abnormalities

• Stages of tooth development

  1. formation of primary epithelial band

  2. down growth of dental lamina

  3. development, differentiation & morphogenesis of tooth bud

  4. bud

  5. cap

  6. bell

  7. crown

  8. dentinogenesis

  9. amelogenesis

  10. root formation

  11. tooth eruption

  
• Stages of odontogenesis and associated disturbances

  • Initiation: Anodontia, Supernumerary teeth
  • Bud: Microdontia and macrodontia
  • Cap: Dens in dente, Gemination, Fusion
  • Tubercle
  • Apposition and maturation: Amelogenesis imperfecta, Dentinogenesis imperfecta, Concrescence, Enamel pearl

  
• Developmental anomalies of teeth

  • Localised developmental defects of teeth
  • Enamel defects
  • Dentine defects
  • Acquired defects: Fluorosis, Tetracycline pigmentation, Rickets
  • Morphological abnormalities
  • Multisystem genetic disorders: Ectodermal dysplasia, Osteogenesis imperfecta, Ehlers-Danlos syndrome, Hypoparathyroidism, Hypophosphatasia, Epidermolysis bullosa, Cleidocranial dysplasia

  
• Localised developmental defects of teeth

  Enamel defects, Dentine defects

  
• Amelogenesis imperfecta


  • Genetic conditions – genes encoding enamel matrix proteins: Ameloblastin, Enamelin, Tuftelin (autosomal types), Amelogenin (x-linked types)
  • Prevalence: 1:700 – 1:14000
  • Enamel: Hypoplastic, Hypomineralised, Combination of both
  • Exist in isolation or in association with other syndromes
  • Variable inheritance patterns
• Amelogenesis imperfecta


  • Enamel of all teeth affected
  • Tooth discolouration
  • Tooth sensitivity
  • Post-eruptive and pre-eruptive disintegration

  
• Types of amelogenesis imperfecta

  • Hypoplastic
  • Hypomaturation
  • Hypocalcification
• Hypoplastic amelogenesis imperfecta


  • Inadequate matrix formation
  • Pitted, grooved or thin enamel, but hard and translucent
• Hypomaturation amelogenesis imperfecta

  • Normal enamel on eruption
  • Opaque, white, brown-yellow
  • Soft, vulnerable to attrition

  
• Hypocalcified amelogenesis imperfecta

  • Normal enamel matrix quantity
  • Poor calcification
  • Enamel thickness normal at eruption
  • Opaque, chalky appearance
  • Stains and wears rapidly
• Amelogenesis imperfecta - Diagnosis

  • Family history
  • Clinical observation
  • Radiographs
• Differential diagnosis for amelogenesis imperfecta

  • Fluorosis
  • Chronological hypoplasia
• Diagnostic tools for amelogenesis imperfecta

  • Preoperative intraoral photographs
  • Orthopantomograph (OPG)

  
• Dentine defects


  • Dentinogenesis imperfecta
  • Shell teeth
  • Dentinal dysplasia
  • Regional odontodysplasia (affects more than one dental hard tissue)

  
• Dentinogenesis imperfecta

  • Uncommon defect of dentine formation (in dentine sialoprotein)
  • Autosomal dominant trait –related to osteogenesis imperfecta
  • Affects both dentitions

  
• Dentinogenesis imperfecta: Affecting teeth alone, Due to specific mutations in dentine sialoprotein (DSPP). Osteogenesis imperfecta with hereditary opalescent dentine, Previously called dentinogenesis imperfecta type I, Mutations in genes encoding collagen: COL1A1 and COL1A2

  
• Dentinogenesis imperfecta

  • Teeth have normal contour at eruption, but present with a distinctive translucent, opalescent or amber-like hue
  • Although enamel is normal it is weakly attached to the dentine and is rapidly lost meaning the teeth show marked attrition

  
• Radiographically teeth have short, blunt roots with partial or total obliteration of pulp chambers

  
• Histology of dentinogenesis imperfecta

  a thin layer of normal tubular mantle dentine (immediately adjacent enamel or cementum), the remainder of the dentine is abnormal with reduced number of tubules that are often wide and irregular and areas of atubular dentine

  
• Shell teeth

  • Dentinogenesis imperfecta type 3
  • Thin shell of dentine surrounding abnormally large pulp chambers

  
• Dentinal Dysplasia

  Rare autosomal dominant disease, two forms identified: Type I (rootless teeth), Type II (coronal dentine dysplasia)

  
• Dentinal Dysplasia Type I

  Permanent teeth have normal crowns associated with roots composed of dysplastic dentine. Pulp chamber usually obliterated and roots are very short

  
• Dentinal Dysplasia Type II

  Primary teeth have an amber colour and obliterated pulp chambers similar to dentinogenesis imperfecta, Secondary teeth are of normal colour and have normal root length, but pulp chambers are reduced in size and often contain multiple pulp stones

  
• Regional odontodysplasia (ghost teeth)

  • Localised disorder affecting a group of teeth
  • All dental tissues affected
  • Unknown aetiology
  • Maxillary teeth most often affected, abnormal teeth may fail to erupt

  
• Thin enamel and dentine, Irregular enamel and dentine, No enamel prisms, irregular dentine tubules, clefting and interglobular dentine, Erupted teeth are susceptible to caries and wear

  
• Morphological changes in teeth


  • Disturbances in tooth number: Anodontia, Hypodontia, Supernumerary teeth
  • Disturbances in tooth size
  • Disturbances in tooth shape: Fusion, Gemination, Concresence, Dilaceration
  • Disturbances in tooth structure

  
• Hypodontia

  • Isolated hypodontia: 3rd molars, 2nd premolars, maxillary lateral incisors
  • Complete anodontia – rare
  • Association with systemic defects: Ectodermal dysplasia (usually sex-linked recessive)

  
• Supernumerary teeth

  • Conical or malformed additional teeth
  • Midline tooth - mesiodens
  • Supplemental teeth

  
• Fusion

  Union between dentine and/or enamel of two or more separate developing teeth

  
• Gemination

  The partial development of two teeth from a single tooth bud following incomplete division

  
• Concrescence

  Roots of one or more teeth united by cementum after formation of crowns

  
• Dilaceration

  Acquired developmental anomaly, Trauma causing angulated root
• Dens in dente

  • Inward folding to the dental papilla by the enamel organ can form an enamel linked opening from the pulp to the surface of the tooth
  • Maxillary incisors frequently involved

  
• Cingular pit
• This is an introduction – specific to abnormalities of teeth, You will learn more about differential diagnosis of oral disease in year 3

  
• • Teeth can be affected by various developmental abnormalities: Genetic, Non-genetic, Acquired
  • Important clinical implication that affect patients and management