Disorders of teeth Flashcards
What are the 3 distinct stages of normal dental development?
Pre eruptive, prefunctional and functional
What is the pre-eruptive stage?
Initiation of development to the page of crown completion:
- initiation = dental lamina + tooth germs
- morphogenesis = shape of tooth
- histogenesis = mineralised hard tissues
What is pre-functional stage?
eruption
What is the functional stage?
maintenance of occlusion
What is eruption?
The process by which a tooth moves from its developmental position to a functional position in the mouth (begins once the root befits to form)
How many teeth are there in the primary dentition?
20
How many teeth are there in the permanent dentition?
32
What is the normal eruption date for the a’s?
6-12 months
What is the normal eruption dates for the b’s?
9-16 months
What is the normal eruption dates for the c’s?
16-23 months
What is the normal eruption dates for the d’s?
13-16 months
What is the normal eruption dates for the e’s?
23-31 months
What is the normal eruption dates for the 1’s?
6-8 y/o
What is the normal eruption dates for the 2’s?
7-9 y/o
What is the normal eruption dates for the 3’s?
9-12 y/o
What is the normal eruption dates for the 4’s?
10-12y/o
What is the normal eruption dates for the 5’s?
10-12y/o
What is the normal eruption dates for the 6’s?
6-7 y/o
What is the normal eruption dates for the 7’s?
12-13 y/o
What is the normal eruption dates for the 8’s?
18-25 y/o
What is hyperdontia?
too many teeth
What are the two types of hyperdontia?
Supernumerary and supplemental
What are supernumerary teeth?
Additional tooth with abnormalities in the shape, names are based on position in oral cavity (mesodens- in midline, paramolar - to side of, normally buccal aspect, distomolar - behind the upper 8’s)
- 1-3% population in permanent dentition, F>M
What are supplemental teeth?
Additional teeth with normal shape
Upper 2> lower 5 > upper 5
What is hypodontia?
missing teeth
Tell me more about hypodontia:
- congenital loss
- 3-7% population
- F > M
- Uncommon in deciduous
- Usually affects those last in series to develop (8’s, 5’s and 2’s)
What is anodontia?
Complete absence of teeth = extremely rare (permanent dentition fails to form - no dental lamina)
= usually syndrome related
What are the 6 disorders in eruption and exfoliation of teeth?
- premature eruption
- delayed/retarded eruption
- premature loss
- persistence of deciduous
- impaction
- reimpaction
What are natal teeth?
Present at birth
What are neonatal teeth?
Teeth that erupt within the first 30 days
Tell me more about premature eruption of teeth:
- Occurs 1: 4000 live births
- 1 or 2 central incisors
- 4 x more frequent in mandible
- normal tooth germs but developed superficially - early eruption
- radicular dentine and cementum irregular structure due to mobility in jaw
What is the management for premature eruption of teeth?
- extract or spontaneous loss
- if table enough can be left to continue to develop
BUT risk of inhalation or difficulty breast feeding (mother)
What is delayed tooth eruption associated with?
Premature babies, trauma (displacement of tooth germs), nutritional deficiency, chromosomal abnormalities and endocrinopathies (hypothyroidism)
What is premature loss associated with?
Dental caries, chronic periodontal disease and diseases e.g. hypophosphatasia
What is hypophospatasia?
- Rare inherited bone disease
- inborn error of metabolism
- low activity of tissue non-specific isoenzyme of alkaline phosphatase
- deformities of skeleton
- disturbed cementum formation /aplasia (n.b. normally attached to PDL = without = tooth mobility and loss of tooth)
- children lose teeth before 5 y/o
What is persistence of deciduous teeth often associated with?
Fair of eruption of the permanent successor
What is local persistence of deciduous teeth?
Misplaced or displaced teeth
What is generalised persistence of deciduous teeth?
Entire dentition (rare e.g cleidocranial dysplasia or cherubism)
What is cherubism?
Familial multilocular cystic disease (genetic, autosomal dominant) = disruption of signalling pathways associated with maintenance of bone -> normal at birth with progressive facial deformity (bilateral swelling of mandible, eyes upturned to heaven and lack of eruption)
Radiographically: multinodular cystic radiolucencies with absent/unerupted teeth
What is impaction of teeth?
Where a tooth remains unerupted or partially erupted in the time when it would normally have erupted
How many teeth does impaction effect?
1 or several
Tell me more about impaction of teeth:
- can be symmetrical
- is rare in primary teeth
- permanent teeth most likely affected: 3rd molars, mandibular premolars and maxillary canines
What are the causes of impaction of teeth?
- abnormal position of tooth germ (esp. wisdom teeth)
- lack of space
- supernumerary teeth
- odontogenic cysts
- odontogenic tumours
What is reimpaction of teeth?
Where a previously erupted tooth becomes submerged in the tissues
Which tooth is more commonly affected by reimpaction?
E’s
Tell me more about reimpaction of teeth:
- twice as frequent in mandible
- cause unknown
- consequence = deficient development of alveolar process around tooth = root often partially resorbed and ankylosed = difficult to extract
What different form errors of the tooth can there be?
- peg shaped lateral
- invagination/ dens in dente (tooth within a tooth)
- enamel pearl
- dilaceration (kink in root due to tooth movement)
- taurodontism (pulp chamber with greater apico-occlusal height- failure of HERs to invaginate at the correct level)
- double teeth (fusion/germination/concrescence)
What is fusion?
union between dentine and/or enamel of 2 or more separate teeth (e.g. b and c)
What is germination?
partial development of 2 teeth from a single tooth bud followed by incomplete division (e.g. b and b)
What is concrescence?
Roots of 1 or more teeth united by cementum alone after formation of the crowns
What determines the size of teeth and the jaw?
Genetics
How many teeth do size abnormalities effect?
entire dentition or 1-2 teeth (can be symmetrically distributed)
What is macrodontia?
The teeth look too big for the patient
What is microdontia?
Teeth look too small for the patient (looks like lots of retained deciduous teeth - interdental spaces)
What are the two stages of normal enamel development?
Secretory and maturation
What is hypoplastic enamel?
Ameloblasts fail to produce normal volumes of matrix
What is hypo mineralised enamel?
Ameloblasts fail to fully calcify previously formed matrix
What are the causes of enamel defects (4)?
- Local infection/trauma
- Irradiation
- Idiopathic
- Generalised causes = environmental (e.g. infections or chemotherapy or prolonged labour) or genetic (amelogenesis imperfecta)
What are the consequences of congenital syphilis?
= hypoplastic changes, incisors small and tapering with notch (hutchinson’s incisors), first molars are dome shaped crowns (moon molars) or nodular cusps (mulberry molars)
What is amelogensis imperfecta?
Inherited developmental abnormality of enamel = hypoplastoc or hypo mineralised, autosomal dominant or linked, effects both dentitions and characterised by abrasion and attrition of teeth (no increased susceptibility to caries), look yellow (enamel sheared off)
What are the different metabolic causes of dentine defects?
Rickets (increased interglobular/pre-dentine) ad tetracycline (staining and banding = taken up into dentine within incremental lines)
What are the different genetic causes of dentine defects?
Dentinogenesis imperfecta, Dentinal dysplasia and regional odontodysplasia
What is Type 1 dentinogenesis imperfecta?
Associated with osteogenesis imperfecta
What is osteogenesis imperfecta?
- Hereditary disease = group of related disorders characterised by generalised osteoporosis
- Defect in type 1 collagen (bones have narrow poorly formed cortices composed of immature woven bone)
What are the clinical features of osteogenesis imperfecta?
- slender bones/mechanically weak
- deformity/fractures/deafness
- lax ligaments/thin translucent skin/blue sclera
- can be associated with dentinogenesis imperfecta
What is Type 2 dentinogenesis imperfecta?
affects teeth only (including shell teeth = a variant)
Tell me more about type 2 dentinogenesis imperfecta:
Autosomal dominant, M=F, 1: 8000, affects both deciduous and permanent teeth
What are the clinical features of type 2 dentinogenesis imperfecta?
- Enamel looks Opalescent amber (at eruption) -> normal -> translucent (grey/brown.blue)
- normal enamel, attrition means rapidly lost
What are the radiological features of type 2 dentinogenesis imperfecta?
- short blunt roots
- partial/total obliteration of the pulp chamber and root canal by dentine
What are the histological features of type 2 dentinogenesis imperfecta?
- Reduced tubules
- tubular dentine
- vascular inclusion
- straight ADJ (shearing of enamel)
What are the biochemical features of type 2 dentinogenesis?
abnormally high water content and decreased mineral content of dentine = soft
What are shell teeth?
A variant of type II dentinogenesis imperfecta
= very rare, pulp chamber not obliterated, dentine is thin and forms shell around pulp, pulp contains coarse collagen fibres and no odontoblasts
What is dentinal dysplasia Type 1?
Rootless tooth (normal crown, root has dysplastic dentine) = due to defect in HERS)
What is dentinal dysplasia type 2?
coronal dentine dysplasia = primary teeth are amber colour with obliterated pulp chambers
What is regional odontodysplasia?
Ghost teeth
= uncommon with unknown aetiology
= abnormalities of enamel, pulp, dentine and dental follicle
= usually anterior maxilla and unilateral (one quadrant only)
= delayed eruption, irregular shape, hypoplastic enamel defects
What are the different cementum defects?
Hypercementosis and hypocementosis
What is hypercementosis?
Too much cementum = ankylosis = difficult to extract
Caused by: periapical inflammation, mechanical stimulation, functionless/unerupted, pagets
What is hypocementosis?
Too little cementum = tooth wobbly and fall out (uncommon)
Causes: cleidocranial dysplasia and hypophosphatasia (recessive autosomal)
