complications of the local anesthesia used in dentistry

1. COMPLICATIONS OF LA
PRESENTED BY: Dr SHERMIL SAYD

2. • Broadly classified into two sections
– Local complications
– Systemic complications

3. • Local complications
– Needle breakage
– Paresthesia
– Facial nerve paralysis
– Trismus
– Soft tissue injury
– Hematoma
– Pain on injection
– Burning on injection
– Infection
– Edema
– Sloughing of tissues
– Post anesthetic intra oral lesions

4. Needle breakage
• Rare occurrence now due to the introduction
of disposable needles
• Causes:
– Weakening of the dental needle by bending
– Sudden unexpected movement by the patient,
more likely in pediatric patients
– Finer needles are more likely to break
– Needles that have been previously bent
– Defective manufacturing

5. • Problem:
– Can be left of the in the tissue if its removal will cause
more extensive damage
– Infections arising from these needles are very much
rare
– They usually gets embedded in the scar tissue
• Prevention
– Don’t bend the needle
– Use thicker needles
– Use long needles rather than short ones
– Do not insert needles upto its hub
– Do not redirect the needle once it is more than
halfway through

6. • Management
1. When a needle breaks
a) Do not panic
b) Instruct the patient not to move, keep the hand inside and
mouth open
c) If the fragment is visible, remove it
2. If the needle is not visible and not retrievable
1. Do not probe or incise
2. Calmly inform the patient
3. Note the incident on the patients chart
4. Refer the patient to an oral surgeon

7. – Immediate removal of broken needle only if
• Needle is superficial and easily located through the
radiological and clinical examination
• If the attempt proves t be futile for a considerable
amount of time, then the needle should be left as it is
• The needle is located in deeper tissues, then it should
be allowed to remain there without an attempt

8. Paresthesia
• Defn: persistent anesthesia or altered sensation well
beyond the expected duration of anesthesia
• Causes:
– Trauma to the nerve
– Injection of the LA solution contaminated with alcohol(
they are also neurolytic and may cause long term damage
to the nerve
– Trauma to the nerve sheath during the insertion of the
needle
– Insertion of a needle in to the foramen
– Hemorrhage around the nerve sheath
– LA solution itself(haas and lennon-1993)

9. • Problems:
– Can lead to self inflicted injury
– Sense of taste impaired, LN involvement
• Prevention:
– Strict adherence to the injection protocol

10. • Management:
– Be reassuring
• Speak to the patient personally
• Explain
• Appointment to examine the patient
• Record the incident in the dental chart
– Examine the patient
• Determine the extent and the degree
• Explain to the patient that it may persist for upto 1 year
• Tincture of time- reccommended medicine
• Record all the findings

11. – Reschedule the patient for examination every two
months
– If sensory deficit present more than one year,
consultation with a neurologist is recommended
– Dental treatment may be continued, but avoid
injecting the LA solution into the same region
again

12. Facial nerve paralysis
• Cause:
– Introduction of the LA solution into the parotid capsule
– Directing the needle inadvertently posteriorly during IANB
– Over insertion during vazirani akinosi
• Problem:
– Loss of motor function of the muscles of facial expression
– Usually transitory
– Minimal sensory loss
– Unilateral facial paralysis- face appears lopsided
– Unable to close the eye o the affected side

13. • Prevention:
– Adhere to the protocol
– Over insertion during vazirani akinosi should be avoided when
possible
• Management
– Reassure the patient
– Contact lenses should be removed until muscular movements
return
– An eye patch should be given for the eye on the affected side
– Record in chart
– Although there is no contraindication for reanesthesia, it will be
prudent at this point

14. Trismus
• Prolonged tetanic spasm of the jaws by which
normal opening of the mouth is restricted
• Causes:
– Trauma to the muscles or blood vessels in the
infratemporal fossa
– Contaminated LA solution being injected into the site
– Injection of LA IM or supramuscularly
– Hemorrhage
– Low grade infection after injection
– Multiple needle penetration

15. • Problem
– The average interincisal opening is
13.7mm(range5-23mm)
– Acute phase- leads to muscle spasm and limitation
of movement
– Chronic hypomobility associated with organization
of the hematoma, with subsequent fibrosis and
scar contracture

16. • Prevention
– Use a sharp, sterile, disposable needle
– Properly care for and handle dental LA catridges
– Use aseptic technique
– Practice atraumatic insertion and injection
technique
– Avoid repeat injections
– Use minimum effective volumes of LA

17. • Management
– With mild pain and dysfunction the patient
reports minimum difficulty opening the mouth
– The patient should be prescribed with heat
therapy, warm saline rinses, analgesics and if
necessary muscle relaxants
– The patient should be advised to initiate
physiotherapy consisting of opening and closing of
the mouth
– Sugarless chewing gums can also be prescribed

18. • If the needed dental treatment in the affected
area is urgent, then alternate techniques like
vazirani akinosi technique can be used
• Usually there I will be an improvement after
after24-48hrs
• Therapy should be continued until the patient is
free of symptoms
• If the pain and dysfunction continues abate
48hrs, then infection should be suspected and
antibiotics should be added into the regimen

19. • Other therapies which include ultrasound or
appliances also can be used in these situations
• Surgical interventions may be necessary to
correct the chronic dysfunction

20. Soft-tissue injury
• Self inflicted trauma to the lips and tongue is
frequently caused by the patient inadvertently
biting o chewing these tissues while still
anesthetized
• Cause:
– Common in children, physically and mentally
disabled
– It occurs due to the prolonged anesthesia of the
soft tissues than that of the pulp

21. • Problem:
– Trauma to anesthetized tissues can lead to swelling
and significant pain when the anesthetic effect
resolves
– Remote instances of development of infection
• Prevention:
– A cotton roll can be placed between the lips and the
teeth secured with floss wrapped around the teeth
– Warn the patients guardian about this
– A self adherent warning sticker can be used on
children on their forehead

22. • Management
– Analgesics for pain as necessary
– Antibiotics as necessary
– Lukewarm saline rinses to reduce the swelling and
pain
– Petroleum jelly to cover up the lip lesion

23. Hematoma
• The effusion of blood into extravascular space is
called as hematoma
• Cause
– A large hematoma may develop from either arterial or
venous puncture following a PSA or IA nerve block
– The tissues surrounding this vessels more readily
accommodate significant volumes of blood and
continues to do so until clot forms
– IANB hematomas are visible only intraorally while PSA
hematomas are visible extraorally

24. • Problems:
– Includes pain and trismus
– Swelling and discoloration usually subsides within 7-14
days
• Prevention:
– Knowledge of normal anatomy
– Modify the injection technique based upon the patients
anatomy
– Use a short needle for PSA to reduce the risk of hematoma
– Minimize the number of needle penetrations into tissue
– Never use a needle as a probe in tissues

25. • Management:
– Immediate:
• When swelling becomes evident during the injection,
pressure should be applied over the area, for not less than 2
mins
• For IANB, pressure applied onto the medial aspect of the
ramus
• For ASA, pressure is applied on the skin directly over the
infraorbital foramen
• For mental nerve block, placed directly over the mental
foramen
• Buccal nerve block or palatal injection, at the site of bleeding
• For PSA, digital pressure applied in the mucobuccal fold as
far distally as possible. Icepack extraorally

26. – Subsequent:
• Advise the patient about the possible soreness and
limitation of the movement
• If soreness develops, advise analgesics
• Heat may be applied to the area from the next day
onwards to increase the rate of resorption of the clot
• Tincture of time is the most important factor in the
management of trauma

27. Pain on injection
• Causes:
– Careless injection technique
– A needle can become dull from multiple injections
– Rapid deposition of the anesthetic solution may cause
tissue damage
– Needles with barbs also cause pain
• Problem:
– Can lead to increase in patient anxiety and may lead
sudden and unexpected movement increasing the risk
of needle breakage

28. • Prevention:
– Proper technique of injection
– Use sharp needles
– Use topical anesthetic before injection
– Use sterile local anesthetic solution
– Inject slowly
– Be certain that the temperature of the solution is
correct

29. • Management:
– No management necessary

30. Burning on injection
• Causes:
– Primary cause is the pH of the solution
– Rapid injection of the local anesthetic solution
– Contaminated local anesthetic solution
– Solution warmed to body temperature are
considered too hot by the patient
• Problems:
– Although transient, may lead to postanesthetic
trismus, edema, or possible paresthesia

31. • Prevention:
– Slow injection,1ml/min. recommended rate of
1.8ml/min should not be exceeded
– Cartridge should be stored at room temperature
• Management:
– No immideate management necessary

32. Infection
• Cause:
– Contamination of the needle before
administration
– Improper technique in handling the LA equipment
– Injecting the LA solution into an area of infection
• Problem:
– Can cause infection and lead to trismus

33. • Prevention:
– Use sterile disposable needles
– Proper care for handling of the needles and catridges
– Properly prepare the tissues before injection
Management:
• Immediate treatment consists of antibiotics and
analgesics, muscle relaxant if needed and
physiotherapy
• Antibiotics should be started for a 7-10 day course
• Penicillin is the drug of choice and erythromycin, if
allergic to penicillin

34. Edema
• Causes:
– Trauma during injection
– Infection
– Allergy
– Hemorrhage
– Injection of irritating solution
– Hereditary angioedema

35. • Problem:
– Angioneurotic edema produced can cause airway
obstruction
– Edema of the tongue, larynx or pharynx may develop
and represent a potentially life threatening situation.
• Prevention:
– Proper handling of the LA armamentarium
– Atraumatic injection technique
– Complete medical evaluation

36. • Management
– When produced by traumatic injection or introduction
of irritating solutions, edema is of low degree and
resolves without any formal therapy
– Analgesics for pain can described
– after hemorrhage edema resolves more slowly
– Edema due to infection doesn’t subside
spontaneously but may in fact become more
progressively more intense if untreated
– Allergy induced edema is potentially life threatening

37. • If edema causes airway obstruction, then
– P- if unconscious, the patient placed supine
– A-B-C- BLS administered as required
– D- definitive treatment: EMS summoned
– Epinephrine is administered: 0.3mg(adult),
0.15mg(child)IM or IV every 10-15 mins until respiratory
distress resolves
– Histamine blocker is administered
– Corticosteroid IM/IV
– Preparation for cricothyrotomy should be done if total
airway obstruction seems to be developing
– Patients should be evaluated thoroughly before the next
appointment

38. Sloughing of tissues
• Causes
– Epithelial desquamation:
• Application of the topical anesthetic to the gingival
tissues for prolonged period
• Heightened sensitivity of tissues to a LA agent
• Reaction in an area where a topical has been applied
– Sterile abscess-
• Secondary to prolonged ischemia resulting from the
use of LA with vasoconstrictor
• Usually develops on hard palate

39. • Problems:
– Pain
– Infection in these areas
• Prevention
– Use topical anesthetics as recommended
– Do not use overly concentrated solutions containing
vasoconstrictor
• Management:
– No formal management necessary
– Symptomatic management

40. Post anesthetic intraoral lesions
• Cause:
– Recurrent apthous stomatitis or herpes simplex can
occur after the injection of the local anesthetic
solution
– Trauma to tissues by a needle or cotton swabs or any
other instrument may activate the latent form of the
disease process that was present in tissues before
injection
• Problem:
– c/o acute sensitivity in the ulcerated area

41. • Management:
– Primary management- symptomatic
– Pain develops after 2 days
– No management is necessary if the pain is not
severe
– Preparations can be used to reduce the pain and
irritations caused by these lesions

42. Ocular problems
• signs and symptoms including tissue blanching,
hematoma formation, facial paralysis, diplopia,
amaurosis, ptosis, mydriasis, miosis,
enophthalmos, and even permanent blindness
have been reported
• The mechanism of action is not fully understood
• Aspiration at the time of administration of local
anesthesia is very important and minimizes the
risk of ocular complications.
• When ocular complications persist, an
ophthalmology consultation is prudent

43. Systemic complications
• Caused by adverse drug reaction.
• There are mainly three types of complications
– Allergic reactions
– Toxicity
– Methemoglobinemia

44. Allergic reactions
• Allergic reactions due to the administration of
local anesthesia are uncommon but can occur
• There are a few different tests that can be used
by the allergist to document an allergy to local
anesthesia, such as the skin prick test, the
interdermal or subcutaneous placements test,
and/or the drug provocative challenge test(gold
standard)
• Allergies to local anesthetic may be type I or type
IV hypersensitivity reactions, with the type I
response more commonly reported

45. • type I
– symptoms include skin manifestations (erythema,
pruritus, urticaria), gastrointestinal manifestations
(muscle cramping, nausea and vomiting, incon-
tinence), respiratory manifestations (coughing,
wheezing, dyspnea, laryngeal edema), and cardio-
vascular manifestations (palpitations, tachycardia,
hypotension, unconsciousness, cardiac arrest)

46. • Treatment
– depends on the severity of the reaction.
– Mild- managed by oral or intramuscular
antihistamines, such as diphenhydramine, 25 to 50
mg.
– If serious signs or symptoms develop, immediate
treatment becomes necessary, and this includes basic
life support, intramuscular or subcutaneous epineph-
rine 0.3 to 0.5 mg, and activating the emergency
response system for transportation to the local
hospital for acute therapy.51

47. Toxicity
• Toxicity can be caused by excessive dosing of
either the local anesthetic or the
vasoconstrictor
• Cause:
– inadvertent intravascular injection
– repeated injections of the local anesthetic
– excessive volumes are used in pediatric dentistry

48. • Prevention
– Adhering to local anesthetic dosing guidelines
– simple way to calculate maximum safe dosages for
all anesthetic formulations used in dentistry is
called the rule of 25, which states that a dentist
may safely use 1 cartridge(1.8ml) of any local
anesthetic for every 11.4 kg (25 lbs) of patient
weight

49. • Phases of toxicity
– excitatory phase-manifest as tremors, muscle
twitching, shivering, and clonic tonic convulsions
– generalized central nervous system depression and
possible life-threatening respiratory depression
– With extremely high doses, cardiac excitability and
cardiac conduction decrease and leads to ectopic
rhythms, bradycardia and ensuing peripheral
vasodilation, and significant hypotension.
– Treatment should address respiratory depression and
convulsions. Vital signs should be monitored, the
airway maintained, basic life support administered,
and the emergency medical support services should
be called. Intravenous diazepam or midazolam may be
administered for a seizure that does not stop

50. Methemoglobinemia
• Methemoglobinemia is a reaction that can occur after
administration of amide local anesthetics, nitrates
• Prilocaine and benzocaine are used in dentistry and may
induce methemoglobinemia
• Signs and symptoms usually do not appear for 3 to 4 hours
after the administration of large doses of local anesthesia
• Clinical signs of cyanosis are observed when blood levels of
methemoglobin reach 10% to 20%, and dyspnea and
tachycardia are observed when methemoglobin levels
reach 35% to 40%
• 55 Co-oximetry is a conventional pulse oximetry that
measures the methemoglobin and carboxyhemoglobin
levels

51. • Treatment
– Methylene blue 1 to 2 mg/kg intravenously is used
for the treatment of methemoglobinemia.

52. summary
• Local anesthetics are a routine part in all oral
and maxillofacial practices. Minimizing
adverse outcomes is the goal of all
practitioners. This goal can be accom-plished
by using the appropriate local anes-thetics in
certain situations

53. • Malamed SF. Handbook of local anesthesia. 5th
edition. Philadelphia: Elsevier Mosby; 2004.
• R david, Complications of Local Anesthesia Used
in Oral and Maxillofacial Surgery: Oral
Maxillofacial Surg Clin N Am 23 (2011) 369–377
• Pogrel MA, Thamby S. Permanent nerve involve-
ment resulting from inferior alveolar nerve
blocks. J Am Dent Assoc 2004;131:901–7.
• Local anesthesia, monheims