Dental Anomalies I Flashcards
How are teeth formed?
Ectoderm of facial process and mesenchymal cells from neural crest lead to differentiation, forming ameloblasts and odontoblasts
Advanced specialisation of cells
Stages of tooth development?
Initiation
Morphodifferentiation
Cytodifferentiation
- Crown formed 1st
- Then root formation
What occurs in tooth initiation?
Starts tooth formation and ensures the right number of teeth in the correct location in the jaws
What occurs in tooth morphodifferentiation?
Formation of teeth of the correct shape
What occurs in tooth cytodifferentiation?
Differentiation of cells to produce specific dental tissues
Types of dental anomalies impact what?
Structure
Shape/form
Size
Number
Aetiology of dental anomalies?
Genetic
- Genetic component - polygenic and environmental component
- Chromosomal anomalies e.g. down syndrome
- Single gene syndromes =e.g. ectodermal dysplasia
- Single genes of localised effect - maxillary lateral incisors
- Environmental insults e.g. rubella, irradiation
Environmental
- Localised (trauma, infec)
- Generalised (infec, drugs)
Cellular response to stimuli
- Developmental stage
- Adaptive range
- Stimulus severity, duration, interaction
- Individual’s response capacity
Anomalies regarding tooth number?
- Hypodontia (oligodontia = absence of more than 6 teeth primary or 2ndry)
- Supernumerary teeth (hyperdontia)
- Anodontia
Hypodontia features for primary teeth?
B more common
Maxillary > mandibular
F = M
0.1 - 0.9% caucasian
Hypodontia features for secondary teeth?
8 most common Max = mandibular 8>5>2>4 F:M 4:1 3.5-6.5% Mild, moderate, severe (oligo)
Aetiology of hypodontia?
Obscure
Polygenic, plus intrauterine systemic factor
Frequency increased with low birth weight, multiple births, increased maternal age
Single gene mainly for 2
PAX9, MSX1
What can hypodontia occur with?
Down syndrome
Rubella, thaliodomide embryopathy
What is severe hypodontia and microdontia linked with?
X linked hypohidrotic ectodermal dysplasia
AR chondroectodermal dysplasia
Cleft lip/palate
Types of supernumerary teeth?
Supplemental - normal series
Accessory - atypical form
Location - mesiodens (adjacent to midline structure)
What percentage of supernumerary teeth erupt?
25%
Where are supernumerary teeth most common?
Premaxilla
What can supernumerary teeth do?
Prevent eruption
Supernumerary teeth prevalence - primary and permanent?
Primary 0.2-0.8%
Permanent 1.5 - 3.5% unilateral
M:F 2:1
Maxilla:mandible 5:1
If someone has a primary supernumerary tooth premaxilla, how likely is it to occur in the permanent dentition?
30-50% of primary in premaxilla followed by permanent
Implications/associations of supernumerary teeth?
Invaginated teeth Palatal clefts Syndromes: - Cleidocranial dysplasia - Oral-facial-digital syndrome - Gardner syndrome
Who has smaller teeth?
Females have smaller teeth than males
Mirodontia and megadontia - define?
Micro = smaller teeth Megadontia = larger teeth
Tooth size anomalies?
Microdont
Megadont/macrodont (1, 5)
Whole tooth, crown or root
Isolated teeth, multiple, uni or bi-lateral
Microdontia features?
Unusual form, tapering
Primary teeth - uncommon 0.2-0.5%
Permanent 2.5%
F>M
Megadontia/macrodontia
- 1.1% permanent dentition
- Generalised - pituitary gigantism, unilateral facial hyperplasia
- Isolated megadont - hereditary gingival hyperplasia hypertrichosis
Aetiology of megadontia/macrodontia?
Mutlifactorial - polygenic and environment
For microdontia - single gene inheritance described, associated with Down, Ectodermal dysplasia
What can go wrong with tooth form?
Double teeth - fusion, gemination
Labial segment mand>max (primary)
1>2 (0.5-1.6%)
F = M
Why do abnormalities occur in tooth form?
Mode of development unclear Genetic? Minor notch to almost separate crowns Common pulp space, root canal Concrescences = fusion of 2 teeth due to excess cementum, occurs after tooth development
Chance of permanent anomalies in tooth form following double primary teeth?
30-50% caucasian
70% japanese
What can primary double teeth cause?
Delayed eruption due to retarded root resorption
Tooth form anomalies - accessory cusp features?
Carabelli (6s)
• Talon (1s + 2s) - Can impact occlusion
• Buccal cusp (paramolar tubercles)
(4s + 5s and molars)
Tooth form anomalies - invaginated tooth (odontome) features?
• Permanent (1 - 5%), maxillary incisors
- Enamel epithelium into dental papilla
- Dens in dente, invaginated odontome
- Deep cingulum pit
M:F 2:1
Bilateral symmetry (plus supernumeraries)
Enamel complete or incomplete
Dentine missing
Tooth form anomalies - evaginated tooth (odontome) features?
Premolars
Enamel epithelium or focal hyperplasia of ectomesenchyme
Rare in caucasians
Enamel, dentine, pulp
Tooth form anomalies - root size features?
- Large - 3’s
M > F (5 : 1) - Small - primary and permanent, dentine dysplasias
Irradiation - shortened roots
Racial variation
Tooth form anomalies - what is taurodontism?
Multi-rooted
Crown elongated corono-apically
ACJ constriction (cervix) absent
Syndromes and polygenic inheritance
Tooth form anomalies - accessory roots?
Carabelli tubercle
Paramolar tubercle
Enamel pearls
Trauma or genetic
Tooth form anomalies - pyramidal roots?
Mutlirooted (fused)
