recessive or x‐linked
1.6.4 Clinical/Radiographical Features
Three types of amelogenesis imperfecta have been identified – hypoplastic, hypocalcified and hypomaturation:Hypoplastic type:Enamel is of reduced thickness due to a defect in the formation of normal matrixEnamel is pitted, grooved, stained and thinEnamel is normally mineralized; hard and translucentRadiographically, the enamel contrasts normally from dentineHypocalcified type:Enamel matrix is normal in quantityEnamel calcification is defectiveEnamel is weak in structure and vulnerable to attritionTeeth become opaque, stained and rapidly wear down (Figure 1.6)Radiographically, enamel is less radio‐opaque than dentineHypomaturation type:Enamel is normal in thickness, shows opaque brownish‐yellow patchesEnamel mimics fluorotic mottled enamel in appearanceEnamel is soft and vulnerable to attrition
Other features that may occur in any of the above types of amelogenesis imperfecta include:Delay in dental eruptionMicrodontiaDeviant crown and morphologyRoot resorptionShort rootsEnlarged pulp chamberPulp stonesDens in dente (dens invaginatus)Tooth agenesisCrowding of teethFigure 1.6 Amelogenesis imperfecta (hypocalcified type); the enamel is stained and vulnerable to attrition(source: by kind permission of Professor Charles Dunlap, Kansas City, USA).
1.6.5 Differential diagnosis
Dental fluorosis
Dentinogenesis imperfecta
Enamel hypoplasia
Trauma
Molar incisor hypomineralization
1.6.6 Diagnosis
History including a detailed family history
Pedigree plotting (family health history tree)
Clinical examination
Radiography
1.6.7 Management
Aesthetic treatment
Treatment for symptoms if present (e.g. tooth sensitivity)
1.7 Dentinogenesis Imperfecta
1.7.1 Definition/Description
A group of autosomal dominant genetic conditions characterized by abnormal dentin structure affecting both the primary and secondary dentitions
1.7.2 Frequency
Incidence of 1 in 6000 to 1 in 8000
1.7.3 Aetiology/Risk Factors
Mutations in dentin sialoprotein genes
1.7.4 Clinical Features
Primary and permanent teeth are affected
Teeth appear amber, brown/blue, or opalescent brown (Figure 1.7a)
Syndromic form, osteogenesis imperfecta: opalescent dentine, blue sclera and short stature
1.7.5 Radiographical features
The crowns may appear bulbous (Figure 1.7b)
Pulp chambers are often small or obliterated
The roots are often narrow with small or with obliterated root canalsFigure 1.7 Dentinogenesis imperfecta. (a) Note tooth wear and opalescent crowns. (b) Radiograph shows bulbous crowns and cervical constriction of molars.(source: by kind permission of Professor Charles Dunlap, Kansas City, USA.)
1.7.6 Differential Diagnosis
Hypocalcified forms of amelogenesis imperfecta
Osteogenesis imperfecta
Congenital erythropoietic porphyria
Conditions leading to early tooth loss
Permanent teeth discolouration due to tetracyclines
Vitamin D‐dependent and vitamin D‐resistant rickets
1.7.7 Diagnosis
Family history
Pedigree construction
Detailed clinical examination
Radiography
1.7.8 Management
The aims of treatment are to remove sources of infection or pain, restore aesthetics and protect posterior teeth from wear
Preservation of occlusal face height, maintenance of function and aesthetic needs are priorities
For the primary dentition, stainless steel crowns are recommended
1.8 Dentinal Dysplasia (Dentin Dysplasia)
1.8.1 Definition/Description
A rare inherited disorder of dentin formation characterized by either absent or short conical roots
Two types occur: radicular dentin dysplasia (type 1) and coronal dentin dysplasia (type 2)
Coronal dentin dysplasia is a severe form of dentinogenesis imperfecta
1.8.2 Frequency
Type 1: 1 in 100 000
Type 2: 1 in 6000 to 1 in 8000
1.8.3 Aetiology/Risk Factors
Defective dentin sialoprotein gene for both types
1.8.4 Clinical Features
Radicular type (type 1):Diffusely affects both dentitions: severe manifestations in deciduous teethCoronal enamel and dentin are normalRadicular dentin is defective: short roots result in tooth mobility and premature tooth lossStrength of roots is reducedHypersensitive dentinLoss of pulpal vitalityAbsent root canalsBifurcation is close to the apex in molarsPeriapical pathology is common (seen as periapical radiolucency)
Coronal type (type 2):Primary and permanent teeth are affectedTeeth appear amber, brown/blue or opalescent brown
1.8.5 Radiographical features
Coronal type:The crowns may appear bulbousPulp chambers are often small or obliteratedThe roots are often narrow with small or obliterated