Developmental disturbances of teeth can involve abnormalities in morphodifferentiation (tooth development) or histodifferentiation (tooth structure). Disturbances in morphodifferentiation include abnormalities in tooth number, size, and shape. Tooth number abnormalities include hypodontia (missing teeth) and hyperdontia (extra teeth). Size abnormalities include microdontia (small teeth) and macrodontia (large teeth). Shape abnormalities include double teeth, accessory cusps, dens invaginatus (tooth within a tooth), ectopic enamel, taurodontism, and dilaceration (bent root). Many of these disturbances have genetic and syndromic causes. Treatment depends on the specific abnormality but may

1. DEVELOPMENTAL DISTURBANCES
OF TEETH
By
Dr. Hagir Abd Rahman

2. classification
 Abnormalities of morphodifferentiation:
 abnormalities in the differentiation of the dental
lamina and the tooth germs.
 Abnormalities of histodifferentiation:
 abnormalities in the formation of the dental hard
tissues resulting in disturbances in tooth structure

3. Abnormalities of morphodifferentiation
1. Disturbances in number of teeth
2. Disturbances in size of teeth
3. Disturbances in shape of teeth

4. Disturbances in
number of teeth
Hypodontia
Hyperdontia

5. etiology
 Genetic. As part of a syndrome or alone.
 autosomal dominant or autosomal recessive or X-linked
pattern.
 hyperdontia is the result of a localized and independent
hyperactivity of dental lamina.
 Hypodontia can result from damage before tooth
formation; Trauma, infection, radiation, chemotherapeutic
medications, endocrine disturbances, and severe
intrauterine disturbances

6. Hypodontia

7.  Anodontia: is a complete absence of one or both
dentitions.
 Hypodontia: lack of development of one or
more teeth
 Oligodontia: lack of development of six or more
teeth

8.  more common in the permanent dentition.
 more common in females.
 If deciduous teeth were absent, permanent successor
tooth will also be absent.
 Hypodontia is associated positively with microdontia

9.  In permanent: Third molars, maxillary lateral
incisors, and mandibular second premolars most
commonly involved.
 In deciduous: maxillary lateral incisors and
mandibular incisors.

10. Syndromes Associated with Hypodontia
Ectodermal dysplasia. Incontinentia pigmenti Hypoglossia-
hypodactylia syndrome
Down syndrome. Turner syndrome. Lacrimo-auriculo-dento-
digital (LADD) syndrome
Crouzon syndrome. Sturge-Weber
syndrome
Cranio-oculo-dental
syndrome
Goldenhar syndrome Ehlers-Danlos syndrome hereditary hypohidrotic
ectodermal dysplasia

11. Hypodontia

12. Hypodontia

13. Hypodontia

14. Dental transposition
 normal teeth erupting
into an inappropriate
position
 increased prevalence
of hypodontia
 Maxillary canines and
first premolars

15. Treatment and Prognosis
 Treatment: prosthetic replacement

16. Hypohidrotic ectodermal dysplasia
 inherited as an X-linked recessive trait.
 characterized by the congenital absence of ectodermal
structures.
 partial or total absence of sweat glands.
 smooth, dry skin with fine, scanty hairs.
 delayed eruption, deformed, and frequently have
conical crowns

18. Hyperdontia

19.  is the development of an increased number of teeth
 The additional teeth are termed supernumerary
 more common in males
 maxillary incisor region, followed by the molar
region, then premolars, canines, and lateral incisors.

20.  usually single.
 unusual in the deciduous dentition.
 Hyperdontia is positively correlated with
macrodontia

21. terms to describe supernumerary teeth,
depending on their location
mesiodens
• between the
maxillary
central
incisors
• The most
common
Paramolar
• lingually or
buccally to a
molar tooth
Distomolar
• distal to a
third molar

22. supernumerary
supplemental:
normal size and
shape
Rudimentary:
abnormal shape
and size
Conical
(small, peg-
shaped)
tuberculate
(more than one
cusp)
molariform
(small premolar/
molarlike).

23. Natal teeth
 present at or shortly after birth.
 teeth present in newborns have been called natal teeth;
those arising within the first 30 days of life are
designated neonatal teeth.
 May represent predeciduous supernumerary teeth,
however most are prematurely erupted deciduous teeth.
 85% are mandibular incisors, 11% are maxillary
incisors, and 4% are posterior teeth.

24. Hypohyperdontia
 both hypo- and hyperdontia.
 missing mandibular incisors followed by second
premolars.
 supernumerary teeth seen most frequently in the
anterior maxilla followed by canines or maxillary
premolars.

25. Syndromes Associated with Hyperdontia
Apert syndrome Crouzon syndrome Down syndrome
Cleidocranial
dysplasia
Ehlers-Danlos
syndrome
Sturge-Weber
syndrome
Gardner syndrome Incontinentia pigmenti Leopard syndrome

27. Mesiodens

28. Bilateral
inverted

29. Right
mandibular
dentition
exhibiting four
erupted
bicuspids

30. Distodens

31. Paramolar

32. Natal
Teeth

33. Riga-Fede
syndrome:
Traumatic
ulcerations of
the adjacent
soft tissue

34. Effects of supernumerary teeth
delay eruption and resorption of permanent teeth
displacement of the teeth with associated
crowding
Dilaceration
eruption into the nasal cavity
development of odontogenic cysts and tumors

35. Treatment
 Treated by surgical removal

36. Disturbances in size of teeth
Macrodontia
Microdontia

37. Microdontia

38.  teeth that are physically smaller than usual.
 maxillary lateral incisor is affected most frequently
and typically appears as a peg shaped crown
overlying a root that often is of normal length.
 Third molars are also commonly affected.

39.  Diffuse microdontia is uncommon but may occur in
Down syndrome., and pituitary dwarfism.
 relative microdontia: Normal-sized teeth that
appear small when widely spaced within jaws that
are larger than normal (macrognathia).

40. Diffuse
Microdontia.

41. Isolated
Microdontia
(Peg Lateral).
Small, cone-
shaped right
maxillary
lateral incisor.

42. megalodontia
megadontia
Macrodontia

43.  teeth that are physically larger than usual.
 Diffuse involvement is rare, and has been noted in
association with pituitary gigantism
 Unilateral cases are associated with hemifacial
hyperplasia.
 Isolated macrodontia is most common in incisors or canines
 relative macrodontia: normal-sized teeth crowded within
a small jaw

44. Macrodontia.
The patient’s
left maxillary
central incisor
is abnormally
large

45. Disturbances in shape of teeth
Double teeth Concrescence Accessory
cusps
Dens
invaginatus Ectopic enamel Taurodontism
Hypercementosis Dilaceration

46. connate teeth
conjoined teeth
DOUBLE TEETH

47.  two teeth appear joined together.
 They exhibit union by dentin and (perhaps) pulps.
 The union may be the result of fusion of two adjacent
tooth buds or the partial splitting of one.
 The degree of union is variable and may involve the
crown, the roots, or both.
 higher frequency in the anterior maxillary regions

48. Double
teeth
fusion gemination

49. Fusion
 the union of two normally separated tooth buds with the
resultant formation of a joined tooth.
 The fusion may be complete over the full length of the
teeth or only partial.
 The tooth count reveals a missing tooth when the
anomalous tooth is counted as one.
 Occasionally, fusion in the primary dentition is associated
with absence of the underlying permanent successor

50. Gemination
 the partial development of two teeth from a single
tooth bud following incomplete division.
 abnormally formed tooth with usually one root and
root canal.
 the tooth count is normal when the anomalous tooth is
counted as one

51. Gemination
Two double
teeth. The
tooth count
was normal
when each
anomalous
tooth was
counted as
one

52. Gemination
Mandibular bicuspid
exhibiting bifid crown
bifid crown and shared root
canal

53. Fusion
Double tooth
in the place of
the
mandibular
right lateral
incisor and
cuspid

54. Fusion
Bilateral double teeth in the place of
the mandibular lateral incisors and
cuspids

55. treatment
 sectioning: with or without endodontic therapy.
 shaping with or without placement of full crowns.
 surgical removal with prosthetic replacement.

56. CONCRESCENCE

57.  the union of two
teeth by cementum
without confluence
of the dentin.

58. Union by cementum of
maxillary second and third
molars

60. ACCESSORY CUSPS

61. three distinctive patterns:
cusp of Carabelli
talon cusp
dens evaginatus

62. Cusp of Carabelli
 is an accessory cusp located on the palatal surface of
the mesialingual cusp of a maxillary molar.
 varies from a definite cusp to a small pit or fissure.
 most pronounced on the first molar.
 When present, the remaining permanent teeth often
are larger than normal mesiodistally.

63. Cusp of Carabelli

64. Talon cusp
 Additional cusp that is located on the surface of an
anterior tooth and extends at least half the distance
from the cemento-enamel junction to the incisal edge.
 Most common in maxillary incisors.
 A deep developmental groove may be present where
the cusp fuses with the affected tooth .

66.  Radiographically, the
cusp is seen overlying
the central portion of
the crown and includes
enamel and dentin.
Only a few cases
demonstrate visible
pulpal

67. Syndromes associated with talon cusp
• Rubinstein-Taybi syndrome
• Mohr syndrome
• Ellis-van Creveld syndrome
• incontinentia pigmenti
• Sturge-Weber syndrome

68. Dens Evaginatus
 a cusp-like elevation of enamel located in the central
groove or lingual ridge of the buccal cusp of premolar
or molar teeth
 Mandible.
 usually bilateral
 Consists of enamel, dentin, and sometimes pulp.

70.  tuberculated occlusal
anatomy.
 Attrition on the
accessory cusp led to
pulpal necrosis and
periapical
inflammation.

71.  Frequently, dens
evaginatus is seen in
association with shovel-
shaped incisors.
 Affected incisors
demonstrate prominent
lateral margins, creating
a hollowed lingual
surface that resembles
the scoop of a shovel

72. dens in dente
DENS INVAGINATUS

73.  is a deep surface invagination of the crown or root
that is lined by enamel.
 Frequency in decreasing order; lateral incisors,
central incisors, premolars, canines, and molars.
 2 patterns: coronal and radicular

74.  Type I: an
invagination that is
confined to the crown.
 type II: extends below
the cementoenamel
junction.
 Type III extends
through the root and
perforates in the
apical or lateral
radicular area without
any communication
with the pulp.
classification

75.  Type I is the most common pattern.
 the invagination may be large and resemble a
tooth within a tooth (dens in dente).

77. Type II Type II

78.  Type III. enamel
invagination parallels the
pulp canal and perforates
the lateral root surface.
Type III. Parulis. The cuspid
contained a dens invaginatus
that perforated the mesial
surface of its root

79. Radicular dens invaginatus:
 invagination in the root of the
tooth
 Radiographically, the
affected tooth demonstrates
an enlargement of the root.

80. Treatment
 Restoration/ endodontic therapy.
 Extraction.

81. ECTOPIC ENAMEL

82. ECTOPIC
ENAMEL
Enamel Pearls
Cervical
Enamel
Extensions
The presence of enamel in
unusual locations, mainly the
tooth root.

83. Enamel pearls
 hemispheric structures that may consist entirely of
enamel or contain underlying dentin and pulp tissue.
 Found most frequently on the-roots of maxillary
molars, followed by mandibular molars
 May consist entirely of enamel or contain
underlying dentin and pulp tissue.

85.  well-defined
radiopaqe nodules
along the root's surface

87. Cervical enamel extensions
 A triangular extension of the coronal enamel that
develops on the buccal surface of molar teeth.
 Mandibular molars are affected more frequently.

88. Normal cervical
enamel
Cervical enamel
extension

90. Effects of the tooth
 The enamel pearls prevents normal periodontal
attachment.
 the exophytic nature of the pearl is conducive to
plaque retention and inadequate cleansing.

91. Treatment
 Thorough oral hygiene should be maintained to
prevent localized loss of periodontal support.
 Exposed enamel pearl: surgical removal.
 For teeth with cervical enamel extensions:
appropriate cleaning.

92. TAURODONTISM

93.  tauro = bull; dont = tooth. Bull-like tooth.
 is an enlargement of the pulp chamber of a
multirooted tooth, with apical displacement of
the pulpal floor and bifurcation of the roots.

94.  The pulp chamber has a greater apico-occlusal height
than in normal teeth, with no constriction at the level
of the cemento-enamel junction.
 affects multi-rooted teeth.
 unilateral or bilateral

95. TAURODONTISM
Normal mild moderate severe

97. • Amelogenesis imperfecta
• Ectodermal dysplasia
• Down syndrome
• Hypophosphatasia
• Ellis-van Creveld
• Microdontia-taurodontia-dens invaginatus
• Oculo-dento-digital dysplasia
• Cranioectodermal dysplasia
syndromes associated with Taurodontism

98. DILACERATION

99.  is an abnormal angulation or bend in the root or,
less frequently, the crown of a tooth
 displacement of the root from its normal alignment
with the crown.
 usually the result of mechanical trauma.
 most frequently involves the maxillary incisors.

103. HYPERCEMENTOSIS

104.  Is the deposition of excessive cementum that is
continuous with the normal cementum.
 May be isolated, may involve multiple teeth, or may
appear as a generalized process.
 Radiographically, affected teeth demonstrate a
thickening or blunting of the root.

105. Factors Associated with ↑ Hypercementosis
Local Factors
Abnormal occlusal trauma
Unopposed teeth
Adjacent inflammation
Systemic Factors
Gardner syndrome
Thyroid goiter
Paget's disease of bone
Arthritis & Rheumatic
fever
Acromegaly and
pituitary gigantism

107. Histopathologic Features
 The periphery of the root exhibits deposition of an
excessive amount of cementum.
 The excessive cementum may be hypocellular or
exhibit areas of cellular cementum that resemble
bone (osteocementum).

108. The dividing line between dentin
and cementum is indistinct
Polarized light: the sharp dividing
line between the tubular dentin and
osteocementum.

109. Thank you