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BDS4 Oral surgery > third molars 1 > Flashcards

third molars 1 Flashcards

1
Q

what age radiographically is crown calcification begin for 3rd molars

A

between 7-10 years old

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2
Q

what age is crown calcification finished in 3rd molars

A

18

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3
Q

what age is root calficiation finished

A

18-25

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4
Q

what is agenesis

A

failure of an organ to develop

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5
Q

who is agenesis more common in

A

females and more common in maxilla
1 in 4 adults have at least 1 3rd molar missing

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6
Q

at what age would you suspect no 3rd molar to be present

A

if missing radiographically by age 14 would almost always fail to develop

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7
Q

what are M3Ms usually impacts against

A

adjacent teeth, alveolar bone, surrounding mucosal soft tissue or a combination of these factor

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8
Q

what is the incidence of impacted M3M

A

36-59%

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9
Q

what are the consequence of impacted M3M

A

caries, pericoronitis or cyst formation

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10
Q

what nerves are at risk during 3rd molar surgery

A

IAN
lingual nerve
nerve to mylohyoid
long buccal nerve

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11
Q

what does lingual nerve suply

A

anterior 2/3 of dorsal surface and central mucosa of the tongue and gives off a branch to supply the gingiva of lingual

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12
Q

where is lingual nerve situated

A

close relationship to lingual plate in mandibular retromolr pad area

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13
Q

what are the pre-op identifiable factors for lingual nerve injury

A

none - injury is largely down to surgical technique

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14
Q

what is the guidance regarding removal of M3M

A

previously discouraged removal unless there was pathology associated with it
new evidence states that not removing them could just be delaying the inevitable surgery and could make pathology worse

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15
Q

what are the indications for extraction

A

infection - caries, pericoronitis, periodontal disease
cysts
tumours
external resorption of the 7 or 8
pericoronitis

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16
Q

what is most common cyst

A

dentinogenesis

17
Q

is mandible or maxilla more common for a cyst

A

mandible - 10x more common

18
Q

what ages is extneral resorption of 7 or 8 more common

A

21-30

19
Q

if pt has a tumour why would you extract the 8’s before starting treatment

A

if need to remove it after radiotherapy then there is a risk of osteoradionecrosis

20
Q

what is the surgical indications for removal of M3M

A

for orthognathic surgery, fractured mandible
may need extracted to allow for primary closure

21
Q

what are the medical indications for extraction

A

awaiting heart surgery
immunosuppressed
before starting Bisphosphonates

22
Q

how are 3rd molars used for auto transplantation

A

if pt missing 1st molars can remove 8’s and put into the space of 6’s
very low success rate

23
Q

what is pericoronitis

A

inflammation around the crown of a partially erupted tooth

24
Q

what is the operculum

A

flap of gum sitting over the tooth

25
Q

what can the operculum cause

A

food trapping and debris getting stuck under it as hard to clean

26
Q

what age range gets pericoronitis

A

20-40

27
Q

what general health condition can increase case of pericoronitis

A

upper respiratory tract infection - unclear why

28
Q

what bacteria are involved in pericoronitis

A

anaerobic microbes mainly
streptococci, actinomyces, prevotella, bactericides, fusobacterium, staphylococci

29
Q

signs and symptoms of pericoronitis

A

pain on biting - variable
swelling - intra/extra-oral
bad taste
pus discharge
occlusal trauma to operculum
ulceration of operculum
evidence of cheek biting
limited mouth opening
dysphagia
pyrexia
malaise
regional lymphadenopathy

30
Q

in severe cases of pericoronitis what swelling can occur

A

extra-oral
starts at the angle of the mandible and commonly travels into the submandibular area, or laterally into the cheek, or disto-buccaly under the masseter

31
Q

what is swelling going under the masseter called

A

sub-masseteric abscess and main sign is unable to open mouth, severe trismus

32
Q

treatment of pericoronitis

A
  • LA depends on pt and pain
  • irrigate with warm saline or CHX mouthwash = 10-20ml syringe with blunt needle under the operculum
  • extract upper 3rd molar stop traumatising operculum
  • pt instructed on frequent warm saline/CHX
  • advice regarding analgesia
  • soft/liquid diet if necessary
  • used to do operculectomy
  • if large swelling and systemically unwell refer to max fax or A&E
33
Q

are antibiotics prescribed for pericoronitis

A

generally no, unless systemically unwell, e/o swelling, immunocompromised

34
Q

what are the predisposing factors for pericoronitis

A

partial eruption and vertical ditto-angular impaction
opposing maxillary 3rd molar causing trauma
upper respiratory tract infections as well as stress and fatigue
poor OH
insufficient space between the ascending ramus of the lower jaw and the distal aspect of the M2M
white race
a full dentition

BDS4 Oral surgery (7 decks)

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