Developmental Anomalies of
Teeth
Classification
Affecting the size
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Microdontia
Macrodontia
Rhizomicri
Rhizomegaly
Affecting the Number
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Anodontia
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Supernumerary teeth
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Pre-deciduous dentition
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Post permanent dentition
Affecting the Shape
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Gemination
Fusion
Concrescence
Talon’s cusp
Dens invaginatus
Dens evaginatus
Taurodontism
Dilaceration / Flexion
Supernumerary root
Extra cusps
Enamel pearl
Cervical enamel extension
Affecting the position
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Ectopia
Rotation
Trans-position
Inversion
Trans-migration
Affecting Eruption
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Premature eruption
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Delayed eruption
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Impacted tooth
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Embedded tooth
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Submerged tooth
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Eruption sequestrum
Affecting the Structure
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Enamel
Enamel hypoplasia
Amelogenesis imperfecta
Dentin
Dentinogenesis imperfecta
Dentin dysplasia
Enamel + Dentin
Regional odontodysplasia
Microdontia
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This term is used to describe teeth which are smaller than
normal,
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More in females
Etiology
 Genetic factors
 Environmental factors
Types
1. Generalized microdontia (>14)
- True
- Relative
2. Focal microdontia (<14)
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TRUE GENERALIZED MICRODONTIA
 All the teeth in both arches are well formed but, uniformly
smaller than normal
 Associated with
- Pituitary dwarfism
- Down’s syndrome
- Congenital heart disease
RELATIVE GENERALIZED MICRODONTIA
 Large jaw size relative to the teeth makes the normal teeth
seem smaller
 Hereditary condition
 Spacing between teeth
True generalized microdontia
Relative generalized microdontia
Focal Microdontia
One or more teeth are smaller than normal
 More common than generalized microdontia
 Frequently involved teeth are maxillary laterals &
maxillary 3rd molars
E.g. – Peg laterals
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Macrodontia (Megadontia / Megalodontia)
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Condition in which one or more teeth are larger than
normal.
Types
1. Generalized macrodontia
- True
- Relative
2. Localized macrodontia
Macrodontia
True generalized macrodontia
All the teeth in both arches are well formed & uniformly
larger than normal
Eg- Pituitary gigantism
Relative generalized macrodontia
 Small jaw size relative to the teeth makes the normal teeth
seem larger
 Hereditary condition
 Crowding of teeth
Localized macrodontia
 One or more teeth are larger than normal
 Should not be confused with fusion
Eg- Facial hemi-hypertrophy
Rhizomicri
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It is a condition where root of the teeth are smaller than
normal
Teeth most commonly affected are maxillary laterals,
maxillary 3rd molars, maxillary & mandibular 1st premolars
Clinical significance
 Involved tooth cannot be used as anchorage &
abutment
Rhizomegaly
Condition where in root of the teeth is larger than normal
 Most commonly affected teeth are maxillary & mandibular
cuspids
 Clinical significance
- Extraction difficulties
- Oro-antral fistula
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Normal
Rhizomegaly
Rhizomicri
Anodontia
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Condition in which there is absence of teeth in
the oral cavity
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Etiology:
- Hereditary factor
- Familial tendency
- Radiation injury to developing tooth germs
- Hereditary ectodermal dysplasia
- Mutation
Types of Andontia
Anodontia
Pseudo Anodontia
True Anodontia
Total
Hypodontia
False Anodontia
Partial
Oligodontia
Pseudo anodontia
 Condition in which teeth are present within the jaw bones
but are not erupted
E.g. - Impacted tooth
- Embedded tooth
False anodontia
 Condition in which the teeth are missing in oral cavity due
to extraction or exfoliation
True anodontia
 Condition which occurs due to failure of development of
tooth in the jaw bones
 Can be total or partial
Complete / Total anodontia
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Congenital absence of all teeth
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Extremely rare condition
Partial anodontia
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Congenital absence of one or more teeth
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Commonly seen in third molars, maxillary
lateral incisors and the second premolars
Hypodontia
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Congenital absence of one or more teeth but less
than 6
Oligodontia
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Congenital absence of more than 6 teeth
Conditions & syndromes associated
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Hereditary ectodermal dysplasia
Ehlers – Danlos syndrome
Rieger’s syndrome
Down syndrome
Book syndrome
Supernumerary teeth (Hyperdontia)
Presence of tooth in excess of the normal number
in the dental arch
 Common in males
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Etiology:
- Accessory tooth bud
- Splitting of the regular normal tooth bud
- Hereditary
- Atavism
Classification
I. Based on Number & Shape
Conical
Single
Complex
Compound
Tuberculate
Supernumerary
teeth
Supplemental
Non-syndrome
associated
Multiple
Syndrome associated
II. Based on location
Mesiodens
 Distomolar / Destodens
 Paramolar
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Mesiodens
Most common type of supernumerary tooth
 Located between the upper central incisors
 Small conical in shape
 Erupted / impacted / inverted
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Distomolar (Distodens)
Small rudimentary tooth
 Located distal to 3rd molars in the dental arch
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Paramolar
Small rudimentary tooth
 Located on buccal / lingual aspect of the normal
molars
 Occurs most commonly in maxilla
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Supplemental tooth
Distomolar
Clinical significance
Crowding, malocclusion & aesthetic problems
 May lead to increased incidence of dental caries &
periodontal problems
 Dentigerous cyst may develop from impacted
supernumerary tooth
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Treatment:Extraction
Conditions & syndromes associated
Cleido cranial dysplasia
 Apert syndrome
 Gardner syndrome (multiple supernumerary
teeth)
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Ehlers Danlos syndrome
 Down’s syndrome
 Cleft lip & palate
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Predeciduous dentition
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Infants occasionally are born with structures
which appear to be erupted teeth
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Earlier thought to arise from accessory bud
from accessory dental lamina & the concept is
no more in use
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Now thought as hornified epithelial structures
filled with keratin occurring on gingiva on crest
of ridge & are termed as ‘dental lamina cyst of
new born’
Postpermanent dentition
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It is a condition in which several teeth erupt into
oral cavity after all permanent teeth are lost
particularly after the insertion of full denture
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Earlier it was thought to be the third dentition
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Now it is regarded as the delayed eruption of
embedded or impacted permanent teeth or it
can be eruption of multiple supernumerary
unerupted teeth
Gemination
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It’s a developmental anomaly which refers to the
partial development of 2 teeth from a single
tooth bud following incomplete division
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Affects both deciduous & permanent dentition
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Commonly affects deciduous mandibular
incisors & permanent maxillary incisors
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Clinically the tooth reveals
extremely widened crown
with indentation / groove as
a mark of attempted
division
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Gemination consist of same
number of teeth (32) in oral
cavity
Fusion
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It is defined as the union of 2 adjacent normal
tooth germs at the level of dentin
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It results in one anomalous large crown in place
of two normal teeth
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Affects both deciduous & permanent dentition
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Incisor teeth are frequently affected
Types
Fusion
Complete
Fusion takes place before
the calcification of crown
has occurred
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Incomplete
Fusion begins at later
stages
of
tooth
development & may
be limited to roots
only
Fusion consist of one teeth less (31) in the
oral cavity
Concrescence
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Developmental anomaly where the roots of 2 or more
adjoining teeth have been united by cementum
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It occurs after root formation of involved teeth are
completed
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Causes:
- Traumatic injury
- Crowding of teeth
- Hypercementosis associated with chronic
inflammation
Types
Concrescence
True
The union occurs during
tooth development
False
The union occurs after
completion of root
formation
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Occurs frequently between maxillary 2nd & 3rd
molars
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Clinical significance:◦ Difficulty in extraction
Dilaceration
(Flexion)
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Refers to a sharp bend / curve / angulation in
root or crown of tooth
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Etiology:- Trauma
- Curved / tortuous path of eruption
- Injury to deciduous tooth
- Idiopathic
Pathogenesis
Trauma
Partially calcified tooth germ
Displacement of hard calcified
crown portion of tooth
Uncalcified root portion develops
by forming an angle
More common in maxillary incisors
 Curve may be present at apical / middle / cervical
portion of root depending on the portion which is
forming at the time of trauma
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Clinical significance:Difficulties in extraction & RCT
Talon cusp (Dens evaginatus of anterior tooth)
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Anomalous projection or additional cusp arising lingually
from cingulum area & extends to the incisal edge as a
prominent “T” shaped projection
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Common in permanent dentition & rare in deciduous
dentition
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Seen commonly on permanent maxillary incisors (more
in laterals) and less frequently on mandibular incisors
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Forms a three pronged pattern and resembles an eagle’s
talon
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Causes:-
- Local environmental factors
- Genetic factors
Clinical significance
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Talon cusp consist of normally appearing enamel
& dentin. In few cases there can be presence of
vital pulp tissue
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Usually asymptomatic
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May interfere with occlusion
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Susceptibility to caries (lingual pits)
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Treatment:- Restoration of lingual pits to prevent dental
caries
- Reduction of cusp if it interferes with
occlusion
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Syndromes associated:1. Rubinstein – Taybi syndrome
(developmental retardation, broad thumbs and great toes,
characteristic facial features, delayed or incomplete
descent of testes in males, and stature, head
circumference, and bone age below the fiftieth percentile)
2. Sturge – Weber syndrome
3. Mohr syndrome
Dens invaginatus
Dens – in – Dente
 Tooth – with in – Tooth
 Pregnant tooth
 Dilated composite odontome
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Developmental
morphologic
variation
characterized by deep surface invagination of
the crown / root
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Presence of enamel lined cavity with in tooth
led the early investigators to believe that a
tooth with in a tooth & hence the name
“Dens – in – Dente”
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The condition is most probably caused by an
invagination of enamel organ before
calcification
Types
Based on occurrence
Dens invaginatus
Coronal
Invagination / infolding
occurs on crown portion
of the tooth
Radicular
Invagination / infolding
occurs on root portion
of the tooth
Coronal dens invaginatus
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Type I / Mild form
Invagination confined to crown within the CEJ
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Type II / Intermediate form
Invagination extends below CEJ may or may not
communicate with pulp
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Type III / Extreme form
Invagination extend beyond the pulp through the root &
perforate the apical / lateral radicular area without any
communication with the pulp
Type I
Type II
Type III
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More common is coronal type
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Common in permanent dentition
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More common in maxillary teeth
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Commonly affected teeth are maxillary laterals, central
incisors & premolars
Before eruption the invagination is filled with soft tissue
which is similar to dental follicle, which on eruption
becomes necrotic
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Radicular dens invaginatus
 Rare condition
 Thought to arise secondary to a proliferation of
HERS, with the formation of a strip of enamel
that extends along the root surface
 The root reveals an invagination with the opening
on the lateral aspect of the root
Radiographic feature
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Affected tooth demonstrates an enlargement
with deep pear shaped invagination lined by
enamel
Clinical significance
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The invagination is extremely prone to caries
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Type III form of Dens invaginatus provides
direct communication between oral cavity &
periapical tissues leading to inflammatory lesions
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Treatment:Early detection & prophylactic restoration
Dens Evaginatus
Leong’s premolar
Evaginated odontome
Occlusal tuberculated
premolar
 Occlusal enamel pearl
 Central tubercle
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Developmental anomaly of the tooth in which a
focal area of the crown shows ‘globe’ shaped
outward projection on occlusal surface
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Clinically appears as an extra cusp
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Common in individuals of Mongolian origin & rare
in whites
Pathogenesis
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Develops as a result of localised elongation &
proliferation of inner enamel epithelium as well as
the odontogenic mesenchyme into the dental
organ
Clinical features
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Primarily affects the premolars (Molars also)
Usually bilateral with mandibular predominance
Presents as an extra cusp located on the occlusal
surface between buccal & lingual cusps
Can interfere with tooth eruption
Cases occlusal disharmony
Some times the extra cusp may contain vital pulp,
its attrition / facture may result in pulp exposure
leading to associated complications & pain
Note
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Shovel shaped incisors
◦ Variant of Dens Evaginatus
◦ Prominent marginal ridges which creates a
hollowed lingual surface resembling a scoop
of a shovel
Treatment
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Asymptomatic – No treatment needed
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Occlusal disharmony – Minor reduction
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Pulp exposure – RCT
Taurodontism (Bull teeth)
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Term coined by Sir Arthur Keith
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Developmental anomaly in which the crown portion
of the tooth is enlarged at the expense of the roots
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Was found commonly in ancient neanderthal man
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The overall shape resembles that of the molar teeth
of cud-chewing animals (Tauro = Bull)
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There is altered crown-to-root ratio
Causes
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Failure of hertwig’s epithelial root sheath to invaginate
at proper horizontal level during development of teeth
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Primitive pattern
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Atavism
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Mendelian recessive trait
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Mutation resulting from odontoblastic deficiency during
dentinigenesis of roots
Clinical & radiographic features
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Affects permanent teeth more frequently than
deciduous teeth
Unilateral or bilateral
Molars are frequently involved
Teeth are usually rectangular in shape
Minimal constriction at cervical area
Elongated crown & enlarged pulp chamber
Apically placed furcation area
Exceedingly short roots
Types
Based on degree of apical displacement of pulpal
floor / furcation area (by Shaw)
1. Hypotaurodont (Mild)
Furcation area placed below normal but
within cervical 1/3rd of root
2. Mesotaurodont (Moderate)
Furcation area placed at middle 1/3rd of
root
3. Hypertaurodont (Severe)
Furcation area placed at apical 1/3rd of root
Normal
Mild
moderate
severe
Syndromes associated
Klinefelter’s syndrome (males with
one or more extra X chromosomes)
 Down syndrome
 Poly X syndrome
 Ectodermal dysplasia
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Supernumerary root
Refers to the presence of one or more extra
roots than normal
 Roots may be curved / straight / divergent
 Affects both deciduous & permanent dentition
 Commonly involved teeth are permanent molars,
mandibular cuspids & premolars
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Clinical significance:Difficulties in extraction & RCT
Enamel pearl
Enameloma
 Enamel drops / nodule
 Enamel exostoses
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These are white dome shaped calcified
projections of enamel located at the furcation
areas of molar teeth
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They may consist entirely of enamel or contain
underlying dentin & pulp
Ectopia

Remote location of a tooth away from its normal
position
E.g:1. Maxillary canine erupting in nasal cavity / maxillary
sinus / at the inner canthus of eye
2. Mandibular 3rd molar erupting at angle of mandible
/
lower border of mandible / through the skin of
cheek
Transposition

Condition where in 2 teeth exchange position
E.g:1. Exchange of position between maxillary canine
& premolar
2. Exchange of position between mandibular canine
& lateral incisors
Rotation

Developmental anomaly where in a tooth turns
partially / completely
Commonly seen in,
Maxillary 2nd premolar (Complete rotation)
Maxillary central & 1st premolar (Partial rotation)
Premature eruption

Tooth erupts into oral
cavity much earlier than
normal time of eruption

Frequently involved tooth
are deciduous mandibular
central incisors
Types
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Natal teeth
Erupted deciduous teeth present at the time of birth
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Neonatal teeth
Deciduous teeth which erupt within first 30 days of life
Causes
Endocrinal disturbances
- Adreno-cortical syndrome
- Hyperthyroidism

Premature loss of deciduous teeth causes
premature eruption of permanent teeth
Delayed eruption

Tooth erupts into oral
cavity much later than
normal time of eruption

Affects both deciduous &
permanent dentition
Causes

Systemic factors
- Rickets
- Cleidocranial dysplasia
- Cretinism
Local factors
- Fibromatosis gingivae
- Cleft lip & palate
- Retained deciduous tooth
 Idiopathic
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Impacted teeth

Teeth which are prevented from eruption into
oral cavity by some physical barrier in eruptive
path or non availability of space
Causes
- Micrognathia
- Retained deciduous teeth
- Supernumerary teeth
- Odontogenic cyst & tumors
- Cleft palate
- Syndrome associated
Embedded teeth

It refers to those teeth that are unerrupted due
to lack of eruptive forces
Submerged teeth

It refers to ankylosed deciduous teeth

Frequently involved teeth are deciduous molars

Occlusal table of the ankylosed deciduous tooth
is located below the occlusal plane of the rest of
the permanent teeth in the arch giving an
submerged appearance

In such cases the underlying permanent tooth
may become impacted or may erupt either
buccally / lingually