Third Molars Flashcards
When do third molars erupt into mouth?
- Between 18-24y
When does crown calcification of third molar begin and completes?
- Begins between 7-10yrs
- Completes age 18yrs
When is root calcification complete of third molars?
- 18-25yrs
What is the probability that at least 1 third molar is missing?
1 in 4
What is Molar agenesis?
Third molar never forms
- More common in Maxilla and in females
At what age would we say a third molar is never going to form if missing on radiograph?
- Age 14
What does M3M mean?
- Mandibular third molar
What does Impacted mean?
- Tooths eruption is blocked
- Blocked by adjacent tooth, alveolar bone, surrounding mucosal soft tissue or a combo of these factors
- Can be unerupted , partially erupted or fully erupted
If a third molar is impacted does that mean surgery?
- Not indication for surgery
- That is balanced by many other factors
Define partially erupted?
- When some of the tooth has erupted into oral cavity
Define unerupted
- Tooth completely buried
- Has not erupted into oral cavity
What is the incidence of impacted M3M’s?
- 36-59%
What are some consequences of impaction?
- Caries
- Pericorinitis
- Cyst formation
What nerves are at risk during third molar surgery?
- Inferior alveolar nerve
- Lingual nerve
- Nerve to mylohyoid
- Long buccal nerve
Label this diagram
Where does the inferior alveolar nerve come from?
- Peripheral sensory nerve
- Derived from V3 mandibular division of trigeminal nerve
What does the inferior alveolar nerve supply?
- Mandibular teeth on that side
- Lower lip and chin on that side
What is the location of lingual nerve?
- Close relationship to lingual plate in mandibular and retromolar area
- At or above level of lingual plate in 15%-18% of cases
- Between 0-3.5mm medial to mandible
What does the lingual nerve innovate?
- Branch of the mandibular division of trigeminal nerve
- Anterior 2/3rds of the dorsal and ventral mucosa of tongue
- Lingual gingivae and floor of mouth
What guidelines can we look at at for third molars?
- NICE
- SIGN publication number 43
- FDS, RCS 2020
What did the NICE guidlines state in 2000 that was confirmed by SIGN about XLA wisdom teeth?
- Any justified to remove if visible pathology
- Caries, periodontal disease, infection, cyst formation etc
What are some therapeutic indications for extraction?
- Infection (caries, pericorinitis, periodontal disease or local bone infection
- Cysts
- Tumours
- External resorption of 7 or 8
What type of impaction is particularly prone to periodontal disease of distal of 7?
- Horizontal medio-angle impaction
- Early extraction
What type of cysts is most commonly associated with impacted third molars?
- Dentigerous cyst
- Arises from reduced enamel epithelium separation from crown
What are some other non therapeutic reasons for extraction?
- surgical indications i.e. within surgical field (orthognathic , fractured mandible, in resection of diseased tissue)
- High risk of disease
- Medical indications e.g. awaiting cardiac surgery, immunosuppressed or to prevent osteonecrosis
- Accessibility - limited access
- Pt age , complications and recovery time increase with age
- Autotransplantation
- GA (consider emoval of opposing and contralateral)
Why might a third molar be extracted post fractured mandible?
- To allow for adequate open reduction internal fixation
Why might an extraction of third molar be accepted in pts awaiting cardiac surgery?
- Required to be signed off as dentally fit to avoid complications
- If dentist suspects the 8 may cause issues in the future might opt to have removed prophylactically
If pt is immunosuppressed or about to be immunosuppressed why might be a good idea to remove third molar before starting txt?
- Reduced ability to heal due to immunosuppression
- **
Why might you consider removing third molar if pt going to start bisphophonates?
- Remove poor or doubtful prognosis teeth before starting txt
- Reducing chance of getting MRONJ
- Medicated related osteonecrosis of the jaw
What is pericorinitis?
- Inflammation around crown of partially erupted tooth
- Sometimes you need to probe distal to second molar to show there is a small communication
- Food and debris get trapped under the operculum resulting in inflammation and infection
When does pericornitis occur?
- 20-40yrs
What health condition has been found to be related to incidences of pericoronitis?
- Upper respiratory tract infections
What anaerobic microbes have been found in pericoronitis?
- Streptococci
- Actinomyces
- Propionibacterium
- Prevotella
What are the signs of pericoronitis?
- Throbbing Pain
- Swelling intra and extra
- bad taste
- Pus discharge
- Hard to open their mputh
- Difficulty chewing
- Malaise
- Transient and intermittent pain
What symptoms are common to pericoronitis?
- Occlusal trauma to operculum
- Ulceration of operculum
- Evidence of cheek biting (traumatic ulceration)
- Foetor oris
- Lim mouth opening
- Dysphagia
- Pyrexia (fever)
- Malaise
Regional lymphadenopathy
What is the txt for pericoronitis?
- Incision of localised pericoronal abscess if required
- LA if the pt wants it depening on pain and pt
- irrigate with warm saline or chlorhexidine mouthwash using 10-20ml syringe with blunt needle under operculum
- XLA upper third molar if traumatising operculum
- Pt instructed on frequent warm salty mouth rinse or chlorhexidine mouthwash
Why do some health boards not authorise the use of chlorhexidine in irrigation of pericoronitis?
- Very rare but some cases of anaphylaxis
- Check your health board
What pt advice would you give for pericoronitis?
- Analgesia pt can take , do not exceed recommended dose on back of packet
- paracetamol 4g , ibuprofen 2.4g
- Keep fluid levels up and keep eating soft/liquid diet if necessary
- Warm salty mouth rinse frequently
When would you prescribe antibiotics for pericoronitis?
- Severe pericoronitis
- Systemically unwell
- E/O swelling
- immunocompromised e.g. diabetic
If pt present with large extra/oral swelling, systemically unwell, trismus, dysphagia with pericoronitis what should you do?
- Refer to maxillofacial unit or A&E
What are some predisposing factors to pericoronitis?
- PE and vertical or distoangular impaction
- Opposing maxillary third molar or second molar causing mechanical trauma contributing to infection
- Poor oral hygiene
- Insufficient space between ascending ramus of lower jaw and distal aspect of mandib second molar
- White race
- URTI and stress and fatigue
- Full dentition
During extra-oral exam what features are you assessing?
- TMJ
- Limited mouth opening
- Facial symmetry
- Lymphodenopathy (unilateral, bilateral)
- MOM
When assessing the third molar what thinhs do you need to note ?
- PE or UE
- How much of the crown can be seen i.e. 2/3rds
- Is there operculum covering
- Is there pus
- Is there food trap
- State of margins i.e. any erythema
- Caries
- Bleeding
- Impaction
When are you to take a radiograph?
- Only if surgical intervention is being considered
What radiograph do you take for third molar extraction?
- OPT
Upon the radiographic report of OPT for third molar what should you note?
- Presence or abscence of disease in 3M or anywhere else
- Anatomy of 3M (crown size, shape, condition, root morhpology)
- Depth of impaction
- Orientation of impaction
- Working distance (distal of lower 7 to ramus of mandible
- Follicular width (2.5-3mm considered pathology)
- Periodontal status
- Relationship or proximity of upper third molar to maxillary antrum and of lower third molars to Inferior dental canal
- Any other assoc pathology
What are some radiographic signs that the third molar is close to the inferior alveolar nerve canal?
- Interruption of white lines/lamina dura of canal
- Darkening of root where crosses by canal
- Diversion/ deflection of inferior dental canal
- Defelction of root
- Narrowing of IANC
- Narrowing of root
- Dark and bifid root
- Juxta apical area
What are the 3 signs that have been demonstrated to be significantly increased risk of nerve injury during 3M surgery?
- Diversion of IANC
- Darkening of root where crossed by canal
- Interruption of white lines of canal
- SIGN guidelines and FDS guidelines
What does this image show?
- Normal root morphology of IANC
What does this image show ?
- Diversion/ deflection of IANC
What does this image show?
- Darkening of the root where crossed by the IANC
What does this image show?
- Interruption of the white lines/ lamina dura of IANC
What does this image show?
- Deflection of root
What does this image show?
Narrowing of IANC
What does this image show?
- Narrowing of root of 3M
What change to 3M does this image show?
- Dark and bifid root
What change to 3M does this image show?
- Juxta apical area
- A well circumcised area lateral to root
- Not usually found at apex of tooth
If you suspect a close relationship to IANC what radiograph other than OPT can yiu get?
- CBCT
What does transverse angulation of 3M mean?
- Crown is buccally placed and roots are lingually placed or vice versa
What does aberrant angulation of 3M mean?
- Tooth positioned in odd place
In what order does different types of angulation in lower 8’s most commonly occur?
- Mesial 40%
- Vertical 30-38%
- Distal 6-15% (most likely to be reffered to specialist as hardest to XLA)
- Horizontal 3-15%
- Transverse or aberrant (less common - quite rare)
How is the angulation / orientation of 3M measured?
- Measured against curve of spee
- On an OPT draw the curve of spee
- Draw a straight line through the 8 from the furcation and straight line through the 7
- Assess how they meet
How would you classify these lower molars?
- Lower right 48 mesially impacted on 47
- Lower left 38 horizontally impacted
How would you classify this impaction of lower molars?
- Lower right 48 horizontally impacted
- Lower left 38 distally impacted
Why are distally impacted lower molars hard to remove and require specialist referral?
- Need to remove distal bone of ramus of mandible to remove 8
- Roots lie close to the 7s roots meaning hard to get an application point and need to be careful do not damage 7
How would you classify these lower third molars ?
- True vertical impaction 48
- Distal impaction 38
How would you classify this molar?
- Transverse impaction 48
How would you classify this third molar?
- Aberrant position 38
What feature of a third molar gives us an indication of the amount of bone removal required during surgery?
- Depth of impaction
What are the 3 ways Depth of impaction can be described?
- Superficial
- Moderate
- Deep
What does superficial depth of imoaction mean?
- Crown of 8 related to crown of 7
What does moderate depth of impaction mean?
- Crown of 8 related to crown and root of 7
What does deep depth of impaction mean?
- Crown of 8 related to root of 7
How would you classify the depth of the lower m olars?
- 48 moderate impaction
- 38 superficial impaction
How would you classify this lower molar in terms of depth?
- Superficial impaction 38
How would you classify this depth of impaction of lower molar?
- Moderate impaction 48
What are the txt options for third molars (common pathways)?
- Referral to specialist/ dental hospital with oral surgery unit/ MFS
- Clinical review
- Removal of 3M
- XLA maxillary third molar
- Coronectomy
What is a clinical review?
- Assessing the pts signs and symptoms at check ups
What is a coronectomy?
- Removal of the crown of the tooth and roots left in situ
- Done with 3M if thought to have close relationship to IANC
What other rare txt options are available for 3M?
- Operculectomy
- Surgical exposure
- Pre-surgical orthidontics
- Surgical reimplantation/ autotransplantation
If tooth is asymptomatic but is diseased or at high risk of disease developing what is the management of M3Ms?
- If risk high surgical intervention considered
- If tooth at higher risk of surgical complications ( close approximation to IANC) then active surveillance recommended until symptoms develop or early disease progression proven
If tooth is asymptomatic and non-diseased or at low risk of disease devlopment what is the management of M3M?
- Clinical review supplemented with radiographic assessment at appropriate intervals
If tooth is symptomatic and is diseases or at high risk of disease devlopment what is the management of M3M?
Consider therapeutic XLA indicated for
- Single sever acute or recurrent subacute pericornitis
- Unrestorable caries M3M or assist restoration of adjcent tooth
- Periodontal disease compromising M3M and/or adjacent tooth
- Resorption of M3M and/or adjacent tooth
- Fractured M3M
- M3M PA abscess, irreversible pulpitis, or acute spreading infection
- Surrounding pathology
What medical factors do you need to consider when determining prophylactic removal txt option?
- Pt undergoing planned medical txt that may complicate likely surgery of M3M
- Bisphosphonates
- Antiangiogenics
- Chemotherapy
- Radiotherapy to head and neck
- Immunosuppresant therapy
What surgical factors do you need to consider when considering prophylactic removal of M3M?
- Third molar lies within the perimeter of surgical field
- Mandibular fractures
- Orthognathic surgery
- Resection of disease ( benign and mlaignant lesions)
What to do if tooth is symptomatic but no assiocated disease?
- Leave deeply impacted M3M with no associated disease
- Txt other diagnoses causing pain in that region
- TMD disorders
- Parotid disease
- Skin lesions
- Migraines
What methods of anaesthesia available?
- LA
- GA
- Conscious sedation (IV with midazolam)
What consent do you require for surgical management?
- Written and verbal
- Form listing risks and warnings
When gaining consent for the procedure what do you need to explain to the pt in order to get informed consent?
- Explain procedure to pt in words they will know
- If tooth is needing sectioned explain this
- Give pt ide what to expect during , no pain but will feel vibrations
- Explain minor surgical procedure, may need flap, possible drilling, sutures (stitches help gum to heal)
- Risk to adjacent restoration but will place temp and replace at later date
in edentulous / atrophic mandible pt what is the risk associated even if it is small?
- Aberrant lower 8 closer to lower border of mandible
- Large cystic lesion associated with wisdom tooth
- Risk of jaw fracture
- Very rare
- Arranged to have this fixed in a hosiptal at the time
What post op complications do you need to tell the pt in order to gte consent?
- Pain
- Swelling , normal to see up to two weeks after
- Brusiing , varies but is normal and setlle within a week or two
- Jaw stiffness/ limited mouth opening so may need to have soft diet for up to two weeks, if sever contact us
- Bleeding - normal to see a little bits of blood on pillow or when brushing teeth - bite down on guaze for 15mins if a lot
- Infection - signs and symptoms of infection
- Dry socket (most common in 3M)
What would you say to pt when consenting them for nerve damage?
- May experience sensory deficit
- Numbness or tingling of the lower lip, chin, side of tongue
- 10-20% will experience temporary numbness or tingling lower lip and chin from IAN and may take weeks /months to improve
- Most healing takes place first 9 months , unlikely to heal after 18-24 months
- <1% experience permanent numbness or tingling
- Lingual nerve alters one of tongue, taste
- Altered sense of taste (rare)
- Painful sensation (dysaesthesia)
- Rudeced sensation (hypoaestheisa) or increased sensation
How does the Chorda tympani relate to altered taste in surgical extractions?
What acroynym is useful for referral?
- SBAR
Situation
Background
Assessment - extra and intra / MH etc
Recommendation - your opinion
What are the basic principles of surgical removal?
- Risk assessment
- Verbal and written consent in terms pt can confirm
- Medical history
- Aseptic technique
- Minimal trauma to hard and soft tissues
What is the step by step of how to surgically remove third molar?
- Anaesthesia
- Access
- Bone removal if necessary
- Tooth division as necessary
- Debridement
- Suture
- Achieve haemostatis
- Post op instructions v+w
Step by step how do you gain access for surgical removal? 6 points
- Access to tooth gained by raising buccal mucoperiosteal flap
- +/- raising a lingual flap (controversial)
- Maximum access with minimal trauma
- Larger flap heal as quick as smaller one
- Use scalpel in firm continuous stroke around gingival margin of 7
- Minimise trauma to dental papillae
Step by step approach for reflection of the tissues during surgical removal of third molar?
- Relieving incision from mesial 5
- Raise flap at base of relieving incision where it is already gaping / bone is visible
- Undermine / free anterior papilla before proceeding with reflection distally to avoid tears with a Warwick James elevator
- Reflect with periosteal elevator firmly on bone (raise in one piece)
What instruments are used during reflection of flap off the bone?
- Mitchells trimmer
- Howarths periosteal elevator
- Ash periosteal elevator
What are the most difficult areas to reflect?
- Papilla
- Mucogingival junction
Label the instruments highlighted
- Left is Howarths periosteal elevator
- Middle is Mitchells trimmer
- Right is Ash periosteal elevator
What is this instrument?
- Rake retractor
What is this instrument?
- Minnesota retractor
Step by step for retraction during surgical removal of 8?
- Use Howarths periosteal elevator, rake retractor or Minnesota retractor for :
- Access to operative field
- Protection of soft tissues
- Flap design facilitates retraction
- Done with care
- Atraumatic / passive retraction
What is atraumatic / passive retraction?
- Rest retractor firmly on bone
- Be aware of adjacent structure like the mental nerve
- Minimise trauma
What do we use when doing bone removal of lower molar?
- Electrical straight handpiece with saline cooled bur
- Round or fissure stainless steel and tungsten carbide burs
What can air driven handpieces lead to during bone removal?
- Surgical emphysema
What site is the bone gutter carried out?
- Buccal aspect of the tooth beginning at distal aspect of impaction
- Do not start mesial as if you loose control of drill and it plunges into soft tissue distal of 8 then lingual nerve may be damaged
How would you describe the bone gutter required?
- Deep narrow gutter around crown of wisdom tooth
- To allow correct application of elevators on mesial and bucaal aspects of tooth
Why is irrigation vital in bone removal?
- maintain visibility
- Avid bony necrosis
When would be appropriate to decide if the tooth needs dividing upon removal?
- If adequate bone has been removed and tooth cannot be removed in its entirety with elevators or a combo of elevators and forceps
How can the tooth by divided for surgical removal?
- Either section the crown of the tooth from the roots and then elevate each in turn (horizontal crown section)
- Or vertical divide the tooth with a bur at the bifurcation and elevate each section
What are the 3 methods of debridement?
- Physical
- Irrigation
- Suction
What do you do for Physical debridement?
- Bone file or handpiece to remove sharp bony edges
- Mitchells trimmer or Victoria curette to remove soft tissue debris
What do you do for Irrigation?
- Sterile saline into socket and under mucoperiosteal flap
What must you do after removal of tooth?
- Aspirate under flap to remove debris
- Check socket for retained apices etc
- When the tooth is removed any debris must be cleaned out and any follicular tissue or granulation tissue from chronic infection should be curetted – especially that hidden behind the second molar
What instrument is highlighted
- bone file
What are the aims of auturing?
- Reposition tissues (approximate tissues)
- Cover bone
- Prevent wound breakdown
- Achieve haemostasis
Describe this 3 sided suture placement
- 3 sided mucoperiosteal flap with distal and mesial relieving incision
- Sutures placed distal of 8 and buccal aspect of 7 to reposition tissues
Describe this 3 sided suture placement
- 3 sided mucoperiosteal flap with distal and mesial relieving incision
- Sutures placed distal of 8 and buccal aspect of 7 to reposition tissues
- Another suture placed more buccal along mesial incision as still a gap in the tissues (clinical decision)
Describe this 3 sided suture placement
- 3 sided mucoperiosteal flap with distal and mesial relieving incision
- Sutures placed distal of 8 and buccal aspect of 7 to reposition tissues
- Another suture placed through papilla from buccal to lingual aspect distal of 7 (papilla loose or not approximated enough)
Describe this envelope suture placement
- Distal relieving incision but no mesial relieving incision
- Place interupted suture distal of 8 and buccal to lingual distal of 7 through dental papilla
Post op instructions given verbally and written to pt?
- No smoking for 48hrs and consider cessation
- No alcohol at least 24 hrs
- No rigorous exercise , take it easy
- Avoid eating until LA wears off
- Keep diet soft foods esp that evening and eat on other side
- Try and avoid touching socket with tongue or finger as this increases bacteria introduction or dislodges the blood clot
- Take painkillers before LA wears off and regularly to keep on top of the pain, do not exceed recommended dose
- Pain is worse 24-48hrs then should start to receed so take analgesia when required
- Swelling expected and is normal , can use ice pack to reduce swelling
- If any swelling becomes present under jaw , down neck or up to the eye and you feel eye is closing over then contact us asap
- Bleeding normal for next 72hrs , just a little bit on you pillow or when youre brushing - give gauze and instructions ot stop bleeding
- Brusijng normal but if gets worse after 3 days contact us
- Signs and symptoms of infection are if pain or swelling getting worse after 3 days tor notice ous or bad tatse then contact us or own dentist
- Jaw stiffness to be expected , usual for this to occur for 2-3 weeks after
- Limiting mouth opneing can be helpful
- IDB lasts for 3 hours but if they feel sensation has returned to most areas except a little bit then ocntact us
- Warm salty mouthrinse helpful 3-4 times a day beginning tommorow or may dislodge blood clot and increases chance of dry docket
- Contact details for practice or hospital or NHS 24 (111)
Why perform a coronectomy instead of surgical removal?
- Alternative when there appears to be increased risk of IAN damage with surgical removal
- Aim is to reduce risk of IAN damage
What is the process of Coronectomy?
- 3 sided / envelope mucoperiosteal flap
- Transection of tooth 3-4mm below enamel of crown into dentine
- Elevate/ lever crown off without mobilising roots
- Pulp left in place untreated
- If needed further reduction of roots with rose head bur to 3-4mm below alveolar crest (not always poss)
- Irrigate socket with saliner
- Replace flap (can leave socket open or close flap)
- AB not prescribed routinely
What is the follow up for a coronectomy?
- Review 1-2 weeks
- Further review 3-6 months then 1 year (discharge back to GDP)
- Radiographic review 6months ,1yr and thereafter if symptomatic
What are the risks assoicated with Coronectomy?
- If root is mobilised during crown removal then entire tooth must be removed (more likely wiht ocnical fused roots)
- Leaving roots behind can result in infection
- Can get a slow healing/painful sockety
- Root may migrate later and begin to erupt through mucosa and may require XLA
Are upper third molars easier to remove than lowers?
- Yes
- Althouggh occasionally difficult due to dense cortical bone
How are upper third molras removed?
- Removed by elevation only or elevtaion and forceps
- Elevation with straight or curved Warwick James elevators or couplands
- care taken that tooth doesnt pop out and go down pt throat
- Forceps like the Boynets upper third molras used
How do you take care in not causing maxillary tuberosity fracture?
- Support tuberosity with finger and thumb
- Excessive force can fracture it , use forceps and supporting tuberosity helps
