Developmental disturbances of teeth and bone

Developmental
Disturbances Of Teeth &
Bone
BY: QAZI JAWAD HAYAT
KHYBER COLLEGE OF DENTISTRY, PESHAWAR.

Developmental Disturbances Of Teeth
The abnormalities in teeth development are mainly classified into TWO types.
1. Developmental Alteration Of Teeth
2. Environmental Alteration Of Teeth

1. Developmental Alteration Of Teeth
The Developmental Alteration Of Teeth development can be :
i. In No. Of Teeth.
ii. In Size Of Teeth.
iii. In Shape Of Teeth.
iv. In Structure Of Teeth.

i. Developmental Alteration In No. Of
Teeth
It can be of following TWO types :
Hypodontia
Hyperdontia

 Hypodontia
Definition: The lack of Development of One or More teeth is termed as Hypodontia.
Clinical Features: Failure of teeth formation is one of the most common Developmental
anomaly, with a Prevalence rate of 1.6 to 9.6% in permanent dentition (excluding 3rd Molar).A
female predominance of 1.5 : 1 is reported. Hypodontia is uncommon in Deciduous teeth.
Hypodontia is positively associated with :
a. Microdontia.
b. Reduced Alveolar Development.
c. Increased Freeway Space.
d. Retained Primary Teeth.

Genetic control appears to exert a strong influence on development of teeth. Some of the Genes
in which mutation can lead to Hypodontia are:
o PAX9 Gene [Autosomal Dominant Trait] , affects mostly Permanent Molars.
o MSX1Gene [Autosomal Dominant Trait] , affects distal tooth of each type mostly Second
Premolar and Third molar.
o AXIN2 Gene [Autosomal Dominant Trait] , affects Second and Third Molars, Second Premolars,
Lower Incisors, and Maxillary Lateral Incisors.

TREATMENT AND PROGNOSIS
The management of the patient with Hypodontia depends on severity of the case. No Treatment
may be required for a single missing tooth; Prosthetic Replacement often is needed when
multiple teeth are absent. Therapeutic options include:
RPDs,
Traditional Fixed Prosthodontics [Not recommended for Children because of risk of pulp
exposure during abutment preparation, and ankylosis of teeth held together by prosthesis] ,
Resin Bonded Bridges, or
Osseointegrated Implants [It’s use is also not recommended before completion of skeletal
growth and for patients with anodontia].
Orthodontic Therapy.

 Hyperdontia
Definition: The Increased development of one or more teeth is termed as Hyperdontia.
Clinical Features: Supernumerary is a term used for the additional teeth formed as a result of
Hyperdontia.
The Prevalence rate of supernumerary teeth is between 0.1 to 3.8% in Whites with a slightly
higher rate seen in Asians. Approximately 76 to 86% of cases represent Single-Tooth
Hyperdontia.
The most common site for formation of Supernumerary Teeth is Maxillary Central Incisor
region, Maxillary fourth Molar, Mandibular Fourth Molars, Premolars, Canines, and Lateral
Incisor region.
A male predominance of 2 : 1 is reported and is positively associated with Macrodontia.

Depending on location, several terms have been used to describe supernumerary teeth. for
example:
Mesiodens is the supernumerary teeth in the Maxillary Anterior Incisor region,
Distodens or Distomolar is an accessory fourth molar,
Paramolar is the posterior supernumerary tooth situated lingually or buccally to a molar tooth.
Supernumerary Teeth are divided into TWO types:
i) Supplemental Supernumerary Teeth having normal size and shape.
ii) Rudimentary Supernumerary Teeth having abnormal shape and small size.It has been further
classified as: Conical (small peg shaped), Tuberculate (barrel shaped anterior with more than
one cusp), and Molariform (small premolar or molar like).

Early diagnosis and treatment are crucial in minimizing the Aesthetic and Functional Problems.
Only 7 to 20% of supernumerary teeth exist without clinical complications, the standard Of care
is Removal Of the Accessory Tooth during the time of Early Mixed Dentition.
Spontaneous Eruption of adjacent teeth occurs in approximately 75% of the cases if the
supernumerary tooth is removed early. Impacted Permanent Teeth having closed apices or
those associated with a tuberculate mesiodens may show a reduced tendency for spontaneous
eruption.

ii. Developmental Alteration In Size Of
Teeth
It can be of the following TWO types:
Microdontia
Macrodontia

 Microdontia
Definition: When the teeth are physically smaller than usual, then it is termed as Microdontia.
Clinical Features: The Prevalence rate of microdontia varies from 0.8 to 8.4% of the
population.The most frequently affected teeth is Maxillary Lateral Incisor and typically appears
as a peg shaped crown overlying a root that often is of normal length. The Mesio-Distal
diameter is reduced , and the proximal surface converge towards the Incisal edge. In addition
isolated microdontia often affects Third Molar too. Interestingly, the Maxillary Lateral Incisors
and Third Molars are among the most frequent teeth to be congenitally missing.
Normal sized teeth may appear small when widely spaced with in the jaws that are larger than
normal. This appearance is termed as Relative Microdontia.
Diffuse true microdontia is uncommon but may occur in some conditions like
o Down Syndrome
o Pituitary Dwarfism etc etc.

 Macrodontia
Definition: When teeth are physically larger than usual, then it is termed as Macrodontia.
Clinical Features: Isolated macrodontia is reported to occur most frequently in Incisors or Canines but
also has been seen in Second Premolars and Third Molars.
Macrodontia should not be confused with Relative Macrodontia which include Normal sized teeth
crowded with in a Small Jaw.
Diffuse macrodontia has an association with:
o Pituitary Gigantism
o XXY Males
o Otodental Syndrome
o Pineal Hyperplasia
o Hyperinsulinism etc etc

Treatment of the dentition is not necessary unless desired for Aesthetic consideration.
Maxillary Peg Laterals often are restored to full size by Porcelain crowns.

iii. Developmental Alteration In Shape Of
Teeth
It can be of the following types:
 Gemination
 Fusion
 Concrescence
 Accessory Cusps [Cusp of Carabelli, Talon Cusp, and Dens Evaginatus]
 Taurodontism
 Dilaceration
 Hypercementosis
 Others [ Ectopic Enamel, Enamel Pearls, and Dens Invaginatus etc ].

 Gemination
Definition: A single enlarged tooth or joined tooth in which the tooth count is normal when the
anomalous tooth is counted as one is called Gemination.
Clinical Features: Historically, gemination was defined as an attempt of a single tooth bud to
divide, with the resultant formation of a tooth with a bifid crown, and usually, a common root
and root canal.
It occurs in both primary and permanent dentition with a Prevalence rate of 0.5 to 2.5% in
primary and 0.3 to 0.5% in permanent dentition in Whites, with Asian population having a bit
higher prevalence rate than Whites.
Incisors and Canines are the most commonly affected teeth. Maxilla is the most common site.

The presence of double teeth [i.e Gemination, or Fusion] in the deciduous dentition can result
in crowding, abnormal spacing, and delayed or ectopic eruption of the underlying permanent
teeth. When detected, the progression of eruption of the permanent teeth should be monitored
closely by careful Clinical and Radiographic observations.
Double Teeth often will demonstrate a pronounced labial or lingual groove that may be prone
to develop caries. In such cases, placement of a fissure sealant or composite restoration is
appropriate if the tooth is to be retained
Endodontic Therapy can also be performed.

 Fusion
Definition: A single enlarged tooth or joined tooth in which the tooth count reveals a missing
tooth when the anomalous tooth is counted as one is called Fusion.
Clinical Features: Historically, Fusion was defined as the union of two normally separated tooth
buds with the resultant formation of joined tooth with confluence of dentin.
It occurs in both primary and permanent dentition with a Prevalence rate of 0.5 to 2.5% in
primary and 0.3 to 0.5% in permanent dentition in Whites, with Asian population having a bit
higher prevalence rate than Whites.
Incisors and Canines are the most commonly affected teeth. Mandible is the most common
site.

The presence of double teeth [i.e Gemination, or Fusion] in the deciduous dentition can result
in crowding, abnormal spacing, and delayed or ectopic eruption of the underlying permanent
teeth. When detected, the progression of eruption of the permanent teeth should be monitored
closely by careful Clinical and Radiographic observations.
Double Teeth often will demonstrate a pronounced labial or lingual groove that may be prone
to develop caries. In such cases, placement of a fissure sealant or composite restoration is
appropriate if the tooth is to be retained.
Endodontic Therapy can also be performed.

 Concrescence
Definition: When two fully formed teeth are joined along the root surfaces by cementum, It is
termed as Concrescence.
Clinical Features: This process is noted more in the Posterior and Maxillary region. The
developmental pattern often involves a Second Molar tooth in which it’s roots closely
approximates the adjacent impacted Third Molar. The Post-Inflammatory pattern frequently
involves carious Molars, in which the apices overlie the roots of horizontally or distally
angulated Third Molars.
Cemental repair is then followed.

Patients with concrescence often require No Therapy unless the union interferes with eruption;
then surgical removal may be warranted.
Post-Inflammatory concrescence must be kept in mind whenever extraction is planned for a
non-vital tooth with apices that overlie the roots of an adjacent tooth.

 Accessory Cusps
Definition: Cusp of Carabelli, Talon Cusp, and Dens Evaginatus are termed as Accessory Cusps.
Clinical Features: When an accessory cusp is present, the other permanent teeth often exhibit a
slightly increased tooth size.

Cusp Of Carabelli: It is an accessory cusp located on the palatal surface of the mesiolingual
cusp of the Maxillary Molar. The cusp may be seen in both the primary and permanent
dentition and varies in size from a definite cusp to a small indented pit or fissure. An analogous
accessory cusp is seen occasionally on the mesiobuccal cusp of a mandibular permanent or
deciduous molar and is termed as Protostylid.

Patients with Cusp of Carabelli require No Therapy, unless a deep groove is present between the
accessory cusp and the surface of the mesiolingual cusp of the molar.

Talon Cusp: It is a well-delineated additional cusp that is located on the surface of an Anterior
Tooth and extends at least half the distance from Cemento-Enamel junction to the Incisal edge.
3/4th of all the reported talon cusps are located in permanent dentition. It mainly is present on
Maxillary Lateral Incisor(55%), or Central Incisor(33%), but can also be present on Mandibular
Incisor(6%) or Maxillary Canine(4%). Most talon cusp, contain a pulpal extension.
Talon cusp has an association with syndromes like Rubinstein-Taybi syndrome, Mohr syndrome,
Sturge-Weber angiomatosis etc.It also has a genetic influence.

Patients with Talon Cusp on the mandibular teeth often require No Therapy; Talon Cusp on the
maxillary teeth frequently interfere with occlusion and should be removed. Removal without
loss of vitality may be accomplished through periodic grinding of the cusp, with time allowed
for tertiary dentine deposition and pulp recession.
After successful removal of the cusp, the exposed dentin can be covered with Calcium
Hydroxide, the peripheral enamel etched, and a composite resin placed.

Dens Evaginatus: Also known as Central Tubercle, Tuberculated Cusp, Accessory Tubercle,
Occlusal Pearl, Evaginated Odontome, Leong Premolar, Tuberculated Premolar. It is a cusp like
elevation of enamel located in the central groove or lingual ridge of the buccal cusp of premolar
or molar teeth.
It typically occurs on the Premolars, is usually bilateral, and demonstrates a marked Mandibular
predominance. Radiographically, the Occlusal surface exhibit a tuberculated appearance, and
often a pulpal extension is seen in the cusp. Dens Evaginatus is also seen in association with
another variation of coronal anomaly known as Shovel-Shaped Incisors.

Dense Evaginatus results in occlusal problems and often leads to pulpal death. In affected teeth,
removal of the cusp often is indicated, but attempt to maintain vitality have met with only
partial success.
Slow periodic grinding of the cusp, with removal of minimal dentin and treatment of the area
with Stannous Fluoride has been recommended.

 Taurodontism
Definition: The enlargement of the body and pulp chamber of a multi-rooted teeth, with apical
displacement of the pulpal floor and bifurcation of the roots, is termed as Dilaceration.
Clinical Features: In taurodontism, the affected teeth tend to be rectangular, and exhibit pulp
chambers with dramatically increased Apico-Occlusal height and a bifurcation close to the apex.
According to apical displacement of the pulpal floor, Taurodontism has been classified into
THREE types:
o Mild or Hypotaurodontism
o Moderate or Mesotaurodontism
o Severe or Hypertaurodontism

Taurodontism may be Unilateral or Bilateral. There is NO sex predilection, and the Prevalence
rate is highly variable from 0.5 to 46%. Taurodontism is positively associated with:
a) Hypodontia
b) Cleft Lip
c) Cleft Palate.

As coronal extension of the pulp is not seen; therefore, the process does not interfere with
routine restorative procedures,, and hence require NO specific Therapy.

 Dilaceration
Definition: The abnormal angulation or bend in root or, less frequently in the crown of a tooth is
termed as Dilaceration.
Clinical Features: Although most cases are idiopathic, a number of teeth with dilacerations
appear to arise after an injury or trauma that displaces the calcified portion of the tooth germ,
and the remainder of tooth is formed at an abnormal angle. Injury related dilacerations more
frequently affects the anterior dentition, and often create both aesthetic and functional
problem.
Less frequently the bend develops secondary to the presence of an adjacent cyst, tumour, or
odontogenic hamartoma etc.The most commonly affected teeth are Mandibular Third Molars,
Maxillary Second Premolars, and Mandibular Second Molars. The Maxillary and mandibular
Incisors are the least frequently affected.

The treatment and prognosis varies, depending on the severity of the case. Extraction is
indicated in deciduous teeth when necessary for the normal eruption of succedaneous teeth.
Those teeth that exhibit delayed or abnormal eruption may be exposed and orthodontically
moved to it’s position.
Endodontic Therapy is also done.

Hypercementosis
Definition: The non-neoplastic deposition of excessive cementum that is continuous with the
normal radicular cementum is termed as Hypercementosis.
Clinical Features: Radiographically, affected teeth demonstrate a thickening or blunting of the
root, but the exact amount of cementum often is difficult to ascertain because cementum and
dentin demonstrate similar radiodensities. On occasion, the enlargement may be significant
enough to suggest the possibility of a cementoblastoma.
Hypercementosis may be isolated, involve multiple teeth, or appear as a generalized process.

Hypercementosis occurs predominantly in Mandibular Molars, Mandibular Second Premolar,
Maxillary Second Premolar, and Mandibular First Premolar. It also occurs predominantly in
Adulthood and the frequency increases with age.
Factors associated with Hypercementosis include
oAbnormal Occlusal Trauma
oPulpal, Periodontal, Periapical Inflammation
oUnopposed Tooth [i.e Impacted, Embedded, without antagonist]
oPaget’s Disease
oAcromegaly and Pituitary Gigantism
oOther [ i.e Arthritis, Calcinosis, Rheumatic Fever, Gardner Syndrome, Vit.A Deficiency etc]

HISTOPATHOLOGY
The periphery of root exhibit deposition of an excessive amount of cementum over the original
layer of primary cementum.The excessive cementum may be hypocellular or exhibit areas of
cellular cementum that resemble bone (Osteocementum) The material is often arranged in
concentric layers.
On routine light microscopy, distinguishing between the dentin and cementum is difficult, but
polarized light helps to discriminate the the two layers.

Patients with hypercementosis require No treatment. Because of thickened root, occlusional
problems have been reported during the extraction of an affected tooth.
Sectioning of the tooth may be necessary in certain cases to aid in removal.

 Others [Ectopic Enamel]
Definition: The presence of enamel in unusual location, especially the tooth root is termed as
Ectopic Enamel.
Clinical Features: The most widely known are the Enamel Pearls. These are hemispheric
structures that may consist entirely of enamel, or contain underlying dentin and pulp tissue.
Most enamel pearls project from the surface of the root and are thought to arise from a
localized bulging of the odontoblastic layer.
In addition to enamel pearls, Cervical Enamel Extensions also occur along the surface of dental
roots. These extensions represent a dipping of enamel from cementoenamel junction toward
the bifurcation of Molar tooth.

Enamel pearls are most commonly found on the roots of Maxillary Molars, and Mandibular
Molars. It is uncommon in Maxillary Premolars and Incisors. The Prevalence rate varies from
1.1 to 9.7%.
Radiographically enamel pearls appear as well defined, radio-opaque nodules along the root
surface. The exophytic nature of enamel pearl is conducive to plaque retention and inadequate
cleansing.
In case of cervical enamel extensions, the Mandibular Molars are slightly more affected than
the Maxillary Molars.
The cervical enamel extensions have been associated with development of inflammatory cysts
that are histopathologically identical to inflammatory periapical cysts.

When enamel pearls are detected radiographically, the area should be viewed as a weak point of
periodontal attachment. Meticulous Oral Hygiene should be maintained in an effort to prevent
localized loss of periodontal support.
If removal of the lesion is contemplated, then it should be remembered that enamel pearls
sometimes contain vital pulp tissue.
For teeth with cervical enamel extensions, Therapy is directed.

 Others [Dens Invaginatus]
Definition: A deep surface invagination of the crown or root of a tooth that is lined by enamel is
termed as Dens Invaginatus.
Clinical Features: Coronal Dens Invaginatus is frequently seen with a Prevalence rate of 0.04 to
10%. The teeth affected most oftenly include Permanent Lateral Incisors, Central Incisors, and
Premolars and Molars are affected are also. A strong Maxillary predominance is seen.The depth
of invagination varies from a a slight enlargement of the cingulum pit to a deep infolding that
extends to the apex.
Historically, Coronal Dens Invaginatus has been classified into THREE types:
o Type I Invagination that is confined to the crown
oType II invagination that extends below the cementoenamel junction and ends in a blind sac
oType III Invagination that extends through the root and perforates in the apical or lateral
radicular area

Occasionally, the invagination may be rather large and resemble a tooth with in a tooth, termed
as dens in dente.
In other cases the invagination may be dilated and disturb the formation of a tooth, termed as
Dilated Odontome.
Radicular Dens Invaginatus is rare and thought to arise secondary to proliferation of Hertwig’s
epithelial root sheath, with the formation of a strip of enamel that extends along the surface of
the root. The pattern of enamel deposition is similar to that frequently seen in association with
radicular enamel pearl.
Radiographically, the affected tooth demonstrates an enlargement of the root. Close
examination reveals a dilated invagination lined by enamel, with the opening of the invagination
along the lateral aspect of the root.

In small type I invagination the opening should be restored after eruption, in an attempt to
prevent carious involvement and subsequent pulpal inflammation.
In large invaginations, the carious dentin must be removed and then treatment with Calcium
Hydroxide is done.
Endodontic Therapy is also a choice.

iv. Developmental Alteration In Structure
Of Teeth
It can be:
Amelogenesis Imperfecta
Dentinogenesis Imperfecta
Dentin Dysplasia
Regional Odontodysplasia

 Amelogenesis Imperfecta
Definition: A complicated group of conditions that demonstrate developmental alterations in the
structure of enamel in the absence of a systemic disorder, is termed as Amelogenesis Imperfecta.
Clinical Features: At least Fourteen different hereditary subtypes of amelogenesis imperfect exist,
with numerous patterns of inheritance and a wide variety of clinical manifestations. To date, mutation
in FIVE Genes have been associated with amelogenesis imperfecta. Each gene can be mutated in a
variety of ways, often creating diverse and distinct phenotype patterns.
The hereditary defects of the formation of enamel is divided into FOUR types:
a) Hypoplastic Amelogenesis Imperfecta
b) Hypocalcified Amelogenesis Imperfecta
c) Hypomaturation Amelogenesis Imperfecta
d) Amelogenesis Imperfecta with Taurodontism.

The genes responsible for Amelogenesis Imperfecta include:
oAMELX Gene
oENAM Gene
oMMP-20 Gene
oKLK4 Gene
oDLX3 Gene
oAMBN Gene etc.
oAmelogenesis imperfect may be inherited as autosomal dominant, autosomal recessive, or X-
linked disorder. In general, both the primary and permanent dentitions are diffusely involved.

 Hypoplastic Amelogenesis Imperfecta
In this condition, the basic alteration centers on inadequate deposition of enamel matrix.
It has about SEVEN variants according to classification by Witkop, which includes
IA,IB,IC,ID,IE,IF, and IG. The IE variant is inherited in X-linked Dominant pattern, while the IA,
IB, ID, and IF variants are inherited in Autosomal Dominant pattern, and the IC, and IG variants
are inherited in Autosomal Recessive pattern.
In the IA variant, pin-point to pin-head sized pits are scattered across the surface of teeth, the
arrangement of which can be in rows or columns, It is termed as Generalized Pattern.
In the IB and IC variants, the affected teeth demonstrate horizontal rows of pits, a linear
depression, or one large area of hypoplastic enamel, surrounded by a zone of hypocalcification,
this is termed as Localized Pattern.
In the IF variant, the enamel is thin, hard and rough surfaced, demonstrate open contact points,
and Radiograph exhibit a thin peripheral outline of radio-dense enamel, this is termed as Rough
Pattern. Often an anterior open bite is also present in such cases.

In the ID variant, the enamel exhibit a smooth surface and is thin, hard and glossy. The absence
of appropriate enamel thickness results in teeth that are shaped like crown preparations, and
demonstrate open contact points, this is termed as Autosomal Dominant Smooth Pattern.
anterior open bite is not rare in such cases.
Males of the IE variant, exhibit diffuse, thin, smooth and shiny enamel in both dentitions. The
teeth often have the shape of crown preparation, and the contact points are open. Radiograph
demonstrate a peripheral outline of radio-opaque enamel.Females of the IE variant, exhibit
vertical furrows of thin, hypoplastic enamel, alternating between bands of normal enamel, this
is termed as X-Linked Smooth Pattern. anterior open bite is seen in almost all males and some
females.
In the IG variant, there is total lack of enamel formation, the teeth are the shape and color of
Dentin, with open contact points. Radiographs demonstrates no peripheral enamel overlying
dentin, this is termed as Enamel Agenesis Pattern. anterior open bite is seen frequently.

 Hypomaturation Amelogenesis
Imperfecta
In this condition, the enamel matrix is laid down appropriately and begins to mineralize;
however, there is defect in maturation of the enamel’s crystal structure.Affected teeth are
normal but exhibit a mottled, opaque white-brown yellow discoloration. The enamel is softer
than normal and tends to chip from the underlying dentin. Radiographically, the affected
enamel exhibit a radio-density that is similar to dentin.
In accordance to Witkop classification, it has FOUR variants, which includes IIA,IIB,IIC, and IID.
IIA and IID are Autosomal linked while, the IIB and IIC are X-linked.
In IIA variant the enamel often fracture from the underlying dentin and is soft enough to be
punctured by a dental explorer. anterior open bite is uncommon. The surface is enamel is
mottled and agar-brown, this is termed as Pigmented Pattern.
In IIB the enamel tends to chip off and often can be pierced with a dental explorer point. The
teeth demonstrate vertical bands of white opaque enamel and translucent enamel,

which are present randomly and asymmetrically. Radiographically, the bands are not perceptible
and the contrast between enamel and dentin is within normal limits, this is termed as X-linked
Pattern.
IIC and IID variant exhibit a zone of white opaque enamel on the incisal or occlusal third of the
crown. both the primary and permanent dentitions are affected. The affected teeth often
demonstrate an antero-posterior distribution and have been compared with a denture dipped in
white paint. Most cases demonstrate an X-linked pattern of inheritance but an Autosomal
Dominant form is also possible, this is termed as Snow-Capped Patterns.

 Hypocalcified Amelogenesis
Imperfecta
In this type the enamel matrix is laid down appropriately but no significant mineralization
occurs. In accordance with Witkop classification, it has two variants, which include IIIA and IIIB.
Both of the variants are Autosomal linked,. The teeth are normal on eruption, but enamel is very
soft and easily lost and is yellow-brown or orange colored, but often becomes stained brown to
black and exhibit rapid calculus apposition. With years of function the coronal enamel is
removed, except for the cervical portion that is occasionally calcified better. anterior open bite
is not rare. Radiographically the density of enamel and dentin are similar.

 Amelogenesis Imperfecta with
Taurodontism
This type of amelogenesis imperfect exhibit enamel hypoplasia in combination with
hypomaturation. Historically, two patterns have been recognized that are differentiated by
thickness of the enamel and tooth size. The two patterns include Hypomaturation-hypoplastic
Pattern and Hypoplastic-hypomaturation Pattern.
In the Hypomaturation-hypoplastic pattern the predominant effect is one of enamel
hypomaturation in which the enamel appears as mottled yellow-white to yellow-brown. Pits are
seen often on the buccal surface, and Radiographically the enamel appears similar to dentin in
density.
In the Hypoplastic-hypomaturation pattern, the predominant effect is one of the enamel
hypoplasia in which the enamel is thin but also hypomature. Radiographically it differs from the
hypomaturation-hypoplastic pattern in that a decrease in thickness of enamel is seen.
Tricho-dento-osseous syndrome is similar to Amelogenesis Imperfecta with Taurodontism, but
is a systemic disease characterized by kinky hairs, osteosclerosis, and brittle nails.

The clinical implications of amelogenesis imperfect vary according to the subtype and it’s
severity, but the main problem is Aesthetics, Dental Sensitivity, and Vertical Dimension. In
addition in some types there is an increased Prevalence rate of caries, anterior open bite,
delayed eruption, tooth impaction, and gingival inflammation etc.
Veneering can be done.
Overdentures and Full Dentures can be used.

 Dentinogenesis Imperfecta
Definition: A complicated condition that demonstrate developmental alterations in the structure of
dentin in the absence of a systemic disorder, is termed as Dentinogenesis Imperfecta.
Clinical Features: Similar dental changes may be seen in conjunction with systemic hereditary disorder
of bone, termed as Osteogenesis Imperfecta. The dentin disorders associated with this bone disease
is termed as Osteogenesis Imperfecta with opalescent teeth [Dentinogenesis Imperfecta I]
Various types of osteogenesis imperfect have been associated with mutation of the COL1A1 or
COL1A2 gene that encodes production of type I collagen. Dentinogenesis Imperfecta is associated
with mutation in DSPP gene. Currently Eight mutations of this gene are known; Seven of which are
associated with dentinogenesis imperfecta, while the Eighth known to create Dentin Dysplasia type
II. Dentinogenesis imperfect formerly was divided into TWO types:
o Hereditary Opalescent Dentine also termed as Shields type II [Dentiogenesis Imperfecta II]
o Brandywine Isolate also termed as Sheilds type III [Dentinogenesis Imperfecta III].

The defining phenotypic feature of the Brandywine isolate was the presence of unusual pulpal
enlargement termed as Shell Teeth.
The dental alterations in dentinogenesis imperfecta and osteogenesis imperfecta with
opalescent teeth are similar clinically, radiographically, and histopathologically. All teeth in both
dentitions are affected, deciduous teeth are affected more severely, followed by permanent
incisors and first molars, with the second molar and third molar being least altered. The
dentitions have a blue to brown discoloration often with a distinctive translucency. The enamel
frequently separates easily from the underlying defective dentin. Radiographically, the teeth
have bulbous crown, thin roots, cervical constriction, and early obliteration of the root canal
and pulp chambers.
Shell teeth demonstrate normal thickness enamel with extremely thin dentin and dramatically
enlarged pulps. The thin dentin may involve the entire tooth or be isolated to the root.

Histopathology
The affected teeth demonstrate altered dentin. The dentin adjacent to enamel junction appears
similar to normal dentin, but the remaining is distinctly abnormal.
Short misshapen tubules course through an atypical granular dentin matrix, which often
demonstrates interglobular calcification. Scanty atypical odontoblasts line the pulp surface, and
cells can be seen entrapped within the defective dentin. In ground sections the enamel is
normal in most cases, however, about one third of the cases have Hypoplastic or Hypocalcified
defects.

The teeth are not good candidates for full crown because of cervical fracture, so Overlay
Dentures placed on teeth that are covered with Fluoride releasing Glass Ionomer cement have
been used with success in some cases.
Additional therapeutic approaches have been used but long term follow up is incomplete.

 Dentin Dysplasia
It was initially categorized in 1939, TWO major pattern exists; type I and type II.
Dentin Dysplasia type I: It is also known as rootless teeth, because the loss of organization of the
root dentin often leads to a shortened root length. The process exhibit autosomal dominant pattern
of inheritance. The enamel and coronal dentin are normal clinically and well formed, but the
radicular dentin loses all organization and subsequently is shortened dramatically. It has been further
classified into FOUR sub-groups which includes:
o DDIa: No pulp chamber, and no root formation and frequent periapical radiolucencies
o DDIb: A single, small, horizontally oriented, crescent shaped pulp with roots only of few millimeters,
and frequent periapical inflammation.
o DDIc: Two horizontally oriented, crescent shaped pulpal remnants surrounding an island of dentin,
significant but shortened root length and variable periapical radiolucencies.
o DDId: Visible pulp chambers and canals, near normal root length, enlarged pulp stones thar are
located in coronal portion of the canal and few periapical radiolucencies.

Dentin Dysplasia type II: It is also termed as Coronal Dentin Dysplasia. In contrast to type I, the
root length is of normal length in both dentitions, and the deciduous teeth closely resembles
that of dentinogenesis imperfect. Clinically, the teeth demonstrate a blue to amber to brown
translucence. Radiographically, the dental changes include Bulbous crown, Cervical constriction,
Thin Roots, and early obliteration of pulp. The permanent teeth demonstrate normal clinical
coloration, but radiographically, the pulp chambers exhibit significant enlargement and apical
extension. This altered anatomy of pulp is termed as Thistle tube-shaped, or Flame-shaped.

Histopathology
In case of type I, the coronal enamel and dentin are normal. Apical to the point of
disorganization, the central portion of the root forms whorls of tubular dentin and atypical
osteodentin. These whorls give the appearance of “ stream flowing around boulders “ to the
roots.
In case of type II, the deciduous teeth demonstrate the pattern of Dentinogenesis Imperfecta,
while the permanent teeth exhibit normal enamel and coronal dentin. Adjacent to the pulp,
numerous areas of interglobular dentin are seen. The radicular dentine is atubular, amorphous,
and hypertrophic. Also pulp stones develop in any portion of the chamber.

In case of dentin dysplasia type I, Preventive care is of foremost importance, because shortened
roots can result in early loss of periodontitis. In addition pulp vascular channels extend close to
the dentinoenamel junction, and even a shallow occlusal restoration can result in pulpal
necrosis.
If periapical inflammatory lesion develop, the root length guides the therapeutic choice.
Pulpal ramification can also be done in case of type I.
Conventional Endodontic Treatment can be done in case of type I as well as in type II.
In case of type II, meticulous oral hygiene must be established.

 Regional Odontodysplasia
Definition: A localized, non-hereditary developmental anomaly of teeth with extensive adverse
effects on the formation of enamel, dentine, and pulp is termed as Regional Odontodysplasia.
Clinical Features: It is also termed as Ghost Teeth. Regional Odontodysplasia is an uncommon
finding, affecting both the dentitions, and exhibit a maxillary predominance for anterior teeth
with a slight female predilection. Typically the process affects a focal area of the dentition, with
involvement of several contiguous teeth. Involvement of the deciduous dentition is typically
followed by same similarly affected permanent teeth. In the area of altered teeth, the
surrounding bone often exhibit a lower density and hyperplasia of the soft tissue may be noted
in affected teeth that are impacted.
Radiographically, the altered teeth demonstrate extremely thin enamel and dentin surrounding
an enlarged radiolucent pulp resulting in a pale wispy image; hence the term Ghost teeth is
used. The enlarged pulp frequently demonstrate one or more pulp stones. Many of the affected
teeth fail to erupt, Erupted teeth demonstrate small irregular crown that are yellow to brown,
often with a very rough surface. Caries and periapical inflammatory lesions are very common.

Histopathology
In ground section the thickness of enamel varies, resulting in an irregular surface. The prism
structure of enamel is irregular or lacking with a laminated appearance.
The dentin contain clefts scattered through a mixture of interglobular dentin and amorphous
material. Globular areas of poorly organized tubular dentin and scattered cellular inclusions
often are seen.
The pulp tissue contain free or attached stones, that may exhibit tubules or consist of laminated
calcification.
The follicular tissue surrounding the crown may be enlarged and typically exhibit focal
calcifications of basophilic enamel like calcifications called Enameloid Conglomerates, but it is
not specific only for Regional Odontodysplasia. Scattered islands of odontogenic epithelium and
other patterns of intramural calcification also are seen.

The basic approach to therapy of regional odontodysplasia is directed toward retention of the
altered teeth.
Endodontic Therapy can be done on non-vital tooth.
Unerupted tooth should remain untouched, until skeletal growth is completed.
Tooth preparation is contraindicated because of fragile nature of coronal hard tissue and ease
of exposure of the pulp tissue.
Osteointegrated Implants can be used in patients who have completed pubertal growth.

2. Environmental Alteration Of Teeth
The environmental effects on tooth structure may result in alterations, which include:
i. Developmental
ii. Post-developmental
iii. Discoloration of teeth
iv. Localized Disturbance

i. Developmental Effects
The ameloblasts in developing tooth germ are extremely sensitive to external stimuli and many
factors can result in abnormalities in enamel. The timing of the ameloblastic damage has a great
effect on the location and appearance of the defect in the enamel. The environmental enamel
abnormalities are very common with a Prevalence rate of about 68.4%.
The developmental effects caused by Environmental changes include:
 Turner’s Hypoplasia
 Molar Incisor Hypomineralization
 Hypoplasia caused by Anti-neoplastic Therapy
 Dental Fluorosis
 Syphilitic Hypoplasia

 Turner’s Hypoplasia
Definition: The condition of enamel defects seen in permanent dentition caused by periapical
inflammatory disease of the overlying deciduous teeth is termed as Turner’s Hypoplasia.
Clinical Features: The appearance of the area varies according to the time and severity of the disease.
The enamel defects vary from focal area of white, yellow, or brown discoloration to extensive
hypoplasia, which can involve the entire crown. The process is noted most frequently in Permanent
Bicuspids because of their relationship to the overlying molars.
Factors that determine the degree of damage to the permanent tooth by the overlying infection
include:
o Stage of tooth development
o Length of time the infection left untreated
o Host resistance to infection
o The virulency of infective organism.

 Molar Incisor Hypomineralization
In the Molar Incisor Hypomineralization, one or more first permanent molars have Enamel
defects. The altered enamel may be white, yellow, or brown, with a sharp demarcation between
the defective and normal surrounding enamel. Often the involved enamel is soft and porous
with a resemblance to discolored chalk or “Old Dutch Cheese”. Frequently the Incisors too are
affected, but the defects generally are much less severe.
Often the affected molars are sensitive to Cold, Warm, or mechanical trauma. Toothbrushing is
frequently painful. The lack of normal enamel and absence of appropriate hygiene lead to rapid
development of caries. During dental therapy, these teeth often are highly sensitive and very
difficult to anesthetize.
The Prevalence rate of this condition ranges from 3.6 to 25%.

 Hypoplasia Caused By Anti-Neoplastic
Therapy
Although both chemotherapeutic and radiation therapy can be responsible for developmental
abnormalities, the most severe alterations are associated with radiations. Doses as low as 0.72
Gy are associated with mild developmental defects in both enamel and dentin. As the dose
escalates, so does the effect on developing teeth and jaws. Frequently noted alterations include
Hypodontia, Microdontia, Radicular Hypoplasia, Mandibular Hypoplasia, and Enamel Hypoplasia
etc. The severity is more when the age is less than TWELVE years and most extensively in those
younger than FIVE years.

 Dental Fluorosis
The ingestion of excess amount of fluoride can result in significant enamel defect, termed as
Dental Fluorosis. The optimum range for drinking water fluoridation is between 0.7 to 1.2 ppm.
Above it’s range the fluoride causes stains on the teeth which are termed as Dental Fluorosis.
Fluoride appears to create it’s significant enamel defects through retention of the Amelogenin
protein in the enamel structure, leading to Hypomineralized enamel. These alterations create a
permanent hypomaturation of the enamel in which an increased surface and subsurface
porosity of the enamel is observed. This enamel structure alters the light reflection and creates
the appearance of white, chalky areas. The severity of fluorosis is dose dependent with higher
intake of Fluorides during critical period of tooth development being associated with more
severe fluorosis. The affected teeth are caries resistant, with altered tooth structure appears as
lusterless, white opaque enamel that may have zones of yellow to dark-brown discolorations.
The commonly affected teeth include the permanent First Molars, and Maxillary Central
Incisors.

 Syphilitic Hypoplasia
Congenital Syphilis results in a pattern of enamel hypoplasia termed as Syphilitic Hypoplasia.
The Anterior teeth altered by syphilis are termed as Hutchinson’s Incisors and exhibit crowns
that are shaped like straight-edge screw driver. The altered posterior teeth are termed as
Mulberry Molars.

Most defects in the enamel are cosmetic rather than functional dental problem. Aesthetically
and functionally the defective teeth can be restored through a variety of cosmetically pleasing
techniques, which include:
Acid-etched Composite Resin Restoration
Labial Veneers
Full crowns.

ii. Postdevelopmental Effects
Tooth structure can be lost after it’s formation by a variety of influences beyond the obvious cases related to
caries or traumatic fractures.
Tooth Wear also termed as Tooth Surface Loss is a normal physiological process that occurs with aging but must
be considered pathologic when the degree of destruction creates functional, aesthetic, or dental sensitivity
problem. The tooth wear includes:
a. Attrition: loss of tooth structure caused by tooth to tooth contact during occlusion and mastication.
b. Abrasion: Loss of tooth structure or restoration secondary to the mechanical action of an external agent.
c. Abfraction: Loss of tooth structure from occlusal stresses that create repeated tooth flexure with failure of
enamel and dentin at a location away from the point of loading.
d. Erosion: Loss of tooth structure caused by non-bacterial chemical process.
o When tooth wear is accelerated by chewing an abrasive substance between opposing teeth, the process is
termed as Demastication.
o Erosion from dental exposure to gastric secretions, is termed as Perimolysis.

iii. Discoloration Of Teeth
The color of normal teeth varies and depends on the shade, translucency, and thickness of
enamel. The discoloration of teeth is classified as:
Extrinsic Stains
Intrinsic Stains

iv. Localized Disturbances
It includes:
Impaction: Teeth that cease to erupt before emergence.
Ankylosis: The cessation of eruption after emergence.

Developmental disturbances of teeth and bone

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