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ortho year 4 > 1. Aetiology and extractions > Flashcards

1. Aetiology and extractions Flashcards

1
Q

Describe the main aetiological factors in malocclusions

A
  • GENERAL FACTORS
  • SKELETAL RELATIONSHIP
  • TOOTH SIZE / ARCH SIZE DISPROPORTION
  • soft tissues
  • genetic and developmental disorders
  • TMJ trauma / growth abnormalities
  • LOCAL FACTORS (more important to us as they are the ones we can identify and prevent/ treat in children/adolescents)
  • EARLY LOSS / PROLONGED RETENTION OF DECIDUOUS TEETH
  • ECTOPIC TEETH
  • Absent teeth, supernumeraries
  • Impaction, delayed eruption
  • Fraenum, local pathology
  • Dental trauma
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2
Q

Describe the main local factors and anomalies that may present in the developing dentition

A
  • Deciduous Teeth
    – Early loss or prolonged retention of deciduous teeth
  • Permanent: number of teeth
    –Absent teeth
    –supernumeraries
    –early loss (6s, 1s)
  • Permanent: position of teeth
    –ectopic canines
    –impaction of 1st molars, or premolars
  • Fraenum
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3
Q

what are the effects of early loss of upper E

A

impacted and crowded lower premolar

(E extracted due to caries)
6 drifting mesially and not leaving enough space for the 4 and 5 ie posterior crowding

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4
Q

Fitted in patient who has lost both lower Es-
(to prevent the 6 drifting forwards

A

Space maintainers ie lingual arch (fixed)

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5
Q

Early Loss of Deciduous Teeth
Effects depend on:

A
  • Tooth lost
  • Age
  • Degree of Crowding in the Arch
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6
Q

Effects of early loss of deciduous teeth- tooth loss

A

–D, E space loss as 1st permanent molars drift mesially
(causes premolar crowding)
–C incisor midline shift as permanent incisors drift into
space
–A, B minimal effect

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7
Q

Effects of early loss of deciduous teeth- age

A

–Effects more severe with earlier loss

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8
Q

Effects of early loss of deciduous teeth- degree of crowding in the arch

A

–more space loss with D or E loss if crowding present
– greater midline shift with C loss if perm incisors crowded

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9
Q

Prolonged Retention of Deciduous
Teeth
(how common, which teeth and effects? what happens?)

A
  • Relatively common
  • Usually Es or Ds (radiograph re. successor)
  • May delay permanent successor
  • May become “submerged” or “infraoccluded” due to ankylosis
    –tipping of adjacent teeth (first molars)
    –almost all exfoliate naturally
    –extract only if becoming completely submerged
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10
Q

Developmental Absence of
Permanent Teeth (“Hypodontia”)
how common and what other type of lack of teeth canyou have?

A

Relatively common (2-3%)
* Anodontia (complete absence)

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11
Q

what are the most common teeth missing? and what is severe hypodontia?

A

excluding 3rd molars:
upper laterals, then 2nd premolars, and lower central incisors

6 or more missing teeth (excluding 8s)

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12
Q

Tx of hypodontia?

A
  • space closure
  • Open or maintain space then bridgework / implants / denture
  • accept (e.g. lower 5s)
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13
Q

Hypodontia: Upper Laterals
. how common
. associated with?
. Tx?

A
  • Common (2-3%)
  • Associated with ectopic canines and small
    contralateral lateral incisors
    *–space closure (crowding, Class II cases, 3s acceptable)
    –bridgework (no crowding, 3s poor colour)
    –usually need fixed appliances
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14
Q

Absent Second Premolars
- how common?
- can appear on Rx as late as?
- Tx?
- Prognosis?

A
  • Common (2%)
  • Can appear on radiographs as late as age 8 years
  • – space closure (extract deciduous early)
    – bridgework
    – use space to treat crowding
    – accept and retain Es
    0 uncertain, unusual to last beyond age 30
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15
Q

Absent Lower Central Incisors- features?
treatment?

A
  • Rare
  • A`s usually retained
  • Close space or bridgework
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16
Q

Supernumerary Teeth ($)
incidence? and location?

A
  • Incidence 1-2%
  • 80% are in the anterior maxilla
    (* OPG
  • anterior occlusal)
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17
Q

Supernumary teeth classification?

A
  • Morphology (Coniform and Tuberculate)
  • Position (Mesiodens, Supplemental, Paramolar)
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18
Q

Supernumary teeth clinical effects?

A
  • delayed eruption of teeth (e.g. Upper centrals)
  • may erupt (mesiodens), crowding
  • midline diastema (mesiodens)
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19
Q

Supernumerary Teeth: Treatment

A
  • No treatment
  • Extract
  • Exposure and alignment of teeth with delayed eruption (Upper incisors)
  • However, more than 70% of unerupted upper central incisors will erupt following removal of a supernumerary tooth
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20
Q

Impacted teeth

A
  • First permanent molars
  • Premolars
  • Third molars
21
Q

Impacted Teeth: Perm First Molars
incidence
location
prognosis?

A

3-4 percent
almost always in maxilla
2/3 will correct spontaneously, although unlikely to improve after 8 years

22
Q

treatment of impacted permenant first molars?

A
  • extraction of E
  • Simple URA to disimpact
23
Q

Impacted Teeth: Premolars
- what tooth and why

A

Usually 2nd premolars
Early loss of E

24
Q

Tx of impacted premolars

A
  • Extract 4 to allow eruption of 5
  • Extract 7 and distalise 6 to create space
  • Extract 5 (surgical)
  • No treatment and review regularly
25
Q

Ectopic Maxillary Canines
incidence?

A

2 percent
see separate lecture

26
Q

Local Factors: Labial Fraenum-
what is it and sometimes associated with?

A

Abnormally thick upper labial fraenum
* midline diastema

27
Q

Treatment of labial fraenum?

A
  • wait until upper canines erupted before
    treating
  • fraenectomy during or after space closure
28
Q

Early loss of Permanent Teeth- with which?

A
  • 1st molars (caries)
  • Upper incisors (trauma)
29
Q

Early loss of Permanent 1st Molars
* Why is it a problem?

A
  • Residual space
  • overeruption of opposing first molar
  • space is difficult to use with appliances for treating anterior crowding or overjet
30
Q

ideal age for spontaneous closure of 6s?

A

8-9

31
Q

features of early loss of 6s?

A

upper spaces close better than lower
unopposed 6s overerupt

32
Q

what is minimal with early loss of 6s?

A

midline shift with unilateral loss of a 6

33
Q

management of carious 1st molars is done how?

A

extraction best at age 8-9

34
Q

risk of later extraction?

A

tipping

35
Q

consideration for extraction of carious 6s

A

extraction of both upper and lower

36
Q

lower 3rd molars?

A

very weak associated with lower incisor crowding
later lower incisor crowding alone is not an indication for lower 3rd molar extraction

37
Q

urgical removal of impacted third molars should be limited to patients with

A

evidence of pathology

38
Q

Early Loss of Permanent Upper
Incisors is due to … and is seen in

A

trauma
class II Div 1

39
Q

early loss of permenant upper incisors is associated with

A

poor lower lip coverage

40
Q

treatment of early loss of permenant upper incisors?

A

try to save if at all possible, (RCT, re-implant)

41
Q

what are the options if lost or unsavable permanant upper incisors?

A
  • Maintain space with prosthesis
  • Close space orthodontically and crown lateral poor gingival margin & canine colour
42
Q

abnormal tooth form?

A
  • Dilaceration of permanent upper incisors
  • Peg shaped upper lateral incisors
  • strong association with ectopic canines
  • other lateral may be absent
43
Q

what is dilaceration of upper lateral incisor, due to what

A
  • root bent
  • trauma to deciduous predecessor, age 4-5
44
Q

prognosis of dilacerated upper lateral

A
  • delayed or non-eruption
  • orthodontic alignment sometimes possible
45
Q

peg shaped upper laterals have a strong association with … and the … may be absent

A

ectopic canines
other lateral

46
Q

most malocclusions are the result of complex and poorly understood interaction of

A

genetic and environmental factors

47
Q

… and … are superimposd on the genetic background

A

habits and local factors

48
Q

simple measures can solve and treat successfully

A

local factors and habits

49
Q

more complex treatment may be needed for

A

skeletal problems and tooth-arch size disproportions (crowding and spacing)

ortho year 4 (11 decks)

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