A lecture for third class students of dentistry college

1. Local Anasthesia in dentistry
Dr.Mohamed Rhael Ali
2016 - 2017

2. Terminology

3.  Pain ; unpleasant physical sensation experienced
followed the application of noxious stimuli
 Analgesia ; loss of pain sensation only
 Anesthesia ; loss of all modalities of sensation which
include pain and touch
 Parasthesia ; altered sensation (tingling sensation)
and this may occur when a damaged nerve is
regeneration or when a local anesthesia is either starting
to work or its effect is wearing off

4. • Depolarization; rapid influx of Na ions to the interior of
the nerve
• Repolarization; reestablishment of polarity, especially
the return of a cell's membrane potential to resting potential
after depolarization. This occur by the movement of
positively charged K+ ions out of the cell.

5. local anesthesia

6. Definition
 loss of sensation in a circumscribed area of the body
caused by depression of excitation in nerve endings or
inhibition of the conduction process in peripheral nerves
 differ from general anesthesia by which the loss of
sensation occur without loss of consciousness.

7. Requirement of local anesthesia
 it should not be irritating to the tissue to which it is applied
 it should not cause any permenant alteration to the nerve
structure
 its systemic toxicity should be low
 the time of onset of anesthesia should be as short as possible
 the duration of action must be long enough to permit
completion of the procedure
 it should be free from producing allergic reactions
 it should be either sterile or be capable of being sterilized by
the heat without deterioration
 it should have potency sufficient to give anesthesia without
using harmful concentration
 it must be effective regardless of wether it is injected into the
tissue or applied locally to mucous membranes.
 It should be stable in solution and readily under go
transformation in the body

8. Uses of local anesthesia
Diagnostic uses
Therapeutic uses
Preoperative uses
postoperative uses

9. Indications of local anesthesia
 Almost all dental procedures …..
a. in oral surgery for extraction of teeth, apicoectomy,
incisions and drainage of abscesss , removal of cysts,
ranula and all other surgical procedures.
b. In conservative treatment
c. periodontal diseases
d. some cases of prosthodontics and orthodontic
treatments

10. Contraindications for local anesthesia
• Absolute contraindication ; as in patients with history
of allergy to local anesthesia
• Relative contraindications ; as in presence of acute
inflammation at the site of injection ,or in patients
with significant medical diseases as cardiovascular
diseases,clinical hyperthyroidism

11. Advantages of local anesthesia
• No special preparation of the patient is needed
• No complicated apparatus are needed
• No risk of respiratory obstraction
• Anesthesia last for at least an hour
• Patient remains awake and cooperative and no need for
care posoperatively
• Seriously ill patient as with heart diseases can usually
tolerate local anesthesia without any risk.

12. Disadvantages of local anesthesia
No true disadvantages to the use of local anesthesia
when the patient is normal and there is no
contraindications to its use