molars with
DDE and AI
18 cases,
prospective, 24
cases, split
19 PMC
23 nickel
chrome alloy
adhesive casts
Mean =
94.7% acceptable
91.3% acceptable,
Adhesive casts 4 times more expensive
than PMCs
Kotsanos et
al [2003]
36 +
136 molars
7.7 ±
35 sealants
18 amalgam
59 composite
24 PMC
33.0 (±
32.3 (±
48.3 (±
87.1% acceptable
38.9% acceptable
100% acceptable
Lygidakis et
al [2003]
49 molars
49 Composite
(18 two surfaces, 31 three
100% full retention, Ryge A:
Surfaces appearance 93.8%
Colour match 79.5%
Marginal adaptation 100%
Anatomic form 91.8%
0/49 with pulp necrosis at the end
Mejare et al
153 molars
(8.5 ±
63 GIC
14 compomer
34 composite
32 amalgam
9 castings
49.2% acceptable
64.3% acceptable
78.1% acceptable
100% acceptable
5/153 with pulp necrosis
Lygidakis et
al [2009]
47 sets of
21 maxilla
26 mandible
Prospective, half
Adhesive FS
(group A) vs
(Group B)
Group A: 70.2% were fully sealed, 29.7%
partly sealed, none unsealed.
Group B: 25.5% fully sealed, 44.6% partly
sealed, 29.7% unsealed
* age in years at time of first examination; ** years; NR – not recorded; DDE – dental developmental defects; PMC – preformed metal crown
Amalgam is a non-adhesive material and its use in these
atypically shaped cavities is not indicated; the inability to
protect the remaining structures usually results in further
enamel breakdown [Croll 2000; Fayle, 2003; William et al.,
2006a]. The few existing clinical studies of amalgam restorations in MIH molars support this view as they report lower
success rates when compared with CR [Kotsanos et al.,
2005; Mejare et al., 2005].
Regarding other restorative materials and options there is
very little evidence to support their use [Fayle, 2003; MathuMaju and Wright, 2006]. Restorations with GIC, RMGIC and
PMCR are not recommended in the stress bearing areas of
FPMs and they can only used as intermediate approach until
a definite restoration is placed [Mahoney 2001; William et
al., 2006a; Willmott et al., 2008]. GIC has been additionally
proposed as an intermediate layer restoring the dentinal
contours, prior to composite placement, in cases that the
cavity involves large areas of dentine [Mathu- Maju and
Wright, 2006].
European Archives of Paediatric Dentistry // 11 (Issue 2). 2010
The only material that appears to be usable for one or more
surfaces restorations in MIH molars is CR. There are 3 clinical studies dealing with the outcome of such restorations
in MIH molars (Table 1a). Lygidakis et al. [2003] evaluating
the success rate of CR restorations placed on two or more
surfaces including cusps of affected molars, reported good/
acceptable results after 4 years. Following a strict clinical
procedure, none of 49 restorations (18 two/31 three surfaces) needed replacement by the end of the study. Mejare
et al. [2005] followed 76 children with various types of restorations for a period of 5.2±3.29 years. In FPMs, GIC had
the lowest and CR the highest success rate, amalgam and
compomers being in the middle. From the 34 CR placed,
29 (85.3%) had a good/acceptable outcome, the remaining
needing replacement. Finally Kotsanos et al. [2005] reported
a 74.4% success rate of CR restorations placed on MIH
molars in children aged 7.7±1.3 after 48±30.6 months of
follow-up. These authors also reported that restorations and
FS in affected children had over 3 times greater probability
of needing re-treatment than interventions on children of a
control group.
Treatment in molar-incisor-hypomineralisation
Comments on materials. In commenting on the restorative
approaches it is still unclear which approach is better for cavity preparation and further laboratory research is required.
From the 3 existing clinical studies only one mentions clearly
the cavity preparation technique, stating ‘removal of all carious tissues together with possible previous, failed amalgam
restoration and enamel easily penetrated by probe’ [Lygidakis et al., 2003]. From all available restorative materials,
many reviews [Fayle, 2003; Mathu-Muju and Wright 2006;
William et al., 2006a; Willmott et al., 2008], agree on the
superior properties of CR, combined with the new adhesive
materials. The 3 clinical studies available have particular
limitations. Kotsanos et al. [2005] was retrospective with no
defined treatment procedure and methodology criteria and
a very wide time-span of evaluation (48±30.6 months). Similar limitations apply to Mejare et al. [2005] study that is also
unclear about patients’ ages and year of treatment (meaning
different restorative materials). The Lygidakis et al. [2003]
study dealt with the previous problems adequately but it
had no controls for evaluation. Further long-term clinical
trials should be organised, preferably multi-centre, in order
to finalise this approach and the type of composite material
most appropriate.
Adhesion to hypomineralised enamel. The use of various
adhesive resin systems has certain limitations in MIH teeth as
a result of defective enamel. A recent study by William et al.
[2006b] demonstrated that adhesion to MIH enamel is possible, but the enamel-adhesive interface of defective enamel
was porous with cracks, had decreased bond strength, and
a higher likelihood of cohesive failure compared with sound
enamel. This possible ability of adhesion to MIH enamel was
found by the study of William et al. [2006b], strenghtens the
previous findings by Seow and Amaratunge [1988], in AI
variants, which reported that the etching patterns in hypomineralized types of AI may occasionally resemble those of
normal enamel despite the presence of hypomineralisation
abnormalities and morphological changes at the crystallite
level. A number of studies dealing with the ultrastructure and
biochemical make-up of MIH enamel [Jälevik et al., 2001a,
2005; Jälevik and Norén 2000; Fearne et al., 2004; Mahoney
et al., 2004; Al-Dobiyan et al., 2006] and dentine [Fearne et
al., 2004; Heijs et al., 2007] indicated that the ‘full thickness
enamel’ surrounding the clinically defective lesions is less
affected and the underlying dentine has no major structural
changes. These findings may explain the acceptable results
for adhesive CR restorations in molars with MIH, if all apparently defective enamel is removed.
The type of adhesive used should also play a role. William et
al. [2006b] suggested that self-etching adhesives (SEA) have
superior bond strength to hypomineralised enamel compared
with all-etch single-bottle alcohol containing adhesives
(SBA) possibly attributed to omiting rinsing thus eliminating
the contamination of residual water on the bond and micromechanical and chemical bonding to hydroxyapatite of the
SEA, as compared with micromechanical only for the SBA.
However the hydrophilic properties of acetone included
in some other SBA systems, may play the same role for
removing the residual water from the etched enamel surface
enhancing the enamel-adhesive interface. An acetone-containing adhesive system that was used prior to CR and FS
in two of the clinical studies in MIH molars, mentioned previously, revealed good long-term results regarding adhesion
[Lygidakis et al, 2003, 2009].
An additional procedure prior to etching in order to enhance
adhesion to hypomineralised enamel has been proposed by
Mathu-Maju and Wright, [2006]. They recommend pre-treatment of the enamel with 5% sodium hypochlorite in order to
remove intrinsic proteins encasing the hydroxyapatite and
therefore facilitate etching and resin penetration.
Comments on adhesion. The study by William et al. [2006b]
covers the subject well and makes some valuable suggestions for the clinician. However, there is a limitation namely
that the absence of cavity preparation prior to material
placement means that results apply to defective enamel
exclusively and not to ‘less defective’ enamel and the ‘normal’ dentine surrounding the lesion. Additionally, the MIH
affected FPM examined for adhesion revealed yellow-brown
demarcated opacities with posteruptive breakdown. This
was given as the reason for failure, being a cohesion failure within the enamel, while high microshear bond strength
was found in some specimens having milder whitish-creamy
defects. Further laboratory research in that area is required
followed by clinical trials applying the suggestions regarding the adhesive types most effective in MIH. Furthermore,
the suggestion of Venezie et al. [1994] and Mathu-Maju and
Wright [2006], on pre-treatment, should be evaluated in vitro
and in clinical trials. It should be noted however that at the
time of the original publication in 1994 there were no adhesive agents and their widespread use today might reduce the
clinical value of the 5% sodium hypochlorite pre treatment.
Restoring hypomineralised permanent molars with full
coronal coverage. Preformed metal crowns (PMC) for use
on FPM have been used for many years to cover molars
with defective enamel and they are still recommended as a
treatment option for MIH posterior teeth [Fayle, 2003; William et al., 2006a; AAPD, 2008]. They prevent further tooth
loss, control sensitivity, establish correct interproximal and
proper occlusal contacts, are not costly and require little
time to prepare and insert. Kotsanos et al. [2005] reported
that no replacement was needed for PMC placed on 24
molars with MIH, for a period of 3-5 years (Table 1a). Zagdwon et al. [2003] reported good success rate with only one
failure of 19 PMC placed over a 2 year-period; they also
found that there were no significant differences between
the longevity and success rates for PMC and cast adhesive
copings (nickel chrome alloy) (Table 1a). Adhesive cast copings conserved more tooth tissue but were more technique
sensitive and time consuming; additionally in young children
European Archives of Paediatric Dentistry // 11 (Issue 2). 2010
N.A. Lygidakis
there are short clinical crowns and large pulps and a child’s
cooperation might be questionable [William et al., 2006a].
From another clinical study similar acceptable results were
reported for laboratory-fabricated crowns on defective
molars, either gold in 29 teeth or tooth-coloured in 12 teeth
[Koch and Garcia-Godoy, 2000]. From the 41 crowns placed
with a modified technique for crown preparation, in children
aged 6-8 years, only 2 recorded minor marginal problems,
the remaining 39 being in good condition 2-5 years post
placement (Table 1a).
Restoring hypomineralised permanent incisors. As the recent
research on MIH has shown, up to 71.6% of affected children may have incisors as well as FPM involved [Jälevik et al
2001b; Chawla et al, 2008; Lygidakis et al., 2008a]. In addition the most frequent (23.5%) combination of affected teeth
in children with all 12 ‘index’ teeth erupted is 4 molars/2 incisors [Lygidakis et al., 2008a]. Some of these children have
serious aesthetic problems that require treatment. Unfortunately the literature lacks evidence-based results for the
management of such defects for the anterior teeth (Table 1b).
Comments on coronal coverage. Although PMC have been
used for many years by our specialty, there are only 2 clinical studies evaluating their use in MIH molars. The study of
Zagdwon et al. [2003] was prospective, very well conducted
with clear methodology and a detailed technique procedure,
although the follow-up period was limited to 2 years (usually
the time requirement for PMC maintenance is up to 10 years)
and there were no follow up periapical radiographs to evaluate possible pathology. The study by Kotsanos et al. [2005],
although it does provide very good results, was retrospective with no defined treatment procedure and methodology
criteria and a very wide time-span of evaluation (50.2 ± 23.3
years). Therefore long-term (>7 years) prospective clinical
trials are needed in order to evaluate their performance in
such teeth.
According to Jälevik and Noren [2000] the yellow or brownish-yellow defects are of full thickness and more porous,
whilst those that are creamy-yellow or whitish-creamy are
less porous and variable in depth, located in the inner part
of the enamel. As a result, the former defects may respond
occasionally to bleaching with carbamide peroxide, while
microabrasion using abrasive paste and 18% hydrochloric
acid might be effective only in shallow patchy whitish defects
(Table 1b) [Fayle, 2003; William et al., 2006a; Mathu-Muju
and Wright, 2006; Joiner, 2006]. More pronounced enamel
defects might be dealt with by combining the two methods [Sundfeld et al., 2007]. Both techniques are however
questionable in immature teeth as microabrasion involving
aggressive reduction of the enamel resulting from duration,
number, and intensity of applications may occur [Sapir and
Shapira, 2007]. An alternative method of polishing with
pumice and etching with 37.5% phosphoric acid has been
proposed to overcome these problems, but again this has
not been studied on immature anterior teeth [Peariasamy
et al., 2001] (Table 1b). Additionally, bleaching with 10% –
38% carbamide peroxide for brownish-yellow defects is not
recommended in immature teeth as it is frequently followed
by side effects, such as sensitivity, mucosal irritation and
enamel surface alterations, while symptoms are frequently
increased with higher concentrations [Joiner 2006; AAPD,
2009]. These techniques for tooth whitening are described
in detail in the UK Clinical Guidelines [Wray and Welbury,
2001], while the long-term experience with microabrasion is
thoroughly evaluated in the review by Sundfeld et al. [2007].
The use of cast adhesive copings, as proposed by Harley and
Ibbetson, [1993] for other dental defects, namely AI and DI,
do seem to have a potential for the treatment of MIH molars
as shown by Zagdwon et al. [2003]. Further clinical research
is, however, needed in order to justify their long-term use
and evaluate further the possibility of using alternative toothcoloured materials instead of various alloys.
With the use of laboratory fabricated full crowns there is still
great concern for the destructive nature of crown preparation
to these immature teeth. The study by Koch and GarciaGodoy, [2000], although presenting good results, evaluated
a very limited number of coloured crowns, as compared in
addition to much larger sample of gold crowns. The use of
the latter however would not be well accepted by parents
nowadays. Additionally, there is the transitional stage of the
occlusion that children undergo during the years involved
in the placement of such restorations must be considered.
Finally, as Koch and Garcia-Godoy, [2000] stated:
“Placement may be difficult owing to short crowns,
large pulps, previous loss of enamel and subgingival
placement of crown margins. The impression material
must allow for good wetting of dental surfaces. Polyether impression materials (which appear to be ideal for
these cases) require a long setting time. The treatment
requires the fabrication of a temporary crown, and the
patient must cooperate, maintain a good oral hygiene
status and, preferably, have a low risk of developing
European Archives of Paediatric Dentistry // 11 (Issue 2). 2010
It should be noted that all these methods, discussed above,
have mainly been studied in diffuse fluorotic opacities or
post-orthodontic white spots, therefore their application to
hypomineralised MIH enamel should be with caution. MIH
has morphological differences and distinct characteristics
from the former other defects [Jäalevik et al, 2001a, 2005].
An interesting approach, namely etch-bleach-seal technique,
has been suggested by Wright [2002]. According to this conservative approach for yellow-brown defects the lesions are
etched with 37% phosphoric acid for 60 s, bleached with 5%
sodium hypochlorite for 5-10 min, re-etched and covered
with a FS over the surface to occlude porosities and prevent
re-staining. Acceptable clinical results were reported for a
5 years period. Recently the technique was evaluated in 33
children aged 8-12 years, but with diffuse fluorotic opacities
Treatment in molar-incisor-hypomineralisation
Table 1b: Papers/studies reporting on clinical modalities in hypomineralised incisors (MIH).
No of
No of MIH teeth Study design
children evaluated
Age *
Restoration Methods
Duration* Results
Welbury [1991]
52 incisors/
canines with
(from a group of
289 teeth***)
Composite resin veneers
with feathered or bevelled or overlapped incisal
86% acceptable
Failures due to partial or
complete loss of composite, adhesive failure,
poor colour match.
Ashkenazi and
Sarnat [2000]
NR. Teeth
brown or white
DDE resembling
Microabrasion with
pumice and 37% HCl
Up to 4
‘surprising’ satisfactory
Peariasamy et
al [2001]
30 molars with
demarcated or
diffuse opacities
with controls
Pumicing for 30-35
sec and etching for 1
or 2 min with 37.5%
phosphoric acid.
Removal of 34±4 μm
of the surface enamel
without mineral loss
in the subsurface.
Formation of a ‘new’
mineralized surface
22±3 μm, with favorable
optical properties
Wong and
Winter [2002]
15 out
of 32
30 central
incisors with
Microabrasion with
Prèma abrasive paste
and 18% HCl
Statistically significant
(p=0.03) immediate
and long term satisfaction with the result by
patients and parents
Wright [2002]
Surface etched with 37%
phosphoric acid for 60
s, b) bleached with 5%
sodium hypochlodite for
5-10 min, c) re-etched
and covered with a
Up to 5
Good results with
‘no-staining after resin
* age in years at time of first examination; ** years; ***Remaining patients or teeth revealed different type of defects; NR – not recorded; DDE – dental developmental defects
in their incisors and good results for colour improvement
were obtained [Cardenas Flores et al., 2009]. Some other
authors have suggested that aesthetic improvement can be
achieved when any enamel reduction is followed by opaque
resins and direct CR veneering [Fayle, 2003; Weerheijm,
2004]. Opaque resins as intermediate layers are also quite
frequently necessary in order to mask the reflection of the
deep discoloured lesions [Fayle, 2003].
Restorations with CR and veneers are an alternative choice
for anterior MIH defective teeth in children and adolescents
with larger enamel defects that require treatment [Wray and
Welbury, 2001]. The choice between direct and indirect
veneers depends upon a clinician’s personal choice and
skill and the implicated cost. It should however, be kept in
mind that in the majority of cases immature teeth with large
pulps are involved and therefore a conservative approach is
required. Additionally, the continuous recession of the gingival margin of the anterior teeth during development implies
later problems with aesthetics of full coverage veneers.
Wakiaga et al. [2004] undertook a systematic review of
direct versus indirect CR veneers for intrinsic dental stains
and found 6 acceptable papers all in adolescents and adults
but none in children. They concluded that there was no reliable evidence to show that either approach was superior
to the other with regard to longevity. In the only study in
young patients, Welbury [1991] looked at directly placed CR
veneers in children and adolescents and found that after
three years 14% had failed (Table 1b). At the time of that
research there were no modern adhesives available and
therefore the study, although the only one in the literature,
does not reflect the present situation. Veneers using CR in
long term may suffer from susceptibility to discolouration,
wear and marginal fractures, reducing thereby the aesthetic
long-term result [Peumans et al., 1997a,b]. In such cases
and in older children and adolescents porcelain veneers are
indicated [Wray and Welbury 2001; AAPD, 2008]
Comments on incisal MIH treatments. There are no studies
at all evaluating the success rate of for CR restorations for
MIH affected incisors. Indications for their use and success
rates can nevertheless be drawn from CR studies in molars,
as essentially the same technique is used. Further matters to
be addressed in the anterior teeth are the additional use of
opaque resins and the different mastication forces involved.
The etch-bleach-seal technique [Wright, 2002] should be
clinically evaluated further in large samples of MIH incisors, as it appears promising for interceptive early approach
in aesthetic problems. Chair-side bleaching with 10%
European Archives of Paediatric Dentistry // 11 (Issue 2). 2010
N.A. Lygidakis
carbamide peroxide, for brownish-yellow defects should
be investigated but only in older children. Note should be
taken of the side effects of sensitivity, mucosal irritation and
enamel surface alterations [Wray and Welbury, 2001; Dahl
and Pallesen, 2003; Joiner, 2006]. Micro-abrasion followed
by CR restorations for creamy-whitish defects needs to be
evaluated adequately in larger patient groups. Either 18%
hydrochloric acid or 37% phosphoric acid can be used
as both produce similar results [Berezza et al., 2005]. The
replacement of micro-abrasion by local enamel thickness
reduction, using high-speed headpiece, should be also evaluated. In any case all these approaches should be delayed
as much as possible as clinical experience has shown that
defective areas tend to get better in the oral environment.
The CR veneers for young children and adolescents with
severe defects need clinical evaluation in respect to the new
adhesives properties when used on defective enamel as
discussed previously. In addition porcelain veneers with the
new-age materials should be evaluated but only in adolescents and young adults.
Extraction and Orthodontics. In children with MIH severely
affected FPM, the first clinical consideration is to decide
whether to restore or extract. Although both the profession
and the public believe nowadays in a more conservative
treatment plan, some thought might still be given for such
a radical approach, resulting usually in the extractions of
several permanent teeth. Variables affecting this decision
include the child’s age, orthodontic considerations, presence of other dental anomalies, degree of severity of MIH,
pulp involvement, presence of third molar germ(s), restorability of the tooth/teeth and expected long term treatment
cost [Mejare et al., 2005; Mathu-Maju and Wright, 2006].
The FPM is not an orthodontist’s first choice for extraction,
because later orthodontic treatment may be complicated
[Williams and Gowans, 2003]. Therefore, the decision to
extract any of the FPM should be seriously evaluated and
discussed with an orthodontist as early as possible if a good
result is to be anticipated [Williams and Gowans, 2003;
Mathu-Maju and Wright, 2006]. If such a decision has been
taken the dental age of 8.5-9 years is the ideal time for their
extraction. A full clinical examination and a panoramic radiograph will help to evaluate particular contributory signs for
acceptable results [Williams and Gowans, 2003].
Complete crown formation and initiation of the calcification
of the bifurcation of the permanent second molar, particularly in the mandible, has the potential to help the eruption
of the second molar into a good contact with the second
premolar, especially when crowding is present. When there
is little or no crowding, a space will remain and fixed appliance treatment will be required at a later stage for closure.
Considerations should be given also for further FPM extractions in the maxilla for compensation and to the contralateral
molar or premolar of the same jaw for balancing, particularly
European Archives of Paediatric Dentistry // 11 (Issue 2). 2010
in crowded cases, in order to avoid a midline shift [Williams
and Gowans, 2003].
It should be stressed that all the above suggested treatment
outcomes are valuable, but only in cases of extractions during the indicated best period of development. In all other
cases the expected problems of such an approach (e.g.
drifting and rolling of adjacent teeth, periodontal defects,
occlusion problems, increased spacing), require full term
orthodontic treatment with fixed appliances. Such treatment
is usually of much longer duration than the one anticipated in
cases of premolar extractions [Williams and Gowans, 2003;
Seddon 2004].
However, looking to long term prognosis and treatment
outcomes, Mejare et al. [2005] found that at 18-years of
age the space closure that had occurred was acceptable in
87% of the individuals with extracted MIH molars, and the
sagittal relationships did not differ between individuals with
and without extraction, from a sample of 76 individuals that
24% had 1-3 molars extracted and 18% had all four FPM
extracted. These results are challenging, particularly if we
consider that the average age for extractions was 10·5 years
for mandibular and 10·6 for maxillary FPMs, in the cases
that received no orthodontic treatment. Additionally, a recent
study by Jälevik and Møller [2007] stated that the extraction
of severely affected FPM in MIH patients was an adequate
treatment alternative to restorative care. They examined the
orthodontic status of 20 patients 3.8-8.3 years after extractions and concluded that 15 of them had an acceptable
occlusion. Space reduction and favourable development
could be expected if the extractions were undertaken prior
to the eruption of the permanent second molar teeth.
Comments on extractions. When extractions of MIH FPMs
have been carried out, the two clinical long term studies reported acceptable results for space closure without
orthodontic treatment, if defective FPM extractions are
performed in due time. However, both studies present some
methodological limitations and additionally it is worth noting
that children in these studies were first seen and treated in
the 1990s, a period when the profession was not fully aware
of MIH and not many options for treatment were available.
Further prospective clinical research is obviously needed in
order to justify this convenient but still invasive approach in
judged as unrestorable cases.
Meanwhile taking into account all previously evaluated studies, a treatment decision plan (Table 2) can be proposed in
order to help the clinician deal with these MIH defects in his/
her everyday practice. The main concept for this proposal is
to ‘define the defect severity by individual tooth’ following an
initial overall decision whether to keep or to extract the tooth.
Treatment in molar-incisor-hypomineralisation
Table 2: Proposed treatment decision plan for MIH teeth.
Mild Defects
Moderate/Severe Defects
Enamel opacities without break-down,
no/slight sensitivity, mild aesthetic problems, no caries
Enamel break-down, atypical restorations,
sensitivity, caries, aesthetic problems
Incisors if needed
Incisors if needed
Fluoride varnish in partially
erupted teeth
In brownish-yellow defects, etchbleach-seal approach in younger
children, or chair-side bleaching
with 10% carbamide peroxide
in older.
Consider extractions
Wait until the defect gets better,
since a degree of enamel
mineralisation may occur in the
salivary environment
When fully erupted, sealants with
prior adhesives
In whitish defects, microabrasion followed if needed by
CR restoration
Fluoride varnish or GIC in
partially erupted teeth
CR restorations or veneers following micro-abrasion or enamel
reduction and intermediate
opaque resins
CR restorations if break-down or
caries occur
CR restorations following enamel
CR restorations for up to 3
Porcelain veneers if needed in
Full porcelain crowns, if needed,
in adulthood
PM crowns or copings for more
than 3 surfaces
Full porcelain crowns in
Ongoing preventive care for all cases
The information provided on treatment of MIH in the international literature is limited and empirical, relying mainly on
case reports and few clinical studies. However advances in
dental materials have provided clinical solutions in cases
that were regarded as unrestorable in the past. Intensive
individually prescribed preventive programs may postpone
the initiation of the actual restorative treatment and reduce
in long-term patient’s discomfort. In mild and moderate MIH
cases composite restorations using modern adhesives is the
treatment of choice and may last for many years until permanent restorations may placed. In severe cases transitional
treatment for function and aesthetics can be provided, using
the various modalities now available until adolescence when
permanent prosthetic approach with crowns in molars and
veneers in incisors can be initiated. Long term clinical trials supported by laboratory studies are needed to provide
‘guidelines’ for treating MIH.
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