Developmental abnormalities Flashcards
1
Q
List developmental defects affecting tooth number
A
Hypodontia
Oligodontia
Anodontia
Supernumerary teeth
2
Q
Define: hypodontia
A
Congenital absence of 1-6 teeth excluding the third molars
3
Q
Which teeth are most commonly missing due to hypodontia?
A
Upper second premolars
Upper lateral incisors
Lower second premolars
Lower central incisors
4
Q
Define: oligodontia
A
More than 6 congenitally missing teeth
5
Q
Define: Anodontia
A
Complete congenital absence of one or both dentitions
6
Q
Define: Supernumerary teeth
A
Addition to the normal series of tooth
7
Q
What would multiple supernumerary teeth indicate?
A
Disease or syndrome e.g. CLP, Gardner syndrome or Ehlers-Danlos
8
Q
What is the most common supernumerary tooth?
A
Mesiodens
9
Q
List the types of supernumerary teeth
A
Supplemental
Conical
Tuberculate
Odontome
10
Q
Define: supplemental tooth
A
Extra tooth of normal form occurring at the end of a series (most commonly lateral incisor)
11
Q
Where do conical supernumerary teeth occur
A
Anterior maxilla in the midline (mesiodens)
12
Q
When will a conical supernumerary remain unerupted
A
If it is inverted
13
Q
Where do tuberculate supernumary teeth occur
A
In the anterior maxilla on the palatal aspect of central incisors
14
Q
What is an odontome?
A
Benign tumour linked to tooth development
15
Q
What are the types of odontomes
A
Complex
Compound
16
Q
Define: Complex odontome
A
Calcified structure with no resemblence to the anatomical arrangement of dental tissues
17
Q
Define’ Compound odontome
A
Calcified structure made up of rudimentary teeth
18
Q
What is thought to be the developmental issue causing hypodontia
A
Defect in dental epithelial growth
19
Q
What stage of development does anodontia occur?
A
Dental lamina formation stage
20
Q
What is the developmental issue causing supernumerary teeth
A
Disturbance during initiation and proliferation stages
21
Q
What are the theories of supernumerary teeth
A
- Dichotomy (division) of tooth buds
- Organised hyperactivity of the dental lamina
22
Q
Define: peg laterals
A
Small tapered maxillary lateral incisor
23
Q
What stage is important for peg lat formation
A
Morphodifferentiation stage
24
Q
Define: microdontia
A
Teeth smaller than nrmal
25
Define: macrodontia
Teeth larger than usual
26
What stage is implicated in macrodontia
Disturbance in initiation and proliferation stages
| Morphodifferentiation stages
27
Define: Taurodontism
Multirooted teeth with a long body and pulp chamber and short roots. The Pulp chambers are elongated and the pulp is apically displaced
28
Which teeth are often implicated in Taurodontism
Mandibular molars
29
Hypothesised cause of taurdontism
Disturbance in growth of hertwig's epithelial root sheath or morphodifferentiation stage
30
Define: dens envaginates
Formation of an accessory cusp whose morphology is described as tubercle, elevation, protruberance, extrusion or bulging.
31
What makes up the dens envaginates
Enamel covering a dentine core and pulp tissue
32
Which teeth are often implicated in dens envaginates
```
Anterior teeth (lingual or palatal aspect)
Occlusal surface of premoalrs
```
33
What stage is implicated in dens envaginates formation
Organic matrix apposition and primary mineralisation stage
34
Define: dens invaginatus (Dens in dente)
Infolding of enamel into dentine
35
Where is dens in dentine more common
Maxillary lateral incisors, central incisors, canines then molars
36
Stage implicated in dens in dente
Morphodifferentiation
37
Define: dilaceration
Deviation or bend in the linear relationship of the crown relative to the root
38
Which type of dilaceration is more common
Root dilaceration > crown dilaceration
39
Where do root dilacerations occur
Posterior region of permanent dentition
40
Where do crown dilacerations occur
Permanent maxillary and mandibular teeth
41
Cause of dilaceration
Trauma to primary tooth causing damage to permanent predecessor
42
Define: Fusion
Two normally seperate adjacent tooth germs fuse into one large tooth, sharing the same enamel and dentine
43
When does complete fusion occur
If fusion occurs before calcification stage
44
When does incomplete fusion occur
If fusion occurs later on (after calcification stage)
45
What stage is implicated in fusion
Initiation and proliferation stages
46
Define concresence
Cemental union of adjacent teeth without confluence of dentine, they have separate pulp chambers and root canals
47
Which teeth are often implicated in concresence
Posterior maxillary teeth, often 7s
48
What is the cause of developmental concresence
Close proximity of developing roots of adjacent teeth
49
Define germination
Two teeth from the same follicle attempt to divide, but division is incomplete thus forming an abnormally large tooth
50
Which teeth are often affected by germination
Anterior teeth
51
What are enamel pearls
Localised formation of enamel on the root of a tooth
52
What is the cause of enamel pearls
Continued formation of Hertwig's epithelial root sheath
53
Define amelogenesis imperfecta
Group of inherited enamel disorders leading to altered enamel morphology, alongisde normal dentine and pulp formation
54
What are the types of AI
Hypoplastic
Hypocalcified/hypomineralised
Hypomatured
55
Define hypoplastic enamel
Reduction in the amount of enamel matrix protein secretion thus causing thin enamel, surface pitting or vertical grooves
56
Define hypomineralised enamel
Normal enamel matrix present but the enamel is deficiently mineralised causing soft enamel
57
Define hypomatured enamel
Normal enamel matrix present but the enamel lacks hardness forming opaque, discoloured enamel that easily fractures
58
Define dentinogenesis imperfecta
Genetic disturbance of dentine formation leading to altered morphology of dentine
59
Features of dentiogenesis imperfecta
Brown, opalescent discolouration and fracture of overlying enamel
Rapid wear/attrition of teeth
Progressive pulp obliteration
60
What is regional odontodysplasia
Hypoplastic and hypocalcified enamel and dentine
61
Features of regional odontodysplasia
Small, brown teeth with large pulp chambers and root canals
62
Define: molar-incisor hypomineralisation
Developmental defect resulting in 1-4 hypomineralised permanent first molars, frequently associated with similarly affected permanent incisors
63
What is the prevalence of MIH
2.8-40%
64
What are the stages of amelogenesis
Secretory
Transition
Maturation
65
Which stage of enamel formation is associated with enamel hypoplasia
Secretory
66
Which stages of enamel formation are associated with hypomineralised/hypomatured enamel
Transition
| Maturation
67
Aetiology of MIH
Unknown
| Possibly systemic in origin
68
What age is the critical period for enamel defects in incisors and 6s ? WHY?
1yo - as it coincides with early maturation phase
69
Proposed etiological factors of MIH
- Maternal illness, diabetes, medicines or pyrexia
- Complicated delivery, c section, hypoxia, premature
- ENT infections, respiratory problems, antibiotics, chickenpox/measles/mumps
70
Stages of management of MIH
```
Early diagnosis
Risk identification
Remineralisation & desensitisation
Prevent caries + PEB
Restorative care/extractions
Maintenance
```
71
Presentation of MIH
- 1-4 permanent molars (or incisors) with signs of hypomineralised enamel e.g. opacities
- Post eruptive enamel breakdown
- Atypical caries pattern
72
What are the consequences of MIH
- Caries
- PEB
- hypersensitivity and difficulty obtaining LA
- Frequent restorative failure
73
What are the features of the hypomineralised lesions
- Clear demarcated opacities which -
1 - Vary in colour - white, cream, yellow or brown
2- Vary in size
74
What is post-eruptive enamel breakdown (PEB)
Severely affected enamel subject to masticatory forces results in rapid breakdown, exposure of dentine and rapid caries development soon after eruption
75
What type of prevention is required in MIH ptsq
ENHANCED PREVENTION - includes high dose fluoride, frequent recalls, dietary advice
76
What remineralisation products can be used for MIH
- CPP-ACP
- Enamelon
- Novamin
77
How does CPP-ACP work
Incr bioavailability of calcium and phosphate within saliva and prevents spontaneous precipitation, thus encouraging remineralisation deep into lesions and desensitisation
78
What are the two options to prepare MIH affected teeth for restorative tx
- Remove all defective enamel until sound surface reached
| - Remove porous enamel only until resistance to the bur is felt
79
Disadvantages of a minimally invasive approach in MIH
- Since not all the defective enamel is removed, the tooth is still susceptible to breakdown thus restorative failure
80
What does restorative tx for MIH depend on?
- Cooperation of patient
- Longevity required
- Extent of PEB (cuspal involvement, restorable?)
- Orthodontic needs
81
Methods for restoring MIH 6s
Direct - RMGIC as temporary, Composite
| Indirect - Crowns or cast onlays
82
Indications for planned loss of 6s
- Poor long term prognosis
- Underlying malocclusion
- Extent and location of crowding
- No missing teeth (8s present)
- Correct timing
- Which 6s are affected
83
When is the ideal timing for extraction of 6s ?
DPT showing calcification of the bifurcation of 7s
84
Why is timing important in planned loss of 6s
Provides good prognosis for the 7s replacing the position of the 6s
85
Are balancing / compensating extractions done in MIH
- balancing to prevent asymmetry
| - Compensating is not recommended
86
When is timing of planned loss of 6s most important?
for MANDIBULAR 6s
87
Why is timing of planned loss of 6s not a big concern in the maxilla
The 7 usually takes up a good occlusal position anyway
88
What is the most favourable age for planned loss of 6s?
8-10
| After laterals erupt but before 7s and/or 5s
89
What happens if planned loss of 6s occurs too early
Loss of space due to 5 drifting distally, retroclination of labial segments and incr overbite
90
What happens if planned loss of 6s occurs too late
7s are well formed and will not erupt into the space of the 6
Risk of mesial tilt or rotation of 7s
Risk of 5s drifting distally
91
Explain MIH and LA issues
Hypomineralised enamel is a poor insulator therefore the pulp is not well protected and becomes hypersensitive and difficult to numb up
92
Options to treat MIH incisors
```
Bleaching
Resin infiltration
Microabrasion
Composite restorations/veneers
Porcelain veneers
```
93
Timing of treatment of MIH incisors
Aesthetic tx should be postponed until older as immature teeth have large and sensitive pulps
94
What is resin infiltration
Hcl as an etchant and low viscosity resin to penetrate demineralised enamel
95
What is microabrasion
Removal of a small layer of superficial enamel using abrasion and erosion with 18% hcl and pumice
96
Age and bleaching
GDC states products containing 0.1-6% hydrogen peroxide cannot be used on under 18s unless wholly intended to prevent/treat disease
97
Differential diagnosis of MIH
Fluorosis
AI
WSL
Traumatic hypomineralisation
