Hard Tissue Abnormalies

• What are abnormalities of Morphodifferentiation?

  interruption in the differentiation of the dental lamina and tooth germs causing disturbance in number / size / form
• What are abnormalities of histodifferentiation?

  interruption in the formation of dental hard tissues causing disturbances in structure

  
  

  (later stage)
• What are abnormalities and how can they happen?

  • Can affect primary and permanent dentition

  • May be prenatal or postnatal

  • Genetic / environmental / combination

  • May be associated with a syndrome

  • Psychological impact

  • Recognition and evaluation require a thorough knowledge of NORMAL development
• What needs to be considered in management of abnormalities in children?

  • Reassurance of child and parent / carer

  • Genetic counselling

  • Elimination of pain

  • Restoration of aesthetics

  • Provision of function

  • Maintenance of occlusion

  • Delay of definitive treatment until optimum age

  • Involvement of multidisciplinary team
• What are anomalies of number?

  Hypodontia - missing teet

  Hyperdontia - Extra Teeth

  Anodontia - complete absence of teeth, rare (congenital)

  Oligodontia - more than 6 missing
• Hypodontia is most common in the primary dentition in...

  the Maxilla (upper B's)

  Permanent Dentition Most commonly:

  • 3rd molars
  • Lower second premolars (3%)
  • Upper lateral incisors (1.7%)
  • Upper second premolars (1.5%)
• What is the aetiology of number anomalies?

  • Mostly genetic

  
  

  • Occasionally environmental

  - Chemotherapy / radiotherapy

  - Maternal infection during pregnancy

  - Trauma

  
  

  • Often associated with syndromes

  - Ectodermal dysplasia

  - Cleft lip / palate

  - Down syndrome
• What is Ectodermal Dysplasia?

  • Abnormal development of one of more structures of Ectoderm
  • causes partial or complete Anodontia
  • X-linked recessive trait, mainly affects maleS
  • Associated characteristics: Thin, sparse hair, Dry skin, Lack of sweat glands, Multiple missing teeth
  • May die of hyperthermia in infancy if undiagnosed

  
• How is Hypodontia managed?

  • Multidisciplinary teams

  - Paedodontist, orthodontist, restorative specialist

  • Prevention is key

  • Delayed until all permanent teeth have erupted

  • May involve- Orthodontic treatment- Modification of tooth shape (composites)- Dentures / bridges / implants
• What is supplemental hyperdontia?

  looks like a normal tooth, just extra
• What is supernumerary hyperdontia?

  An extra tooth made up of tooth tissue but doesnt look like a normal tooth

  - Conical

  - Tuberculate

  - Odontome
• Features of Supplemental Hyperdontia are:

  • Most commonly lateral incisor

  
  

  • Again, usually seen at the end of a series

  - Premolar

  - Molar

  • Paramolar (adjacent)

  • Distomolar (distal)

  
  

  • Often cause crowding

  
  

  • Extract the most displaced

  
• What is a conical tooth?

  • Most common supernumerary

  • Conical crown with normal root

  • Usually in maxillary midline(mesiodens)

  • Can be unerupted / inverted

  • Doesn’t usually affect eruption of normal incisors but can cause displacement => median diastema

  • Erupted – extract

  • Unerupted – leave and monitor

  
• What is a Tuberculate tooth?

  • Barrel shaped

  • Poor or absent root formation – width = length

  • Rarely erupt

  • Often paired

  • Usually located on palatal aspect of upper centrals

  • Often prevent eruption of upper centrals

  • Early detection essential

  barrel shaped with several tubercles or cusps and have incomplete or abnormal root formation

  
• How are Tuberculate tooth managed?

  • Remove any retained primary teeth

  • Maintain / create space for eruption of 1s

  • Surgically remove tuberculate(s)

  • Monitor for spontaneous eruption

  • May require surgical exposure and orthodontic extrusion

  
• What is Odontome?

  Normal Dental Tissue grown in an irregular way

  • Mixture of enamel, dentine, cementum

  - small, separate tooth like structures

  • Anterior maxilla / lower molar region

  • Cause physical obstruction

  
• What syndromes are hypodontia/hyperdontia associated with?


  • Cleft palate
  • Cleidocranial dysplasia(picture)
  • Gardner's syndrome

  
• What is Macro/Megadontia?

  •Larger than normal

  • Rare – 1% in permanent dentition

  • Normal morphology

  • Tends to affect a single tooth – commonly upper central incisor

  • Not to be confused with fusion / gemination

  •Management– Reshape / extract + replace
• What is Microdontia?

  • Smaller than normal

  • Rare in primary dentition

  • ~ 2% in permanent dentition

  • More common in females

  • Usually upper lateral incisors – peg shaped

  • Often associated with hypodontia

  •Management– Leave + build up / extract + close space

  
• What are variations of root size?

  • Subject to racial variation

  • Larger – Typically upper central incisors – More common in males – Patients of African origin

  • Smaller – Oriental patients – Upper central incisors (2.5% children) – May be associated with ortho / trauma / chemo
• What are the main anomalies of tooth form in the crown and root?

  
• What are double teeth?

  Umbrella term

  • Concrescence: 2 teeth joined by cementum only
  • Fusion: 2 teeth joined by pulp + dentine; 2 root canals
  • Gemination: Incomplete division of a single tooth germ to produce 2 separate teeth; 1 root canal

  • Count the teeth clinically then determine radiographically

  
• What is the prevalence of double teeth?

  • More common in the primary dentition (up to2.5%)

  • Most typically anterior mandible

  • Affects males + females equally

  • Varied appearance - From a minor notch on the incisal edge to 2 separate crowns
• What do you call 2 teeth joined by cementum only?

  Concrescence
• What do you call 2 teeth joined by pulp + dentine and has two root canals?

  Fusion

  
• What is Gemination?

  • Incomplete division of a single tooth germ to produce

  
  

  2 separate teeth; 1 root canal

  
• How are double teeth managed?

  •Primary teeth –no need to treat but delayed root resorption may impact on eruption of permanent successor

  • Permanent teeth– Prone to caries development

  • Prevention is key– Poor aesthetics– Multidisciplinary approach

  • Assessment may include CBCT (3D radiography)

  • Retain / extract / surgically divide
• What is Invagination?

  • AKA Dens invaginatus / Dens-in-dente

  • Invagination in crown; in folding of enamel into dentine

  • Occurs before calcification is complete

  • May extend in to the root

  • Classified by Oehler, 1957

  
• How are Invagination teeth managed?

  • Prophylactically fissure seal at earliest opportunity

  • May develop necrotic pulp easily

  • Treatment usually carried out by specialist- MTA- RCT- Extract + replace
• What is Evagination?

  • AKA Dens evaginatus

  • Enamel covered tubercule projecting from the occlusal surface of a premolar

  • Usually bilateral

  l• More common in the mandible

  • More common in Chinese population

  •Contains pulp tissue in 43% of cases

  • Typically fractured off / worn down=> Pulp exposure => poor prognosis

  
• What is Taurodontism?

  • *bull like tooth*
  • pulp chamber enlarged
  • furcation located near apex
  • no constriction of tooth at CEJ
  • No treatment.
  • Distance from CEJ to bifurcation of the root is greater than length of roots => Long crown + short roots
  • Failure of invagination of Hertwig’s root sheath

  
• What syndromes are Taurodontism associated with?

  - AI (amelogenesis imperfecta)

  - Down syndrome

  - Ectodermal dysplasia

  - Klinefelter's syndrome
• What are accessory roots?

  • Can be found onanytooth

  • Prevalence– Primary dentition 1-9%– Permanent dentition 1-45%

  • Often disto-lingual /palatal aspect

  • May be difficult to identify radiographically

  • May cause problems with extraction / RCT

  
• What is Dilaceration?

  • "Bend" in crown or root

  
  

  • Most commonly upper central incisors

  
  

  • Usually as a result of trauma to primary pre-decessor causing displacement of the hard tissue which has already formed

  
• What can disturbances in tooth structure affect?

  Enamel

  Dentine

  Cementum
• What are the classifications/causes of tooth discolouration?

  • Congential / Acquired

  • Extrinsic / Intrinsic

  • Enamel / Dentine

  • Generalised / Localised

  
• What are localised defects (single tooth, limited number of teeth) caused by?

  - Trauma

  - Radiation

  - Infection

  - Idiopathic
• What are generalised defects?

  Symmetrical/ multiple teeth

  
• What is molar-incisor hypomineralisation?

  • First described by Weerheijm et al, 2001

  •Only seen in permanent dentition

  • 6s and incisors

  • Caused by reduced mineralisation of enamel

  • Systemic disturbance in third trimester or 1st three years

  • Approx 1 in 6 children worldwide

  
• What is the management of Molar - Incisor Hypomineralisation?


  • Mild / Moderate / Severe

  • Prevention is key - main role for DHT

  • Incisors - aesthetic treatment

  • Molars - restore / extract?

  - Restore with composite

  - Maintain until appropriate developmental age for extraction