Dental Anomalies 1 Flashcards
1
Q
An abnormality in dental lamina formation leads to …
A
an abnormality in the number of teeth
2
Q
An abnormality in morphodifferentiation leads to …
A
an abnormality in the shape and size of the teeth
3
Q
An abnormality in matrix deposition and mineralisation leads to …
A
an abnormality in structure
4
Q
What is anodontia ?
A
no teeh
5
Q
Fewer than normal teeth refers to …
A
hypodontia
6
Q
Hypodontia can also be historically referred to as…
A
partial anodontia
Oligodontia
7
Q
What is hyperdontia?
A
more teeth than normal present
8
Q
Deciduous teeth are rarely missing (anodontia). True or false
A
True
9
Q
What teeth are most frequently implicated in hypodontia ? (arrange in the order of most frequently implicated to least)
A
3rd molars> maxillary lateral incisors > lower second premolars
10
Q
There is no familial tendency in hypodontia. True or false
A
false
11
Q
What hypodontia tendency is most commonly found nationally in Sweden and Japan?
A
L1’s
(notes wrote lower first molars, but is it lower first incisors?)
12
Q
Explain the reason for the absence of permanent teeth if their deciduous predecessor is missing?
A
this is because the tooth germ of the permanent successors from as a result of proliferative activity in the dental lamina, lingual to the deciduous tooth germ.
is dental lamina correct here?
is it proliferative activity in the tooth bud?
13
Q
Why might molars not affected by the absence of deciduous teeth?
A
this is because they have no deciduous predecessor and they tooth germ originates directly from the dental lamina
14
Q
What are the most common clinical signs of hypodontia?
A
- retained deciduous teeth, well after date of exfoliation
- spaces
- infraoccluding deciduous teeth (submerging teeth)
15
Q
What radiographic images are required for the assessment of missing teeth?
A
- OPG
- upper occlusal
16
Q
In the absence of an upper occlusal radiograph, what alternative can be used instead?
A
periapical radiographs
17
Q
What factors can potentially cause infraoccluding teeth?
A
- ankylosis
- impaction
- absence of permanent successor
- trauma causing damage to hertwigs epithelial root sheath
- infection, chemical or thermal irritation
- failure of bone growth
- abnormal tongue pressure
- genetic aetiology has also been suggested as it has been observed in siblings
18
Q
What IOTN has been ascribed to infraocclusing teeth?
A
5s
19
Q
What are some clinical considerations you must make regarding infraoccluded teeth?
A
- orthodontic assessment 5S
- If extractions indicated; are they ankylosed or impacted
- the need for advanced restoration; stainless steel crowns for prevention, fissure sealants?
20
Q
Give examples of medical conditions that may be associated with missing teeth
A
- Hereditary ectodermal hypoplasia
- cleft lip and palate
- down syndrome
21
Q
What teeth are most commonly absent in downs syndrome?
A
3rd molars are absent in 90% of cases
22
Q
What are the clinical signs of hereditary ectodermal hypoplasia?
A
(affects ectodermal tissues
* hair is absent/thin/sparse
* small conical and sometimes missing teeth (rarely 100% missing teeth)
* reduction in/absence of sweat glands; dry smooth skin
* decreased skin pigment or colour
* abnormal fingernails
* small maxilla (maxillary hypoplasia)
* poor hearing, vision and decreased tear production
23
Q
What is the pattern of inheritance for hereditary ectodermal dysplasias?
A
- X linked recessive
- autosomal dominant
- autosomal recessive
- ectodermal dysplasia is a group of genetic disorders. Inheritance pattern will depend on the type of dysplasia present; may be passed on from parent, mutations may occur at egg or sperm formation or at fertilisation
24
Q
When is it best to perform cleft lip and palate repairs?
A
- it has been found that repairs have better outcomes the earlier they are performed
25
What are some general characteristics of cleft palates ?
* 75% of clefts are unilateral
* left side is more common than the right
* affects more boys than girls 3:2
* less frequent in African populations
26
What are some suggested factors that contribute to the development of cleft lip and palate?
* genetics
* environment
* drugs (corticosteroids, phenytoin - anticonvulsant)
* infections in pregnancy (rubella)
* alcohol consumption, smoking, some dietary deficiencies (folic acid/vitamin A)
* maternal age
27
What teeth sit on the medial nasal prominence ?
the 4 incisal teeth
28
What dental issues can arise in cleft palate?
* hypodontia
* hyperdontia (rare cases)
* presence of natal or neonatal teeth (teeth present at birth)
* microdontia
* fused teeh
* enamel hypoplasia
* poor periodontal support
* germination and dilacerations
* anterior and posterior crossbite
* class III tendency
* spacing and crowding
29
What is the most common cause of downs syndrome?
trisomy 21
this is where there is a third copy of chromosome 21
30
What are some common developmental issues in downs syndrome that can lead to oral complications?
* hypoplasia of mid face
* underdeveloped maxilla
* poorly developed paranasal sinus due to small maxilla
31
What issues are associated with under-developed maxilla in downs syndrome?
* poorly developed maxilla which can make breathing difficult- considerations for dental chair position
* maxillary hypoplasia means that most are class III and have a protrusive tongue
32
Outline some dental issues associated with people with downs syndrome
* anterior open bite with lateral incisors missing
* teeth appear smaller and can also be missing (hypodontia)
* delayed eruption
* relatively low incidence of caries
* rapidly progressive periodontal disease is associated with downs syndrome
* heavily fissured and enlarged tongues
33
What clinical considerations can be made for hypodontia ?
* do nothing
* direct restoration disguises (canines to laterals)
* orthodontics with/without restoration
* restoration of space with: implants, removable prosthesis, fixed prosthesis
34
Hyperdontia is most commonly present in what arch?
Maxilla
Maxilla 90% , premaxilla 98%
mandible 10%
35
How are hyperdontic teeth classified?
by shape
36
What are the classifications of hyperdontic teeth?
* supplemental
* supernumerary
37
What are the classifications of supernumerary teeth?
* conical (inverted/everted)
* tuberculate
38
What are the characteristics of supplemental teeth?
* same structure as normal
* erupt normally
* usually tagged onto a series
39
What is the cause of supplemental teeth?
excessive but organised growth of the dental lamina
40
Supernumerary teeth can prevent the eruption of other teeth. True or false
True
41
What are the most common instances of hyperdontia in maxilla?
* mesiodens (located in the centre line); conically shaped
* paramolars (4th molars)
* maxillary lateral incisors
42
What are the most common instances of hyperdontia in the mandible ?
* premolars
* 4th molars
* extra incisors
43
What radiographic examinations need to be performed for a diagnosis of hyperdontia?
* OPG
* upper occlusal
44
Give an example of a medical condition associated with supernumerary teeth
cleinocranial dysplasia
45
Outline some characteristics of cleinocranial dysplasia
* aplasia/hypoplasia of one or both clavicles
* delayed ossification of fontanelles
* short stature
* increased number of supernumerary teeth
* delayed eruption
* dentigerous cysts
* frontal bossing
46
What is the inheritance pattern of cleionocranial dysplasia?
autosomal dominant - mapped to short arm of chromosome 6
spontaneous mutation
47
What are the clinical considerations for supplemental teeth?
* do nothing
* plaque traps
* aesthetics
48
What are the considerations of supernumerary teeth?
* diagnosis is crucial as they are often unerupted
* possible effects on rest of dentition e.g. prevention of eruption
* possible resorption of adjacent teeth
* aesthetics
*
49
What is microdontia ?
one or more teeth that are smaller than normal
## Footnote
can either be generalised or localised
50
What is macrodontia?
one or more teeth that are larger than normal
## Footnote
can either be generalised or localised
51
Although uncommon, give an example of a cause of true generalised microdontia ?
pituitary dwarfism
52
Give instances associated with relative generalised microdontia?
* jaw size larger than normal but teeth are normal size, this casues spaces and give the illusion of small teeth
* spaces due to strong tongue (as is the case in downs syndrome)
53
What teeth are most commonly affected by microdontia ?
* lateral incisors (peg)
* maxillar third molars (peg molars)
* they both often appear small and conical
54
Microdontia is not present in ...
second premolars
55
Microdontia can have iatrogenic aetiology. Give an example of this
Chemotherapy; teeth that are forming at the time that chemotherapy is being received will experience insult
56
What is a cause of true generalised macrodontia?
pituitary gigantism
57
Explain the circumstances behinds relative generalised macrodontia?
jaw size appears smaller than normal, but teeth are normal size so teeth are crowded
58
Outline causes of regional macrodontia
* hemifacial hypertrophy
* segmented odontomaxillary dysplasia
59
Localised macrodontia should not be confused/misdiagnosed with ...
fusion
60
What is rhizomegaly/radiculomegaly?
uncommon condition where the roots of teeth are longer than normal
61
What teeth are commonly implicated in rhizomegaly?
mandibular canines
62
What is a dilaceration?
a sharp bend or angulation involving the root of a tooth
63
What are the potential casues of dilaceration ?
* trauma to a developing tooth
* discrupted root formation along a tortuous path
* this can cause root to from at an angle to the normal axis of the tooth
*
64
What is taurodontism?
this is a molar with an elongated crown and apically placed furcation, this results in an enlarged rectangular coronal pulpal chamber
65
What is the characteristic appearance of taurodontism?
* large pulpal chamber
* no constriction at a-c junction
* short pulpal canals
66
Taurodontism affects both permanent and deciduous molars. True or false
True
67
What is the cause of taurodontism?
late invagination of hertwigs root sheath
68
What conditions can be associated with taurodontism?
* amelogenesis imperfecta
* Klinefelter syndrome
* downs syndrome
69
Define Dens invaginatus
(invaginated odontome)
developmental anomaly with deep enamel lined pit extending to varying lengths into the underlying denting, often displacing the pulp and altering the root shape
70
Dens invaginatus is also known as ...
dens in dente
71
An extreme form of dens invaginatus is referred to as ...
dilated odontoma
72
Dens invaginatus is more likely to affect which type of teeth ?
permanent maxillary lateral incisors
Peg shaped laterals are more common
73
Why is prevention key in dens invaginatus ?
the base enamel pit is thin, there is also defective enamel /dentine
this makes the tooth vulnerable
74
Give examples of supernumerary cusps
* cusp of carabelli (MP surface of maxillary first molar)- common
* dens evaginatus
* talon cusps
75
Define dens evaginatus
a developmenral anomal characterised by a cusp like supernumerary focal enamel protrusion (spur) on the occlusal or lingual surface of the crown
76
Dens evaginatus mainly affects _______ teeth
premolar
77
What is the characteristic appearance of dens evaginatus in a premolar tooth ?
abnormal globe shape prohection of enamel in central groove
78
Dens evaginatus is more common in what populations?
* chinese
* japanese
* filipino
* american indian
* singapore/malaysia (leong premolar)
79
What is a possible consequence of a dens evaginatus projection fracturing off?
pulpal exposure
80
What tooth are talon cusps usually found and where ?
* lingual aspect of maxillary lateral incisor
* can extend to incisal edge
81
81
Why must you avoid reducing pulp horns?
this is due to the presence of a prominent pulp horn
82
Fused and germinated teeth are more common in what type of dentition?
deciduous dentition
83
Define fusion
a develomental anomaly characterised by abnormally shaped tooth with either a wide crown and one root or a normal crown with an additional root (or a combination)
combination of two adjacent tooth germs united by dentine
84
Briefly describe the pulp in a fused tooth
pulp can be seperate or fused
85
Fused teeth are less vulnerable to caries and periodontal disease. True or false
false
86
Define germination
developmental anomaly where a single rooted tooth (unusually wide), with a partly divided crown or two seperate crowns
87
What is the cause of germination ?
partial division or twinning of a single tooth germ
88
What is the difference between fusion and germination ?
microscopically they appear the same but they have different developmental pathways
89
What is hypercementosis ?
apposition of excessive amounts of cementum
90
What are some causes of hypercementosis ?
ageing
inflammation
91
What type of teeth are affected by hypercementosis ?
functionless and unerupted teeth
92
What is a possible consequence of hypercementosis ?
concrescence
93
93
Define concrescence ?
union of roots caused by conflucence of cementum only
94
Concresence is a type of ______
fusion
95
What are possible causes of concresence ?
* trauma
* crowding with interseptal bone loss
96
When can concresence occur?
before or after tooth eruption
97
What are enamel pearls ?
ectopic droplets of enamel that primarily occur in bifurcation or trifurcation areas on roots of molars
98
How do enamel pearls appear on radiographs ?
1-3mm radiopacities
99
Enamel pearls may have a central core of __________.
dentine
100
Why is the treatment of enamel pearls avoided?
may create root caries, external root resorption or pulpitis
101
What causes enamel pearls (enamelomas)?
ameloblasts displaced below the amelocementa junction
