Complications of Local Anesthesia in Dentistry

Complications of Local Anesthesia

Broken Needle

• Use a new needle if there is any suspicion of inadequate product quality
• Do not redirect a needle once it is inserted into the tissue
• Management:
  • Stay calm and try to localize the broken part in the tissue
  • Tell the patient what has happened and try to relax and comfort them
  • Stabilize the patient's jaws to keep the needle in place
  • Remove the broken part with a hemostat if visible, or refer the patient to an oral and maxillofacial surgeon if not

Facial Nerve Paralysis

• Cause: inserting the needle too far back and behind the ascending ramus
• Solution: depositing the anesthetic in the parotid gland, causing paralysis of the facial muscles
• Clinically:
  • Patient complains of transient paralysis of the muscles of the chin, lower lip, upper lip, eyelid, and eyebrow
• Management:
  • Reassure the patient of the transient nature of the event
  • Advise the patient to use an eye patch until motor function returns

Trauma

• Occurs more frequently in younger children and mentally retarded patients
• Prevention:
  • Select a local anesthetic of appropriate duration
  • Place a cotton roll between the lip and teeth if they are still anesthetized
  • Warn the patient against drinking hot fluid, and biting the lips or tongue
• Management:
  • Symptomatic management with analgesics, antibiotics, warm saline rinses, and lubricants

Hematoma

• Cause: penetrating a blood vessel with the needle during injection
• Commonly associated with:
  • Pterygoid venous plexus
  • Posterior superior alveolar vessels
  • Inferior alveolar vessels in the pterygomandibular space
  • Mental vessels
  • Infraorbital vessels
• Prevention:
  • Learn anatomical landmarks and injection technique
  • Avoid relocating the needle to different sites inside the tissue
• Management:
  • Apply direct pressure if possible
  • Inform the patient of what happened and reevaluate the possibilities of continuing treatment
  • Instruct the patient to avoid applying heat to the area and prescribe analgesics and antibiotics if necessary

Infection

• Causes:
  • Contamination of the needle by touching the mucous membrane
  • Improper technique in handling local anesthetic equipment
  • Injecting the solution into an area of infection
• Prevention:
  • Use sterile disposable needles
  • Properly handle the needle to avoid contact with non-sterile surfaces
  • Use cartridges only once and store them in their original container
• Management:
  • Treat with antibiotic for 7 days
  • Manage as trismus if infection occurs

Systemic Complications of Local Anesthesia

Fainting (Vasovagal Attack)

• Most common systemic complication in the dental office
• Cause: sudden transient loss of consciousness due to cerebral ischemia
• Predisposing factors:
  • Anxiety
  • Emotional stress
  • Pain of sudden and unexpected nature
  • The sight of blood, surgical or other dental instruments
  • Sitting in an upright position or standing for a prolonged period
  • Hunger or starvation
  • Poor physical condition
  • Hot, humid, and crowded environment
• Mechanism:
  • Brainstem activation leading to simultaneous enhancement of parasympathetic nervous system tone and withdrawal of sympathetic nervous system tone
  • Cardioinhibitory response and vasodepressor response
• Prevention:
  • Good preoperative assessment
  • Proper injection technique
  • Use of sedation for relief of anxiety
• Management:
  • Lower the head of the patient and elevate their legs
  • Loosen tight belts and collars
  • Stimulate respiration
  • CPR if necessary

Hypersensitivity or Allergy to Local Anesthesia

• More commonly seen with ester type agents than amide type
• Causes:
  • Local anesthetic agent
  • Vasoconstrictor
  • Additives like bisulfite
• Rare, representing less than 1% of all complications of local anesthesia