Aetiology of Malocclusion 2 - Local Causes, Part 2 Flashcards
How can teeth vary in size or form?
Too large - macrodontia
Too small - macrodontia
Abnormal form
Describe macrodontia
Tooth/teeth larger than average
Can be localised or generalised
Can cause crowding, asymmetry and aesthetic problems
Describe microdontia
Tooth/teeth smaller than average
Localised or generalised
Leads to spacing
Linked to hypodontia
Give examples of abnormal form of teeth
Peg shaped laterals
Dens in dente
Germinated/fused teeth
Talon cusps
Dilaceration
Accessory cusps and ridges
Which teeth are most likely to be ectopic?
Third molars (8s)
Upper canines (3s)
First permanent molars (6s)
Upper centrals (1s)
Describe the prevalence of ectopic maxillary canines
Affects 1-3% of population
80% are palatal
Describe ectopic canines
Have a long path of eruption (eye teeth)
Palatal canines often occur in well aligned arches
Higher incidence in absent/peg shaped laterals and in class II div 2 incisor relationship
Buccal canines more associated with crowding
What happens in a clinical assessment of ectopic canines?
- Visualisation/palpating of any obvious bumps of 3
- Inclination of 2s
- Mobility of Cs or 2s
- Colour of Cs or 2s
How are ectopic canines found on radiographs?
2 radiographs needed to localise position - usually OPT and upper anterior oblique occlusal
Use parallax technique: 3 Ps - presence, position, pathology
What are the management options for ectopic canines?
Prevention
Extraction of c to encourage improvement in position of 3 (interceptive)
Retain 3 and observe (accept its position)
Surgical exposure and orthodontic alignment
Autotransplantation
What aids in prevention of ectopic canines?
Appropriate monitoring from age 9 onwards
Clinical assessment
Symmetry
How are palatally ectopic canines treated?
Surgically exposed and aligned with fixed appliances
Describe the prevalence of ectopic first molars
Affects less than 5% of population
Reversible before the age of 8
Caries risk
What are the signs of ectopic first molars?
Crowding (greater in cleft lip and palate)
Mesial path of eruption
Abnormal morphology of E
How can ectopic first molars be managed?
- Separator
- Attempt to distalise 6
- Extract E
How can ectopic upper central incisors be prevented?
Check for sequence and symmetry
What are the possible causes of ectopic upper central incisors?
May be no obvious cause
Supernumerary - tuberculate or odontome
Trauma to primary predecessor - ankylosis of primary tooth, displacement of tooth germ, dilaceration of tooth
What are transpositions and how are they classed?
Interchange in the position of two teeth
Can be true or pseudo
Which teeth are most commonly affected by transposition?
Upper canines and first premolar
Lower canines and incisors
What are the treatment options for transpositions?
Accept
Extract
Correct
Give examples of causes of local abnormalities of soft tissues?
Digit sucking
Fraenum
Tongue thrust
What may be caused by a non-nutritional digit sucking habit?
Proclined upper incisors
Retroclined lower incisors
Anterior open bite
Unilateral posterior crossbite - due to narrow maxillary arch, may cause mandibular displacement
What is the negative consequence of a labial frenum?
May cause a median diastema
Which local pathology may cause malocclusion?
Caries
Cysts
Tumours
