13. Hard tissue anomalies Flashcards
When does dental lamina begin to differentiate?
6 weeks in utero
When do hard tissues start to form?
13 weeks- 10 years
Where is enamel and dentine derived from?
Enamel- ectoderm
Dentine and supporting structures- mesoderm
What is the definition of hypodontia?
Less than 6 teeth congenitally absent, excluding third molars
What is the definition of oligodontia?
More than 6 teeth congenitally absent, excluding third molars
What is the definition of anodontia?
Total lack of development of teeth
What is the rate of occurrence of hypodontia in primary dentition?
- 0.1-0.9% in primary teeth
- 1 female: 1 male
Which teeth does hypodontia in primary teeth affect most?
More common maxilla- upper b’s
What is the rate of occurrence of hypodontia in permanent dentition?
3.5-6.5%
4 female: 1 male
Where does hypodontia in permanent dentition occur most?
Maxilla and mandible
List the frequency of absent teeth from most to least?
- 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
What are environmental causes for hypodontia?
- chemotherapy
- tooth bud gouging
What are non-syndromic causes for hypodontia?
- autosomal dominant
- incomplete penetrance
- variable expression
- MSX1, PAX9, AXIN2
What are features of ectodermal dysplasia?
- sparse, fine hair
- dry, scaly skin
- lack of sweat glands
- nails ridged
- middle one third of face under developed
- bridge of nose depressed
Name 5 syndromes that may cause hypodontia?
- ectodermal dysplasia
- chrondo-ectodermal dysplasia (ellis van creveld)
- oral clefting
- down syndrome
- SMMCI
What are features in primary teeth seen in ectodermal dysplasia?
- coronoid primary incisors
- taurodont second primary molars
- supernumerary cusps
What are features in permanent teeth seen in ectodermal dysplasia?
- incisal crowns conical/pointed
- molar crowns have a reduced diameter
How do you manage teeth in ectodermal dysplasia?
Multidisciplinary approach
- orthodontic space closure
- prosthetic/restorative space closure
- composite build ups
- bridges or dentures
- definitive treatment 18 years plus
What is SMMCI?
The only central incisor present in the midline of the maxillary alveolus. It is not a supernumerary tooth (mesiodens).
What is the cause and occurrence of SMMCI?
- 1 in 50000 live births
- aetiology is unknown
What other midline abnormalities is SMMCI associated with?
– Midline nasal cavity defects
– Holoprosencephaly
– Microcephaly
– Congenital heart disease
– Cleft lip and palate
– Oesophageal/ duodenal atresia
– Hypopituitarism
– Hypotelorism
What is the occurence of supernumeraries in primary dentition?
0.2-0.8%
What is the occurence of supernumeraries in permanent dentition?
1.5-3.5%
What is the ratio of supernumeraries affecting maxilla and males?
2 male: 1 female
5 maxilla: 1 mandible
Permanent anomalies in 50% of primary cases
What are the 4 types of supernumeraries?
- supplemental
- conical
- turberculate
- odontome
What is a supplemental supernumerary?
- resemble those of normal series
- often cause crowding- so extract most displaced
What are the most common supplemental supernumeraries?
- most commonly lateral incisor
- premolars
- molars- paramolars or distomolars
What is the most common supernumerary?
Conical
Where is conical supernumerary most commonly found?
Usually in maxillary midline
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
Name features of turberculate supernumeraries?
- barrel shaped
- poor or absent root formation
- rarely erupt
- often paired
- commonly prevent eruption of upper 1’s
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
Why do odontomes occur?
Due to a disturbance in dental organogenesis
What is a compound odontome?
Tooth like formations- look like collection of small teeth
What is a complex odontome?
Hazardous arrangement of dental hard tissue
Where are odontomes usually found?
Anterior part of maxilla or lower molar regions
What syndromes are associated with supernumeraries?
- Cleft lip and palate syndrome
- Cleidocranial syndrome
- Gardner’s syndrome
- Oro-facial-digital syndrome
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
What is macrodontia?
- larger crown than normal variation but normal morphology
What teeth does macrodontia normally affect?
- usually upper 1’s followed by lower 5’s
- usually bilateral
What is the percentage likelihood of macrodontia?
- affect single tooth in 1% of population
- 0.1% of population have generalised macrodontia
What are the treatment options for macrodontia?
- section/reshape the tooth
- extract- maintain the space by partial denture, resin bonded bridge or implant
- autotransplantation
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
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
What is the most common teeth microdontia is associated with?
Upper 2’s
Most often peg/conical shaped
- hypodontia
Which diseases is microdontia associated with?
Ectodermal dysplasia
Down Syndrome
What are the treatment options for microdontia?
- leave
- composite build up
- orthodontic space closure
- extract
Does root size have a racial variation?
Yes- pt from oriental backgrounds tend to have smaller roots
Which teeth is large root size most often seen in?
Upper 1’s
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
What are 5 anomalies of crown form?
- double teeth
- accessory cusps
- invagination
- evagination
- dilaceration
What are anomalies of root form?
- taurodontism
- accessory roots
- dilaceration
- enamel pearl
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
What is gemination?
Incomplete attempt of tooth germ to divide into two
(the single bud has attempted to divide when it should not have)
What is fusion?
Complete or partial fusion between dentine/enamel of two separate teeth
(Fusion of more than one tooth bud)
What are the management principles for double teeth?
- malocclusion
- crown width
- root morphology
- may require CBCT
- multidisciplinary meeting
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
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
What are accessory cusps?
- supplemental cusps
- cusp of carabelli most common (seen on maxillary molars)
- does not contain pulp
- limited/no clinical significance
What is dens evaginatus/talon cusp?
Cusp like elevation located in the central groove
- contains pulp
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%
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
What is dens invaginatus/dens in dante?
Deep surface invagination of crown that is lined by enamel.
- represents an accentuation of the lingual pit
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
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
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
What is taurodontism?
- bull like teeth
- multirooted teeth where body and pulp is enlarged at the expense of the roots
Which teeth are most affected by taurodontism?
6.3% of mandibular molars
What diseases are taurodontism associated with?
- amelogenesis imperfecta
- klinefelter’s syndrome
- tricho-dento-osseous syndrome
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
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%
What are enamel pearls?
Ectopic mass of enamel on the roots, normally at the furcation area.
