Oral surgery Flashcards
When do third molars erupt and why do they sometimes fail to?
They are the last teeth to erupt at 18-23 years. They are often absent or fail to erupt into normal occlusion. An impacted tooth is one which is prevented from reaching normal position by the presence of another structure. This is usually an adjacent tooth but may include the ascending ramus or overlying soft tissues. Removal of the third molars is one of the commonest surgical procedures carried out in the NHS.
What problems are associated with 3rd molars?
- Abnormal position which can lead to cheek biting (upper 8s)
- Caries, pulp and periapical pathology in 2nd and 3rd molars
- Periodontal problems
- pericoronitis
Resorption (internal and external for 7s) - Cyst formation
- Difficulty with OHI and food packing
- Crowding of lower incisors
- Often involved in line of mandibular fractures
- In the way of orthognathic surgery
- Potential risk in the future for vulnerable and medically compromised patients
What is pericoronitis?
It is inflammation in the soft tissues around the crown of a partially erupted tooth. It is caused by bacterial infection and/or trauma. It is the most commonly sited reason for the extraction of 8’s.
What are the symptoms of pericoronitis?
- Pain or discomfort
- Soft tissue swelling in the region of the partially erupted tooth
- Difficulty eating, swallowing or opening the mouth
- Tenderness on closing if opposing tooth is in contact with inflamed soft tissues
- Unpleasant taste or smell
- May feel unwell with pyrexia
- May be a recurring problem
What are the signs of pericoronitis?
- Inflammation in the soft tissues around the crown or the partially erupted tooth
- Localised intraoral swelling
- Evidence of trauma from opposing tooth?
- +/- pus
- +/- local lymphadenopathy
- +/- facial swelling
What is the management of teeth with pericoronitis?
First manage with local measures:
- Irrigation beneath gum flap with saline/chlorhexidine mouthwash
- Remove upper 8 if traumatic occlusion
- Advise HSMW/chlorhexidine and analgesics
- Antibiotics if spreading infection or if medical problems, immuncompromised etc. Give metronidazole 200mg tds (anaerobic)
- Drain pus if present
- Formal review
What should be done at review?
- Assess the outcome of the treatment and manage appropriately
- Assess 3rd molars
- Likely to erupt and be functional - monitor
- Unlikely to erupt - if problematic consider removal if not then leave and monitor
- Persistent, recurrent or severe problems - consider removal
What clinical guidelines are available for the removal of third molars?
- Royal college of surgeons of England 1997
- NICE 2000/3
- American association of oral and maxillofacial surgery 2007 - recommend removal of third molars at young age
What do the NICE guidelines say about removal of third molars?
- Routine practice of prophylactic removal of pathology free impacted third molars should be discontinued on the NHS
- Removal should be limited to patients with evidence of pathology
- Surgical removal of impacted third molars should be limited to patients with evidence of pathology
- Plaque formation is a risk factor but is not in itself an indication for surgery
- Adherence to guidelines should be audited and history and justification should be documented
- This will save money if prophylactic removal of third molars is discontinued
- Numbers of patients on the waiting list might reduce if these criteria are applied
- Not ethical to expose patients to unnecessary procedures
What are the NICE guidelines on pericoronitis?
The degree to which the severity of the recurrence rate of pericoronitis should influence the decision for surgical removal of a third molar remains unclear. A first episode unless severe should not be an indication for surgery. Second or subsequent episodes should be considered appropriate indication for surgery.
What justification is there for prophylactic removal?
- To prevent crowding
- Reduce complications in older individuals
- Better able to cope when young
- If GA then do all at once
What does a cochrane review advise with regards to removal of third molars?
It is from 2002 but was edited in 2008. It is independent of NICE. It states that there is no difference in clinical effectiveness between removal and retention. There is no difference in cost effectiveness between removal and retention. The conclusion is that there is no clear evidence to support or refute the benefits of prophylactic third molar removal other than prevention of late lower incisor crowding.
It appears to be more cost effective to leave in situ, prophylactic removal with subsequent nerve damage would be negligent.
What should be assessed in a radiograph of a third molar?
- Diagnosis
- Type of impaction
- Depth of tooth within bone
- Crown form
- Root form and number
- Coronal or root pathology
- Other pathology (cyst, caries in 2nd molar)
- Relationship with mandibular canal (IAN)
Assess the entire tooth, adjacent molar, surrounding bone, ID canal and lower border.
What are the types of impaction?
- Vertical - the easiest to extract, risk of pericoronitis
- Mesio-angular - more difficult, risk of food packing and caries in 2nd molar
- Horizontal - even more difficult, risk of food packing and caries in 2nd molar
- Disto-angular - very difficult, risk of pericoronitis
- Transverse - tricky
Buccal or lingual version adds additional complexity.
What is the most appropriate radiograph for third molars?
Sectional panoramic films are most appropriate for the assessment of third molars because it is often difficult to get all of the tooth and the mandibular canal on a periapical film. The object here is to assess the degree of surgical difficulty. A CT scan may be taken to determine the location of the ID nerve.
What should you note about the roots in the radiograph?
- Fused or conical
- Straight and separate
- Pincer shaped - needs division
- Complex
What pathology would you look at in a radiograph of a third molar?
- Caries and periapical disease
- Dentigerous cyst - risk of fracture
- External resorption with secondary osteomyelitis
How would you manage different proximities to the ID canal?
- Ideal - roots clear of the canal
- No increased risk - canal cortication visible
- Canal narrowed - roots have an intimate relationship with nerve
- Canals deviated - same as above
- Superior cortical boundary not visible - if you can’t see the two white lines then the nerve is right next to the root
- Dark band across the root - high risk
How do you decide the treatment for a third molar?
Ask yourself is the third molar the cause of the patients problem? Does the patient need immediate care? for example a dressing to treat acute pulpitis. What are the risks and benefits of the various treatment options and get informed consent.
What are the treatment options for a third molar?
- Removal
- Observation
- Operculectomy (remove flap of gum overlying tooth
- Coronectomy (removing crown)
Can be done with LA, LA and sedation, GA (day case) or GA (in patient).
What is coronectomy and how is it done?
It is the removal of the crown of a tooth and leaving the roots in place.
- Raise buccal flap
- Cut at 45 degrees to crown, passing completely through (minimises risk of mobilising roots)
- Use fissure bur to reduce root to 3mm below alveolar crest
- Periosteal release and primary closure
When is coronectomy used and the risks and contraindications?
The evidence for it is unclear but it is increasingly utilised with high risk cases. It appears to be a valid technique for reducing the risk of IAN damage.
It can be used when the tooth is in close proximity to IDN, no evidence of active infection or tooth mobility and avoid horizontal/mesio-angular teeth.
The patient must be warned of the potential for a second procedure to remove roots if they erupt or become infected (root removal in 2-6% of cases). Mobility of roots appears to be predominant factor for success. It is not indicated for co-morbidity patients e.g. chemotherapy, diabetes, immunosuppressed, bisphosphonates.
What minor complications can occur with third molar extraction?
- Pain, swelling, trismus
- Infection
- Fracture including tuberosity
- Bleeding and bruising
- TMJ problems
- Temporary nerve damage
- Periodontal problems
- Damage to other teeth
- Oral-antral communication
Displacement of upper 8’s into pterygomandibular fissure (have retractor round the back of 8’s to prevent this)
When does pain, swelling and trismus occur after extraction?
Pain is guaranteed after surgical removal of lower 3rd molars and can be severe. Pre-operatively warn the patient and advise on analgesics. Swelling and trismus is also guaranteed after surgical removal. It is variable but can be marked. Pre-operately warn the patient and provide advice on how to minimise (NSAIDs).
Are infections likely and should antibiotics be used?
There is a higher rate of incidence of post-operative infection in lower third molar sockets. There needs to be good oral hygiene post operatively. There is no good evidence for routine use of antibiotics. Consider all the variables as antibiotics do have a role for example in co-morbidity, local and systemic.
What does damage to adjacent teeth include and how do you manage this risk?
It includes mobilisation of second molars, damage to restorations and fracture of adjacent teeth. Pre-operatively assess the adjacent teeth clinically and radiographically, warn the patient and have a plan in place to minimise the risk and deal with the complication.
Why may the mandible fracture?
- Elderly, edentulous patients with atrophic mandible
- Pre-existing bone pathology
- Large bone defects
- Excessive use of force - cryers, large elevators
What can cause trigeminal nerve damage and what is the incidence?
Removal of wisdom teeth is the most common cause, also implantology, other surgery such as orthognathic, trauma, soft tissue surgery, needle stick (neuropraxia) and endodontics. The incidence is: IAN: - Temporary 5-7% - Permanent 0.5-1% Lingual: - Temporary 3-7% - Permanent 0.3-0.5% Know these figures. There are a minimum of 300 (pss 600) lingual nerve injuries a year and a higher rate of IAN injuries.
What nerves are around lower wisdom teeth?
On the lingual side there is the lingual nerve and below this the mylohyoid nerve. On the buccal side there is the long buccal nerve and below this the inferior alveolar nerve.
What causes lingual nerve injuries?
They are mainly drill injuries, lingual flaps still being raised and coronectomy. A lingual flap is made in some cases and a retractor placed down to protect the lingual nerve. This can lead to crushing of the nerve so is not done.
What are the effects of trigeminal nerve injury?
- Complete loss of sensation to half the anterior tongue and/or chin/lip
- Paraesthesia - reduced sensation
- Dysaesthesia - pain, tingling, burning
- Allodynia (painful response to non-painful stimuli)
- Loss of taste
What do patients with nerve injuries complain of?
- Pain, unpleasant burning and tingling
- Feel like they’re dribbling
- Bite their lip
- Avoid eating in public
- Don’t enjoy kissing
- Bite their tongue
- Tongue feels like a large lump of jelly
- Lose food under their tongue
- Don’t enjoy food
What is the current management of lingual nerve injury?
It is managed with a surgical technique where a lingual flap is raised and the lingual periosteum is divided. The central and distal nerve stumps are identified and mobilised. The damaged segment of the nerve (4-14mm mean 9.5mm) is excised and there is direct reapposition with 5-10 (mean 7) 8/0 ethilon epineural sutures. All patients are given dexamethasone and antibiotics. It is effective and the majority of patients regain some sensation and fewer patients tend to bite their tongue.
How can the outcomes of lingual nerve repair be measured and which ones show significant improvement?
- Light touch
- Pin prick
- Two-point discrimination
- Gustatory response
- Altered sensation - dysaesthesia
- Subjective assessment
Significant improvement shown with light touch stimuli, pin prick stimuli, gustatory stimuli and two point discrimination. Will never return to normal.
What is the step by step management of lingual nerve repair?
If the division of the lingual nerve is noted during the operation there should be immediate microsurgical repair or urgent referral. When reviewing the patient if there is a problem, the patient should be informed and monitor the recovery by doing light touch, pink prick or 2 point discrimination. Review 3 months after injury and if there is some recovery continue to monitor but if there is no evidence of recovery consider referral to a specialist centre for exploration/repair.
Should you repair the IAN immediately at the time of third molar removal?
The nerve is usually well supported within the mandibular canal. Even after transection the ends do not usually retract so primary repair is not normally required. Control bleeding with temporary packing with gauze.
What should you avoid following injury to IAN?
Diathermy, whitehead’s varnish and other medicaments, surgicel (neurotoxic) and bone wax.
How do injuries to the IAN occur in implantology?
It can be from the drill or implant. Many drills are longer than the implant length (Y dimension can be 1.5mm). It can occur due to overdrilling e.g. in low resistance bone and slippage of drill or pressing at roof of canal. It can occur due to miscalculation of the position of the IAN. Immediate placement (primary stability) is more likely to cause IAN. The safety zone is 2-4mm.
How can the mental foramen be avoided with implants?
4mm anterior to ensure avoidance of anterior loop. Consider surgical exposure.
What factors may indicate damage to the nerve?
- Sudden give
- Electric shock
- Arterial bleed (large percentage of injuries are secondary to haematoma)
- May be sensible to wait 2 days and then place implant to prevent compression ischaemia
- No evidence though
What is the management post nerve injury due to implants?
There is good evidence that neural recovery with implant related injuries is inversely proportional to time. Ideally you should remove the implant within 24-36 hours. There should be a post-operative call the same day or the following day. Short term you should remove the implant. The patient should be informed. Take a radiograph for localisation of the lesion. Evaluate the time that has elapsed, the proximity of the implant etc. Neurosensory evaluation.
What are the indications for surgical intervention after nerve damage?
- Persistent anaesthesia
- Dysaesthesia/pain
What does IAN decompression/neurolysis involve?
- Cannot excise complete segment
- Can remove bony obstruction
- Can remove bony compression
- Can remove soft tissue tethering/tension
Can remove neuroma - dysaesthesia
What is the result of IAN decompression?
It reduces the number of patients with dysaesthesia, significantly improves the level of sensation, the level of improvement is modest. It gives no improvement in some patients, never results in complete recovery and we cannot predict who will benefit. It should be offered to patients with severe symptoms.
How do needle stick injuries cause injury to nerves?
The incidence of permanent nerve injury following nerve block is very low. Incidence has been reported to be between 1 in 20000 and 1 in 850000. Most nerve injuries are caused by multiple injections and there can be direct injection of the agent intraneurally also. There is a disproportionate increase with articaine.
How does articaine cause more nerve damage?
It makes up 25% of sales compared to 54% with lidocaine and makes up 30% of cases compared with 35% with lidocaine. It is high risk for permanent dysaesthesia with IAN blocks. It is good for infiltrations but avoid mental area and IANs. Most lidocaine injuries recover.
How do endodontic filling materials cause damage?
Most are endotoxic so contact surgeon immediately.
