Amelogenesis Amelogenesis ImperfectaImperfecta

By:By:

Shabeel PNShabeel PN

Amelogeneis Amelogeneis Imperfecta Imperfecta  It is a heterogenous group of It is a heterogenous group of

hereditory disorders of enamel formation hereditory disorders of enamel formation affecting both deciduous & permanent affecting both deciduous & permanent dentition.dentition. prevalence is1 in 700 to 4000 with slight prevalence is1 in 700 to 4000 with slight male predilictionmale prediliction

Development of enamel has three major Development of enamel has three major stages:  (1) Elaboration of the organic matrix; stages:  (1) Elaboration of the organic matrix; (2) (2) Mineralization of the matrix; and  (3) Maturation Mineralization of the matrix; and  (3) Maturation of the of the enamel enamel

At least 14 subtypes related to above with a At least 14 subtypes related to above with a variety of variety of inheritance and clinical patterns inheritance and clinical patterns

Modes of Mendelian Inheritance Modes of Mendelian Inheritance Associated withAIAssociated withAI

Autosomal Dominant InheritanceAutosomal Dominant InheritanceCan have male to male transmission. Can have male to male transmission. On average, half of the offspring of an affected individual will On average, half of the offspring of an affected individual will be affected. There is a 50% chance for the child of an affected be affected. There is a 50% chance for the child of an affected individual to be affected. individual to be affected. Affected males and females have similar clinical presentationAffected males and females have similar clinical presentation. .

Autosomal Recessive InheritanceAutosomal Recessive InheritanceUnaffected parents will have affected offspring. Unaffected parents will have affected offspring. On average, one in four offspring of carrier parents will be On average, one in four offspring of carrier parents will be affected. affected. More likely to occur when parents are related More likely to occur when parents are related (consanguineous relationship). (consanguineous relationship).

X-linked recessive inheritanceX-linked recessive inheritanceDo not have male to male transmission. Do not have male to male transmission. All daughters of an affected male are carriers. All daughters of an affected male are carriers. Half of the sons born to a carrier female will be affected. Half of the sons born to a carrier female will be affected. Affected males have more severe manifestations than females. Affected males have more severe manifestations than females. Females can show no manifestations to severe manifestations Females can show no manifestations to severe manifestations due to lyonization. Females express only one X chromosome due to lyonization. Females express only one X chromosome per cell with the other X chromosome becoming the bar body. per cell with the other X chromosome becoming the bar body. If adequate numbers of cells express the X chromosome If adequate numbers of cells express the X chromosome carrying the mutant allele, they will have varying degrees of carrying the mutant allele, they will have varying degrees of the enamel defect. the enamel defect.

ClassificationClassification Witkop classification combines inheritance Witkop classification combines inheritance

and clinical patterns and clinical patterns Type I hypoplastic(60-73%); Type I hypoplastic(60-73%);

generalized/localized, smooth/pitted/rough, generalized/localized, smooth/pitted/rough, AD, AR. X-linked AD, AR. X-linked

Type II hypomaturation(20-40%); Type II hypomaturation(20-40%); pigmented/non-pigmented, diffuse/snow pigmented/non-pigmented, diffuse/snow capped; AD, AR, X-linked capped; AD, AR, X-linked

Type III Hypocalcified(7%); diffuse AD/AR Type III Hypocalcified(7%); diffuse AD/AR Type IV Hypomaturation-hypoplastic or Type IV Hypomaturation-hypoplastic or

hypoplastic-hypomaturation with hypoplastic-hypomaturation with taurodontism; AD taurodontism; AD

Hypoplastic Amelogenesis Hypoplastic Amelogenesis Imperfecta  Imperfecta 

Inadequate deposition of enamel matrix  Inadequate deposition of enamel matrix  Generalized pattern – pinpoint sized pits Generalized pattern – pinpoint sized pits

scattered across surface of teeth scattered across surface of teeth Localized pattern – horizontal rows of pits, linear Localized pattern – horizontal rows of pits, linear

depression or one large area of hypoplastic depression or one large area of hypoplastic enamel enamel

Autosomal dominant smooth pattern – smooth Autosomal dominant smooth pattern – smooth surface, enamel is thin, hard, and glossy surface, enamel is thin, hard, and glossy

X-linked dominant smooth pattern – alternating X-linked dominant smooth pattern – alternating zones of normal and abnormal enamel related to zones of normal and abnormal enamel related to active X chromosomes active X chromosomes

Rough pattern – thin, hard, rough enamel Rough pattern – thin, hard, rough enamel Enamel agenesis – total lack of enamel formation Enamel agenesis – total lack of enamel formation Teeth exhibit complete absence or thin layer of Teeth exhibit complete absence or thin layer of

enamel.enamel.  

Hypomaturation Amelogenesis Hypomaturation Amelogenesis

ImperfectaImperfecta     Enamel matrix laid down appropriately and begins Enamel matrix laid down appropriately and begins

to mineralize, but there is defective maturation of to mineralize, but there is defective maturation of enamel’s crystal structure; normal shape but enamel’s crystal structure; normal shape but abnormal mottled, opaque white-brown color  abnormal mottled, opaque white-brown color 

Pigmented pattern (AR) – surface enamel is Pigmented pattern (AR) – surface enamel is mottled and brown  mottled and brown 

X-linked pattern – deciduous are opaque white; X-linked pattern – deciduous are opaque white; permanent are yellow-white that darken with age  permanent are yellow-white that darken with age 

Snow-capped pattern – zone of white opaque Snow-capped pattern – zone of white opaque enamel on incisal or occlusal surface of the crown enamel on incisal or occlusal surface of the crown

Enamel can be pierced with an explorer tip with Enamel can be pierced with an explorer tip with firm pressure ,teeth often show chipping of enamel firm pressure ,teeth often show chipping of enamel from dentin surface.from dentin surface.

Hypocalcified Amelogenesis Hypocalcified Amelogenesis

ImperfectaImperfecta    Enamel matrix laid down appropriately Enamel matrix laid down appropriately

but no significant mineralization occurs but no significant mineralization occurs (very soft enamel) (very soft enamel)

Normal shape but enamel soft and easily Normal shape but enamel soft and easily lost lost

Teeth yellow-brown to orange Teeth yellow-brown to orange Unerupted teeth and anterior open bite Unerupted teeth and anterior open bite

fairly common . fairly common . Enamel is normal in thickness ,but is soft Enamel is normal in thickness ,but is soft

and can easily removed by a blunt and can easily removed by a blunt instrument.instrument.

Hypomaturation/hypoplastic Hypomaturation/hypoplastic Amelogenesis Imperfecta Amelogenesis Imperfecta 

Enamel hypoplasia combined with Enamel hypoplasia combined with hypomaturation. hypomaturation.

Hypomaturation-hypoplastic pattern – Hypomaturation-hypoplastic pattern – primary defect is enamel primary defect is enamel hypomaturation; mottled yellow-white to hypomaturation; mottled yellow-white to yellow-brown. yellow-brown.

Hypoplastic-hypomaturation pattern – Hypoplastic-hypomaturation pattern – primary defect is enamel hypoplasia (thin primary defect is enamel hypoplasia (thin enamel). enamel).

Both patterns seen in tricho-dento-Both patterns seen in tricho-dento-osseous dysplasia syndrome osseous dysplasia syndrome

Taurodontism is the main feature.Taurodontism is the main feature.

Clinical and Hereditary Characteristicsof Four Clinical and Hereditary Characteristicsof Four Main AI TypesMain AI Types

TypeType Clinical Clinical AppearanceAppearance

Enamel Enamel ThicknessThickness

Radiographic Radiographic AppearanceAppearance

InheritanceInheritance

Hypoplastic Hypoplastic (Type I)(Type I)

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

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

Enamel has Enamel has normal to slightly normal to slightly reduced contrast/ reduced contrast/ thinthin

Autosomal Autosomal dominant, dominant, recessive, or X-recessive, or X-linkedlinked

HypomaturaHypomaturationtion(Type II)(Type II)

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

Normal thickness Normal thickness with enamel that with enamel that often chips and often chips and abrades easilyabrades easily

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

Autosomal Autosomal dominant, dominant, recessive, or X-recessive, or X-linkedlinked

HypocalcifieHypocalcifiedd(Type III)(Type III)

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

Normal thickness Normal thickness with enamel that with enamel that often chips and often chips and abrades easilyabrades easily

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

Autosomal Autosomal dominant, dominant, recessiverecessive

HypomaturaHypomaturation/ tion/ Hypoplasia/Hypoplasia/TaurodontisTaurodontismm(Type IV)(Type IV)

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

Reduced, Reduced, hypomineralized hypomineralized areas and pits areas and pits

Enamel contrast Enamel contrast normal to slightly normal to slightly > dentin, large > dentin, large pulp chambers pulp chambers

Autosomal Autosomal dominant dominant

Clinical Features:Clinical Features: Affect both dentition Affect both dentition Colour of tooth is chalky Colour of tooth is chalky

white-yellow or dark white-yellow or dark brownbrown

Proximal contact points Proximal contact points are mostly open while are mostly open while occlusal surfaces and occlusal surfaces and incisal edges are incisal edges are severely abraded.severely abraded.

Sometimes enamel Sometimes enamel completely absent shows completely absent shows severe abrassion of severe abrassion of dentin.dentin.

Clinical features:Clinical features:

Rarely enamel looks normal Rarely enamel looks normal with few grooves and with few grooves and wrinkles on the surface.wrinkles on the surface.

It does not increase It does not increase susceptibility to cariessusceptibility to caries

In mildest form of In mildest form of hypomaturation type the hypomaturation type the enamel is near normal in enamel is near normal in hardness and some white hardness and some white flecks are seen at incisal flecks are seen at incisal edges. Called “SNOW edges. Called “SNOW CAPPED TEETH”CAPPED TEETH”

Amelogenesis imperfecta Amelogenesis imperfecta at a glance………………at a glance………………

Radiographic featuresRadiographic features

Thickness & Thickness & radiodensity of enamel radiodensity of enamel varies greatlyvaries greatly

In hypoplastic type-R D In hypoplastic type-R D of enamel>dentinof enamel>dentin

In hypomaturation type-In hypomaturation type-R D of enamel=dentinR D of enamel=dentin

If present enamel If present enamel mostly seen on tip of mostly seen on tip of cusp and interproximal cusp and interproximal areas.areas.

Histopathology:Histopathology:

Hypoplastic type: lack of Hypoplastic type: lack of differentiation of ameloblast cells differentiation of ameloblast cells with little or no matrix formation.with little or no matrix formation.

Hypomaturation type: Alternation of Hypomaturation type: Alternation of enamel rod and rod sheath enamel rod and rod sheath structures.structures.

Hypocalcification type:Defective Hypocalcification type:Defective matrix structure and abnormal or matrix structure and abnormal or sub normal mineral deposition .sub normal mineral deposition .

Treatment of Treatment of AmelogenesisAmelogenesis ImperfectaImperfecta  

Treatment of Treatment of HypoplasticHypoplastic AI Types AI Types Treatment of Treatment of HypomaturationHypomaturation and and

HypocalcifiedHypocalcified AI Types AI Types Gingival Health Management in AI Gingival Health Management in AI Treatment of Dental MalocclusionsTreatment of Dental Malocclusions Depends on severity; Problems include Depends on severity; Problems include

aesthetics, sensitivity, vertical dimension, aesthetics, sensitivity, vertical dimension, caries, open bite, delayed eruption and caries, open bite, delayed eruption and impaction impaction

Where enamel is very thin, full coverage Where enamel is very thin, full coverage needed as soon as possible needed as soon as possible

Less severe cases, aesthetics are main Less severe cases, aesthetics are main consideration.  Full crowns or facial veneers consideration.  Full crowns or facial veneers

Treated CasesTreated Cases

BibliographyBibliography Shafer’s Oral Pathology : 5Shafer’s Oral Pathology : 5thth Edn Edn Oral & Maxillofacial Pathology –Neville,2Oral & Maxillofacial Pathology –Neville,2ndnd Edn Edn Essential of Oral Pathology –Swapan Kumar PurkaitEssential of Oral Pathology –Swapan Kumar Purkait The World Wide Web:The World Wide Web:

www.dent.unc.edu/research/defects.cfmwww.dent.unc.edu/research/defects.cfm www.dental.mu.edu/oralpath/spresent/www.dental.mu.edu/oralpath/spresent/amelogenesisamelogenesis

.htm.htm www.rarediseases.org/search/rdbdetail_abstract.html www.rarediseases.org/search/rdbdetail_abstract.html

en.wikipedia.org/wiki/en.wikipedia.org/wiki/AmelogenesisAmelogenesis__imperfectaimperfecta

THANK YOU !!!

By:Dr Shabeel PN.

RDC