Molar Incisor Hypomineralisation: The Bigger Picture

Molar Incisor Hypomineralisation:
The Bigger Picture
Helen Rodd, Professor of Paediatric Dentistry,
School of Clinical Dentistry, University of Sheffield

Today’s challenge…. what can I tell you about MIH
that you don’t already know?

MIH–related publications
Number
Journal special MIH issues
Eur J Paed Dent 2003 v4
Eur Arch Paed Dent 2008 v9 issue 4
16
14
12
10
8
6
4
2
0
2008 1 2007 2 2006 3 2005 4 2004 5 2003 6 2002 7 2001 8
Year of publication
NS Willmott et al. Molar Incisor Hypomineralisation:
A Literature Review. Eur Arch Paed Dent 2008; 9: 173-179.
International symposia
EAPD, Helsinki, May 2009

Lecture aims
To provide an overview of MIH
from the laboratory to the person
To review current data on the prevalence
and aetiology of MIH
To describe laboratory investigations of
the hard and soft tissues hypomineralised
teeth
To highlight challenges in clinical
management of this condition in children
To consider the views and experiences of
children themselves

Is this a new
clinical
condition?
MIH: definition
A clinical diagnosis to
describe
“hypomineralisation of
systemic origin of one to
four first permanent molars,
frequently associated with
affected incisors”
(Weerheijm et al., 2001)
‘idiopathic hypomineralisation’
‘cheese molars’

MIH: clinical presentation
Affected molars present with
well-demarcated
white/yellow or brown/yellow
enamel opacities
1-4 FPMs may be affected,
conflicting data as to
whether maxillary or
mandibular teeth more at
risk
In severe cases, defective
enamel is lost soon after
eruption to expose
underlying dentine

MIH: clinical presentation
Affected incisors also
present with welldemarcated
white/yellow or
brown/yellow enamel
opacities
Post-eruptive enamel loss is
not usually a feature
Increased risk of
hypomineralised incisors
where molars are more
severely affected

Differential diagnosis
Amelogenesis imperfecta
Dental fluorosis
Chronological hypoplasia
Which is hypoplasia and which is
post-eruptive enamel loss?

Chronological hypoplasia Hypomineralisation
(Now it’s easy!)

MIH: prevalence=3-25%, equal gender distribution
Is it
becoming
more
common?
Percentage Population Study
14%
19%
10%
2,339 Slovenian children
aged 12-18 yrs
488 Finnish children
aged 7-13 yrs
497 Dutch children aged
11 yrs
6% 2,408 German children
aged 10-17 yrs
10%
???
15-25%
18%
3,518 Greek children
aged 5.5-12 yrs
5,277 Danish children
aged 7 yrs
516 Swedish children,
aged 7-8 yrs
Kosem et al., 2004
Leppaniemi et al., 2001
Weerheijm et al., 2001
Dietrich et al., 2003
Lygidakis et al., 2008
Esmark & Simonson,
1995 (in Weerheijm &
Mejare, 2003)
Jalevick et al., 2001
14% 442 Dutch children Jalulaiyte et al., 2008
aged 9 yrs

MIH: underlying mechanisms
Results from an insult to enamel formation
from around 37 weeks to 3 years
Transitional and maturation phase of
enamel is affected – may be reversible or
irreversible damage to ameloblasts with
qualitative disturbance to enamel
formation
Results from protein retention and poor
crystal formation
Can be produced experimentally in rats
with conditions of low pH and low calcium
and phosphate availability

Lygidakis et al. Eur Arch
Paed Dent, 2008;9:207-
217.
88% of Greek children with
MIH (n=360) had known
medical problem vs 19%
recorded medical problems
in control group.
MIH: aetiology/associations
1. Pre-natal
factors
9% of MIH cases
Maternal pyrexia
Medication
Prolonged
vomiting
Maternal
diabetes

Lygidakis et al. Eur Arch
Paed Dent, 2008;9:207-217
MIH: aetiology/associations
2. Peri-natal factors
34% of MIH cases
Caesarean section*
Prolonged/complicated
delivery
Prematurity/low birth
weight
Twins

Lygidakis et al. Eur Arch
Paed Dent, 2008;9:207-217
MIH: aetiology/associations
3. Post-natal factors
34% of MIH cases
Ear/nose/throat infections
Respiratory problems
Pyrexia
Seizures
Prolonged medication
Urinary infections

MIH: aetiology/associations
Most ‘causes’ seem to be
associated with hypocalcaemia
and hypoxia
May also involve a genetic
susceptibility?
No obvious causes in 10-24% of
MIH patients (VanAmerogen & Kreulen,
1995; Jalevik & Noren, 2000)
Conflicting findings regarding role
of environmental pollutants such
as dioxins (Alaluusua et al., 1996; Laisi et al.,
2008)

MIH: Laboratory investigations of hard tissues
Affected enamel is:
very porous – thin irregular enamel rods
with wide inter-rod zones
has significantly lower hardness and
elasticity
has a reduced mineral content (5-20%)
Lower calcium to phosphorus ratio and
increased carbon content
outermost highly mineralised layer
achieves poor etch pattern with
phosphoric acid
cervical enamel usually has a normal
structure

MIH: Laboratory investigations of hard tissues
What about the dentine?
paucity of information on dentine in MIH
no obvious structural changes? (Heijis et al.,
2007)
reduced mineral content? (Fearne et al.,
2004)
Sparse reparative dentine, presence of
interglobular dentine
Influx of bacteria (Fagrell et al., 2008)

MIH: Laboratory investigations
of pulp tissues
Is there is an underlying pulpal
inflammation in MIH teeth?
Rodd HD, Boissonade FM, Day P (2007). Pulpal
status of hypomineralized permanent molars.
Pediatric Dentistry 29: 514-520.
Rodd HD, Morgan CR, Boissonade FM, Day P
(2007). Pulpal expression of TRPV1 in molar incisor
hypomineralisation. European Archives of Paediatric
Dentistry 8:184-188.

Experimental approach
• 25 intact & 19
hypomineralised
molars (9 with intact
enamel, 10 with
missing enamel)
• Mean age of
subjects = 9.4 yrs
• History of sensitivity
to cold/sweet noted
Analysis of -
• pulpal innervation
• immune cells
• vascularity
• TRPV1

MIH: key findings
Significant increases in neural density (green
labelling) in the pulp horn and subodontoblastic
region of MIH samples
Normal MIH

MIH: key findings
Significant increases in immune cell accumulation (red labelling)
in MIH samples, especially with post-eruptive enamel loss
Normal tooth
% area LCA
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Pulp horn Subodontoblastic
plexus
Region of analysis
MIH with post-eruptive enamel loss
Normal Series1
MIH Series2 – enamel intact
MIH Series3 – enamel loss
Mid-coronal region

MIH: key findings
There was a significant increase in vascularity (blue
labelling) in sensitive MIH samples
MIH – non-sensitive
MIH - sensitive

MIH: key findings
There was a significant increase in TRPV1 expression (yellow)
within pulpal nerves and blood vessels of MIH samples
15µm
Normal MIH
% area PGP 9.5 labelled for TRPV1
70
60
50
40
30
20
10
0
B
A
Pulp horn Subodontoblastic plexus Mid-pulp
Intact Hypomineralised
B
A

Why are
these teeth so
sensitive?
MIH: pain mechanisms
Dentine hypersensitivity: porous
enamel or exposed dentine
facilitates fluid flow within dentine
tubules to activate Aδ nerve fibres
(hydrodynamic theory)
Peripheral sensitisation: underlying
pulpal inflammation leads to
sensitisation of C-fibres
Central sensitisation: from
continued nociceptive input?

MIH: clinical challenges
Extreme sensitivity to normally innocuous
thermal, mechanical and chemical stimuli
(tooth brushing, cold, sweet things)
Failure to achieve adequate level of
analgesia for restorative treatment
Anxious and poorly compliant young
patients
High failure rate for adhesive restorations
Rapid caries development in
hypomineralised first permanent molars
(FPMs).

MIH: clinical challenges - supporting studies
A Swedish study of 9-yr-olds with
MIH and matched controls (Jalevik
and Klingberg, 2002) reported:
MIH children were significantly
more anxious about dental
treatment. 44% of MIH children
had dental behaviour management
problems as compared to 2% of
the controls
Restorations placed in
hypomineralised FPMs had failed
at least twice by the age of 9

MIH: treatment considerations
1. Prevention/remineralisation
2. Management of FPMs
3. Aesthetics of incisors
4. Child-centred approach

MIH: preventive considerations
Desensitising fluoridated
toothpastes
Casein-phospho-peptideamorphous
calcium oral care
products (e.g. ‘Tooth mousse’)

MIH: preventive considerations
Fluoride varnishes – regular
applications are advocated to reduce
sensitivity and encourage remineralisation
Strict dietary control is indicated, as
hypomineralised molars are more
susceptible to caries and erosion
Fissure sealants are recommended (but
may have adhesive bond failure in
hypomineralised enamel – pre-use of 5%
sodium hypochlorite? (Mathu-Muju & Wright, 2006)

MIH: management of first permanent molars
Early assessment of long-term prognosis
of FPMs and orthodontic status
Extraction
Extraction at the optimum stage of dental
development is likely to produce an
acceptable occlusal situation (Mejare et
al., 2005. Jalevik & Moller, 2007)
Restoration
(short-, mid-, long-term?)
Aims to reduce sensitivity
& protect hard tissues
50% of 18-yr-olds had an additional
treatment need with life-long cost and
maintenance implications (Mejare et al.,
2005)

Extraction of FPMs of poor prognosis
If necessary, carry out at optimum stage of
dental development (dental age of 9-11 years)
Balancing extractions not indicated unless
contralateral tooth also of poor prognosis or
premolar crowding
Class I cases – usually compensate lower FPM
extraction with upper FPM extraction
Class II cases – try to maintain upper FPMs
unless crowded case and upper FPM is
unopposed and third permanent molars present.
Additional premolar extractions may be necessary
Class III cases – try to restore
(Williams & McMullan, RCS Eng, 2004)

The ‘no choice’ case

Too early!

Too late!

Ensure optimum
behaviour management
and analgesia
Restoration of FPMs
resin-modified glass ionomer
composite resin
amalgam
preformed metal crowns
cast onlays/crowns

Adhesive restorations
GICs are useful as a short-term restoration
prior to definitive restoration or extraction (e.g
Fuji Triage, GC America Inc)
composite resins – only indicated for mildly
affected teeth with no cuspal involvement –
margins of restoration should extend beyond
visibly affected enamel

Preformed metal crowns
Advantages:
prevent further tooth deterioration
control tooth sensitivity
establish correct interproximal
contacts and occlusal relationships
not as technique-sensitive or costly as
cast restorations
require little time to prepare and insert
Disadvantages:
adverse reactions in patients with a
nickel allergy
production of anterior open bite if not
fitted correctly
gingival inflammation
not a permanent restoration
Tip – the use of elastic separators may obviate the need for interproximal
tooth preparation

Cast restorations
Indirect gold onlays - are
the restoration of choice for
moderate/severe
hypomineralisation where
the maintenance of FPMs is
indicated in the long term
Placement is usually
considered in the late
mixed or early permanent
dentition

Longevity of posterior restorations in MIH
1. Study of clinical performance of 40 gold crowns and 12 ceramic
crowns in 12 children aged 6-8 yrs found favourable outcome at
2-5 yr follow up for all crowns (Koch and Garcia-Godoy, 2000)
2. Study of 91 children found high level of clinically unacceptable
restorations (at 4-5 yr follow up) in hypomineralised FPMs
(GICs=51% unacceptable, Compomers=36% unacceptable,
Amalgams=22% unacceptable, Composites=16% unacceptable)
(Mejare et al., 2005)
3. Prospective clinical trial of children with variety of enamel
defects found no significant differences in successful outcome of
PMCs vs cast metal crowns (Zagdown et al., 2003)

MIH:management of hypomineralised incisors

Justification for treatment?
Essentially to improve dental
appearance – emerging
evidence to indicate negative
effect of poor dental appearance
on some individual’s
psychosocial status and the way
in which children are judged by
their peers
Decision for treatment should
be made by the child themselves

MIH: management of hypomineralised incisors
Take good clinical photos pre- and post-
treatment, ask child to indicate exactly
which ‘mark’ concerns them
Microabrasion
Microabrasion
& composite
restoration

MICROABRASION
a technique that involves the
chemical (acid) and mechanical
removal of intrinsic and superficial
enamel staining (50-250 microns)
first developed in 1984 – McClosky
(then well described by Croll and
Cavanagh)
safe, effective, conservative,
simple and economical

MICROABRASION Commercially
available as
‘Opalustre’ by
Ultradent
6.6% HCL with
Silicon carbide
Microparticles
Or 18% HCL
mixed with pumice

Pre-microabrasion Post-microabrasion

Pre-microabrasion Post-microabrasion and
thin composite ‘veneer’
Tip – use an opaquer to block out opacities under a composite restoration
(Esthet-X, Dentsply Caulk)

Pre-microabrasion
Post-microabrasion &
thin composite ‘veneer’

MIH: Taking a child-centred approach
Are children satisfied with the
treatment we provide?
What psychosocial impact do ‘marks on front teeth’
have on children and affect their social interactions
with others?
Do visible dental differences
affect a child’s experience
of transition to secondary
school?
What expectations do children have of treatment for
MIH, and what is their role in decision making?
What do children think about preformed
metal crowns?

Rationale………
‘Given it is the child who undergoes the treatment,
and lives with the consequences, it is important that
any research on the effectiveness of interventions
considers not just what clinicians think is in the
child’s best interests, but seeks their own
perspectives, desires and expectations.’
(Mouradian. Angle Orthodontist 1999;69:300-305)
UK National Service Framework for
Children, Young People and Maternity
services, 2004. ‘Services are to be childcentred,
and meet the needs of parents,
children and their families.’
Paucity of oral health research which
engages children as active participants.
(Marshman et al., Int J Paed Dent, 2008.)

Management of visible enamel defects:
seeking children’s perspectives
Yesudian G, Abdul-Karim A, Marshman Z and Rodd HD. Int J Paed Dent, 2009.
Aim: to explore how children felt before,
and after, cosmetic improvement of their
discoloured permanent incisors
Instrument: Development of specific
patient satisfaction questionnaire, based on
qualitative responses from 32 children,
aged 7-16 years, who had received
microabrasion ± composite restoration for
permanent incisor with enamel defect.

Participants and method:
A 10-item questionnaire, developed with
children themselves, was sent to 88
patients who had received microabrasion
and/or composite restorations, for a variety
of enamel defects, at Sheffield Dental
Hospital, UK.
Responses were graded using a 10cm
visual analogue scale (VAS) where a score
of 10 represented the most negative
response, and zero, the most positive.
Additional comments were invited.

Results:
Anonymous replies were
received from 62 children (70%
response rate)
Mean age of participants was
11.9 years (range 7-16)
42% were male, 58% were
female
55% reported teasing at school
No significant differences in
responses according to gender,
with the exception that, before
treatment, girls were reportedly
more worried about their teeth
than boys (P=0.012,
independent t-test).
Pre-treatment, children were found to be
very concerned about their front teeth
Qu 1. Did you feel worried about your front teeth? Mean VAS=6.8
I wasn’t worried at all I was very worried
Qu 2. Were you embarrassed about your front teeth? Mean VAS=6.9
I wasn’t embarrassed at all I was very embarrassed
Qu 3. How yellow or discoloured were your teeth? Mean VAS=7.3
not at all yellow/discoloured very yellow/discoloured
Post-treatment, children felt much better
about themselves and their teeth
Qu 4. Do your teeth look better after your treatment? Mean VAS=1.1
They look much better They look worse
Qu 5. How happy are you now with your front teeth? Mean VAS=2.2
I am very happy I am very unhappy
Qu 6. How confident are you now after your treatment? Mean VAS=1.6
I feel much more confident I don’t feel more confident
Feedback about treatment was positive
Qu 7. Were the staff on our clinic friendly? Mean VAS=0.4
The staff were very friendly The staff were very unfriendly
Qu 8. How well did the dentist explain things to you? Mean VAS=0.6
They explained everything well They did not explain things at al all

Individual comments
‘Is there anything else you would like to
tell us…?’
1. After treatment some children reported a profound
improvement in well being
‘I can not fault my treatment which
has made me gain some confidence,
which has helped me in this difficult
year of exams.’
(Girl, aged 15)
‘I am a lot happier now, people don’t
pick on me.’
(Boy, aged 10)
‘After the treatment I now feel I can
smile again.’
(Boy, aged 11)

Individual comments
‘Is there anything else you would like to
tell us…?’
2. But in some cases, expectations were not always fully met
‘I was looking forward to seeing my
teeth completely white, but they were
not completely white. They looked
better, but they should have said it
wasn’t going to do all my teeth white.’
(Girl, aged 13)
‘My teeth were treated well, and they
did all they could, but I would like a
little more done to them.’
(Boy, aged 10)
‘The initial effect was very encouraging, but over the months
since my treatment ended, the staining is returning, and I am
not as confident about the long term as I was last year.
Thanks for trying though ’ (Girl, aged 14)

Individual comments
‘Is there anything else you would like to
tell us…?’
3. Children felt they had been listened to and were well looked
after by our dental team
‘Everyone was kind and willing to
listen to my own opinion. I do not like
going to the dentist much, but I was
made to feel at ease’
(Girl, aged 13)
‘I was never afraid of my treatment as
it was explained in a way I could
understand.’
(Boy, aged 11)
‘The professor explained things well
and was clear about what work would
be done, Thank you.’
(Girl, aged 15)
‘Don’t give to students, they don’t
know what they are doing.’
(Boy, aged 13)

‘’I think my teeth are very clean and I think you did a very good job, thank you.
Since you did a good job, have a sweet!! Don’t forget to brush your teeth. Ha Ha!’
(Ethan, age 12)

Part 2. To be continued………………………!
Acceptability of preformed metal crowns:
children’s and parents’ perspectives
Bell, SJ and Rodd HD. Int J Paed Dent, 2009.
22%
14%
What do you think about your silver
tooth?
Was it ok having the silver cap put on
your tooth?
64%
I really like my silver tooth
64%
I don't mind my silver tooth
29%
I really hate my silver tooth
7%
Yes, it was really easy 64%
It was OK 22%
No, I hated it 14%

Thank you for your attention