Supplementary LA Techniques and Complications

• Supplementary LA techniques:

  • Intra-osseous
  • Intraligamentary (periodontal ligament)
  • Intrapulpal
• Supplementary LA techniques are:

  • Useful in both jaws
  • Useful in overcoming failure
  • Not all LA injections will work on 1st attempt, so supplementary techniques are used when that happens
  • Occasionally used as first-choice
• Intra-osseous anaesthesia:

  • LA solution directly injected into cancellous space of the bone
  • Specialised syringe system required
  • Perforator needed to drill a hole into the alveolus, distal to the tooth that needs to be anaesthetised
  • LA is then injected through that hole to achieve anaesthesia in the tooth
  • To work out where to drill the hole: picture a line along the gingival margin of the teeth, and another line bisecting the papilla. The hole would then be created 2mm below that line
• Intraligamentary anaesthesia:

  • AKA periodontal ligament anaesthesia (PDLA)
  • Form of intra-osseous anaesthesia
  • High force needed; LA being injected into periodontal ligament space around tooth (small space)
• Technique for intraligamentary anaesthesia:

  • Clean gingival margin
  • Use 30 gauge needle
  • Use specialised syringe
  • Approach mesio-buccal aspect of root at an angle of 30 degrees
  • Advance needle down PDL to maximum penetration
  • Inject 0.2ml at each root slowly (over 30 seconds)
  • Wait 10 seconds before withdrawing needle; if you don't the LA solution will flow straight back out the periodontal ligament space and won't work
  • NOT A SAFETY PLUS SYSTEM!
• There are perforations between the alveolus and the periodontal ligament space. So during an intraligamentary LA injection, as LA solution is forced into the periodontal ligament space, it's forced through the perforations, into the alveolus.
• Advantages of intraligamentary anaesthesia:

  • Works in both jaws
  • Limited soft tissue anaesthesia (but not limited to single tooth anaesthesia)
  • Small dose
  • Useful in overcoming failure; has a very high success rate (only teeth not so good on is mandibular incisors, because there aren't many perforations in the alveolus near them)
  • Rapid onset
• Disadvantages of intraligamentary anaesthesia:

  • Short-acting (get pulpal anaesthesia for around 15 mins) - therefore may need to keep topping it up
  • Discomfort (but it doesn't last long)
  • Systemic effects, similar to intravenous injection
  • Tissue damage (therefore can't use it on a tooth if you're wanting to restore it)
  • Periodontal ligament
  • Tooth
  • Alveolus
  • Successor teeth (therefore shouldn't be used in deciduous teeth)
• Intra-pulpal anaesthesia:

  • Direct deposition of solution into pulp canals
  • Limited application (because pulp chamber needs to be accessed - so used in root canal treatment or in oral surgery if the tooth decoronates)
  • For it to work, the LA must be injected under pressure; the high pressure is what causes the anaesthesia, not the LA solution
  • Needs tight adaptation of needle to defect in chamber or at each pulp canal
  • Each canal injected separately
• At the point of pulp access, the patient has complained of pain, therefore an intrapulpal injection would be given. If a small area of pulp chamber is uncovered, the needle can be just placed in the hole. But if whole pulp chamber is uncovered, place a needle in each root canal.
• Complications of LA:

  • Localised complications
  • Pain associated with injection
  • LA failure
  • Intravascular injection
  • Nerve damge
  • Trismus (stiff jaw - limited mouth opening for a few days)
  • Other tissue damage
  • Facial paralysis
  • Generalised complications
  • Psychogenic reactions to LA
  • Toxicity
  • Allergies to LA
  • Drug interactions (mainly with the adrenaline in LA)
  • Infection
• Localised complications of LA:

  • Pain associated with injection
  • Speed (1ml over 30 seconds is ideal)
  • Inappropriate site (injecting under periosteum will cause pain, therefore need to make sure you're supraperiosteal for all injections)
• Localised complications of LA:

  • LA failure
  • Poor operator technique
  • Insufficient volume of LA delivered
  • Accessory nerve supply
  • Midline
  • Other nerves
  • Infection
• Localised complications of LA:

  • Intravascular injection (can be largely avoided by remembering to aspirate) - can increase risk of LA systemic toxicity and put patient at risk of temporary paralysis and temporary blindness
  • Intra-arterial
  • Intravenous (more likely to do this; when a needle punctures an artery it's more likely to constrict and stop you injecting any solution)
  • Nerve damage
• Localised complications of LA:

  • Trismus (stiff jaw - limited mouth opening for a few days)
  • Common complication associated with inferior alveolar nerve block; the needle can catch the medial pterygoid muscle, which would leave the patient with trismus
  • Other tissue damage
  • Self-inflicted trauma (biting tongue or lip common if they're numb) - particularly common in children
• Localised complications of LA:

  • Facial paralysis
  • Associated with IANB; if needle ends up in parotid gland it can anaesthetise the facial nerve
  • Only temporary, will reverse once the LA has worn off and been metabolised
• Generalised complications of LA:

  • Psychogenic reactions to LA
  • Patients who are anxious regarding LA and will have a tendency to feel dizzy/faint and complain of palpitations associated with LA injections
• Generalised complications of LA:

  • Toxicity
  • All local anaesthetics have a maximum dose, which is dependent on the patient's body weight
  • 1/10th of a cartridge per kilo of body weight
  • 1 cartridge per 10kg
  • Allergies to LA
  • Infection
  • Always use a clean, sterile needle
  • Needlestick injury
• Generalised complications of LA:

  • Drug interactions (mainly with the adrenaline in LA):
  • Beta-blockers
  • Calcium channel blockers
  • Anti-parkinsonian drugs
  • Tricyclic antidepressants
  • Diuretics
• Needlestick injuries = "A percutaneous injury from a needle or other object contaminated with blood or saliva"
• Prevention of needlestick injuries:

  • Never re-sheathe
  • Disposable syringes
  • Be equally careful with matrix bands and scalpels, scalers and burs
• Management of a needlestick injury:

  • Always report to Head Nurse
  • Wash the wound
  • Make the wound bleed whenever possible
  • Get blood from:
  • Recipient - baseline
  • Donor - HBC, HCV, HIV
  • Post-exposure prophylaxis
  • Prevention is best
  • Impression/appliance disinfection
  • Clearing away:
  • Sharps to sharps bin
  • Contaminated non-sharps to yellow bags
  • Domestic waste to black bags
  • Instrument kits checked and stacked with care and consideration