Boy et al, Developmental structural tooth defects in dogs Flashcards
Frontier 2016 - Grossely Steenkamp
What can you see in this image ?
Enamel changes - typical for focal enamel hypoplasia FEH
what is Turner’s hypoplasia?
Enamel hypoplasia
What is the most common type of dog tooth abnormality seen in private practice?
Enamel hypoplasia
What is this image ?
Focal enamel hypoplasia
restoration of EH
Turners tooth
What is this image?
Focal enamel hypoplasia
Turners tooth( if 1 tooth is affected )
Most common cause of EH ?
Environmental:
trauma - bite wound in 1st 8 to 10 weeks of life ***
infection
chemicals- fluoride
what is this and what happened ?
EH - extreme form
Trauma to developing tooth germ cause structural disturbance of AB layer with complete change of developing tooth crown
what is this ?
EH or Turners tooth
What causes diffuse enamel hypoplasia DEH?
Systemic diseases, direct infection of active enamel producing AB
Amelogensis imperfecta AI - What causes it and how does it present?
AI hereditary type of EH
Genetics
Affects all deciduous teeth and or permanent teeth
What are the 3 types of AI?
Hypoplastic type - defective matrix secretion by AB
Hypocalcified type - defective mineralization of the matrix
Hypomature type - enamel crystal growth during maturation is defective due to ineffective enamel protein removal
What is internalized discoloration?
extrinsic stains gets incorporated in the tooth substance
How does internalized discoloration in extrinsic type of discoloration happen?
due to structural enamel defects either through developmental abnormality of acquired defects following tooth wear, GR, caries, restorative material
Chromogens ( compound that forms colored compounds by oxidation) enter porous defects or open dentinal tubules discoloration which cannot be removed by scale and polish
what can cause extrinsic staining of the tooth?
extrinsic staining: 1) staining of enamel due to pigmentation deposits on enamel surface
2)
how many causes of staining exists?
intrinsic and extrinsic staining
what is the cause of intrinsic staining on enamel
influenced by thickness and structural properties of enamel -influences the scattering and light absorption of light within the enamel
there is a local and a systemic cause
what are the local causes of intrinsic discoloration ?
pulp necrosis, pulpal hemorrhages, pulp tissue remnants after RCT, deposition of hemoglobin related pigments in dentin
What are the systemic causes of intrinsic discoloration?
drug related discoloration tetracycline, metabolic fluorosis , genetic: porphyrins and hyperbilirubinemia deposits as a by product hemolysis , structural defect as AI, dentinogenesis imperfecta abnormal dentin structure- not enough support to enamel fractures
What is dentinogenesis imperfecta?
abnormal dentin structure- not enough support to enamel fractures
Tetracycline staining
Permanent yellow to brown discoloration to areas of the tooth that was in the process of matrix mineralization and maturation
Do not give to pregnant bitches or puppies <6 months of age
Irreversible staining but does not affect the dental hard tissue structure
Doxycycline – staining less dramatic
list 4 developmental abnormalities
Germination, twinning, fusion, concrescence
Another term for germination
schizodontism
What is germination?
A single tooth germ tries to develop divide into 2 separate teeth
Which teeth are mostly affected by germination? and which dog breed?
incisors, canines, premolar teeth,
mainly Boxers
what is true germination?
2 halves of joined crown are anatomically similar. mirror image with a groove that extends between 2 teeth through incisal edge of crown
gemination affects deciduous or permanent dentition in animals?
permanent dentition
Gemination
Describe fusion
- 2 separate tooth buds unite at the crown and /or roots before hard tissue formation is complete
What is this image ?
Fusion with 201, 202 -with double tooth
how many root canals does fused teeth have ?
usually have separate root canals
What is concrescence?
Union of 2 or more fully formed teeth by only their cementum without dentin or enamel involvement
What is this image ?
Concrescence between canine and supernumerary tooth . shared only cementum bridge but not dentin or other hard dental tissue
- True concrescence ( developmental)
trauma or crowding with abnormal resorption of interproximal bone and cementum deposition between adjacent roots
- Acquired concrescence ?
inflammation induced hypercementosis
Another name for Dens invaginatus DI
dens in dente
Dens invaginatus DI
Tooth crown surface invaginates into developing tooth pulp before mineralization
What is this image?
dens invaginatus
there are 3 types of dens invaginatus
Which one is the most uncommon in dogs?
Type 1 = invagination in the crown only not extend beyond CEJ
Type 2= invagination extends beyond CEJ – into root canal and ends as a blind sac
Type 3= invagination extends through the root or lateral surface to form additional opening or foramen but with no communication to existing pulp canal
Type 3 is most uncommon
What is dilaceration ?
Developmental abnormality of a sharp bent curve along root or crown of a tooth
what is this image?
Dilaceration of the crown
What is this image?
Dilaceration of the roots
What is dilaceration ?
Developmental abnormality of a sharp bent curve along root or crown of a tooth
Degree of curvature – varies from 20 to 90 degrees
what is the difference between dilaceration and root angulation?
root angulation is is a more gradual change in developmental direction of developing tooth
in dogs dilaceration is found which condition?
X linked hypohidrotic ectodermal dysplasia
How is dilaceration formed ?
Acute mechanical trauma with intrusion of deciduous tooth and permament physical damage to tooth
o Mineralized and harder part of developing tooth is displaced and softer non mineralized part and continues developing
What are enamel pearls?
Small nodules of enamel <4 mm located on root surface of tooth close or at CEJ
What are enamel pearls made out of?
Core of dentin covered by enamel- may contain a pulp chamber
where is commonly found?
bi or trifurcation of molars
rare on incisors
what does neural crest cells form?
ectomesenchyme which is important for teeth development
It does not from enamel and some of the cementum
Odontogenesis is initiated by ….
Formation of a band of thick oral epithelium which give rise to dentinal laminae, thin down growths of epithelium extending from the overlying epithelium into developing jawbone
what does the enamel organ consist of?
Enamel organ consists out of OEE, IEE, SR
amelogenesis can be divided into 2 forms
o Hypoplasia of enamel due to incomplete or disruptive enamel matrix production
o Hypoplasia because of inadequate matrix mineralization
Eruption time ranges for different types of teeth in the dog
Incisors 12 to 16 weeks
Canines and premolars 16 to 24 weeks
Molars 20 to 32 weeks
What does HERS consist of and what is its role ?
HERS - Consists of OEE and IEE
Outlines the future root and responsible for shape, length, size, number of roots
What is the Bell stage?
Bell stage histological differentiation develops – enamel organ develops into outer enamel epithelium OEE, inner enamel epithelium IEE, stellate reticulum SR, ameloblast and odontoblast differentiate
What is the cup stage ?
epithelial cells from a cap over condensed ectomesenchyme dental papilla and origin to the dental follicle
o The ectomesenchyme & odontogenic epithelium surrounds it tooth germ or dental organ
o The tooth germ continues to proliferate until it looks like a bell
What is the age of dental hard tissue formation in permanent teeth in the dog?
hard tissue formation of all permanent teeth occurs starts about from early birth to 8 weeks and local infection /trauma in developing canines and max 4th PM as late as 12 weeks of age
What happens if there is any interference during odontogenesis ?
Any interference of odontogenesis result in structural abnormalities of enamel and gross anatomy of tooth
