Third Molars Flashcards
What does the trigeminal nerve supply?
Sensation
What supplies the muscles of facial expression?
Facial nerve
What does the inferior alveolar nerve supply?
Sensation to all of the lower teeth, gingivae and exits through mental foramen, terminal branch supplies sensation to lip and chin.
Where does the mylohyoid nerve supply?
Tiny bit of skin on chin
What does the lingual nerve supply?
Sensation to the tongue - anterior 2/3rds
What does the chorda tympani supply?
Taste to anterior 2/3 of tongue
What is the lingula?
Variety of shapes - triangular, truncated and nodular
25% prominent lingula
Used in landmarks for blocks
What are high risk signs on radiographs for removal of third molars?
- Deviation of canal
- narrowing of canal
- periapical radiolucent area
- darkening of the root
- narrowing of root
- curved roots
- loss of lamina dura
When looking at roots on a radiograph what signs are we looking out for?
Number of roots
Curvature of roots
Degree of root divergence
Size and shape of roots - bulbous, conical, long, short, hooked
Other - root resorption, caries, ankylosis
If you see signs of a difficult extraction how would you manage this?
Take a CBCT scan
Why does age impact the condition of surrounding bone?
<18 - less dense, pliable, expands and bends and easier to cut
>35 - much denser, decreased flexibility, decreased ability to expand, more bone removal required and higher risk of fracture
What predicts difficulty?
Alveolar bone level, tooth position, application depth and point of elevation all dictate how much bone is required to be removed.
What increases complications?
Age, underlying disease, anatomical position of tooth and root, local anatomical relationships, status of adjacent teeth, access, patient co-operation and compliance, bone density, ankylosis, infection and pathology.
What can cause an OAC?
Closeness of tooth to the floor of the antrum, fractured tuberosity.
What is the best way to fix a fractured tuberosity before sending the patient to oral surgery?
Plug the hole with the tooth
How do you know when to stop when extracting an upper 8?
The soft palate starts to move or tear
What else can happen in regards to the antrum and maxillary third molar?
It can get pushed up into the antrum with instruments
What are treatment options for third molars?
Conservative management/monitor
Operculectomy
Complete extraction of third molar
Coronectomy
What are risks?
Pain, bruising, bleeding, swelling, dry socket, damage to adjacent teeth, infection, loss/altered sensation, OAC/OAF, stiff jaw
What must you warn a patient about when having mandibular third molar extractions?
Temporary or permanent loss/altered sensation to the lower lip, skin of chin, gums of lower teeth, lower teeth, tongue and taste.
Altered sensation may be painful (neuralgia) or a tingling sensation
- trismus
- time off work
- significant swelling and bruising which can spread to the neck/chest
- rarely hospital admission requiring treatment
Permanent <1% risk, temporary - 2-4% usually
Why are risks increased using general anaesthetic over local?
Clinicians are less careful under GA
Complications of maxillary third molar removal?
OAC/OAF development
Fractured tuberosity
Damage to adjacent teeth
What is the best way to avoid compliations?
Good anaesthesia
Minimal trauma
Good tx planning
Anatomical knowledge
Why would you do an operculectomy?
Enables oral hygiene to be effective
Often ineffective and sore so not really done
What does surgical removal involve?
Cutting a flap and drilling bone to expose the impacted tooth
What is the anaesthetic and analgesic protocol for surgical extractions?
Pre-op 400mg ibuprofen (no contra indications)
LA - ID block with lidocaine and buccal infiltration with 4% articaine
Check anaesthesia
Post op - 400mg ibuprofen TDS + 1g paracetamol QDS for at least 48 hours
Salt water rinses 4x a day for a week
What are the principles of flap design?
Base > free margin
Width of base> length of flap
Axial blood supply
Preserving vital structures
Margins on sound bone
Uncomplicated closure
How do you remove a vertically impacted tooth?
Drill down into the furcation and remove two separate bits of tooth and root
How do you remove a horizontally impacted tooth?
Decoronate the tooth and lever out roots
What plate of bone do we conserve most of?
Buccal plate
Why don’t we use handpieces that produce air?
Don’t want air in the soft tissues that can lead to surgical emphysema
What do you mention for post operative care?
Analgesics
No smoking or vaping for a week
Written and verbal instructions
Post op call next day
Written contact details for emergencies
What is a coronectomy?
Removal of a crown from the roots of a healthy tooth in healthy patients indicated to prevent IA nerve injury in a high risk case ie for pericoronitis
What are the guidelines for coronectomy?
- NOT with infected teeth
- NOT with mobile teeth
- Leave retained root fragment at least 3mm inferior to the crest of bone
- Leave exposed pulp
- Late migration of root may occur but is unpredictable
Operative site should be closed in tension free manner
Dry socket treated in conventional way
What are considerations for coronectomy?
Caries with pulpal involvement - potential infection risk
Apical disease - progressing to chronic disease
Mobility of roots - potential infection
Pathology eg cyst
Pre orthognathic surgery - in line of cuts
Immunocompromised - risk of infection
Pre-radiotherapy - risk of osteoradionecrosis
