Aetiology of Malocclusion Flashcards
What is the definition of a local cause of malocclusion?
A localised problem or abnormality within either arch, usually confined to one, two or several teeth proceeding a malocclusion.
What is a supernumerary tooth/teeth?
A tooth or tooth like entity which is assertional to the normal series.
What are the four types of supernumerary?
Conical
Tuberculate
Supplemental
Odontome
What is a conical supernumerary?
Conical shaped extra tooth
Usually doesn’t impact eruption of the permanent tooth but can displace the adjacent tooth.
Usually close to the midline.
What is a tuberculate supernumerary tooth?
Tend not to erupt, barrel-shaped tooth.
Usually come in pairs.
Can cause permanent teeth to not erupt.
What is a supplemental supernumerary tooth?
Extra tooth of normal morphology.
Commonly upper laters or lower incisors.
Can be third molars, fourth molars.
What is hypodontia?
Developmental absence of one or more teeth.
Strong genetic component.
What are the most common teeth to be missing in a child?
Upper laterals and second premolars.
In terms of retention of primary teeth, what would set alarms bells off?
A difference of more than 6 months between shedding of contralateral teeth.
Investigate with radiograph (OPT).
Why might a primary tooth be retained in the mouth?
Lack of permanent successor
Ectopic successor
Infra-occluded primary molars
Dentally delayed in terms of development
Pathology/supernumerary
What are the treatment options for a patient with a retained primary tooth and no permanent successor?
Maintain primary tooth if good prognosis
Extract deciduous tooth early and encourage spontaneous space closure.
What does it mean if a tooth is infra-occluded?
Process where a tooth fails to achieve pt maintain it’s occluded relationship with adjacent teeth.
What signs would suggest a tooth is infra-occluded?
Ankylosis- lack of lamina dura on radiograph.
Tooth is below the occlusal surface with adjacent teeth.
Percussion sound.
What is the classification of infraoccluded teeth?
Slight- between occlusal surface and interpoximal contact, less than 2mm.
Moderate- Within occlusion-gingival margins of inter proximal contact.
Severe- Below inter proximal contact point.
Why might a patient prematurely loose a primary tooth?
Trauma
Caries
Periodical pathology
Resorption by successor
What is a balancing extraction?
By extraction of a tooth from the opposite side of the same arch.
What is a compensating extraction?
By extraction of a tooth from the opposing arch of the same side.
Why might you need to do a balancing or compensating extraction?
To maintain occlusal relationships.
Do you require a compensating or balancing extraction if you prematurely lose an incisor tooth?
No, not required.
Do you require a compensating or balancing extraction if you prematurely lose a canine?
Balancing extraction required because it can cause a centre line shift, maybe some medial drift of buccal segments.
What are the consequences of losing a primary molar tooth early?
Mesial drift of 6’s.
More space loss with e’s than d’s
More space loss in upper than lower.
When should 6’s be assessed for prognosis?
8-9 dental age
What factors influence the impact of the loss of 6’s?
Age at loss
Crowding
Malocclusion
How does age at loss of 6’s impact the dentition?
Upper arch doesn’t matter
Matters more in the lower arch
Lost too late- 7 doesn’t move into it’s place
Lost too early- distal drift of 5’s.
How does crowding impact the outcome for early loss of 6’s?
Crowding is desirable- best results for space closure.
If the dentition is aligned or spaced, more likely to have spaces.
How does early loss of a central incisor influence the dentition?
Lost too early- drifting of adjacent teeth
Lost too late- space not closed
You would aim to keep the space open with a denture, re-implant tooth.
What is macrodontia?
Tooth/teeth larger than average
What are some issues associated with macrodontia?
Crowding
Asymmetry
Aesthetics
What is microdontia?
Teeth smaller than average
What are some issues associated with microdontia?
Leads to spacing, linked to hypodontia.
What aspects could make a tooth abnormally formed?
Dens in dente
Peg shaped alterals
Fused teeth
Talon cusps
Dilaceration
Accessory cusps
What are the most common teeth to be ectopic?
Third molars
Upper canines
First permanent molars
Upper centrals
When should you palpate the buccal canine bulge?
9 years onwards to feel if they’re coming through.
If you cannot feel them at this age, then his would warrant further investigation.
What are the four key aspects of clinical assessment of ectopic canines?
Palpation of buccal canine bulge from 9 years upwards
Mobility of c’s and 2’s
Colour of c’s and 2’s
Inclination of 2’s
What radiographic technique would you employ to determine position of the canine?
OPT and upper anterior oblique occlusal.
- utilising parallax technique.
What factors are associated with ectopic canines?
Class 2 division 2 malocclusions
Absent/peg shaped upper laterals
Palatal canines associated with well-aligned arches
Buccal canines associated with crowding
What are the management options for ectopic canines?
Prevention
Extract c’s and encourage improvement in position of 3
Retain 3 and observe (accept position)
Surgical exposure and orthodontic alignment
Extraction (surgically)
Autotransplantation
What are the management options for an ectopic first molar?
Reversible before the age of 8
Separator
Attempt to distalise 6
Extract e
What could be the possible causes of an ectopic upper central incisor?
Supernumerary- tuberculate or odontome.
Trauma to primary tooth
- ankylosis of primary tooth
- Displacement of tooth germ
- Dilaceration of root
What is transposition?
Interchange in the position of two teeth.
What teeth are most commonly transposed?
Upper canines and first premolar
Lower canine and incisors
What are the clinical signs of a thumb sucking habit?
Proclaimed upper incisors
Retroclined lower incisors
Localised AOB or incomplete OB
Unilateral posterior cross bite due to narrow maxillary arch.
What might a prominent labial frenum cause?
Midline diastema.
Why might you want to do a balancing extraction?
Maintain the position of the dental centreline.
Why might you want to do a compensating extraction?
Maintain the buccal occlusion.
What is the consequence of early loss of deciduous teeth?
Localised crowding.
Which primary teeth require balancing extractions?
c’s and d’s
What conditions are associated with supernumeraries?
Cleft lip and palate
Down’s syndrome
Cleidocranial dysplasia
Gardner’s syndrome
