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BDS3 ORTHODONTICS > 4 - Local causes of malocclusion > Flashcards

4 - Local causes of malocclusion Flashcards

1
Q

Define a local cause of malocclusion.

A

Localised problem or abnormality within either arch, usually caused by one, two or several teeth producing a malocclusion

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2
Q

What are categories of local causes of malocclusion?

A
  • variation in tooth number
  • variation in tooth size or morphology
  • tooth position
  • abnormalities of soft tissues
  • local pathology
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3
Q

Describe different ways in which tooth number can vary.

A
  • supernumerary teeth
  • hypodontia
  • retained primary teeth
  • early loss of primary teeth
  • unscheduled loss of permanent teeth
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4
Q

What are supernumerary teeth?

A
  • tooth or tooth like structure which is additional to the normal amount of teeth
  • most commonly found in anterior maxilla
  • more common in males
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5
Q

What are the different types of supernumerary teeth?

A
  • conical
  • tuberculate
  • supplemental
  • odontome
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6
Q

Describe a conical supernumerary tooth.

A
  • small, peg shaped
  • close to midline
  • may erupt
  • do not prevent eruption but can displace adjacent teeth
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7
Q

Describe a tuberculate supernumerary tooth.

A
  • do not erupt
  • paired
  • barrel shaped
  • can cause permanent upper incisors to not erupt
  • usually extracted
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8
Q

Describe a supplemental supernumerary tooth.

A
  • extra tooth with normal morphology
  • most commonly upper laterals or lower incisors (can be premolars)
  • usually extracted based on treatment plan
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9
Q

Describe an odontome supernumerary tooth.

A
  • two types, compound and complex
  • compound are discreet denticles
  • complex are a disorganised mass of dentine, pulp and enamel
  • require extraction
  • can prevent eruption of surrounding teeth
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10
Q

Define hypodontia.

A

Developmental absence of one or more teeth

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11
Q

Describe the prevalence of hypodontia.

A
  • more common in females
  • hereditary
  • most commonly affects upper laterals and second premolars
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12
Q

When should you investigate retained primary teeth?

A

Difference of more than 6 months between exfoliation of contralateral teeth

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13
Q

What are causes of retained primary teeth?

A
  • absent successor
  • ectopic successor or dilacerated
  • ankylosed primary molars (can become infraoccluded)
  • delayed development
  • pathology
  • supernumerary
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14
Q

What is the management for an absent successor?

A
  • maintain primary tooth as long as possible
  • extract early to encourage spontaneous space closure
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15
Q

Define an infra-occluded primary molar.

A
  • process where tooth fails to achieve or maintain occlusal relationship with opposite teeth
  • tooth appears to become more submerged under gingiva
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16
Q

Define slight infra-occlusion.

A

Between occlusal surface and interproximal contact, less than 2mm

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17
Q

Define moderate infra-occlusion.

A

Within occluso-gingival margins of interproximal contact

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18
Q

Define severe infra-occlusion.

A

Below interproximal contact point

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19
Q

What are the causes of early loss of primary teeth?

A
  • trauma
  • periapical pathology
  • caries
  • resorption by successor
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20
Q

Define a balancing extraction.

A
  • extraction of tooth from opposite side of side arch
  • designed to minimise midline shift
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21
Q

Define a compensating extraction.

A
  • extraction of tooth from opposing arch of the same side
  • designed to maintain occlusal relationship
22
Q

What is the management of early loss of primary incisors?

A
  • little impact
  • no compensating or balancing extraction
23
Q

What is the management of early loss of primary canines?

A
  • unilateral loss in crowded arch can cause midline shift
  • consider balancing extraction
24
Q

What is the management of early loss of primary molars?

A
  • more space loss with Es than Ds
  • more space loss in upper than lower (roots are mesial of crown so tilt more easily)
  • 6s drift mesially and impinge on space for 5s
  • no compensating extraction
25
Q

At what age do you assess prognosis of 6s?

A

8-9 years

26
Q

How does loss of 6s affect the upper arch?

A

Potential for rapid space loss

27
Q

How does loss of 6s affect the lower arch?

A
  • spaced dentition will be left with spaces
  • aligned dentition will be left with spaces
  • crowded dentition will be left more aligned if extracted early
28
Q

What effect does timing have on the unscheduled loss of permanent central incisors?

A
  • early results in drift of adjacent teeth
  • late results in permanent space
29
Q

How should you manage unscheduled loss of permanent central incisors?

A
  • reimplant
  • simple denture
  • if lateral shift, reopen space for prothesis or build up lateral to mimic central
30
Q

Define macrodontia.

A
  • tooth is larger than average
  • can be localised or generalised
  • causes issues with crowding, asymmetry and aesthetics
31
Q

Define microdontia.

A
  • tooth smaller than average
  • can be localised or generalised
  • leads to spacing
  • linked with hypodontia
  • genetic link
  • can be managed by composite bonding
32
Q

Describe the different abnormal forms teeth can take.

A
  • peg laterals
  • dens in dente (communication to pulp from enamel)
  • geminated teeth
  • talon cusp
  • dilaceration
  • accessory cusps or ridges
33
Q

What teeth are more commonly ectopic?

A
  • 8s
  • upper 3s
  • 6s
  • upper 1s
34
Q

Where are ectopic canines typically found?

A

80% palatal

35
Q

What circumstances are ectopic canines typically associated with?

A
  • class 2 div 2
  • small or absent upper laterals
  • due to long path of eruption
36
Q

What makes up the clinical assessment for ectopic canines?

A
  • palpate for buccal canine bulge from 9 years
  • inclination of laterals (distally)
  • mobility of c or 2s
  • colour of c or 2s
37
Q

How are radiographs used to assess ectopic canines?

A
  • 2 required, OPT and upper anterior oblique occlusal
  • parallax technique (canine moves up = palatal side)
38
Q

What are the management options of ectopic canines?

A
  • prevention
  • extract C to encourage 3 to erupt in correct position (interceptive)
  • retain and accept position
  • surgical exposure and orthodontic alignment
  • surgical extraction
  • autotransplantation
39
Q

Describe ectopic 6s.

A
  • uncommon
  • more common in upper
  • reversible before age of 8
  • caries risk
40
Q

What does an ectopic 6 indicate?

A
  • crowding (common in CLP)
  • mesial path of eruption
  • abnormal morphology of Es
41
Q

How you manage ectopic 6s?

A
  • distalise 6s
  • extract Es or allow to exfoliate
42
Q

Define transposition.

A

Interchange in position of two teeth

43
Q

What are the classes of transposition?

A
  • true = crown and root aligned
  • pseudo = crown has moved position but roots are crossed
44
Q

Where are transpositions most common?

A
  • upper 3s and 4s
  • lower canines and incisors
45
Q

What are the treatment options for transpositions?

A
  • accept
  • extract
  • (correct)
46
Q

What are the soft tissue causes of malocclusion?

A
  • digit sucking
  • tongue thrust
  • frenum
  • lip strap
47
Q

What are the consequences of digit sucking?

A
  • proclined upper incisors
  • retroclined lower incisors
  • AOB
  • unilateral posterior crossbite (due to narrowed maxillary arch)
48
Q

How can a labial frenum influence tooth position?

A

Can cause median diastema

49
Q

What are the consequences of a tongue thrust?

A

AOB which relapses if treated

50
Q

What local pathology can effect tooth position?

A
  • caries
  • cysts
  • tumours
51
Q

How can cysts impact tooth position?

A
  • cause resorption of roots
  • move roots

BDS3 ORTHODONTICS (10 decks)

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