1. Local anesthetic complications can arise from the drugs themselves or injection techniques. Soft tissue injury and sloughing of tissues from ischemia are complications of the drugs, while needle breakage, hematoma, and failure to achieve anesthesia can result from injection issues. 2. Proper administration techniques such as slow injection, aspiration, and choice of anesthetic agent and dose can help prevent complications. Monitoring for signs of excessive dosage or allergic reaction and having BLS protocols in place are also important for managing potential issues. 3. An understanding of anatomy, use of proper technique, and care in performing injections can help minimize risks. However, despite best efforts, complications may still occur rarely and require prompt treatment of symptoms

1. Complication of
Local anaesthesia
I.Kassem,BDS,MSc,MFDS RCS Ed,MOMS RCPS Glasg,
FDSRCS
Consultant Oral & Maxillofacial surgeon

2. SYSTEMIC COMPLICATIONS

3. Drug Actions
All drugs produce multiple effects
These effects are categorized as:
Desired
OR
Undesired

4. General Principles
No drug exerts a single action
No drug is non-toxic
Potential toxicity is user dependent

5. Adverse Drug Reactions
Direct extensions of usual effects
Side effects
Overdose
Local toxic effects

6. Adverse Drug Reactions
Altered recipient
Disease process
Emotional disturbances
Genetic aberrations
Idiosyncracy

7. Adverse Drug Reactions
Allergic reaction
Immediate - anaphylaxis
Delayed - contact dermatitis

8. Overdose
Dose related
Systemic distribution
Extension of pharmalogic effects
Selective CNS or CVS depression

9. Allergic Reactions
Not dose related
May be systemic or localized
Unrelated to pharmacological effects
Exaggerated immune system response

10. Idiosyncracy Reaction
Unexplained by any known mechanism of
the drug’s action
Neither overdose nor allergic reaction
Unpredictable; treat symptoms

11. Predisposition - Overdose
Patient factors
Age
Weight
Sex
Medications

12. Predisposition - Overdose
Patient factors
Disease
Genetics
Psychological attitude

13. Predisposition - Overdose
Drug factors
Vasoactivity
Concentration
Dose
Route of administration

14. Predisposition - Overdose
Drug factors
Rate of injection
Vascularity of site
Vasoconstrictors

15. Cause of Overdose Levels
Total dose is too large
Absorption is too rapid
Intravascular injection
Biotransformed too slowly
Eliminated too slowly

16. Biotransformation
Esters are hydrolyzed in the plasma and
liver by pseudocholinesterase into PABA
Amides are biotransformed by
microsomal enzymes in liver

17. Elimination
Both esters and amides are eliminated
through kidney, some in unchanged form
eg. (lidocaine - 10%)
Prilocaine is eliminated by lungs

18. Excessive Dose
Maximum dose should be based on:
Age
Physical status
Weight

19. Rapid Absorption
Vasoconstrictors should be used unless
specifically contraindicated

20. Intravascular Injection
Occurrence varies with type of injection:
Nerve Block % positive aspirate
Inf. alveolar 11.7
Mental/Incisive 5.7
Post. sup. alv. 3.1
Ant. sup. alv./ Buccal < 1

21. Prevention
Use aspirating syringe
Use needle - 25 ga or larger
Aspirate in 2 planes
Inject slowly

22. CLINICAL MANIFESTATIONS
of
OVERDOSE

23. Minimal to Moderate
Signs
Talkativeness Apprehension
Slurred speech Excitability
Stutter Euphoria
Dysarthria Nystagmus
Muscular twitching / tremors

24. Minimal to Moderate
Signs (cont.):
Elevated BP Sweating
Elevated heart rate Nausea/vomiting
Elevated resp. rate Disorientation
Failure to follow commands / reason
Lack of response to painful stimuli

25. Minimal to Moderate
Symptoms:
Restless Visual disturbances
Nervous Auditory
disturbances
Numbness Metallic taste

26. Minimal to Moderate
Symptoms (cont.):
Light-headed and dizzy
Drowsy and disoriented
Losing consciousness
Sensation of twitching (before actual
twitching is observed)

27. Moderate to High
Generalized tonic-clonic seizure activity
followed by
Generalized CNS depression
Depressed BP, heart rate
Depressed respiratory rate

28. Pathophysiology
Local anesthetics cross blood-brain barrier,
producing CNS depression as level rises
eg. LIDOCAINE
Blood Level Action Produced
< .5 ug/ml - no adverse CNS effects
0.5-4 ug/ml - anticonvulsant
4.5-7.5 ug/ml - agitation, irritability
> 7.5 ug/ml - tonic-clonic seizures

29. Pathophysiology
Local anesthetics exert a lesser effect on the
cardiovascular system
eg. LIDOCAINE
Blood Level Action Produced
1.8-5 ug/ml - treat PVCs, tachycardia
5-10 ug/ml - cardiac depression
>10 ug/ml - severe depression,
bradycardia, vasodilatation, arrest

30. MANAGEMENT
of
OVERDOSE

31. Mild Reaction -slow onset
Reassure patient
Administer O2
Monitor vital signs
Consider IV anticonvulsant
Allow recovery or get medical help prn
Get medical consultation, esp. if possibility
of metabolic or renal dysfunction

32. Severe Reaction - rapid onset
Stop all treatment
Place patient in supine position, feet up
Establish airway, give O2 (BLS)
If convulsions, protect patient
Summon emergency medical help
Consider anticonvulsant drugs, vasopressors

33. Severe Reaction - slow onset
Stop all treatment
Establish airway, give O2 (BLS)
Administer anticonvulsant
Summon emergency medical help
Consider vasopressors
Get medical consultation, esp. if possibility
of metabolic or renal dysfunction

34. Vasoconstrictor Overdose
Clinical manifestations:
Fear, anxiety
Tenseness
Restlessness
Tremor
Weakness

35. Vasoconstrictor Overdose
Clinical manifestations (cont.):
Throbbing headache
Perspiration
Dizziness
Pallor
Respiratory difficulty
Palpitations

36. Epinephrine Overdose
Sharply elevated BP (systolic)
Increased heart rate
Cardiac tachyarrhythmias

37. Management - v/c overdose
Stop dental treatment
Sit patient up
Reassure patient, administer O2
Monitor BP and pulse until fully recovered

38. Allergic Reactions
Type Mechanism Time Clinical Example
I Antigen induc. sec/min Angioedema,
Anaphylaxis
IV Cell mediated 48 hrs Contact
dermatitis

39. Allergens in Local
Esters - usually to the Para-amino-
benzoic-acid product
Na bisulfite or metabisulfite - found in
anesthetics as perservative for
vasoconstrictors
Methylparaben - no longer used as
perservative in dental cartridges

40. Management of Allergy Pts.
If the patient gives a history of allergy to
local anesthetics - Assume that an
allergy exists
Elective procedures
Postpone until work-up is completed

41. Management of Allergy Pts.
Emergency treatment
Protocol #1 - no invasive treatment ( I&D,
analgesics, antibiotics)
Protocol #2 - use general anesthesia
Protocol #3 - Histamine blocker (Benadryl)
Protocol #4 - Others: electronic dental
anesthesia, hypnosis, adjunctive N2O

42. Allergy - signs/symptoms
Dermatologic:
Urticaria - wheals, pruritis
Angioedema
Minor rash

43. Allergy - signs/symptoms
Respiratory:
Laryngeal edema
Bronchospasm
distress dyspnea
anxiety cyanosis or flushing
wheezing tachycardia
diaphoresis use of accessory
muscles

44. Anaphylaxis
Typical progression *
Skin reactions
Smooth muscle spasms (GI, GU, respiratory)
Respiratory distress
Cardiovascular collapse
*may occur rapidly, with considerable overlap

45. Management of Reactions
Delayed skin reaction
Benadryl - 50 mg stat & Q6H X 3-4 days
Immediate skin reaction
Epinephrine 0.3 mg IM or SC
Benadryl - 50 mg IM
Observation, medical consultation
Benadryl - 50 mg Q6H X 3-4 days

46. Management of Reactions
Bronchial constriction
Semi-erect position, O2 - 6 L/min
Inhaler or Epinephrine 0.3 mg IM or SC
Benadryl - 50 mg IM
Observation, medical consultation
Benadryl - 50 mg Q6H X 3-4 days

47. Mangement of Reactions
Laryngeal edema
Place supine, O2 - 6 L/min
Epinephrine 0.3 mg IM or SC
Maintain airway
Benadryl - 50 mg IV or IM
Hydrocortisone - 100 mg IV or IM
Perform Cricothyrotomy

48. Management of Reactions
Anaphylaxis
Place supine, on flat surface
ABCs of CPR, call for medical help
Epinephrine 0.3 mg IV or IM (Q 5 mins)
O2 - 6 L/min, monitor vital signs
After clinical improvement,
Benadryl and Hydrocortisone

49. Differential Diagnosis
Pyschogenic reaction (Syncope)
Overdose reaction
Hypoglycemia
Stroke (CVA)
Acute adrenal insufficiency
Cardiac arrest

50. PREVENTION
of
SYSTEMIC COMPLICATIONS

51. Prior to Treatment
Complete review of medical status
(including vital signs)
Anxiety / Fear should be assessed and
managed before administering anesthetic

52. Administration of Anesthetic
Place pt. supine or semi-supine position
Dry site, apply topical X 1 min
Select appropriate drug for treatment (time)
Vasoconstrictor unless contraindicated

53. Administration (cont.)
Weakest anesthetic in the minimum volume
(compatible with successful anesthesia)
Inject slowly (minimum of 60 sec / 1.8 ml)
Continually observe -
Never leave patient alone after injection

54. Administration (cont.)
Use only aspirating syringe
Aspirate in two planes, before injecting
Use sharp, disposable needles of adequate
diameter and length

55. ikassem@dr.com
Thank you for
attention!

56. Local Anesthesia
Complication

57. LOCAL COMPLICATION OF
LOCAL ANESTHESIA
1. Complications arising from drugs or
chemicals used for local anesthesia
2. Complications arising from injection
techniques
3. Complications arising from both

58. Complications arising from drugs or
chemicals used for local anesthesia
1. Soft tissue injury
2. Sloughing of tissues (Tissue
ischemia and necrosis)

59. SOFT TISSUE INJURY
■ Causes
1. It is seen in the form
of self-inflicted
trauma to lips,
tongue and cheek
2. It is common in
children and mentally
retarded adults
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60. 2- Sloughing of Tissues
(Tissue Ischemia and Necrosis)
Causes
1. predisposition: Commonly
in hard palate, as in the
region of distribution of
nasopalatine and greater
palatine nerves, because
mucoperiosteum is firmly
attached to the bone.
2. Deposition of excessive
volume of local anesthetic
agent with high
concentration of
vasoconstrictors
3. Rapid deposition of the
local anesthetic solution
with undue pressure
4. Application of topical
local anesthetic agent for
prolonged period
(epithelial desquamation)

61. COMPLICATIONS ARISING
FROM INJECTION TECHNIQUES

62. COMPLICATIONS ARISING FROM
INJECTION TECHNIQUES
1. Breakage of anesthetic cartridge
2. Breakage of needle
3. Needle-stick injuries
4. Hematoma
5. Failure to obtain local anesthesia
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63. Breakage of Anesthetic Cartridge
■ Causes
It occurs when there is
resistance to flow of
local anesthetic solution
in to the tissues
It occurs due to
following reasons:
1. Blockage of the needle
2. Too rapid injection;
especially during
administration of
palatal injection.

64. Breakage of Needle
■ Its very rare since the
introduction of sterile,
stainless steel
disposable needles
■ Causes :
Primary cause: Sudden
unexpected
movements by the
patient

66. Needle-stick Injuries
■ It’s an accidental injuries
occurring to dental staff caused by sharp
instruments such as needles, blades, scalpels,
explorers, root canal instruments, and wires, etc
■ These injuries are not usually serious, unless,
the instruments used were contaminated by
blood from patients with conditions such as
Hepatitis B virus HBV Infection, Hepatitis C virus
HCV Infection, A IDS

67. Failure to Obtain Local Anesthesia
■ Causes
1. OPERATOR-DEPENDENT
II. Selection of local anesthetic agent (type and dose;
too small a dose)
III. Use of a local anesthetic solution which has
crossed its date of expiry
IV. Improper injection technique:
a. Wrong technique: Inaccurate placement of
solution
b. Not waiting long enough for anesthesia to act;
before commencing the surgery
IV. Intravascular administration
V. Intramuscular administration

68. 2- PATIENT - DEPENDENT
I. Anatomical:
b. Barriers to diffusion
c. Anatomical aberrations
d. Additional innervations
II. Psychological:
Fear and apprehension : unco-operative
patient, inadequate opening of the
mouth, movement by the patient

69. COMPLICATIONS ARISING FROM LOCAL
ANESTHETIC SOLUTION AND INJECTION
TECHNIQUE

70. PAIN ON INJECTION
■ This increases patient’s anxiety;
and may lead to a sudden unexpected
movement by the patient and increases
the risk of needle breakage.
■ Management
Not required. However, steps should be
taken to avoid pain associated with
injection of local anesthetic agent

71. PAIN ON INJECTION
■ Causes
1. Careless injection technique
2. Dull needles
3. Rapid deposition of local anesthetic solution
4. Needles with barbs: There is pain while
withdrawal of the needle from the tissues
5. Temperature: Extremes of temperature
such as warm or hot or very cold
(refrigerated) local anesthetic solution

72. TRISMUS
■ Trismus is the inability to normally open
the mouth
■ It is a fairly common complication of local
anesthesia, particularly while giving
pterygomandibular block

73. MUCOSAL BLANCHING
■ It is caused by the spasm of the artery
accompanying
the nerve at the point of injection
Causes
1. Use of excessive amount of vasoconstrictor
2. Deposition of excessive volume of local
anesthetic solution in firm or tight tissue

74. PERSISTENT ANESTHESIA OR
PARESTHESIA (NERVE INJURIES)
■ Persistent paresthesia can lead to self-inflicted
injury. Biting, or thermal or chemical insults can
occur without the patients awareness
■ The condition is more frequent as a result of
operative procedure than injection itself
■ The sensory nerves most frequently traumatized
are inferior alveolar nerve, lingual nerve, and
mental nerves in lower jaw; and infraorbital nerve
in upper jaw

75. POST-INJECTION HERPETIC LESIONS OR
POST-ANESTHETIC INTRAORAL LESIONS
■ Patients’ reporting of
development of ulcerations
around the site of injection a
few days after intraoral injection
of local anesthetic agent. Patient
complains of intense pain
■ Cause
❑ Recurrent Aphthus Stomatitis
(RAS): It is a frequent
manifestation, developing in
gingival tissues (movable part,
i.e. not attached to the bone)

77. FACIAL NERVE PARALYSIS
■ Paralysis of some of the muscles
of facial expression which are
supplied by some of the terminal
branches of facial nerve, when the
solution is deposited in their
vicinity

78. Facial Nerve Paralysis

79. ikassem@dr.com

80. THANK YOU FOR YOUR ATTENTION!
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81. Thank you
• Islam Kassem
• ikassem@dr.com
• 0097455118606
• 00201222209842
• 002034810481
• 00201091472244