6 - Third molars Flashcards
When do third molars typically erupt?
18-24 years
When does third molar crown calcification begin?
7-10 years
When does third molar crown calcification finish?
18 years
When does third molar root calcification finish?
18-25 years
Define agenesis.
Failure to develop
At what age can you determine if third molars agenesis is present?
14 years
Define M3M.
Mandibular third molar
What are the consequences of impacted M3Ms?
- caries
- pericoronitis
- cyst formation
What causes pericoronitis?
Failure of the follicle to break down
What nerves are at risk during third molar surgery?
- IAN
- lingual nerve
- nerve to mylohyoid
- ling buccal nerve
Describe the location of the IAN in relation to the M3M.
Lies within the inferior alveolar nerve canal that passes close to the roots of M3Ms
Describe the location of the lingual nerve in relation to the M3M.
- close relationship to the lingual plate
- lingual to the mandible in the retromolar pad area
- lies on the superior attachment of the mylohyoid muscle
What does the FDS RCS 2020 guidance state for third molar surgery?
- consensus document after reviewing SIGN and NICE guidance which suggest that third molar surgery should only be carried out if there is visible pathology
- new guidance suggests a holistic and intervention approach to avoid postponing inevitable surgery
What are the therapeutic indications for extraction of third molars?
- infection (caries, pericoronitis, perio, or local bone infection)
- cysts
- tumours (prevent ORN)
- ERR of 7 or 8
What are the holistic indications for extraction of third molars?
- surgical (ie within surgical field)
- high risk of disease
- medical indications (ie dentally fit)
- accessibility
- age
- autotransplantation (rare)
- GA (if already undergoing tx)
What is pericoronitis?
- inflammation around the crown of a partially erupted tooth
- food and debris get trapped under the operculum resulting in infection and inflammation
What microbes are associated with pericoronitis?
- anaerobic microbes
- eg streptococci, actinomyces, prevotella
What are the signs and symptoms of pericoronitis?
- pain
- swelling IO or EO
- bad taste
- pus
- occlusal trauma to operculum
- ulceration of operculum
- trismus and dysphagia
- regional lymphadenopathy
What is the treatment for pericoronitis?
- incision of localised abscess +/- LA
- irrigation with warm saline or chlorheixidine under operculum
- XLA of M3M if trauma
- analgesia and stay hydrated
When are antibiotics appropriate for pericoronitis?
- evidence of spreading infection
- systemically unwell
- EO swelling or severe trismus
What are predisposing factors to pericoronitis?
- partial eruption
- vertical or distal impaction
- opposing maxillary teeth causing trauma to operculum
- URTI
- poor OH
- full dentition
