Third Molars Flashcards
Eruption of third molars
18-24
Nerves at risk
IAN
Lingual
IAN supply
Tongue lower lip chin teeth gums that teeth
Mandibular div of trigeminal nerve
Lingual supply
Anterior 2/3rds of dorsal + ventral surface of tongue, gingivae, FOM
Third molar guidelines
Nice - guidance on XLa of wisdom teeth 2020
Sign 43 - Management of UE + impacted 3rd molars
FDS RCS
Indications for XLa of 3rd molars
Infection (caries, pericoronitis, perio disease)
Cysts/tumours
External resorption of 7/8
High risk of disease - mesioangular or horizontally impacted
Medical - awaiting cardiac surgery/dentally fit before cancer tx/ bisphosphonates
What is pericoronitis
Inflammation around the crown of a partially erupted tooth
What type of microbes are associated with pericoronitis?
Anaerobic - prevotella/actinomyces/fusobacterium
Signs + symptoms of pericoronitis
Pain
Swelling - I/O or E/O
Bad taste
Pus
Occlusal trauma to operculum
Ulceration to operculum
Cheek biting
Halitosis
Limited mouth opening
Dysphagia - difficulty swallowing
High temp
Malaise
Regional lymphadenopathy
Tx of Pericoronitis
Irrigate with warm saline
Soft diet/fluids
Analgesia
OH - CHX MW
Metronidazole only if systemic
Predisposing factors to pericoronitis
PE and vertical or distoangular impaction
Poor oH
White race
Insufficient space between the ascending ramus of the lower jaw and 7d
What is the most common cyst associated with an impacted mandibular 3rd molar
Dentigerous cyst
Why do we need an OPT to plan for an 8 XLa
Anatomy (roots)
Bone levels
Proximity to the canal/sinus
Cysts/tumours/PAP
How to assess depth of impaction of 8
Superficial
- Crown of 8 related to crown of 7
Moderate
- Crown of 8 related to crown + root of 7
Deep
- Crown of 8 related to root of 7
Angulation of third molar
Vertical
Mesial
Distal (refer)
Horizontal
Name signs that indicate a close relationship between 3m + ID canal
Interruption of tram lines (lamina dura)
Darkening of root where crossed by ID canal
Deflection of ID canal
Narrowing of ID canal
Deflection of root
Juxta-apical area
Dark + bifid root
Temp altered sensation percentage
10%
Permanent altered sensation percentage
<1%
Common tx options for third molars
Referral + XLa
Coronectomy
Instruments used when raising a flap
Mitchells trimmer
Howarths periosteal elevator
Ash periosteal elevator
WWJ elevator
Risk of air driven hand pieces
Surgical emphysema
Purpose + steps of coronectomy
Used when inc risk of IAN damage
Flap design
Drill 2-4mm below crown and elevate
Roots below level of enamel and into dentine
