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BDS3 Orthodontics > Aetiology of Malocclusion II > Flashcards

Aetiology of Malocclusion II Flashcards

1
Q

The aetiology of malocclusion can be classified in what 4 different ways?

A
  • Skeletal
    • Class III, high FMPA
  • Dental
    • Missing teeth
  • Soft Tissue
    • Lip traps etc
  • Other
    • Habits
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2
Q

What is the definition of a local cause of malocclusion?

A

a localised problem or abnormality within either arch, usually confined to one, two or several teeth producing a malocclusion

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3
Q

Why is it good to recognise a local cause of malocclusion early?

A

As they tend to get worse with time and there is scope for interceptive treatment if recognised early

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4
Q

What are the local causes of malocclusion (5 groups)?

A
  • Varitation in tooth number
  • Variation in tooeh size or form
  • Abnormalities of tooth position
  • Local abnormalities of soft tissue
  • Local pathology
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5
Q

What could result in the variation in tooth number? (then being a local cause of malocclusion)

A
  1. Supernumerary teeth
  2. Hypodontia (developmentally absent teeth)
  3. Retained primary teeth
  4. Early loss of primary teeth
  5. Unschedules loss of permanent teeth
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6
Q

What is a supernumerary tooth?

A

a tooth or tooth-like entity which is additional to the normal series

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7
Q

Where are supernumerary teeth more commonly found?

A

In anterior maxilla and more common in males than females

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8
Q

What are the 4 types of supernumerary teeth you can get?

A
  • conical
  • tuberculate
  • supplemental
  • odontome
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9
Q

Describe conical supernumerary teeth.

A
  • are small peg shaped
  • they may erupt
  • tend to have 1 or 2 in number
  • they tend not to prevent eruption BUT may displace adjacent teeth
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10
Q

What are conical teeth found close to the midline called?

A

Mesiodens

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11
Q

Describe tuerculate supernumerary teeth.

A
  • tend not to erupt
  • barell shaped and paired
  • usually have to be extracted
  • are one of the mian causes of failure of eruption of permanent upper incisors
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12
Q

Describe supplemental supernumerary teeth. How are they dealt with?

A
  • are extra teeth of normal morphology
  • most often upper laterals or lower incisors (but can be premolars or molars)
  • often extracted depending on what tooth looks the best and is in the best position
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13
Q

What kinds of odontone supernumerary teeth can you get?

A

Compound - discrete denticles (tooth like structure)

Complex - diaorganised mass of dentine, pulp and enamel

Note: an odotome/odontoma means a benign tumour

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14
Q

What is hypodontia?

A

Developmental absence of one or more teeth

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15
Q

When should you be concerned/start thinkning that a patient may be retaining their primary teeth?

A
  • if theres a disruption in the sequence of eruption
  • A difference of more than 6 months between the shedding of contra-lateral teeth should ring alarm bells
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16
Q

Why might a patient have retained primary teeth?

A
  • absent successor
  • ectopic successor or dilacerated
  • ankylose primary molars (fused to bone)
  • Dentally delayed in terms of development
  • pathology/supernumerary
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17
Q

What is dilaceration of a tooth?

A

When the root of a prrimary tooth goes into the developing follicle of the permanent successor

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18
Q

What are your treatment options when you have retained primary teeth with no permanent successor?

A
  • maintain primary tooth a long as possible (if good prognosis)
  • Extract deciduous tooth early to encourgae spontaneous space closure in crowded cases
  • Early orthodontic referral for advice
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19
Q

Why might infra-occluded primary molars look like they are sinking? (temp ankylosis)

A

-the tooth has just not moved and has therefore failed to maintain its occlusal relationship with adjacent teeth

Note: Can be slight, moderate or severe

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20
Q

How do you manage infra-occluded primary molars if there is a permanent successor present?

A

-monitor as they usually correct themselves

Would consider extraction if:

  • contact points are going subginigval
  • root formation of the successor is near completion
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21
Q

How do you manage infra-occluded primary molars if there is NOT a permanent successor present?

A

It will depend on the potential of crowding:

-retain if in good condition (onlay)

OR

-extract and plan space management

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22
Q

Early loss of primary teeth can cause localised crowding. What does the liklihood of this happening depend on?

A
  • which tooth is extracted
  • when the tooth is extracted
  • patients inherent crowding
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23
Q

What is a balancing extraction? Why would you do it?

A

Extracting the same tooth that has been lost early from the opposite side of the same arch

Is done to minimise mid-line shift

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24
Q

What is a compensating extraction and what is it used to do?

A

It extracts the tooth from the opposing arch on the same side as the tooth that has been lost early

Done to maintain occlusal relationhip

25
Q
A
26
Q

Loss of what primary teeth have the biggest impact on crowding?

A

molars

27
Q

Describe where space loss occurs the most with regards to molars?

How do we treat if molars lost early?

A
  • more space loss in upper than lower
  • more space loss with e’s to d’s
  • 6’s drift mesially and steal 5 place
  • look for space maintainer and can refer for a second opinion
28
Q

What factors influence the impact on the loss of 6s?

A
  • age at loss
  • crowding
  • malocclusion (if their a class 2 or 3)
29
Q

Loss of 6s in the upper arch isnt as time critical but in the lower arch, when is the best time to extract 6’s?

A

Ideally would extract at the time of bi-furcation development in the 7s

30
Q

Why is it ideal to extract the 6’s at the time of bi-furcation development in 7s?

A
  • if extract once the lower 7 has erupted (late) then often get poor space closure
  • If extract too early then thr 5 tends to drift distally into the space
31
Q

The impact of the loss of 6’s is also influenced by the degree of crowding. If a 6 is extracted from the upper arch, there is potential for what?

If a 6 is extracted from lower arch, what are the 3 possible scenarios?

A

Rapid space loss especially if there is crowding

Spaced dentition = will have spaces

Aligned dentition = will have spaces

Crowded = best results likley (space will be ultilised)

32
Q

Do you need to do compensation extractions if have to remove a 6?

A

U6 = no compensation

lower 6 = often compensation (but need specialist opinion)

33
Q

Are balancing extractions required when removing 6’s?

A

not if well spaced or well aligned

Consider if there is premolar crowding

34
Q

How would you deal with unscheduled loss of central incisors?

A

re-implant in the first instance

-plane how to deal with the space (prosthetics?)

35
Q

What are the different ways that a tooth can vary in size or form? (3)

A
  • too large = macrodontia
  • too small = microdontia
  • abnormal form
36
Q

What are the problems with macrodontia?

A
  • crowding
  • asymmetry
  • aesthetics

(is dealt with by both ortho and restorative team)

37
Q

What are the problems with microdontia?

A

Leads to spacing

Linked to hypodontia

Note: can be localised or general

38
Q

What are some examples of abnormal form of teeth ?

A

-peg shaped laterals

0dens in dente

  • germinated/fused teeth
  • talon cusps
  • dilaceration
  • accessory cusps and ridges
39
Q

What are examples of abnormalities of tooth position?

A
  • ectopic teeth
  • tranpositions
40
Q

An ectopic tooth can be any tooth but what are the most common ectopic teeth that you get?

A
  • 8’s
  • upper canines
  • first permament molars (6’s)
  • upper centrals
41
Q

Are ectopic canines more often buccal or palatal?

A

Palatal (80%)

42
Q

When should you be checking for ectopic canines?

A

From 9 years onwards

43
Q

How do you do a clinical assessment for ectopic canines?

A
  1. Look for canine bulge and palpate the buccal aspect
  2. Inclination of the 2’s (may be pushing on the root)
  3. Mobility of the 2 or c
  4. Colour of the 2 or c
44
Q

How many radiographs do you need to take to localise an ectopic canine and what are these normally?

A

2

OPT and anterior occlusal normally (but not always)

45
Q

What are the 5 management options for ectopic canines?

A
  1. prevention
  2. Extraction of c to encourage imporvement of position of the 3 (interceptive)
  3. Reatin the 3 and observe (accept its position and have a contact between the 2 and 4)
  4. Surgical exposure and ortho alignment
  5. Surgical extraction

Note: autotransplantion was also an option but not really done (remove it from where it is and place it in new position)

46
Q

Ectopic 1st molars are more common in what arch?

A

Upper

47
Q

How do you manage an ectopic 1st molar?

A
  • Use separate
  • attempt distalise 6
  • extract e
48
Q

For ectopic upper central incisors you want to check for what and why?

A

check for sequence and symmetry

Incase of supernumerary or dilaceration

49
Q

What are possible treatements of ectopic upper central incisors?

A
  • surgical exposure, removal of supernumerary (if one) and bond gold chain
  • make space
  • ortho traction if above 9
  • bonded retainer
50
Q

What is the definition of transpositoins?

A

Interchange of the postion of 2 teeth

51
Q

What are the classifications for transpositions?

A

true = both crown and root switch place

pseudo/false = crowns switched but roots in normal place

52
Q

Where are transpositions normally found?

A

upper canines and first premolar

Lower canines and incisors

53
Q

What are the treatment options for transpositions?

A
  • accept
  • extract
  • correct
54
Q

What are some local abnormalitis of soft tissues that can cause malocclusions?

A
  • digit sucking
  • frenum
  • tongue thrust
55
Q

What are some of the clinical signs of a non-nutritional (digit) sucking habit?

A
  • proclines upper incisors
  • Retroclines lower incisors
  • anterior open bite
  • unilateral posterior crossbite
56
Q

What can be the problems with a labial frenum?

A

May cause median diastema (the gap found between central incisors)

57
Q

Tongue thrusting can cause malocclusion?

A

anterior open bite

58
Q

What are some local pathologies that can cause malocclusions?

A
  • caires (loss of tooth substance - substantial caries)
  • cysts
  • tumours

Pic shows possible cyst

BDS3 Orthodontics (11 decks)

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