OS - third molars Flashcards
list the requirements for surgical removal of teeth
- when you cannot remove/ xLA a tooth conventionally
- gross caries
- complex root morphology
- retained roots below bone
- impacted teeth
- displaced teeth
- ectopic teeth
- pathology (cysts, external root resorption)
why may you have to surgically remove a tooth with gross caries?
unable to use forceps
no application point for elevators
why may you have to surgically remove retained roots that are below alveolar bone level?
no application point for elevators
in general terms, why does impaction occur?
prevention of complete eruption into a normal functional position due to lack of space or development in an abnormal position.
why may impaction predispose pathological changes?
while the tooth germ is forming there is a pathological change that affects the tooth - can involve soft tissues or hard and soft tissues.
aetiology of ectopic teeth?
malpositioned due to congenital factors
aetiology of displaced teeth?
malpositioned due to presence of pathology i.e., a cyst
describe completely unerupted teeth?
entirely covered by soft tissue and also partially/ totally covered in alveolar bone
describe ankylosed teeth?
fused with alveolar bone, rare with 8s, occurs after middle age
what is the cause of impacted teeth?
due to lack of space in the arch as a consequence of evolutionary changes and lack of an abrasive diet
list in order the commonest affected impacted teeth?
mandibular third molars
maxillary canines
mandibular premolars/canines
maxillary incisors
maxillary third molars
at what age do mandibular third molars usually emerge?
18-24 years
what is the prevalence of mandibular third molars to fail to develop?
1:4 adults
what is the prevalence of impacted third mandibular molars?
72%
what is is the decision for xLA mandibular third molars?
decision to remove based on balance of risk of observation against removal before overt disease develops
what guidelines are followed for removal of third molars?
National Institute for Clinical Excellence (NICE) 2000
list the indications for removal of mandibular third molars
pericoronitis
unrestorable caries
cellulitis/ osteomyelitis
periodontal disease
ortho reasons
prophylactic removal in medically compromised pts
obscure pain
disease of follicle
orthognathic surgery
transplant donor
what happens to teeth in the line of a fracture?
non vital
what are the relative contraindications for removal of third molars?
asymptomatic teeth
non-compliant patients
overt nerve involvement
what is pericoronitis?
inflammation of the tissues around the crown of any partially erupted/ impacted tooth
how many episodes of pericoronitis makes it an indication for xLA?
2 or more
list the features of pericoronitis?
trismus, pain, dysphagia, malaise, bad taste
signs of inflammation of the pericoronal tissues, with pus under operculum
halitosis, food packing
can progress with systemic symptoms and spread to adjacent tissue spaces
what is commonly performed in America to solve pericoronitis?
operculectomy
why do we not routinely practise operculectomy’s?
operculum will grow back
treatment options for a tooth in whose soft tissues have been traumatised from upper molar?
xLA upper 8
grind upper 8 cusps down
treatment options for pericoronitis?
local measures
- irrigation, OHI (small headed tooth brush/ water pick)
- remove trauma i.e., xLA upper 8 or grind down cusps
general measures
- analgesics, antibiotics if systemically unwell/ immunocompromised
- admission in severe airway threatening cases
list the microbes associated with pericoronitis?
predominantly anaerobic
strep, actinomyces, propionibacterium, a-beta-lactamase producing prevotella, bacteroides, fusobacterium, capnocytophaga and staph
what anaerobes are related to the increased incidence of second and third molar perio pockets deepening over 2 years?
prevotella intermedia
campylobacter
when can antibiotics be prescribed for pericoronitis?
when surgical removal of the cause or drainage of the infection under LA is impossible e.g., trismus, pt compliance
evidence of a systemic spreading infection needing urgent referral for hospitalisation
what are conservative treatment choices for removal of mandibular third molars?
monitor with radiographs
what treatment option is available for mandibular third molars if there is risk of damaging the inferior dental canal?
coronectomy
what may happen to existing TMJ pain after xLA?
worsens
what is the 7 at risk of with xLA of the 8 where there are perio pockets?
distal root exposure - sensitive
what radiographs are generally required to assess mandibular wisdom teeth?
OPG
PA sometimes - shows root apices and relation to IDC
what do radiographs assess with mandibular third molars?
all the tooth and adjacent structures including bone, tooth morphology and number and shape of the roots, hypercemetosis
depth of bone around tooth
follilcular pattern
external root resorption
caries in distal of 7
what classifications are made from radiograph assessment?
relation
angulation to the adjacent teeth
proximity to the IDNerve
when radiographically classifying mandibular third molars, what is relation?
relation to the 7, crown, ACJ or roots
when radiographically classifying mandibular third molars, what types of angulations can you get?
vertical
mesioangular
distoangular
horizontal
transverse
aberrant
what do Winter’s assess?
how much bone will be removed
what are the 3 winters lines?
occlusal plane line
bone margins
vertical line that joins
what is the most common angle of impaction of 3rd molars?
mesial
list 6 radiographic signs of a close relationship between the lower third molar and the IDC
- diversion of IDC
- darkening of root as it is crossed by the IDC
- loss of lamina dura of IDC
- narrowing of IDC
- deflection of roots of lower third molar as they approach the IDC
- juxta apical area
what is a juxta apical area?
free floating apex on one side of the IDC
what is indicated when the IDC passes through the roots of a tooth but both lines are interrupted?
superimposition
what is indicated when there is loss of IDC lamina dura as it passes through the roots of a tooth?
close relationship - can cause bruising to canal which will give pt an altered sensation to the lip
what is indicated when the IDC lamina dura is lost and there is a change in radiolucency of the roots?
suggests less mineralised tissue - canal is sititng in the groove of roots or perforates them
what are the risks with a narrowed IDC?
indicates a close relationship to the roots - short term complication
however, if roots are rotated on removal - long term complication
where do the vast majority of IDC sit?
on the lingual aspect of the third molars (70%)
what must you do with a pt if they IDC is interrupted when the third molar is removed and you can see the contents of the bundle left in the socket?
review and document sensation for 18 months
if still numb after 18 months, unlikely to improve
what is the prevalence of lower lip altered sensation in short and long term post op?
short term - 5%
long term - less than 15%
what is the prevalence of tongue altered sensation short term and long term post op?
short term - 10%
long term - less than 1%
taste can be affected too
what is an alternative surgery performed if the risk is high to the IDN?
coronectomy - remove the crown and leave roots in place
when performing a coronectomy, you realise the roots are mobile, what do you do?
remove them
what are the risks following a coronectomy?
root removal unavoidable
infection
migration of roots
what should happen to the socket after a coronectomy?
socket should fill with bone, roots become intraalveolar
describe anaesthesia after LA
numbness
describe paraesthesia after LA
tingling when LA wearing off
describe hypoaesthesia after LA
reduced sensation
describe disaesthesia after LA
pain
what are the preoperative warnings you tell the pt prior to surgery of 3M?
pain
swelling
bruising
possible hypoaesthesia of lip/tongue
trismus
diet advice
1 week
what must pt be warned of prior to surgery of 3M
post op complications greater than 5% incidence
what are the 5 points planned from a radiograph for surgical xLA of a mandibular 3rd molar?
path of eruption
extrinsic/ intrinsic obstacles to removal
required bone removal
point of application
flap design
what are extrinsic obstacles to removal of mandibular third molars
adjacent teeth
IDN
what are intrinsic obstacles to removal of mandibular third molars?
converge, diverge, bulbous, fused, ankylosed roots
describe a triangular flap
distal relieving incision up the ascending ramus, around crown of 3M, including papilla between 3M and 2M
mesial relieving incision
(3 sided)
how does an envelope flap differ to a triangular flap?
no mesial relieving incision in envelop flap
during a surgical removal of 3M what elevation technique and elevators are used?
atraumatic elevation using periosteal elevators
- mitchells trimmer
- warwick james elevator
- molt no.9 periosteal elevator
- Howarth’s periosteal elevator
during surgical removal of 3M, what is used to raise lingual flap?
Howarths/Mitchells/Molt
*not for novice operators
describe an envelope flap
distal relieving incision
peri-coronal incision round 3M and 2M
how are burs used for bone removal?
round bur creates narrow gutter mesiobuccaly
fissure bur deepens gutter
units of a surgical handpiece?
20000-40000 units per min
how can the crown of a 3M be divided during surgical removal?
horizontally or axially
*ALL horizontally impacted teeth must be sectioned
what is important when planning flap design after surgical xLA 3M?
flap must rest over bone to avoid wound breakdown
what is the most important suture?
one placed from the buccal tissue to the lingual tissue immediately distal to the second molar - encourages good periodontal health
what material is used for suturing?
3/0 vicryl rapide - it is resorbable
post op regime for surgical xLA?
analgesics
soft diet
topical ice pack
HSMW day after
suture removal at 1 week if not resorbed
follow up for immunocompromised or difficult cases
what analgesics are recommended post op?
paracetamol
cocodamol 5 days
NSAIDs
when would you give a pt antibiotics?
immunocompromised
pt returns with infection
how would you tell a pt to use ice packs?
15 mins on 15 mins off day of tx
when is post op bruising common?
elderly as tissue loses elasticity
gravity can make bleeding track down neck
list complications of surgery xLA 3M?
haemorrhage - primary/ secondary
loose teeth/ damage to adjacent teeth/ restorations
fractured mandible
dry socket
sensory deficit
general xLA complications
how are maxillary third molars commonly impacted?
MA
V
why are surgicals of maxillary third molars less complicated?
thin cortical bone
how may access be difficult to maxillary third molars?
malar buttress
buccal position
when would you merit removal of upper 8’s?
GA for removal of symptomatic lower 8s
complications of a buccal placed maxillary third molar?
ulceration of buccal tissue
painful mouth opening
explain surgical removal of unerupted maxillary 3M?
raise buccal flap
thin friable bone removed with couplands
elevate
back and buccal
why do we avoid excessive upwards force with removal of maxillary 3Ms?
possible displacement into antrum
how many sutures are used after removal of maxillary 3M?
1
