Third Molars Flashcards
When does crown calcification begins
- between 7-10yrs and completed by age 18
When does root calcification goes fully complete?
- 18-25yrs
When does 3rd molars erupt?
- erupt between 18-24yrs
What is agenesis?
- congenital absence of one or more teeth
- more common in maxilla and in females
What is impacted 3rd molars?
- tooth eruption is blocked
- most common reason for 3rd molars to fail to erupt
- impacted against adjacent tooth, alveolar bone, surrounding mucosal ST
- incidence are 36-59%
- consequences are caries, pericoronitis, cyst formation
Nerves at risk during 3rd molar surgery
- inferior alveolar nerve
- lingual nerve
- nerve to mylohyoid
- long buccal nerve
Location of lingual nerve
- at/ above level of lingual plate
- 0-3.5mm medial to mandible
Guidelines for 3rd molars
NICE- Guidance on Extraction of Wisdom Teeth, 2000
SIGN Publication Number 43 – Management of Unerupted and Impacted Third Molar Teeth, 2000
FDS, RCS 2020 - Parameters of Care for patients undergoing mandibular third molar surgery
Indications for extractions
- infection (most common)
- caries, pericoronitis, perio, local bone
infection
- caries, pericoronitis, perio, local bone
- cysts
- tumours
- external resorption of 7/ 8s
- surgical indications
- medical indications - cardiac, immunosuppressed, prevent osteonecrosis
- limited access
- pt age
- autotransplantation
- GA
What is pericoronitis?
- inflammation around the crown of a partially erupted tooth
- food & debris gets trapped under operculum -> inflammation and infection
Etiology of Pericoronitis
- occurs 20-40 yrs
- second most common indication for XLA
- anaerobic microbes (Streptococci , Actinomyces, Propionibacterium, a beta-lactamase producing Prevotella, Bacteroides, Fusobacterium, Capnocytophaga and Staphylococci most common)
Signs and Symptoms of Pericoronitis
- pain
- swelling
- pus discharge
- bad taste
- occlusal trauma to operculum due to upper 3rd molars occluding
- ulceration of operculum
- cheek biting
- foetor oris (halitosis)
- limited mouth opening
- dysphagia (difficult swallowing)
- pyrexia (raised body temp)
- malaise (feeling unwell)
- regional lymphadenopathy
Pericoronitis treatment
- incision of localised pericoronal abscess
- LA IDB
- irrigation with warm saline/ chlorhexidine MW
- XLA of upper 3rd if operculum traumatised
- frequent warm saline water/ chlorhexidine MW
- analgesics
- keep soft diet and plenty of fluid
- do not prescribe AB unless more severe pericoronitis, immunocompromised (diabetic), systemically unwell
- refer to MaxFac, if has EO swelling, pt unwell, trismus, dysphagia
Predisposing Factors of Pericoronitis
- partial eruption
- distoangular impaction
- opposing maxillary causing mechanical trauma
- upper respiratory tract infections
- stress
- poor OH
- insufficient space between ascending ramus of lower jaw and distal aspects of M2M
- full dentition
Assessment of 3rd Molars (History)
- general appearance
- PC of recurrent pericoronitis
- HPC (how long, how many episodes, how often, severity, requirement for antibiotics)
- MH (systemic enquiry, medications, allergies)
- DH (history of XLA, dental anxiety, OH)
- SH (smoking, alcohol, occupation, carer)
E/O Clinical
- TMJ
- limited mouth opening
- lymphadenopathy
- facial asymmetry
- MoM
When to take radiograph for removal of 3rd molars?
- only if surgical intervention is being considered
Why take OPT?
- presence/ absence of disease
- check anatomy (crown size, shape, condition, root formation)
- depth of impaction
- orientation of impaction
- working distance
- follicular width
- periodontal status
- proximity of upper 3rd molars to maxillary antrum and lower 3rd molar to IAC
Radiographic assessment
- interruption of white lines/ lamina sura of canal
- darkening of root where crossed by canal
- diversion/deflection of IADC
- deflection of root
- narrowing of IADC
- narrowing of root
- dark and bifid root
- juxta apical area
What increases risks of nerve damage?
- diversion of IDC
- darkening of roots when crossed by canal
- interruption of white lines of canal
Diversion/ deflection of IDC
Darkening of root where crossed by canal
Interruption of white lines/ lamina dura of canal
Deflection of root
Narrowing of IDC
Narrowing of root
Dark and bifid root
Juxta apical area
Angulations of 3rd molars
Measured against curve of Spee
- vertical
- mesial
- distal
- horizontal
Common tx options for 3rd molars XLA
- referral
- clinical review
- removal of M3M
- XLA of maxillary 3rd molars
- coronectomy
Less common tx options
- operculectomy
- surgical exposure
- pre-surgical ortho
- surgical reimplantation/ autotransplantation
Decision making of XLA M3M
- communicate with pt about findings of assessment
- risk status
- treatment options, ie: risk and benefits
- pt access to tx
- good notekeeping
Summary of management
Methods of anaesthesia
- LA alone
- concious sedation
- GA
Post operative complications
- pain
- swelling
- bruising
- bleeding
- jaw stiffness/ limited mouth opening
- infection
- dry socket (localised osteitis)
- numbness (anesthesia) or tingling (paraesthesia) of lower lip, chin, side of tongue
- altered taste - Chorda tympani, arises from taste buds from anterior 2/3 of tongue, carries fibres via lingual nerve
- nerve damage
- Dysaesthesia: painful, uncomfortable, unpleasant sensation of lower lip, chin, tongue
Percentage of nerve numbness
IDN (lower lip/ chin)
- temp- take weeks/ months to improve- 10-20%
- perm - less than 1% experience this
Lingual Nerve (one side of tongue/ taste)
- temp - 0.25 - 23
- perm - 0.14 - 2
How long does nerves take to recover?
- 18-24 months
- after this period, no hope for full recovery
Retraction of ST during surgical removal
- Howarth’s periosteal elevator
- Rake retractor
- Minnesota retractor
Debridement
Physical
- bone file/ handpiece to remove sharp bony edges
- Mitchell’s trimmer/ Victoria curette to remove ST debris
Irrigation
- sterile saline into socket and under flap
Suction
- aspirate under flap to remove debris
- check socket for retained apices
Aims of suturing
- compress blood vessels
- reposition tissues
- cover bone
- prevent wound breakdown
- achieve haemostasis
Why coronectomy?
- when there is increase risk of IAN damage with surgical removal
- aims to reduce risk of IAN damage
- crown is removed with retention of root adjacent to IAN
How is coronectomy done?
- flap design to gain access to tooth
- transection of tooth 3-4mm below enamel of crown into dentine
- elevate/ lever crown off without mobilising roots
- pulp left in place untreated
- can further reduce roots with rose head bur to 3-4mm below alveolar crest
Follow up for coronectomy
- review 1-2 weeks
- review 3-6 months then 1 year
- discharge back to GDP after 6 months/ 1 yr review
- radiograph review 6 months/ 1 year
- after that, only take radiograph if symptomatic
What to warn pt about coronectomy?
- if roots are mobilised durign crown removal, entire tooth must be removed
- leaving roots behind might result in infection
- may get slow healing/ painful socket
- roots may migrate in a later time and erupt through mucosa and may require XLA
