AmelogenesisAmelogenesis ImperfectaImperfecta

Otherwise known as…..Otherwise known as…..

• A IA I

• Hereditary Enamel DysplasiaHereditary Enamel Dysplasia

• Hereditary Brown EnamelHereditary Brown Enamel

• Hereditary Brown Opalescent TeethHereditary Brown Opalescent Teeth

What is Amelogenesis What is Amelogenesis Imperfecta ?Imperfecta ?

Amelogenesis Imperfecta represents Amelogenesis Imperfecta represents a group of a group of hereditary defects of hereditary defects of enamelenamel unassociated with any other unassociated with any other generalized defects. It is entirely an generalized defects. It is entirely an ectodermal disturbanceectodermal disturbance , since the , since the mesodermal components of the mesodermal components of the teeth are basically normal.teeth are basically normal.

The term amelogenesis imperfecta is The term amelogenesis imperfecta is reserved for hereditary defects of enamel reserved for hereditary defects of enamel that are that are not associated with defects in not associated with defects in other parts of the body or other health other parts of the body or other health problems.problems. The enamel defects are highly The enamel defects are highly variable and include abnormalities that are variable and include abnormalities that are classified as hypo plastic ,hypo maturation, classified as hypo plastic ,hypo maturation, and hypo calcified. The enamel in both the and hypo calcified. The enamel in both the hypo maturation and hypo calcified AI hypo maturation and hypo calcified AI types is not mineralized to the level of types is not mineralized to the level of normal enamel and can be described as normal enamel and can be described as hypo mineralized. AI can be inherited as an hypo mineralized. AI can be inherited as an x-linked, autosomal recessive (AR), or x-linked, autosomal recessive (AR), or autosomal dominant (AD) condition.autosomal dominant (AD) condition.

PrevalencePrevalence

• 1 in 700 to 1 in 15,0001 in 700 to 1 in 15,000

Etiology • Dental enamel is a highly mineralized tissue with

over 95% of its volume occupied by unusually large, highly organized, hydroxyapatite crystals. The formation of this highly organized and unusual structure is thought to be rigorously controlled in ameloblasts through the interaction of a number of organic matrix molecules that include

• enamelin• amelogenin• ameloblastin • tuftelin • amelotin• dentine sialophosphoprotein (DSPP;) • enzymes such as kallikrein and• matrix metalloproteinase 20 (MMP20) Any mutations in these proteins can cause AI.

A I & D IA I & D I

Development of enamel..Development of enamel..

• 3 stages.. 3 stages.. formative stageformative stage

deposition of organic matrix.deposition of organic matrix.Calcification stageCalcification stage

matrix mineralizationmatrix mineralizationMaturation stageMaturation stage

crystallites enlarge and maturecrystallites enlarge and mature

A IA I

• 3 Types..3 Types..HypoplasticHypoplasticHypocalcifiedHypocalcifiedHypomaturationHypomaturation

A 4A 4thth type of A I is a combination of type of A I is a combination of hypoplastic & hypomaturation types.hypoplastic & hypomaturation types.

Classification of A IClassification of A I• Based on clinical,histological,&genetic Based on clinical,histological,&genetic criteria-criteria-Witkop & SaukWitkop & Sauk HypoplasticHypoplastic Pitted, ADPitted, AD Local, ADLocal, AD Smooth, ADSmooth, AD Rough, ADRough, AD Rough, ARRough, AR Smooth, X-linked dominant Smooth, X-linked dominant HypocalcifiedHypocalcified DiffuseDiffuse ADAD Diffuse ARDiffuse AR HypomaturationHypomaturation Diffuse , X-Linked recessiveDiffuse , X-Linked recessive Diffuse Pigmented, ARDiffuse Pigmented, AR Snow-capped teeth, X-linkedSnow-capped teeth, X-linked Combination Type Combination Type Hypomaturation-hypoplastic with taurodontism,ADHypomaturation-hypoplastic with taurodontism,AD Hypoplastic-hypomaturation with taurodontism,AD Hypoplastic-hypomaturation with taurodontism,AD

Clinical features..Clinical features..

• Hypoplastic Type.Hypoplastic Type.

The enamel is The enamel is notnot formed to formed to full normal full normal thicknessthickness

Hypocalcified Type.Hypocalcified Type.

• The enamel is so The enamel is so softsoft that it can be that it can be removed by a prophylaxis instrument.removed by a prophylaxis instrument.

• Yellow brown or orange on eruption, Yellow brown or orange on eruption, stained brown to black with time.stained brown to black with time.

• Exhibits rapid calculus apposition.Exhibits rapid calculus apposition.

• Coronal enamel lost with function, Coronal enamel lost with function, except for the cervical portion which except for the cervical portion which is mineralized better.is mineralized better.

• Autosomal recessive—more severe.Autosomal recessive—more severe.

Hypomaturation Type.Hypomaturation Type.• The enamel can be The enamel can be pierced by an pierced by an

explorer pointexplorer point under firm pressure under firm pressure

• can be lost by can be lost by chippingchipping away from the away from the underlying normal appearing dentin.underlying normal appearing dentin.

• Teeth are normal in shape, but Teeth are normal in shape, but exhibit a mottled , opaque white exhibit a mottled , opaque white brown yellow discoloration.brown yellow discoloration.

• Snow capped pattern- exhibit a zone Snow capped pattern- exhibit a zone of white opaque enamel on the incisal of white opaque enamel on the incisal or Occlusal third of the crown.or Occlusal third of the crown.

Other features…Other features…

• Both dentitions are affectedBoth dentitions are affected• In Some cases teeth may appear normal, In Some cases teeth may appear normal,

in others may be extremely unsightly.in others may be extremely unsightly.• Color of the crown can vary from yellow to Color of the crown can vary from yellow to

dark brown.dark brown.• Enamel might have numerous parallel Enamel might have numerous parallel

vertical wrinkles or grooves.vertical wrinkles or grooves.• Open contact pointsOpen contact points• Occlusal surfaces and incisal edges are Occlusal surfaces and incisal edges are

frequently abradedfrequently abraded

Radiographic FeaturesRadiographic Features

• The enamel may appear totally absent The enamel may appear totally absent • When present may appear as a thin When present may appear as a thin

layer , chiefly over the tips of the cusps layer , chiefly over the tips of the cusps & on the interproximal surfaces.& on the interproximal surfaces.

• In some cases calcification is so much In some cases calcification is so much affected that enamel & dentin seem to affected that enamel & dentin seem to have the same radio density, making have the same radio density, making differentiation between the two difficult.differentiation between the two difficult.

Histological FeaturesHistological Features

• Hypoplastic type—disturbance in the Hypoplastic type—disturbance in the differentiation or viability of differentiation or viability of ameloblasts.ameloblasts.

• Hypocalcification type– defects of Hypocalcification type– defects of matrix structure and of mineral matrix structure and of mineral deposition.deposition.

• Hypomaturation type– alteration in Hypomaturation type– alteration in enamel rod & rod sheath structures.enamel rod & rod sheath structures.

Management Management

• Treatment depends on the specific AI Treatment depends on the specific AI type and the character of the type and the character of the affected enamel.affected enamel.

• Treatments range from preventive Treatments range from preventive care using sealants and bonding for care using sealants and bonding for esthetics to extensive removable and esthetics to extensive removable and fixed prosthetic reconstruction. fixed prosthetic reconstruction.

Treatment of hypoplastic Treatment of hypoplastic typetype• Therapy for the hypoplastic AI types Therapy for the hypoplastic AI types

typically involves the use of bonding typically involves the use of bonding procedures to protect the malformed teeth procedures to protect the malformed teeth from caries and improve esthetics. from caries and improve esthetics.

• Hypoplastic teeth usually have reasonably Hypoplastic teeth usually have reasonably well mineralized enamel, albeit thin and/or well mineralized enamel, albeit thin and/or pitted, making them suitable for restorative pitted, making them suitable for restorative therapies involving bonding to the enamel .therapies involving bonding to the enamel .

• Composite resin or porcelain veneers can be Composite resin or porcelain veneers can be bonded to the anterior teeth when the bonded to the anterior teeth when the incisor shape, size and/or color requires incisor shape, size and/or color requires modification.modification.

Continued…..Continued…..• Orthodontic therapy may be used to Orthodontic therapy may be used to

partially close the interdental spaces prior partially close the interdental spaces prior to restoration in those individuals having to restoration in those individuals having small square shaped incisors and small square shaped incisors and interdental spacing that is too excessive to interdental spacing that is too excessive to close with restorative therapy alone. close with restorative therapy alone.

• Individuals with hypoplastic AI often can Individuals with hypoplastic AI often can retain intracoronal restorations such as retain intracoronal restorations such as amalgams and composite resins.amalgams and composite resins.

• if the enamel is extremely thin and if the enamel is extremely thin and malformed the teeth can require full malformed the teeth can require full dental coverage with crowns. dental coverage with crowns.

Porcelain veneers

Treatment of hypocalcified & Treatment of hypocalcified & hypomaturation typeshypomaturation types• The hypomaturation and hypocalcified AI The hypomaturation and hypocalcified AI

types can be restored with conventional types can be restored with conventional approaches if the enamel is not severely approaches if the enamel is not severely involved.involved.

• if enamel is severely hypomineralized and of if enamel is severely hypomineralized and of insufficient strength to retain bonded or insufficient strength to retain bonded or intracoronal restorations, full coverage intracoronal restorations, full coverage restorations should be placed.restorations should be placed.

• In cases of severely hypomineralized In cases of severely hypomineralized enamel, stainless steel crowns are indicated enamel, stainless steel crowns are indicated in the primary and early permanent in the primary and early permanent dentitions. dentitions.

Continued…Continued…

• stainless steel crowns with composite stainless steel crowns with composite inserts or composite crowns that are inserts or composite crowns that are retained both by mechanical undercuts retained both by mechanical undercuts and bonding can greatly reduce tooth and bonding can greatly reduce tooth sensitivity and provide reasonable sensitivity and provide reasonable esthetics. esthetics.

• The dentist should not rely on retention The dentist should not rely on retention from bonding alone in those cases with from bonding alone in those cases with very weak and poorly mineralized enamel. very weak and poorly mineralized enamel.

Continued….Continued….• Resin crowns can be placed on permanent Resin crowns can be placed on permanent

incisors soon after they begin to erupt during the incisors soon after they begin to erupt during the mixed dentition (about age 7 – 10 years). As the mixed dentition (about age 7 – 10 years). As the gingival margin becomes exposed during gingival margin becomes exposed during continued tooth erupt the resins are easily continued tooth erupt the resins are easily modified by adding resin to the gingival margin of modified by adding resin to the gingival margin of the tooth.the tooth.

• Ultimately, porcelain fused to metal or other Ultimately, porcelain fused to metal or other custom fabricated crowns can be placed on the custom fabricated crowns can be placed on the dentition. This may be delayed until late dentition. This may be delayed until late adolescence or early adulthood when all the teeth adolescence or early adulthood when all the teeth are present, the teeth are fully erupted, and the are present, the teeth are fully erupted, and the gingival height around the teeth has stabilized. gingival height around the teeth has stabilized.

• While costly, these types of restorations can allow While costly, these types of restorations can allow even severely affected dentitions to be treated even severely affected dentitions to be treated and achieve excellent function and esthetics. and achieve excellent function and esthetics.

• The severely affected individual shown in Figure The severely affected individual shown in Figure had AR Hypomaturation AI and was treated over had AR Hypomaturation AI and was treated over several years with stainless steel crowns, several years with stainless steel crowns, orthodontics, orthognathic surgery and eventually orthodontics, orthognathic surgery and eventually porcelain fused to metal crowns to achieve this porcelain fused to metal crowns to achieve this excellent result.excellent result.