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BDS3 Orthodontics > Aetiology of Malocclusion II > Flashcards

Aetiology of Malocclusion II Flashcards

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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?

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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
26
Loss of what primary teeth have the biggest impact on crowding?
molars
27
Describe where space loss occurs the most with regards to molars? How do we treat if molars lost early?
- 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
What factors influence the impact on the loss of 6s?
- age at loss - crowding - malocclusion (if their a class 2 or 3)
29
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?
Ideally would extract at the time of bi-furcation development in the 7s
30
Why is it ideal to extract the 6's at the time of bi-furcation development in 7s?
- 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
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?
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
Do you need to do compensation extractions if have to remove a 6?
U6 = no compensation lower 6 = often compensation (but need specialist opinion)
33
Are balancing extractions required when removing 6's?
not if well spaced or well aligned Consider if there is premolar crowding
34
How would you deal with unscheduled loss of central incisors?
re-implant in the first instance -plane how to deal with the space (prosthetics?)
35
What are the different ways that a tooth can vary in size or form? (3)
- too large = macrodontia - too small = microdontia - abnormal form
36
What are the problems with macrodontia?
- crowding - asymmetry - aesthetics (is dealt with by both ortho and restorative team)
37
What are the problems with microdontia?
Leads to spacing Linked to hypodontia Note: can be localised or general
38
What are some examples of abnormal form of teeth ?
-peg shaped laterals 0dens in dente - germinated/fused teeth - talon cusps - dilaceration - accessory cusps and ridges
39
What are examples of abnormalities of tooth position?
- ectopic teeth - tranpositions
40
An ectopic tooth can be any tooth but what are the most common ectopic teeth that you get?
- 8's - upper canines - first permament molars (6's) - upper centrals
41
Are ectopic canines more often buccal or palatal?
Palatal (80%)
42
When should you be checking for ectopic canines?
From 9 years onwards
43
How do you do a clinical assessment for ectopic canines?
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
How many radiographs do you need to take to localise an ectopic canine and what are these normally?
2 OPT and anterior occlusal normally (but not always)
45
What are the 5 management options for ectopic canines?
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
Ectopic 1st molars are more common in what arch?
Upper
47
How do you manage an ectopic 1st molar?
- Use separate - attempt distalise 6 - extract e
48
For ectopic upper central incisors you want to check for what and why?
check for sequence and symmetry Incase of supernumerary or dilaceration
49
What are possible treatements of ectopic upper central incisors?
- surgical exposure, removal of supernumerary (if one) and bond gold chain - make space - ortho traction if above 9 - bonded retainer
50
What is the definition of transpositoins?
Interchange of the postion of 2 teeth
51
What are the classifications for transpositions?
true = both crown and root switch place pseudo/false = crowns switched but roots in normal place
52
Where are transpositions normally found?
upper canines and first premolar Lower canines and incisors
53
What are the treatment options for transpositions?
- accept - extract - correct
54
What are some local abnormalitis of soft tissues that can cause malocclusions?
- digit sucking - frenum - tongue thrust
55
What are some of the clinical signs of a non-nutritional (digit) sucking habit?
- proclines upper incisors - Retroclines lower incisors - anterior open bite - unilateral posterior crossbite
56
What can be the problems with a labial frenum?
May cause median diastema (the gap found between central incisors)
57
Tongue thrusting can cause malocclusion?
anterior open bite
58
What are some local pathologies that can cause malocclusions?
- caires (loss of tooth substance - substantial caries) - cysts - tumours Pic shows possible cyst

BDS3 Orthodontics (11 decks)

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