Complications of local anasthesia in dentistry (part I)

Dr.Mohamed Rhael Ali2016 - 2017

I. Local complications :1. Failure to obtain anasthesia 2. Pain during and after injection 3. Hematoma formation at the site of injection4. Intravascular injection 5. Blanching6. Trismus7. Facial paralysis8. Lip trauma9. Prolonged impairment of sensation10. Broken needle 11. Infection 12. Visual disturbance

II. General complications : 1. Fainting 2. Drug interactions3. Homologous serum jaundice4. Sensetivity reaction5. Occupational dermatitis6. Cardio- respiratory emergencies

Local complications

Failure to obtain anasthesia

It may be complete or partial

Causes :Operator experience Inadequate amount of the local anasthesia Injection in to the blood vesselPresence of infectionExpire date of local anasthesia solutionPatient response to drugs

pain during and after injection

Suggested causes :

a. Injection of either non isotonic or contaminated solutions .

b. Neurological pain during injection due to penetration of nerve sheath by the needle

c. Use of excessive force during deposition of anasthesia solution

Hematoma formationBleeding in the tissue due to injury to blood vessels during

injection

Hematoma formationMainly occure with block injection

• Mostly superior posterior block injection • Less common inferior alveolar and infa-orbital block injection • Bleeding from pterygoid venous plexus clinically appear as

swelling in the cheek followed by discoloration of the overlying skin due to break down of the blood within 24 -48 hours .

• Bleeding from the infraorbital vessels appear as above with black eye

• Bleeding in to the pterygo-mandibular space not show any swelling in the cheek but it may show trismus

Management :

• Reassurance of the patient • Antibiotic to avoid infections• Follow - up

Hematoma formation

Intra – vascular injection• Result in Increase the toxicity of

local anasthetic solution or vasoconstrictor in the blood .

• Clinically patient may show fainting , pale,clammy skin and even decrease in the level of consciousness .

• Can be avoided by using aspiration injection technique

Blanching at the site of injection

Ischemia of the area as aresult of decrease in blood supply

Causes :

• Increase tissue tension due to the deposition of fluid .

• Local effect of local anasthesia

Blanching at the site of injection

Blanching at the site remote from that of injection

Blanching at the site remote from that of injection

Causes :• Intra-vascular injection• Interferance with the autonomic nerve supply of

the blood vessels

Treatment :• No treatment is needed just reassurance to the

patient . Its usually transit

Trismus Difficulty in opening of the mouth due to muscle

spasm

Causes : Injection in to the medial pterygoid muscle may cause injury to the

blood vessels inside the muscle and hematoma formation or infection

Inflamation in the pterygomandibular space

Blood that escape during injection in the pterygomandibular space may cause irritation to the muscle and produce trismus

• Note : if trismus associated with pain ,fever so its due to infection and should treated by drainage of pus , antibiotic , and mouth wash by warm saline

Trismus

Facial paralysis May be partial or complete

Causes :Due to deposition of anasthetica solution in the

parotid which occure when the tip of needle inserted too far back and behind the ramus

Facial paralysis

Facial paralysis

Treatment • Reassurance , and if

eyelids envolved than eye protection is necessary (protective pad or eye shade)

Prolonged impairment of sensation

Occure due to nerve injury

Main causes :Direct trauma from the nerve Injection of a solution contaminated with a

neurotoxic substances as alcoholHemorrhage and infection near the nerve Surgery near the nerve fibers as mental nerve

Prolonged impairment of sensation

• Testing the degree and extent of parasthesia or anasthesia can done by measuring the reactions to pin – prinks and passing of cotton wall wisps over the skin

Prolonged impairment of sensation

Treatment : In case of infection .. Drainage of pus and

anti-biotic coverage Follow up to check the improvement If no improvement then refer the patient to a

specialist

Broken needles

Prevention • The needle must kept straight during injection .• If resistance is encounterd , force must not be applied to

overcome it .• The direction of the needle should not changed within the

tissue .• Bending of the needle should be avoided .• The needle should never embeded completely within the

tissue , at least 5 mm must project from the mucosal surface .

Broken needles

Treatment• If fracture occure the patient should told to stop any

movment to prevent displacemnt of needle within the tissue .

• The needle graspes by artery forceps or pleir and withdrawn .

• If the needle displaced within the tissue then its position must determined radiographically ( two x-ray films must be taken one perpendicular to other ) to confirm the exact position of needle and then removed it surgically by dental surgeon .

infection• Use of contaninated needle may cause infection

especially in pterygomandibular space during inferior alveolar nerve block

Lip trauma

• Anasthetised lip after injection may suffer from trauma by chewing it espcially in children or thermal injury by hot drink or cigarrete in adult .

Visual disturbance

• Rare complication of unknown causes but suspected to be due to vascular spasm or accidental intra-arterial injection

Treatment • Reassurance , usually normal vision retained

within 30 minute

Thank you for listening ….