13. Hard tissue anomalies Flashcards
1
Q
When does dental lamina begin to differentiate?
A
6 weeks in utero
2
Q
When do hard tissues start to form?
A
13 weeks- 10 years
3
Q
Where is enamel and dentine derived from?
A
Enamel- ectoderm
Dentine and supporting structures- mesoderm
4
Q
What is the definition of hypodontia?
A
Less than 6 teeth congenitally absent, excluding third molars
5
Q
What is the definition of oligodontia?
A
More than 6 teeth congenitally absent, excluding third molars
6
Q
What is the definition of anodontia?
A
Total lack of development of teeth
7
Q
What is the rate of occurrence of hypodontia in primary dentition?
A
- 0.1-0.9% in primary teeth
- 1 female: 1 male
8
Q
Which teeth does hypodontia in primary teeth affect most?
A
More common maxilla- upper b’s
9
Q
What is the rate of occurrence of hypodontia in permanent dentition?
A
3.5-6.5%
4 female: 1 male
10
Q
Where does hypodontia in permanent dentition occur most?
A
Maxilla and mandible
11
Q
List the frequency of absent teeth from most to least?
A
- 8’s
- lower 5
- upper 2
- upper 5
- lower 1
- lower 2
- upper 4
- lower 5
- upper 3
- lower 5
- upper 6
- lower 3
- lower 6
- upper 1
12
Q
What are environmental causes for hypodontia?
A
- chemotherapy
- tooth bud gouging
13
Q
What are non-syndromic causes for hypodontia?
A
- autosomal dominant
- incomplete penetrance
- variable expression
- MSX1, PAX9, AXIN2
14
Q
What are features of ectodermal dysplasia?
A
- sparse, fine hair
- dry, scaly skin
- lack of sweat glands
- nails ridged
- middle one third of face under developed
- bridge of nose depressed
14
Q
Name 5 syndromes that may cause hypodontia?
A
- ectodermal dysplasia
- chrondo-ectodermal dysplasia (ellis van creveld)
- oral clefting
- down syndrome
- SMMCI
15
Q
What are features in primary teeth seen in ectodermal dysplasia?
A
- coronoid primary incisors
- taurodont second primary molars
- supernumerary cusps
15
Q
What are features in permanent teeth seen in ectodermal dysplasia?
A
- incisal crowns conical/pointed
- molar crowns have a reduced diameter
16
Q
How do you manage teeth in ectodermal dysplasia?
A
Multidisciplinary approach
- orthodontic space closure
- prosthetic/restorative space closure
- composite build ups
- bridges or dentures
- definitive treatment 18 years plus
16
Q
What is SMMCI?
A
The only central incisor present in the midline of the maxillary alveolus. It is not a supernumerary tooth (mesiodens).
17
Q
What is the cause and occurrence of SMMCI?
A
- 1 in 50000 live births
- aetiology is unknown
18
Q
What other midline abnormalities is SMMCI associated with?
A
– Midline nasal cavity defects
– Holoprosencephaly
– Microcephaly
– Congenital heart disease
– Cleft lip and palate
– Oesophageal/ duodenal atresia
– Hypopituitarism
– Hypotelorism
19
Q
What is the occurence of supernumeraries in primary dentition?
A
0.2-0.8%
20
Q
What is the occurence of supernumeraries in permanent dentition?
A
1.5-3.5%
21
Q
What is the ratio of supernumeraries affecting maxilla and males?
A
2 male: 1 female
5 maxilla: 1 mandible
Permanent anomalies in 50% of primary cases
22
What are the 4 types of supernumeraries?
- supplemental
- conical
- turberculate
- odontome
23
What is a supplemental supernumerary?
- resemble those of normal series
- often cause crowding- so extract most displaced
24
What are the most common supplemental supernumeraries?
- most commonly lateral incisor
- premolars
- molars- paramolars or distomolars
25
What is the most common supernumerary?
Conical
26
Where is conical supernumerary most commonly found?
Usually in maxillary midline
27
What is the treatment for conical supernumeraries?
- do not interfere with the eruption of permanent incisors
- can cause displacement- median diastema
- if erupted- extract
- if unerupted- leave and monitor
- take radiograph annually
- look for resorption, follicular changes
28
Name features of turberculate supernumeraries?
- barrel shaped
- poor or absent root formation
- rarely erupt
- often paired
- commonly prevent eruption of upper 1's
29
What is the management of turberculates?
- remove primary teeth if present
- maintain or create space for permanent tooth
- surgical removal of supernumerary
- wait up to 18 months for spontaneous eruption of upper central incisors
- consider surgical exposure and orthodontic extrusion if needed of centrals
30
Why do odontomes occur?
Due to a disturbance in dental organogenesis
31
What is a compound odontome?
Tooth like formations- look like collection of small teeth
32
What is a complex odontome?
Hazardous arrangement of dental hard tissue
33
Where are odontomes usually found?
Anterior part of maxilla or lower molar regions
34
What syndromes are associated with supernumeraries?
- Cleft lip and palate syndrome
- Cleidocranial syndrome
- Gardner's syndrome
- Oro-facial-digital syndrome
35
36
What are factors that affect the management of supernumerary teeth?
- erupted vs unerupted
- age
- is it interfering with eruption of other teeth
- is it inverted, difficult to get out
- associated pathology
- is it interfering with orthodontic movement
37
What is macrodontia?
- larger crown than normal variation but normal morphology
38
What teeth does macrodontia normally affect?
- usually upper 1's followed by lower 5's
- usually bilateral
39
What is the percentage likelihood of macrodontia?
- affect single tooth in 1% of population
- 0.1% of population have generalised macrodontia
40
What are the treatment options for macrodontia?
- section/reshape the tooth
- extract- maintain the space by partial denture, resin bonded bridge or implant
- autotransplantation
41
What is the problem in the pulp in macrodontia?
They have an enlarged pulp so may have occasional pulpal involvement.
Do Cvek pulpotomy or endodontics
42
What is the occurrence of microdontia in the primary and permanent dentition?
- rare in primary dentition= 0.2-0.5%
- in permanent dentition it is 2. 5% in single tooth, and 0.2% have generalised
- affects females more than males
43
What is the most common teeth microdontia is associated with?
Upper 2's
Most often peg/conical shaped
- hypodontia
44
Which diseases is microdontia associated with?
Ectodermal dysplasia
Down Syndrome
45
What are the treatment options for microdontia?
- leave
- composite build up
- orthodontic space closure
- extract
46
Does root size have a racial variation?
Yes- pt from oriental backgrounds tend to have smaller roots
47
Which teeth is large root size most often seen in?
Upper 1's
48
Which teeth is small root size often seen in and what may it be associated with?
Upper 1's
- may be associated with orthodontic tx, trauma, chemo/radiotherapy
49
What are 5 anomalies of crown form?
- double teeth
- accessory cusps
- invagination
- evagination
- dilaceration
50
What are anomalies of root form?
- taurodontism
- accessory roots
- dilaceration
- enamel pearl
51
What is the incidence of double teeth in primary teeth and permanent teeth?
primary teeth- 0.5%-1.6%
permanent teeth- 0.1-0.2%
male=female
30-50% of primary cases have anomalies in permanent dentition
52
What is gemination?
Incomplete attempt of tooth germ to divide into two
(the single bud has attempted to divide when it should not have)
53
What is fusion?
Complete or partial fusion between dentine/enamel of two separate teeth
(Fusion of more than one tooth bud)
54
What are the management principles for double teeth?
- malocclusion
- crown width
- root morphology
- may require CBCT
- multidisciplinary meeting
55
What are the treatment options for double teeth when there is a single root?
- if there is a single root, can extract double tooth and autotransplant another one
- can modify crown of the tooth
- can extract double tooth and use prosthetic placement
56
What is the options for double teeth when there is separate roots?
- if there is pulpal communication, hemisection, endo tx, crown modification
- if there is no pulpal communication, do hemisection and crown modification
57
What are accessory cusps?
- supplemental cusps
- cusp of carabelli most common (seen on maxillary molars)
- does not contain pulp
- limited/no clinical significance
58
What is dens evaginatus/talon cusp?
Cusp like elevation located in the central groove
- contains pulp
59
Which teeth and people does dens evaginatus affect most?
- often upper 1's and mandibular premolar
- in mandibular premolars they are often bilateral
- chinese people= 1-4%
60
What are the treatment options for dens evaginatus?
- leave= occlusion/aesthetics okay
- fissure seal pronounced groove
- gradually grind down cusp- reactionary dentine formation
- cvek pulpotomy
- extract
- endodontics
61
What is dens invaginatus/dens in dante?
Deep surface invagination of crown that is lined by enamel.
- represents an accentuation of the lingual pit
62
Which teeth and people is dens invaginatus most commonly seen in?
- prevalence varies from 1-10%
- upper 2's most common
- less commonly upper 1's and 3's
- 2 males: 1 female
- bilateral involvement common
- chinese ethnicity
63
What is the Oehlers classification of dens invaginatus?
- type 1= invagination confined to the crown
- type 2= invagination invading root as blind sac, may connect to pulp
- type 3= invagination through root to apical region
64
What are treatment options for dens invaginatus?
- early detection- may present with caries, pain, abscess
- fissure seal pronounced groove/pit on eruption
- root canal but very difficult
- multidisciplinary management needed in type 2/3
65
What is taurodontism?
- bull like teeth
- multirooted teeth where body and pulp is enlarged at the expense of the roots
66
Which teeth are most affected by taurodontism?
6.3% of mandibular molars
67
What diseases are taurodontism associated with?
- amelogenesis imperfecta
- klinefelter's syndrome
- tricho-dento-osseous syndrome
68
Where are accessory roots found?
Almost any tooth
Primary dentition 1 – 9%
Permanent dentition 1 – 45%
Often disto-lingual/ palatal aspect of tooth May be difficult to identify radiographically Potential problems with extraction or RCT
69
What is dilaceration?
Abnormal bend in crown or root of tooth Mostly permanent incisor
Usually result of trauma to primary incisor
Deviation results from traumatic displacement of hard tissue (which has already been formed) relative to developing soft tissue Almost any tooth
Primary dentition 1 – 9%
Permanent dentition 1 – 45%
70
What are enamel pearls?
Ectopic mass of enamel on the roots, normally at the furcation area.
