third molars summary Flashcards
eruption
- approx 18-24yrs, varies
- may still be present and begin to erupt in elderly/edentulous pt
CO denture rocking/no longer fits
crown and root calcification
- crown: begins 7-10yo, completed by 18yo
- root: completed btw 18-25yo
stats of missing
- at least 1 missing in 25% adults
- maxilla
- female
guidance and their summary
SIGN 43 2000 - must justify the need of surgical removal
NICE 2000 - discourage removal unless pathology assoc.
most up to date (currently in use):
FDS RCS 2020 (Faculty of dental surgery, royal college of surgeons) - change from soley therapeutic approach to mixed intervention
nerves at risk during SR L8s
lingual
IAN
mylohyoid and long buccal - less common and effects less obvious
location of lingual n
varies
- lies on superior attachment of mylohyoid muscle
- at level of lingual plate in 15-18%
- 0-3.5mm medial to mandible
impacted meaning
tooth eruption is blocked
- full/ partial functional position
incidence of impacted lower third molar
around 50%
consequence of impaction
- caries
- periconronitis
- cyst formaiton
U removal indications
cheek biting/buccally erupted overeruption traumatising L operculum PE and impacted non-fct pt undergoing GA
therapeutic indication of wisdom extraction
- caries (8/7)
- pericoronitis
- periodontal disease (7d)
- local bone infection
- Dentigerous cyst
- tumours
- external root resorption of 7/8
SIGN vs NICE
SIGN - ≥1 episode of infection
NICE >1
imaging
OPT
(+/- PA)
+/- CBCT (3D relationship to nerve)
clinical assessment of M3M
eruption status - how many cusps seen
PD status - pockets distal to 7?
TMJ - rule out TMJ, similar pain to pericoronitis
exclude other causes
local infection
caries/resorption
occlusal relationship
regional LNs
any associated pathology
degree of surgical access
working space
STs
Types of imapction
- plus transverse (buccal / lingual)
- aberrant ( in odd place)
working space
distance between L7 and ascending ramus
radiological assessment
- orientation and position (impaction)
- impaction depth
- relationship to IDC/MS
follicular width
working distance
crown - size, shape, caries
roots - number, morphology, apical hooks
bone levels
adjacent tooth
any surrounding pathology
- dentigerous cyst
- loss of bone distal to crown
when to consider when follicle turning to dentigerous cyst?
if follicle > 3mm (5mm)size
if >10mm can assume is cyst
3 key radiographic signs of M3M - possible increased risk to IAN
diversion/deflection of canal
darkening of root where crossed by canal
interruption of tram line / lamina dura of canal
8 radiographic signs of possible increased risk to IAN - M3M removal
diversion/deflection of canal
darkening of root
interruption of white lines/LD of canal
deflection of root
narrowing of IDC
narrowing of root
dark and bifid root
juxta apical area?
juxta apical area
well-defined radiolucent area adjacent that isn’t related to PA pathology
can appear corticated
lamina dura round tooth intact
lateral to root rather than apex
what is the most common orientation of impaction? M3M
mesial 40%
what is orientation of impaction measured against?
the curve of spee
- curve of occlusal plane
- draw lines through long axis of 7 and 8 and compare
what are the types of depth of impaction and what does it indicate?
- superficial - 8 crown relate to 7crown
- moderate - 8 crown to 7 crown+root
- deep - 8 crown to 7 root
- amount of bone removal required
why is L. disto-angular 8s difficult to extract?
- bone removal required (ascending ramus dense bone)
- vector of movement during elevation is distal so tooth has nowhere to go
- roots of 8 often v close to roots of 7 - can make it difficult to get an application point to elevate (also care not to damage 7 roots during mesial bone removal)
pericoronitis definition
- Inflammation around the crown of a PE tooth
- need communication with oral cavity
if not visible careful probing 7d for comunication
pericoronitis aetiology
- food and debris get trapped under operculum - inflammation/infection
S+S of pericoronitis
pain swelling (IO or EO) 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
which LNs are often raised and palpable in pericoronitis?
SM or upper cervical chain
pericoronitis EO swelling
severe cases
often at angle of mandible and may extend into SM region
spread of infection of pericoronitis
laterally into cheek
distobuccally under masseter (submasseteric abscess and profound trismus)
sublingual
SM
area around tonsils and paraphyaryngeal space (dysphagia)
less commonly - through anterior pillar of fauces area into SP (dysphagia)
tx of pericoronitis
- I+D of pericoronal abscess if required +/- IDB
- irrigation
- warm saline in 10-20ml syringe w blunt needle
under operculum - ext U8 if traumatising operculum
- usually no ABs unless severe
systemically unwell
EO swelling
immunocompromised e.g. diabetic - if large EO swelling, systemically unwell, trismus, dysphagia - refer to MF/A+E - phone first for advice
- pt instructions
- no removal of 8 until pericoronitis resolved - removal of periculum not recommended - will just grow back
pericoronitis pt instructions
freq warm saline or MW
- teaspoon salt warm water
analgesia
keep fluid levels up and keep eating (soft diet)
pericoronitis astringent/antiseptic
e.g. talbots iodine - applied with college tweezers - one drop beneath operculum
not if have incised a localised pus collection
not on fresh/open wounds
ext of L8 pericoronitis
generally don’t ext affected 8 until acute episode has resolved
- unless in hospital with GA for I+D - ext tooth then
operculectomy
prev
no longer carried out - often grows back
predisposing factors for pericoronitis
- PE (usually 20-25yrs) and vertical or distoangular impaction
- opposing maxillary 8 causing mechanical trauma contributing to recurrent infection
- upper resp tract infections, stress and fatigue PC
- poor OH
- Previous episodes of pericoronitis
- insufficient space between ascending ramus of L jaw and distal aspect of 7
- white race
- a full dentition
SDCEP pericoronitis when to send pt to hospital (emergency )
- FOM swelling
- Difficulty breathing
- Trismus
SDCEP pericoronitis when to prescribe ABx
- spread of infection (cellulitis / swelling)
- systemic involvement (fever, malaise)
- not resolved by local measures
- symptoms or pus >7 days
local measures for pericoronitis
irrigation and debridement (US)
1st line ABs for pericoronitis
metronidazole 400mg, 3 days , x3 daily
avoid alcohol, not if on warfarin
2nd line Abs for pericoronitis
amoxicillin 500mg, 3 days, 9 capsules x3 daily
- hypersensitivity reactions
RCS FDS guidelines - factors regarding M3M status
pt age and medical status (complications and recovery)
risk of complications (IAN/leaving M3M in situ)
pt access e.g. military
opposing contralateral 8 if having GA
RCS FDS guidelines - diseased/high risk of disease development and asymptomatic
assess likelihood of disease development - high/low risk
high risk - consider surgical
if any doubt and tooth has higher risk of surgical complications - active surveillance until symptoms develop/early disease progression has been proven
quiescent pathology may inc undiagnosed 7/8:
- caries
- PDD
- resorption (internal or external)
- cysts or tumours
RCS FDS guidelines - diseased/high risk of disease development and symptomatic
consideration for therapeutic exts is indicated for:
single severe acute or recurrent subacute pericoronitis
unrestorable caries of M3M or to assist Rx of adjacent tooth
PDD compromising M3M and/or adjacent tooth
resorption of M3M and/or adjacent tooth
fractured M3M
M3M periapical abscess, irreversible pulpitis or acute spreading infection
surrounding pathology (cysts/tumours) associated w M3M
tx to be considered:
- therapeutic removal of M3M (or coronectomy)
- removal of U3M
RCS FDS guidelines - non-diseased/low risk of development and asymptomatic
clinical review and radiographs if indicated. Make assessment of risk of disease and review interval
factors for consideration for prophylactic removal
- medical: planned medical tx/therapy that may complicate the likely surgery of M3Ms inc: pharmaceutical therapy (bisphosphonates, antiangiogenics, chemo), radio of HandN, immunosuppressant therapy
- surgical: M3M lies within perimeter of a surgical field: mandibular fractures, orthognathic surgery, resection of disease (benign and malignant lesions)
RCS FDS guidelines - non-diseased/low risk of development and symptomatic
leave deeply impacted M3Ms with no associated disease
manage other diagnoses causing pain in the region
- TMD
- parotid disease
- skin lesions
- migraines or other primary headaches
- referred pain from angina, cervical spine
- oropharyngeal oncology
RCS FDS guidelines - main reason for removal
infection
RCS FDS guidelines - significant radiological signs of risk to IAN
diversion of IAN canal
darkening of root
interruption of cortical white line
RCS FDS guidelines - CBCT
not routinely
evidence it doesn’t offer benefit in reducing incidence of IAN neurosensory disturbance
- if findings expected to alter tx decision
- see if direct contact or bony wall between