AMELOGENESIS IMPERFECTA & ENVIRONMENTAL ENAMEL HYPOPLASIA PPT Prepared from multiple credible sources.

1. Department of Oral Pathology & Microbiology
Seminar
PRESENTOR: ANOOP SHAJI
III BDS
CENTURY DENTAL COLLEGE,KASARGOD,KERALA
PRESENTOR: ANOOP SHAJI
III BDS
CENTURY DENTAL COLLEGE,KASARGOD,KERALA

2. CONTENTS
 AMELOGENESIS IMPERFECTA
1. INTRODUCTION
2. CLASSIFICATION
3. MOLECULAR GENETICS
4. CLINICAL FINDINGS
5. RADIOGRAPHIC FEATURES
6. HISTOLOGIC FEATURES
7. TREATMENT CONCEPTS
 ENVIRONMENTAL ENAMEL HYPOPLASIA
1. INTRODUCTION
2. INFLUENTIAL FACTORS
 REFERENCES

3.  Enamel hypoplasia may be defined as
an incomplete or defective formation of
the organic enamel matrix of teeth
 Two basic types of enamel hypoplasia
exist:
(1) a hereditary type, discussed under
amelogenesis imperfecta, and
(2) a type caused by environmental
factors.

4.  In the hereditary type, both the
deciduous and permanent dentitions
usually are involved and generally only
the enamel is affected.
 In contrast, when the defect is caused
by environmental factors either dentition
may be involved and sometimes only a
single tooth; both enamel and dentin are
usually affected, at least to some
degree.

6. Amelogenesis Imperfecta
(Hereditary enamel dysplasia, hereditary brown
enamel,hereditary brown opalescent teeth)
 A complex inheritance pattern gives rise to
amelogenesis imperfecta (AI), a structural
defect of the tooth enamel.
 It may be differentiated into three main
groups: {Witkop & Sauk 1976}
 hypoplastic (HP),
 hypocalcified (HC), and
 hypomature (HM),
depending on the clinical presentation of the
defects and the likely stage of enamel formation
that is primarily affected
1.Hypoplastic (HP),
2.Hypocalcified (HC), and
3.Hypomature (HM)

7. WITKOP {1989} CLASSIFICATION OF AMELOGENESIS
IMPERFECTA

8.  (*K Gadhia et.al.Amelogenesis imperfecta: an
introduction.British Dental Journal 2012; 212: 377-379)
• Enamel of reduced
thickness due to a
defect in the formation
of normal matrix
• Pitting and grooves
• Hard and translucent
enamel
• Radiographically, the
enamel contrasts
normally from dentine.
• Defect in enamel
calcification
• Enamel of normal
thickness
• Weak in structure
• Appears opaque or
chalky
• Teeth become
stained and rapidly
wear down
• Radiographically,
enamel is less
radio-opaque than
dentine.
HYPOPLASTIC AI HYPOCALCIFIED AI HYPOMATURATIVE AI

9.  The prevalence is estimated to range from
(1 in 718) to (1 in 14,000), depending on
the population studied.
 Hypoplastic AI represents 60–73% of all
cases, hypomaturation AI represents 20–
40%, and hypocalcification AI represents
7%.
 Disorders of the enamel epithelium also
can cause alterations in the eruption
mechanism, resulting in the anterior open
bite.

10. Molecular Genetics
Mutations in the :
Genes found to cause Amelogenesis Imperfecta (non-syndromic form)
 (*Seow WK. Developmental defects of enamel and dentine:
challenges for basic science research and clinical management.
Aust Dent J. 2014;59(Suppl1):143–54)
AMELX,ENAM,
MMP20,
KLK-4,
FAM83H,
WDR72,
C4orf26,
SLC24A4,
LAMB3 and
ITGB6

11.  AMELX and ENAM extracellular matrix
proteins of the developing tooth enamel
 KLK-4 and MMP20 proteases that help
degrade organic matter from the enamel
matrix during the maturation stage of
amelogenesis.
 SLC24A4 calcium transporter that
mediates calcium transport to developing
enamel during tooth development.
 Less is known about the function of other
genes implicated in amelogenesis imperfecta.

12.  Mutations in the ENAM gene are the most
frequent known cause and are most
commonly inherited in an autosomal
dominant pattern.
 The form of disorder which result from
mutations in the ENAM, MMP20, KLK4,
FAM20A, C4orf26 or SLC24A4 genes are
inherited as autosomal recessive pattern.
 About 5% of amelogenesis imperfecta
cases are caused by mutations in the
AMELX gene and are inherited in an X-
linked pattern.

13.  Analysis of X-linked AI has shown the
defective gene for this specific AI type to
be closely linked to the locus DXS85 at
Xp22.
 Interestingly, this also has been
identified as the general location of the
human gene for amelogenin, the
principal protein in developing enamel.

14.  Amelogenesis imperfecta is sometimes associated with
syndromes like, Amelogenesis Imperfecta with taurodontism,
tricho-dentoosseous syndrome, AI with nephrocalcinosis and
cone-rod dystrophy with AI.
 The commonest differential diagnosis which should be kept in
mind during the clinical assessment is dental fluorosis.
 The variability of this condition, from mild white ‘flecking’ of
the enamel to profoundly dense white coloration with random,
disfiguring areas of staining and hypoplasia, requires careful
questioning to distinguish from AI.
 * (Pavlicˇ A, Battelino T, Podkrajsˇek KT, Ovsenik M. Craniofacial
characteristics and genotypes of amelogenesis imperfecta patients.
Eur J Orthod. 2011;33:325–31)

15. CLINICAL FINDINGS
 Parekh et al.* investigated the impact of the alterations of AI on
the quality of life of patients(61 patients, response rate 61 %)
suffering from AI.
 For about 90 % of all patients, the main complaint was the
discolouration of their teeth and about 77 % asked for an
improvement of their smile.
 For nearly the same percentage (74 %), reduction of sensitivity
was the most important reason to seek for dental treatment,
while improvement of the tooth size was important for 60 % of
all patients*.
(*Parekh S, Almehateb M, Cunningham SJ. How do children with
amelogenesis imperfecta feel about their teeth? Int J Paediatr Dent.
2014;24:326–35)

16.  Regarding the intraoral examination, several characteristic findings
have been reported:
A. Often wear of enamel with exposed dentin areas are evident
especially at the occlusal aspects of posterior teeth*.
B. Due to loss or hypoplastic enamel, the lack of proximal contacts is
typical.
C. A further consequence of the loss/lack of enamel is the loss of the
vertical dimension**.
D. Functional problems like decreased masticatory efficiency.
 (*Sholapurkar et.al. Clinical diagnosis and oral rehabilitation of a
patient with amelogenesis imperfecta: a case report. J Contemp
Dent Pract. 2008;9:92–8.)
 (**Shetty YB, Shetty A. Oral rehabilitation of a young adult with
amelogenesis imperfecta: a clinical report. J Indian Prosthodont
Soc. 2010;10:240–5.)

17.  Besides alterations of dental hard tissues,
also craniofacial alterations of patients with
AI have been reported, like anterior open
bite (AOB), posterior open bite (POB),
negative overjet and altered vertical jaw
relationship.
 Some authors described a greater number
of unerupted teeth.
(*Alachioti XS, Dimopoulou E, Vlasakidou A, Athanasiou
AE.Amelogenesis imperfecta and anterior open bite: etiological,
classification, clinical and management interrelationships. J Orthod
Sci. 2014;3:1–6).

18. Radiographic Features
 The overall shape of the tooth may or may
not be normal, depending upon the amount
of enamel present on the tooth and the
amount of occlusal and incisal wear.
 The enamel may appear totally absent on
the radiograph, or when present, may appear
as a very thin layer, chiefly over the tips of
the cusps and on the interproximal surfaces
 In other cases the calcification of the enamel
may be so affected that it appears to have
the same approximate radiodensity as the
dentin,making differentiation between the
two difficult

19. In hypocalcification enamel
RD=or less than dentin
In hypoplastic type- R D of
enamel>dentin
In hypomaturation type-R D of
enamel=dentin

20. Histologic Features
 The general histologic features of the enamel
also parallel the general type of amelogenesis
imperfecta that has been diagnosed.
 There is a disturbance in the differentiation or
viability of ameloblasts in the hypoplastic type,
and this is reflected in defects in matrix
formation up to and including total absence of
matrix.
 In the hypocalcification types there are defects
of matrix structure and of mineral deposition.
 Finally, in the hypomaturation types there are
alterations in enamel rod and rod sheath
structures.

21. TREATMENT
 There is no treatment except for improvement
of cosmetic appearance. However, in some
cases, these teeth do not appear markedly
abnormal to the casual observer.
 Adequate treatment concepts of patients with
AI must be based on an interdisciplinary
approach*
 (*Sabandal.et.al. Amelogenesis imperfecta-review of diagnostic
findings and treatment concepts.Odontology Volume issue
2016)

22.  Especially patients
with hypoplastic and
hypocalcified forms of
AI have a higher
incidence for AOB
 Besides differences in
the vertical growth
pattern, also Class II
and III malocclusions
have been reported
 Especially in subjects
with anterior open
bite orthodontic
surgery may be
necessary, often in
combination with
extraction of some
teeth
ORTHODONTIC
TREATMENT SURGERY

23.  In general, the longevity of
dental restorations in
patients with AI is
considerably reduced and
this correlates with the
severity of AI.
 Treatment with direct
composite restorations
was mostly performed as a
temporary therapy to gain
some time and to perform
the definitive restoration in
an older stage of life.
 Besides full metal crowns
especially in the posterior
region,also porcelain
fused- to-metal crowns
and bridges.
 Recently all-ceramic
crowns have been shown
to allow sufficient long-
term restoration of the
affected teeth.
 Depending on the age of
the patient, also other
materials like composite
crowns, composite
veneers and in younger
patients even stainless
steel crowns may be
beneficial.
RESTORATIVE
TREATMENT
PROSTHETIC
TREATMENT

25. Factors influencing
(1) Nutritional deficiency (vitamins A, C, and D);
(2) Exanthematous diseases (e.g. measles,
chickenpox, scarlet fever);
(3) Congenital syphilis;
(4)Hypocalcemia;
(5) Birth injury, prematurity, Rh hemolytic disease;
(6) Local infection or trauma;
(7) Ingestion of chemicals (chiefly fluoride); and
(8) Idiopathic causes

26.  Hypoplasia results only if the injury occurs
during the time the teeth are developing, or
more specifically, during the formative stage of
enamel development.
 Once the enamel has calcified, no such defect
can be produced.
 Thus, knowing the chronologic development
of the deciduous and permanent teeth,it is
possible to determine from the location of the
defect on the teeth the approximate time at
which the injury occurred.

27. Hypoplasia due to Nutritional
Deficiency and Exanthematous
Fevers
 Some studies have indicated that the
exanthematous diseases, including measles,
chickenpox and scarlet fever, are etiologic
factors, but other investigators have been
unable to confirm this finding.
 In general, it might be stated that any serious
nutritional deficiency or systemic disease is
potentially capable of producing enamel
hypoplasia, since the ameloblasts are one of
the most sensitive groups of cells in the body
in terms of metabolic function.

28.  Clinical studies indicate that most cases of
enamel hypoplasia involve those teeth that
form within the first year after birth, although
teeth that form somewhat later may be
affected.
 Thus the teeth most frequently involved are
the central and lateral incisors, cuspids, and
first molars.
 Premolars and second and third molars are
seldom affected, since their formation does not
begin until about the age of three years or
later.

29.  There has been considerable
controversy as to whether there is any
relation between enamel hypoplasia and
dental caries experience, and clinical
reports have given conflicting results.
 It is most reasonable to assume that the
two are not related, although hypoplastic
teeth do appear to decay at a somewhat
more rapid rate once caries has been
initiated

30. Enamel Hypoplasia due to
Congenital Syphilis
 The hypoplasia due to congenital syphilis is
most frequently notand that, consequently,
congenital syphilis in children under one year
of age increased 117% during the 10–year
period from 1960 to 1969.
 Investigating 271 patients with congenital
syphilis, they found that over 63% had
Hutchinson’s teeth but
 they pointed out that this may not be the true
incidence, since some of the patients had
their teeth extracted.

31.  In addition, approximately 65% of this
group of patients with congenital syphilis
also had the characteristic ‘mulberry
molars.’
 Also, occasional patients will appear to
have Hutchinson’s teeth without having a
history of congenital syphilis.
 The diagnosis of syphilis, particularly in the
absence of the other conditions of
Hutchinson’s triad(Interstitial Keratosis,
hutchinson incisors & Eigth nerve
deafness) must be made without hasty.

32. Hutchinson’s triad
Interstitial keratitis
and strabismus.
The semilunar notch on the
incisal edge of mandibular
incisors (Hutchinson’s teeth).
Enamel hypoplasia of
maxillary central incisors
(Hutchinson’s teeth).
(*Larissa et.al.Clinical aspects of congenital syphilis with Hutchinson’s triad.BMJ
Case Reports 2011)

33. Enamel Hypoplasia due to
Hypocalcemia
 Tetany, induced by a decreased level of calcium
in the blood, may result from several conditions,
the most common being vitamin D deficiency
and parathyroid deficiency (parathyroprivic
tetany).
 In tetany the serum calcium level may fall as low
as 6–8 mg per 100 ml, and at this level enamel
hypoplasia is frequently produced in teeth
developing concomitantly.
 This type of enamel hypoplasia is usually of the
pitting variety and thus does not differ from that
resulting from a nutritional disturbance or
exanthematous disease.

34. Hypoplasia due to Birth Injuries
 The neonatal line or ring, described by
Schour in 1936 and present in
deciduous teeth and first permanent
molars, may be thought of as a type of
hypoplasia because there is a
disturbance produced in the enamel and
dentin, which is indicative of trauma or
change of environment at the time of
birth.

35.  Miller and Forrester have reported a clinical study
with evidence that enamel hypoplasia is far more
common in prematurely born children than in normal
term infants.
- Cases of ring-like staining of teeth in children who
had suffered from Rh hemolytic disease at birth (q.v.)
was reported with enamel hypoplasia {Rh Hump}
 Grahnen and Larsson have also shown an increased
incidence of enamel hypoplasia in premature
children, but interestingly no differences in caries
incidence between this group and a control group of
children

36. Enamel Hypoplasia due to
Local Infection or Trauma
 A type of hypoplasia occasionally seen is
unusual in that only a single tooth is involved,
most commonly one of the permanent
maxillary incisors or a maxillary or mandibular
premolar.
 There may be any degree of hypoplasia,
ranging from a mild, brownish discoloration of
the enamel to a severe pitting and irregularity
of the tooth crown.
 These single teeth are frequently referred to
as ‘Turner’s teeth,’ and the condition is called
‘Turner’s hypoplasia.’

38.  If a deciduous tooth becomes carious during
the period when the crown of the succeeding
permanent tooth is being formed, a bacterial
infection involving the periapical tissue of this
deciduous tooth may disturb the ameloblastic
layer of the permanent tooth and result in a
hypoplastic crown.
 The severity of this hypoplasia will depend
upon the severity of the infection, the degree
of tissue involvement, and the stage of
permanent tooth formation during which the
infection occurred

39.  A similar type of hypoplasia may follow
trauma to a deciduous tooth, particularly
when the deciduous tooth has been driven
into the alveolus and has disturbed the
permanent tooth bud.
 If this permanent tooth crown is still being
formed, the resulting injury may be
manifested as a yellowish or brownish stain
or pigmentation of the enamel, usually on the
labial surface, or as a true hypoplastic pitting
defect or deformity.

40. Enamel Hypoplasia due to
Fluoride: Mottled Enamel
 Mottled enamel is a type of enamel
hypoplasia that was first described under
that term in this country by GV Black and
Frederick.
 Black and McKay recognized that this
lesion exhibited a geographic distribution
and even suggested that it was a result of
some substance in the water supply,
although it was not until some years later
that fluorine was shown to be the causative
agent.

41. Etiology
 It is now recognized that the ingestion of
fluoride containing drinking water during the
time of tooth formation may result in mottled
enamel.
 The severity of the mottling increases with an
increasing amount of fluoride in the water.
 Thus there is little mottling of any clinical
significance at a level below 0.9–1.0 part per
million of fluoride in the water, whereas it
becomes progressively evident above this
level.

42. Indian Geographic Distribution
(*Arlappa N et.al. Fluorosis in India: an overview Int J Res Dev Health. April 2013; Vol 1(2))

43. Pathogenesis
 This type of hypoplasia is due to a
disturbance of the ameloblasts during the
formative stage of tooth development.
 The exact nature of the injury is not known,
but since there is histologic evidence of cell
damage, it is likely that the cell product, the
enamel matrix, is defective or deficient.
 It also has been shown that, with somewhat
higher levels of fluoride, there is interference
with the calcification process of the matrix.

44.  Epidemiologic studies have reported that
not all children born and reared in an area
of endemic fluorosis exhibit the same
degree of mottling even though they all
have used the same water supply.
 Furthermore, a few persons may exhibit
mild mottling even when exposed to a very
low concentration of fluoride.
 These findings may be related to individual
variation in total water consumption and
thus to total fluoride intake

45. Clinical Features
 Depending upon the level of fluoride in the water
supply,Wide range of severity in the Appearance of
mottled teeth, varying from:
(1) questionable changes characterized by
occasional white flecking or spotting of the enamel,
(2) mild changes manifested by white opaque areas
involving more of the tooth surface area
(3) moderate and severe changes showing pitting
and brownish staining of the surface and
(4) a corroded appearance of the teeth.
 Those teeth which are moderately or severely
affected may show a tendency for wear and even
fracture.

47. Treatment
 Mottled enamel frequently becomes
stained an unsightly brown color.
 For cosmetic reasons, it has become the
practice to bleach the affected teeth with
an agent such as hydrogen peroxide.
 This is frequently effective, but the
procedure must be carried out
periodically, since the teeth continue to
stain.

48. Hypoplasia due to Idiopathic
Factors
 Although numerous factors have been
reported as being possibly responsible for
causing enamel hypoplasia, clinical studies
have shown that, even with careful histories,
the majority of cases are of unknown origin.
 Since the ameloblast is a sensitive type of cell
and easily damaged, it is likely that in those
cases in which the etiology cannot be
determined, the causative agent may have
been some illness or systemic disturbance so
mild that it made no impression on the patient
and was not remembered.

49. REFERENCES
 Shafer’s Textbook of Oral Pathology;8th ED
 JOURNAL REFERENCES:
1. K Gadhia et.al.Amelogenesis imperfecta: an introduction.British Dental Journal 2012;
212: 377-379
2. Seow WK.Developmental defects of enamel and dentine: challenges for basic
science research and clinical management. Aust Dent J. 2014;59(Suppl1):143–54
3.Pavlic A.et.al. Craniofacial characteristics and genotypes of amelogenesis imperfecta
patients. Eur J Orthod. 2011;33:325–31
4. Parekh S.et.al. How do children with amelogenesis imperfecta feel about their teeth?
Int J Paediatr Dent. 2014;24:326–35
5. Sholapurkar et.al. Clinical diagnosis and oral rehabilitation of a patient with
amelogenesis imperfecta: a case report. J Contemp Dent Pract. 2008;9:92–8
6. Shetty YB.et.al.Oral rehabilitation of a young adult with amelogenesis imperfecta: a
clinical report. J Indian Prosthodont Soc. 2010;10:240–5
7. Alachioti XS.et.al.Amelogenesis imperfecta and anterior open bite: etiological,
classification, clinical and management interrelationships. J Orthod Sci. 2014;3:1–6
8. Sabandal.et.al. Amelogenesis imperfecta-review of diagnostic findings and treatment
concepts.Odontology Volume issue 2016
9. Larissa et.al.Clinical aspects of congenital syphilis with Hutchinson’s triad.BMJ Case
Reports 2011
10. Arlappa N et.al. Fluorosis in India: an overview Int J Res Dev Health. April 2013; Vol
1(2)