Third Molars Flashcards

1
Q

give 2 causes of lack of space in dental arch - causing impaction.

A

evolutionary changes & lack of an abrasive diet

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2
Q

what are the top 5 most commonly impacted teeth?

A
  1. lower 8s
  2. upper 3s
  3. lower 3s, 4s and 5s
  4. upper 1s and 2s
  5. upper 8s
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3
Q

why are lower 8s the most commonly impacted?

A

they erupt the latest

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4
Q

what causes malpositioning of ectopic and displaced teeth?

A

ectopic - congenital factors
displaced - nearby pathology

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5
Q

what happens to teeth at the level of a jaw fracture?

A

they are rendered non vital

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6
Q

when is it not necessary to XLA impacted lower 8s?

A

asymptomatic, pt has no complaints, XLA risks nerve damage

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7
Q

what is pericorinitis?

A

inflammation of tissues around crown of partially erupted or impacted tooth

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8
Q

symptoms of pericorinitis & when to refer

A

pain, swelling, dysphagia, bad taste, malaise, may lead to cellulitis - if 2 or more cases then refer

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9
Q

is operculotomy recomended?

A

no as will just re-grow

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10
Q

list local measures for pericoronitis

A

irrigate w/ saline, OH measures, remove trauma

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11
Q

what can be done if indentations/trauma seen on operculum?

A

XLA or grind down cusps of opposing 8

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12
Q

when should pt be given antibiotics for pericorinitis? (3) what antibiotic & dose?

A

is systemically unwell
immunocompromised
if cannot drain locally - trismus, pt uncompliant
metranidazole 400mg 3x daily for 3 days

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13
Q

what microbes are involves in pericoronitis?
what 2 bacteria are involved in increased pocket depths between 2nd & 3rd molars?

A

anaerobic
prevotella intermedia & campylobacter rectus associated w/ inc pocket depths of 2nd and 3rd molars

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14
Q

list tx options for impacted lower 8s

A

do nothing, XLA, coronectomy

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15
Q

what radiograph is used to assess lower 8s?

A

half/whole DPT - PA is 2nd choice

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16
Q

what indicates close proximity of 8 to ID canal?

A

darkening, deflection or loss of lamina dura of ID canal as roots pass
roots of teeth get darker or deflect as they pass ID canal
juxta apical area - radiolucent area lateral to tooth

17
Q

what is the most common type of impaction?

A

mesial 1st
vertical 2nd

18
Q

when may CBCT be used to assess impacted 8?

A

when DPT suggests 8 close to IDC/high risk for XLA

19
Q

what is neuropraxia and when is it caused?

A

apex of tooth rubbing against IDC - mildest form of nerve damage

20
Q

how common is change in sensation to lower lip and tongue post XLA?
when should pt be informed of a risk?

A

lower lip - 5% short term, <1% long term
tongue - 10% short term, <1% long term
pt should be informed when risk >5%

review pt after 3 months to assess if long term damage has occured

21
Q

what procedure is indicated when high risk/tooth too close to IDN for XLA? what are risks of this procedure

A

coronectomy - leave roots behind
root migration and infection

22
Q

what flap should be done for lower impacted 8s?
explain design of this flap

A

triangular (3 sided)

distal relieving incision - up ascending ramus
round crown of 8 and half of 7 - include papilla between 7 and 8
mesial relieving incision - from centre of 2nd molar down depth of sulcus

23
Q

when is a 2 sided flap used? what incisions are made?

A

used if pericoronal pathology or cyst
distal relieving incision - up ascending ramus
round crown of 8 and all of 7 - ends just distal to 6

24
Q

what is used to remove bone? why and where is bone removal carried out?

A

round bur in surgical hand piece (chisels no longer used)
create a point of elevator application
create a narrow gutter mesiobuccally

25
Q

when are crown/roots sectioned/divided? (3)

A

horizontally impacted
distoangular crown
pincer roots w/ diff paths of removal

26
Q

what flap should be used for horizontally impacted 8? what must be done after flap raised? (3)

A

triangular
bone removal, section crown at ACJ, section roots at furcation

27
Q

intrinsic & extrinsic obstacles for XLA

A

intrinsic - root morphology
extrinsic - bone, adj teeth, ID canal

28
Q

what should you never do when elevating?

A

use adj tooth as fulcrum

29
Q

what is the most important suture of the flap?

A

suture placed from buccal to lingual tissues immediately distal to 7

30
Q

what material is used for suturing? when are sutures removed?

A

3/0 vicryl rapide
dissolve after 1 week

31
Q

maxillary 8s - thickness of bone, root shape/number, angle/impaction, positioning

A

thin cortical bone
short single conical fused root
mesioangled or vertically impacted - often very buccally placed

32
Q

what should be done to manage impacted upper 8? how many sutures to reposition flap?

A

buccal flap
remove thin friable bone w/ couplands
use elevator to move tooth down, back and buccally
use one suture to reposition flap

33
Q

what is the order of tx planning?

A
  1. path of withdrawal
  2. obstacles
  3. point of application
  4. bone removal
  5. flap design

backwards to how it is carried out
POPBF