1 GOOD MORNING DEVELOPMENTAL DISTURBANCES OF TEETH - PowerPoint Presentation

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GOOD MORNING

DEVELOPMENTAL DISTURBANCES OF TEETH

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CONTENTS

Introduction

Developmental disturbances in number of teethDevelopmental disturbances in size of teeth

Developmental disturbances in shape of

teeth

Developmental disturbances in structure of teethDevelopmental disturbances in eruption of teethConclusionReferences

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DEVELOPMENTAL DISTURBANCES IN NUMBER OF TEETH

True anodontia :

Congenital absence of teeth, may be of two types, total and partial. Total anodontia: All teeth are missing, may involve both deciduous and permanent dentition. This is a rare condition When it occurs, it is frequently associated with a more generalized disturbance, hereditary ectodermal dysplasia. 3

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Total anodontia

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Induced or false anodontia occurs as a result of extraction of all teeth

The term pseudoanodontia is applied to multiple unerupted teeth.

True partial anodontia :Hypodontia or OligodontiaInvolves one or more teeth and is a rather common condition. Although any tooth may be congenitally missing, there is a tendency for certain teeth to be missing more frequently than others.

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Partial anodontia

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Third molars to be congenitally absent in as many as 35 per cent of all subjects examined, with a frequent absence of all four third molars in the same person.

The maxillary lateral incisors and maxillary or mandibular second premolars are commonly missing, often bilaterally.

The overall frequency of patients with congenitally missing teeth (excluding third molars) has ranged from 1.6 –9.6 per cent.

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Congenitally missing deciduous teeth are uncommon but, when occurring, usually involve the maxillary lateral incisor.

Some investigators believe cases of missing third molars to be evidence of an evolutionary trend toward fewer teeth.

Hereditary ectodermal dysplasia may be associated with partial anodontia.

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Syndrome associated with hypodontia-

Cranio-oculo-dental

Crouzon DownEctodermal dysplasiaEhler-danlos

Focal dermal hypoplasia

Gorlin

HurlerProgeria Sturge-WeberTurner9

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SUPERNUMERARY TEETH

A supernumerary teeth may closely resemble the teeth of the group to which it belongs, or it may bear little resemblance in size or shape to the teeth with which it is associated. It has been suggested that supernumerary teeth develop from splitting of the permanent bud itself. Another theory, is the hyperactivity theory, which suggests that supernumeraries are formed as a result of local, independent, conditioned hyperactivity of the dental lamina.

In some cases there appears to be a hereditary tendency for the development of supernumerary teeth.

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The etiology is not completely understood.

Occurrence may be single or multiple, unilateral or bilateral, erupted or impacted, and in one or both jaws.

The conditions commonly associated with an increased prevalence of supernumerary teeth include cleft lip and palate, cleidocranial dysplasia, and Gardner syndrome. Supernumerary teeth associated with cleft lip and palate result from fragementation of the dental lamina during cleft formation.

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Impacted supernumerary tooth

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The frequency of supernumerary permanent teeth in the cleft area in children with unilateral cleft lip or palate or both was found to be 22.2 per cent.

The frequency of supernumeraries in patients with cleidocranial dysplasia ranged from 22 per cent in the maxillary incisor region to 5 per cent in the molar region.

No significant gender predilection in primary supernumerary teethMales are affected approximately twice as frequently as females in the permanent dentition.

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Classification

: Supernumerary teeth are classified according to morphology and location.In the primary dentition, morphology is usually normal or conical. There is a greater vaiety of forms presenting in the permanent dentition.

Four different morphological types of supernumerary teeth have been described :

Conical

Tuberculate Supplemental Odontome. 14

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Syndrome associated with hyperdontia-

Apert

Cleidocranial dysplasiaCrouzonDownEhler-danlosGardner Sturge-Weber

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DEVELOPMENTAL DISTURBANCES IN SIZE OF TEETH

MICRODONTIA This term is used to describe teeth which are smaller than normal, i.e., outside the usual limits of variation. Three types of microdontia are recognized : (1) True generalized microdontia (2) Relative generalized microdontia (3) Microdonita involving a single tooth.

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True generalized microdontia :

All the teeth are smaller than normal.

Aside from its occurrence in some cases of pituitary dwarfism, this condition is exceedingly rare. The teeth are reportedly well formed but are merely small. Relative generalized microdontia :

Normal or slightly smaller than normal teeth are present in jaws that are somewhat larger than normal.

A person may inherit the jaw size from one parent and the tooth size from the other parent so the role of hereditary factors in producing such a condition is obvious.

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Microdontia

involving only a single tooth A rather common condition.

It affects most often the maxillary lateral incisor and the third molar. It is of interest to note, however, that other teeth often congenitally absent, the maxillary and mandibular second premolars, seldom exhibit microdontia. Supernumerary teeth, however, are frequently small in size. One of the common forms of localized microdontia

is ‘

peg lateral’

. Instead of exhibiting parallel or diverging meisal and distal surfaces, the sides converge or taper together incisally, forming a peg-shaped or cone-shaped crown. The root on such a tooth is frequently shorter than usual. 18

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MACRODONTIA

Macrodontia refers to teeth that are larger than normal.Such teeth may be classified in the same manner as a mocrodontia. True generalized macrodontia: The condition in which all teeth are larger than normalIt is extremely rareAssociated with pituitary gigantism,.

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Macrodont

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Relative generalized macrodontia:

Somewhat more common

Result of the presence of normal or slightly larger than normal teeth in small jawsThe disparity in size giving the illusion of macrodontia. As in microdontia, the importance of heredity must be considered.

Macrodontia of single tooth

Relatively uncommon

Unknown etiology. The tooth may appear normal in every respect except for its size. 22

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True macrodontia of a single tooth should not be confused with fusion of tooth, in which, early in odontogenesis, the union of two or more teeth results in a single larger tooth.

A variant of localized macrodontia is the type that is occasionally seen in cases of hemihypertrophy of the face.

Here the teeth of the involved side may be considerably larger than those of the unaffected side. 23

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Fraumeni and coworkers stressed that there appear to be some relationship between hemihypertrophy and neoplasm of kidney, liver and adrenal cortex in children.

Of all reported cases females (63%) are affected more than males (37%).

There is almost equal involvement of right and left side of face.24

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DEVELOPMENTAL DISTURBANCES IN SHAPE OF TEETH

GEMINATION

Geminated teeth are anomalies which arise from an attempt at division of single tooth germ by an invagination, with resultant incomplete formation of two teeth. The structure is usually one with two completely or incompletely separated crowns that have a single root and root canal. It is seen in deciduous as well as permanent dentitionAppears to exhibit a hereditary tendency.

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It is not always possible to differentiate between gemination and a case in which there has been fusion between a normal tooth and a supernumerary tooth.

The term ‘twinning’ has sometimes been used to designate the production of equivalent structures by division resulting in one normal and one supernumerary tooth.

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FUSION

Fused teeth arise through union of two normally separated tooth germs. Depending upon the stage of development of the teeth at the time of the union, fusion may be either complete or incomplete. It has been thought that some physical force or pressure produces contact of the developing teeth and their subsequent fusion. If this contact occurs early, at least before calcification begins, the two teeth may be completely united to form a single larger tooth.

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If the contact of teeth occurs later, when a portion of the tooth crown has completed its formation, there may be union of the roots only.

The dentin, however, is always

confluent in cases of true fusion. The tooth may have separate or fused root canals, and the condition is common in the deciduous as well as in the permanent dentition. In addition to affecting two normal teeth, fusion may also occur between a normal tooth and a supernumerary tooth such as the mesiodens or the distomolar.

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CONCRESCENCE

A form of fusion which occurs after root formation has been completed.

Teeth are united by cementum only. It is thought to arise as a result of traumatic injury or crowding of teeth with resorption of the interdental

bone.

Concrescence may occur before or after the teeth have erupted,

It usually involves only two teeth. 34

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The diagnosis can frequently be established by roentgenographic examination.

The extraction of one may result in the extraction of the other.

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DILACERATIONS

The term ‘dilaceration’ refers to an angulation, or a sharp bend or curve, in the root or crown of a formed tooth. The condition is thought to be due to trauma during the period in which the tooth is forming, with the result that the position of the calcified portion of the tooth is changed and the remainder of the tooth is formed at an angle. The curve or bend may occur anywhere along the length of the tooth depending upon the amount of root formed when the injury occurred.

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It has been emphasized by van Gool that such an injury to a permanent tooth, resulting in dilaceration, often follows traumatic injury to the deciduous predecessor in which that tooth is driven apically into the jaw.

Dilacerated teeth frequently present difficult problems at the time of extraction if the operator is unaware of the condition.

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TALON CUSP

An anomalous structure resembling an eagle’s talon, projects lingually from the cingulum areas of a maxillary or mandibular permanent incisor.

This cusp blends smoothly with the tooth except that there is a deep developmental groove where the cusp blends with the sloping lingual tooth surface. It is composed of normal enamel and dentin and contains a horn of pulp tissue.

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Mellor and Ripa have recommended prophylactically restoring the groove to prevent caries.

If there is occlusal interference, it should be removed but exposure of the pulp horn, necessitating endodontic therapy, is almost certain to occur.

This anomaly is quite uncommon among the general population. It has been reported by Gardner and Girgis that it appears to be more prevalent in persons with the Rubinstein – Taybi syndrome developmental retardation,

broad thumbs and great toes,

characteristic facial features,

delayed or incomplete descent of testes in males, stature, head circumference, and bone age, below the fiftieth percentile 45

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DENS IN DENTE

Dens Invaginatus, Dilated composite odontome

It is a developmental variation which is thought to arise as a result of an invagination in the surface of tooth crown before calcification has occurred.Several causes of this condition have been proposed : Increased localized external pressure focal growth retardation focal growth stimulation in certain areas of the tooth bud.

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The permanent maxillary lateral incisors are the teeth most frequently involved.

In the majority of cases the ‘dens in dente’ appears to represent simply an accentuation in the development of the lingual pit.

The maxillary central incisors are sometimes involved, and the condition is frequently bilateral. Oehlers has emphasized that not only are posterior teeth, sometimes affected but also an analogous form of invagination occasionally occurs in the roots of teeth.

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This radicular variety of ‘dens in dente’ has been discussed by Bhatt and Dholakia,

They pointed out that the radicular invagination usually results from an infolding of Hertwig’s sheath and takes its origin within the root after development is complete.

The term ‘dens in dente’, originally applied to a severe invagination that gave the appearance of a tooth within a tooth, is actually a misnomer.In the mild form, there is a deep invagination in the lingual pit area, which may not be evident clinically.

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The invagination may be dialated and disturb the formation of the tooth, resulting in anomalous tooth development termed

dialated odontome

.The first classification of invaginated teeth was published by Hallet (1953). Most commonly used classification proposed by Oehlers (1957).

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Oehlers (1957)

Type I: An enamel lined minor form occurring within the confines of crown not extending beyond the amelocemental junction.

Type II: Enamel lined form which invades the root but remain confined as a blind sac. It may or may not communicate with the dental pulp. Type III: A form which penetrate through the root perforating at the apical area showing the ‘second foramen’ in the apical or periodontal area. There is no immediate communication with the pulp. The invagination may be completely lined by enamel, but frequently cementum will be found lining the invagination.

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Radicular dens invaginatus

is rare and thought to arise secondary to perforation in HERS, with the formation of a strip of enamel that extend along the surface of root.

Cementum lined invaginations of root are also reported, but these represent a simple variation of root morphology and should not be included under the term radicular dens invaginatus.53

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Roentgenographically, it is recognized as a pear-shaped invagination of enamel and dentin with a narrow constriction at the opening on the surface of the tooth and closely approximating the pulp in its depth.

Food debris may become packed in this area with resultant caries and infection of the pulp.

The more severe forms of ‘dens in dente’ may exhibit an invagination that extends nearly to the apex of the root, and these present a bizarre roentgenogrpahic picture reflecting a severe disturbance in the normal anatomic and morphologic structure of the teeth.

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This condition, particularly in its mild form, is fairly common.

The clinical studies of Amos have shown that if the minor invaginations are included, the incidence may be as high as 5 per cent of all patients examined.

The more severe forms are much less common. To prevent caries, pulp infection, and premature loss of the tooth, the condition must be recognized early and the tooth prophylactically restored.

Fortunately, the defect may be recognized roentgenographically even before the teeth erupt.

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DENS EVAGINATUS

Occlusal tuberculated premolar, Leong’s premolar, Evaginated odontome, Occlusal enamel pearl.

A developmental condition that appears clinically as an accessory cusp or a globule of enamel on the occlusal surface between the buccal and lingual cusps of premolarsMay be unilateral or bilateral It has also been reported to occur rarely on molars, cuspids, and incisors.

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It has been thought to develop only in people of Mongoloid ancestry : Chinese, Japanese, Filipions, Eskimos, and American Indians.

The pathogenesis of the lesion is thought to be the proliferation and evagination of an area of the inner enamel epithelium and subjacent odontogenic mesenchyme into the dental organ during early tooth development.

This ‘extra’ cusp may contribute to incomplete eruption, displacement of teeth and pulp exposure with subsequent infection following occlusal wear or fracture.

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TAURODONTISM

The term ‘taurodontism’ was originated by Sir Arthur Keith in 1913.

A peculiar dental anomaly in which the body of the tooth is enlarged at the expense of the roots. Shaw further classified taurodont teeth into Hypotaurodont Mesotaurodont Hypertaurodont

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Hypertaurodontism being the extreme form in which the bifuracation or trifurcation occurs near the apices of the roots and hypotaurodontism being the mildest form.

A variety of possible causes of taurodontism given by Mangion :

1) A specialized or retrograde character 2) A primitive pattern 3) A mendelian recessive trait 4) An atavistic feature 5) A mutation resulting from odontoblastic deficiency during dentinogenesis of the roots.

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Hammer and his associates believe that the taurodont is caused by failure of Hertwig’s epithelial sheath to invaginate at the proper horizontal level.

Goldstein and Gottlieb stated that the condition appears to be genetically controlled and familial in nature.

Clinical Features : Taurodontism may affect either the deciduous or permanent dentition (more common). The teeth involved are almost invariably molars, (single tooth or several molars in the same quadrant).

The condition may be unilateral or bilateral or may exhibit any combination of quadrant involvement.

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Syndrome associated with taurodontism-

Amelogenesis imperfecta- hypoplastic, type I-E

Amelogenesis imperfecta- taurodontism type IVEctodermal dysplasiaKlinefeltersOral-facial-digital, type IIDown

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Roentgenographic Features :

Involved teeth frequently tend to be rectangular in shape rather than taper toward the roots.

The pulp chamber is extremely large with a much greater apico-occlusal height than normal. In addition, the pulp lacks the usual constriction at the cervical of the tooth and the roots are exceedingly short.

The bifurcation or trifurcation may be only a few millimeter above the apices of the roots.

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PREDECIDUOUS DENTITION

Premature eruption, Natal teeth, Neonatal teeth

Infants occasionally are born with structures which appear to be erupted teeth, usually in the mandibular incisor area. These structures must be distinguished from true deciduous teeth, or the so called natal teeth described by Massler, which may have erupted by the time of birth.

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The predeciduous teeth have been described as hornified epithelial structures without roots, occurring on the gingiva over the crest of the ridge, which may be easily removed.

Prematurely erupted true deciduous teeth are not to be extracted.

These predeciduous teeth have been thought to arise either from an accessory bud of the dental lamina ahead of the deciduous bud or from the bud of an accessory dental lamina.

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DEVELOPMENTAL DISTURBANCES IN STRUCTURE OF TEETH

AMELOGENESIS IMPERFECTA

Hereditary enamel dysplasia, hereditary brown enamel, hereditary brown opalescent teethA structural defect of the tooth enamel with complex inheritance pattern

Depending on the clinical presentation & likely stage of enamel formation that is primarily affected, it may be

Hypoplastic

Hypocalcified Hypomaturative73

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Factors associated with enamel defects

Neurologic disorders

Cerebral palsy Mental retardationMetabolic disordersCardiac disease

Celiac disease

Hypocalcemia

HypothyroidismRenal diseaseMaternal diabetes74

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Hypoparathyroidism

Infection

Cytomegalo virusMeaslesRubellaPneumoniaTetanusSyphilis

Chemicals

Anti-neoplastic chemotherapy

FluorideLeadTetracyclineThalidomideVitamin D75

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Each main clinical group of AI may be further divided into several subgroups depending on the mode of inheritance, as well as the clinical appearance of the defective enamel.

In some cases, overlapping clinical features may make distinction difficult.

Hypoplastic AI: 60-73 per cent of all cases

Hypomaturation

AI : 20-40 per cent

Hypocalcification AI : 7 per cent. 76

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Classification of

Amelogeneis imperfecta according to Witkop

(1989) : Type I : HypoplasticIA : Hypoplastic, pitted autosomal dominant IB : Hypoplastic, local autosomal dominant

IC : Hypoplastic, local autosomal recessive

ID : Hypoplastic, smooth, autosomal

dominant IE : Hypoplastic, smooth x-linked dominant IF : Hypoplastic, rough autosomal dominant IG : Enamel agenesis , autosomal recessive. Type II Hypomaturation : IIA : Hypomaturation, pigmented,ARIIB : Hypomaturation , X- lined recessive

IIC : Snow- capped teeth, AD.

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Type III Hypocalciffied :

IIIA : Autosomal dominant

IIIB : Autosomal recessive. Type IV Hypomaturation – hypoplastic with taurodontism :

IVA : Hypomaturation- hypoplastic with taurodontism, AD

IVB : Hypoplastic – hypomaturation with taurodontism, AD

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Type

Clinical Appearance

Enamel Thickness

Radiographic Appearance

Inheritance

Hypoplastic

(Type I)

Crowns size varies from small to normal, small teeth may lack proxmial contacts, color varies from normal to opaque white – yellow brown

Varies from thin and smooth to normal thickness with grooves, furrows and/or pits

Enamel has normal to slightly reduced contrast/ thin

Autosomal dominant, recessive, or X-linked

Hypomaturation

(Type II)

Varies from creamy opaque to marked yellow/brown, surface of teeth soft and rough, dental sensitivity and open bite common

Normal thickness with enamel that often chips and abrades easily

Enamel has contrast similar to or > than dentin, unerupted crowns have normal morphology

Autosomal dominant, recessive, or X-linked

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Type

Clinical Appearance

Enamel Thickness

Radiographic Appearance

Inheritance

Hypocalcified

(Type III)

Opaque white to yellow-brown, soft rough enamel surface, dental sensitivity and open bite common, heavy calculus formation common

Normal thickness with enamel that often chips and abrades easily

Enamel has contrast similar to or < dentin, unerupted crowns have normal morphology

Autosomal dominant, recessive

Hypomaturation/ Hypoplasia/

Taurodontism

(Type IV)

White/Yellow- Brown mottled, teeth can appear small and lack proximal contact

Reduced, hypomineralized areas and pits

Enamel contrast normal to slightly > dentin, large pulp chambers

Autosomal dominant

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Molecular genetic studies have shown that the aetiology of AI is related to the alteration of genes involved in the process of formation and maturation of the enamel.

Although the genetic origin of the autosomal forms is less understood, 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.

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Histologic Features :

There is a disturbance in the differentiation or viability of ameloblasts in the hypoplastic type.

In the hypocalcification types there are defects of matrix structure and of mineral deposition.In the hypomaturation types there are alterations in enamel rod and rod sheath structures. 84

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Dentinogenesis

Imperfecta

This is an autosomal dominant condition affecting both deciduous and permanent teeth. Affected teeth are gray to yellowish-brown and have broad crowns with constriction of the cervical area resulting in a 'tulip' shape.

Radiographically, the teeth appear solid, lacking pulp chambers and root canals.

Enamel is easily broken leading to exposure of dentin that undergoes accelerated attrition

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The gene maps to chromosome #4.

It encodes a protein called dentin

sialophosphoprotein (DSPP). This protein constitutes about 50% of the noncollagenous component of dentin matrix. Dentin defect associated with osteogenesis imperfecta

was

earlier

listed as dentinogenesis imperfecta type I (Shields classification). 86

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Extensive studies have proven that dentinogenesis imperfecta is clearly a disorder distinct from osteogenesis imperfecta hence the following revised classification is proposed.

Dentinogenesis imperfecta 1:

Dentinogenesis imperfecta without osteogenesis imperfecta (opalescent dentin) this corresponds to dentinogenesis imperfect, tvpe II of Shields chssification.Dentinoenesis Imperfecta 2: Brandywine tvpe dentinogenesis imperfecta: this corresponds to dentinogenesis imperfecta type III of Shields classification.

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Dentinogenesis imperfecta 2 is more rare and paradoxically characterized bv too little rather than too much dentin resulting in 'shell teeth’.

Dentinogenesis imperfecta 2 may be an allelic variant of dentinogenesis impertecta 1 (a different mutation in the same gene), as both genes map to the same region on chromosome #4.

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DENTINOGENESIS IMPERFECTA :1

Opalescent dentin, dentinogenesis impertecta without osteogenesis imperfecta, Opalescent tecth without osteogenesis imperfecta, , Shields type II

Dentinogenesis impertecra 1 is caused by mutation in the DSPP gene (gene map locus 4q21.3) encoding dentin phosphoprotein and dentin sialoprotein. Dentinogenesis impertecta is an entity clearly distinct from osteogenesis imperfecta with opalescent teeth, and affects only the teeth.

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There is no increased frequency of bone fractures in this disorder.

The frequency may be 1 in 6,000-8,000 children.

Witkop and Rao ( 1971) preferred the term opalescent dentin for this condition as an isolated trait, reserving dentinogenesis

imperfecta

for the trait when it is combined with osteogenesis imperfecta. The teeth are blue-gray or amber brown and opalescent. On dental radiographs the teeth have bulbous crowns, roots that are narrower than normal, and pulp chamber and root canals that are smaller than normal or completely obliterated. 91

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The enamel may split readily from the dentin when subjected to

occlusal

stress. .A deficiency of dentin sialophosphoprotein had been suggested as a causative factor in dentinogenesis

imperfecta

.

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Dentinogenesis imperfecta: 2

Shields type III, Brandywiine type dentinogenesis imperfecta

This disorder was found in the Brandywine triracial isolate in southern Maryland. The crowns of the deciduous and permanent teeth wear rapidly after eruption and multiple pulp exposures may occur. The dentin is amber color and smooth.

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Radiographs of the deciduous dentition show very large pulp chambers and root canals, at least during the first few years.

They may become reduced in size with age.

The permanent teeth have pulpal spaces that are either smaller than normal or completely obliterated. Patients with Shields type III, or the Brandywinc type, do not have stigmata of osteogenesis imperfecta

This disorder may be a separate mutation from dentinogenesis imperfccta 1.

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Shields el al

.

(1973) stated that multiple pulp exposures and markedly enlarged pulp chambers in the deciduous teeth do not occur in DGI-1. Recent studies are consistent with the hypothesis that DGI-1 and DGI-2 are allelic or the result of mutations in two tightly linked genes. MacDougall el al. (1999)) stated that the manifestations of DGI-2 can differ from those of DGI-1 by the presence of multiple pulp exposures, normal nonmineralized pulp chambers and canals, and a general appearance of 'shell teeth'.

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They illustrated the amber discoloration of the teeth, attrition, and fractured enamel, as well as the classic 'shell teeth' appearance on radiographs.

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Histologic Features.

The appearance of the enamel is essentially normal except for its peculiar shade, which is actually a manifestation of the dentinal disturbance.

The dentin, on the other hand, is composed of irregular tubules, with large areas of

uncalcified matrix.

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The tubules tend to be large in diameter and thus less numerous than normal in a given volume of dentin.

In some areas there may be complete absence of tubules.

Cellular inclusions,probably odontoblasts, in the dentin are not uncommonThe pulp chamber is usually almost obliterated by the continued deposition of dentin.

The odontoblasts have only limited ability to form well- organized dentinal matrix, and they appear to degenerate readily,becoming entrapped in this matrix.

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Obliterated pulp chambers

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Normal dentin tubules

Dentinal tubules in DI are disoriented irregular & widely spaced

Obliterated pulp

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Chemical and physical features

:

Chemical analysis explains many of the abnormal features of the teeth of dentinogenesis imperfecta-1.Their water content is greatly increased, as much as 60% above normal, while the inorganic content is less than that of normal dentin.

The

micro hardness

of the dentin closely approximates that of Cementum, thus explaining the rapid attrition of affected teeth. 101

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Treatment:

Directed primarily towards preventing the loss of enamel and subsequent loss of dentin through attrition. Cast metal crowns on the posterior teeth and jacket crowns on the anterior teeth have been used. Fillings are not usually permanent because of the softness of the dentin.

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Dentin Dysplasia (Rootless teeth)

A rare disturbance of dentin formation.

Characterized by normal enamel but atypical dentin formation with abnormal pulpal morphology.Previously it was thought to be a single disease. entityShields and his associates separarted it in to

Type I (Dentin dysplasia)

Type II (anomalous dysplasia of dentin).

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Witkop

referred these conditions as

radicular dentin dysplasia (type I) and coronal dentin dysplasia (typeII)

Type I is more common.

The first description of the disease was given by

Ballschmiede.He reported the spontaneous exfoliation of multiple teeth in 7 children of one family in 1920 and called this phenomenon “rootless teeth”.104

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The first concise description of the disease was published in 1939 by

Rushton

, who was also the first to designate it as 'dentin dysplasia. ' Dentin dysplasia, both type 1 and type II, appears to be a hereditary disease, transmitted as an autosomal dominant characteristic. Nothing is known of the mutation rate, but it must be extremely low.

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Conditions associated with dentin dysplasia

Calcinosis universalis

Rheumatoid arthritisVitaminosis D

Sclerotic bone and skeletal anomalies

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Type I (radicular)

Both dentitions are affectedThe teeth appear clinically normal in morphologic appearance and color. On occasion, there may be a slight amber translucency.

The teeth characteristically exhibit extreme mobility and are commonly exfoliated prematurely or after only minor trauma as a result of their abnormally short roots.

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Type II (coronal)

Both dentitions are affected.The deciduous teeth have the same yellow, brown, or bluish-gray opalascent appearance as seen in dentinogenesis imperfecta. The clinical| appearance of the permanent dentition is normal.108

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Roentgenographic Features

Type I (radicular)

In both dentitions, the roots are short, blunt, conical, or similarly malformed . In the deciduous teeth, the pulp chambers and root canals are usually completely obliterated, while in the permanent dentition, a crescent-shaped pulpal remnant may still be seen in the pulp chamber.

The obliteration in the permanent teeth commonly occurs preeruptively.

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Type II (coronal)

The pulp chambers of the deciduous teeth become obliterated as in type I and in dentinogenesis imperfecta.The permanent teeth, however, exhibit an abnormally large pulp chamber in the coronal portion of the tooth, often described as 'thistle-tube

' in shape

Within such areas

radiopaque foci resembling pulp stones may be found. Periapical radiolucencies do not occur unless for an obvious reason.110

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Rootless teeth

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Histologic Features:

Type I (

radicular). A portion of the coronal dentin is usually normal. Apical to this may be areas of tubular dentin, but most of that which obliterates the pulp is calcified tubular dentin,

osteodentin

, and fused

denticles. Normal dentinal tubule formation appears to have been blocked so that new dentin forms around obstacles and takes on the characteristic appearance described as 'lava flowing around boulders'. 114

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Electron microscope studies by Sauk and his coworkers have suggested that this pattern of 'cascades of dentin' results from repetitive attempts to form root structure.

Interestingly, the dentin itself is histologically normal but is simply disoriented.

Type II (coronal)

The deciduous teeth exhibit amorphous and

atubular

dentin in the radicular portion, while coronal dentin is relatively normal. The permanent teeth also show relatively normal coronal dentin, but the pulp has multiple pulp stones or denticles.115

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116

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REGIONAL ODONTODYSPLASIA

Odontodysplasia

, odontogenic dysplasia, odontogenesis imperfecta, ghost teeth

This is an unusual dental anomaly in which one or several teeth in a localized area are affected in an unusual manner.

Apparently the maxillary teeth are involved more frequently than the mandibular

The most frequently affected teeth being the maxillary permanent central incisor, lateral incisor, and cuspid. 117

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Conditions associated:

Ectodermal dysplasiaEpidermal neviHypophosphatasiaNeurofibromatosis

Rh incompatibility

Vascular nevi

HydrocephalusIpsilateral facial hyperplasia118

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The etiology of this disease is unknown.

Suggested etiology:

A somatic mutation or A latent virus residing in the odontogenic epithelium, which subsequently becomes active during the development of the tooth.

Walton and his coworkers observed that in three cases of regional

odontodysplasia

that they reported, all three patients had vascular nevi of the overlying facial skin as infants. These findings suggested to them that local vascular defects are involved in the pathogenesis of the condition. 119

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The teeth affected by odontodysplasia exhibit either a delay or a total failure in eruption.

Their shape is markedly altered, being generally very irregular in appearance, often with evidence of defective mineralization.

The radiographs are uniquely characteristic, showing a marked reduction in radiodensity so that the teeth assume a 'ghost’ appearance. Both the enamel and dentin appear very

thin and the pulp chamber is exceedingly large.

The enamel layer often is not evident.

120

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121

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Indistinguishable DEJ, Ghost teeth appearance

122

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Histologic Features

The most characteristic features of the disease are The marked reduction in the amount of dentin The widening of the pre-dentin layer The presence of large areas of inter-globular dentin An irregular tubular pattern of dentin.

Characteristically, the reduced enamel epithelium around uneruptcd teeth shows many irregular calcified bodies.

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Dentin hypocalcification

Normal dentin is calcified by deposition of calcium salts in the organic matrix in the form of globules, which increase in size by further peripheral deposition of salts until all the globules are finally united into a homogeneous structure.

In dentinal hypocalcification there is failure of union of many of these globules, leaving interglobular areas of uncalcificd matrix. This globular dentin is easily detected in both ground sections and decalcified histologic sections of teeth, but there is no alteration in the clinical appearance.

124

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125

Large area of interglobular dentin

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Many clinicians believe that they can detect areas of globular dentin by the softness of the dental structure.

Although this remains to be proved, it is logical that hypocalcified dentin would be softer than well calcified dentin.

Any factor which interferes with normal calcification, such as parathyroid deficiency or rickets, could produce hypocalcification.

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Certain conditions associated with tooth anomalies:

Mucopolysaccharidosis- Thin enamel with pointed cusp

Lipoid proteinosis- Enamel hypoplasiaDeficiency of vit.A & C- Enamel hypoplasiaHypoparathyroidism- Pitting enamel hypoplasiaHyperparathyroidism- Pulp stonesHypophosphatasia- Reduced cementum and dentin, large pulp chambers enamel hypoplasia

Vitamin-D resistant rickets- Large pulp chambers (reaching DEJ), hypocalcified dentin, abnormal cementum.

Tuberous sclerosis- Pitting of enamel

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Dystrophic calcification- Pulp stones

Osteogenesis imperfecta- Hypoplastic dentin

Downs syndrome- Enamel hypoplasiaOsteopetrosis- Teeth hypoplasia, prone to dental cariesErythroblastosis foetalis- Enamel hypoplasiaChondroectodermal dysplasia- Enamel hypoplasiaEpidermolysis bullosa dystrophica- Hypoplasia of teeth with crown denuded of enamel

128

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Junctional epidermolysis bullosa-Disturbance in enamel and dentin formation in primary and secondary teeth

Ehlers danlos syndrome- Flattening of DEJ , enamel hypoplasia, pulp stones

Focal dermal hypoplasia syndrome- Enamel hypoplasia129

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Thank you

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Conclusion

As new genes and mutations associated with hereditary dental diseases are discovered, it will be possible to describe the classification of these diseases not only on a clinical level but also at molecular level .

Such expanding information could lead to the development of future sensitive diagnostic tools.“Order is never observed; it is disorder that attracts attention because it is awkward and intrusive.” Eliphas Levi

131

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References

Oral & maxillofacial pathology 2

nd edition Neville.Oral pathology 5th edition. Rajendran & Sivapathasundaram

Thoma’s oral pathology 6

th

edition.Human genes for dental anomalies. Oral diseases 1997 (3) 223-8Dens invaginatus. Int. endol. Jour 1997(30) 79-90.132

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discussion.....??????