Third Molars

Question 1

what is the most common reason that third molars do not erupt

Answer 1

impaction

Question 2

in what ways can a third molar be impacted

Answer 2

against adjacent tooth
alveolar bone
surrounding mucosal soft tissue

Question 3

what is the incidence of impacted m3m

Answer 3

36-59%

Question 4

what can the consequence of impaction be

Answer 4

caries
pericoronitis
cyst formation

Question 5

what are the 4 nerves at risk during third molar surgery

Answer 5

inferior alveolar nerve
lingual nerve
nerve to mylohyoid
long buccal nerve

Question 6

where does the lingual nerve run

Answer 6

between 0-3.5mm medial to the mandible

Question 7

what does the NICE guidance 2000 say on extraction of wisdom teeth

Answer 7

do not extract unless caries present

Question 8

what does the SIGN publication of 2000 say about the extraction of wisdom teeth

Answer 8

you must be able to justify third molar removal

Question 9

what does the FDS, RCS 2020 guidance say about the extraction of third molars

Answer 9

recommends changing from a therapeutic approach to a mixed range of treatment based on holistic and informed approach

Question 10

what are the therapeutic indications for XLA

Answer 10

infection - caries, pericoronitis, periodontal disease, local bone infection
cysts
tumours
external resorption of 7/8
surgical indications
high risk of disease
medical indications
accessibility
patient age
autotransplantation

Question 11

what is pericoronitis

Answer 11

inflammation around the crown of a partially erupted tooth caused by trapping of food and debris under the operculum

Question 12

what microbes are involved in pericoronitis

Answer 12

anaerobes

Question 13

what are the signs and symptoms of pericoronitis

Answer 13

pain
swelling
bad taste
pus discharge
occlusal trauma to operculum
ulceration of operculum
evidence of cheek biting
foetor oris
limited mouth opening
dysphagia
pyrexia
malaise
regional lymphadenopathy

Question 14

what is the treatment for pericoronitis

Answer 14

incision of pericoronal abscess if required
give IDB if pain
irrigate with warm saline or chlorhexidine
XLA upper 8s if traumatising operculum
frequent warm saline for patient
analgesic advice
keep fluid levels up

Question 15

when would you prescribe antibiotics for pericoronitis

Answer 15

severe
systemically unwell
extra-oral swelling
immunocompromised

Question 16

what would you do if pericoronitis presents with large extra oral swelling, systemically unwell, trismus and dysphagia

Answer 16

refer to OMFS and A&E

Question 17

why might some health boards not recommend using chlorhexidine to irrigate pericoronitis

Answer 17

anaphylaxis

Question 18

what are the predisposing factors to pericoronitis

Answer 18

partial eruption and vertical or distoangular impaction
opposing 8s cause mechanical trauma
upper respiratory tract infection
poor OH
insufficient space between ascending ramus and distal aspect of M2M
white race
full dentition