Local anaesthesia

Question 1

COMPONENTS OF LA AMPULES

Answer 1

-Analgesic Salt - Provides the anaesthesia eg: Lignocaine

-Vehicle Carries the Analgesic Salt eg: NaCl soln.

-Buffer – Maintains the pH eg: Sodium Bicarbonate

-Vasoconstrictor – Not always present
Constricts blood vessels in area, prolonging effect and reducing bleeding eg: Adrenaline or Felypressin

-Preservative – increased shef-life

-Antiseptic – prevents growth of pathogens in the ampule

Question 2

THE IDEAL LOCAL ANAESTHETIC

Answer 2

•Full Local Anaesthesia
•Rapid Onset
•Long Working Time
• Reversible
•No Negative Side Effects (Non-Toxic, Non-irritant, Non-Addictive, Won’t slow healing or hurt tissues)
•Stable in Solution
• Inexpensive

Question 3

Amides

Answer 3

Lignocaine, Mepivacaine, Bupivacaine,
Etidocaine, Prilocaine

Fewer cases of Hypersensitivity than Esters

More stable than Esters

Question 4

Esters:

Answer 4

• Cocaine, Procaine, Chloroprocaine,
Tetracaine, Amethocaine

• Derived from Benzoic Acid

– Associated with hypersensitivity and allergic reactions

Question 5

CHEMICAL STRUCTURE of LA

Answer 5

Made up of 3 components:

1. Aromatic Ring (Lipophilic end)
2. Intermediate Chain (Ester or Amide) • 3. Terminal Amine

Question 6

ARMAMENTARIUM USED IN LOCAL ANESTHESIA

Answer 6

• Syringe
• Needle
• Cartridge/ Ampules

Question 7

DENTAL SYRINGE TYPES

Answer 7

• 1. Non-disposabl
• Metal or Plastic
• Breech (Side) or Top loading
• Aspirating, Non-Aspirating or Self Aspirating

2. Disposable
   • Safety Syringes
3. Computer Controlled Injectors
4. High Pressure PDL Injectors
5. Jet Injectors –No Needle

Question 8

SYRINGE CRITERIA

Answer 8

The American Dental Association criteria for acceptance of local anaesthetic syringes include

1. Durable and withstand repeated sterilization without damage
2. Compatible with a wide variety of cartridges and needles of different manufactures
3. Inexpensive, self-contained, lightweight, and simple to use with one hand
4. Effective aspiration

Question 9

PRECAUTIONS FOR LA

Answer 9

1.Pregnancy – High dose Adrenaline can cause miscarriage; Felypressin has a Oxytocin Effect can cause coronary artery constriction

2.Toxaemic conditions – Diabetes, Nephritis, septicaemia – slowed healing, injection site may become ulcerated; High Risk for infection

3.Haemorrhagic conditions – Haemophilia, von Willebrands Dx - Excessive bleeding, Haematomas in deep spaces can obstruct airway

4.Chronic Steroid Therapy – A weakened Adrenal Cortex cannot handle the stress of dental injections or extractions and patients may be more likely top faint, nausea, vomiting and even fatal hypotension – 100mg hydrocortisone IV for patients who you suspect are having an adrenocortical insufficiency

5.Epilepsy – LA acts as a Cerebral Stimulant and can induce Epileptic Seizures in uncontrolled patients. Make sure they’ve taken their meds routinely and have a anticonvulsant ready – If you’re not sure REFER

6.Renal Disease – Impaired excretion and toxic effects possible, also look out for Bleeding tendencies and delayed healing

7.Liver Dysfunction – Hep, Cirrhosis, Malaria, Cancer – Bleeding tendencies and clotting issues (DVT); impaired metabolism of drugs also risk for delayed healing and infection

8.Leukaemia – Severe Anaemia, Bleeding and Clotting problems, Impaired healing and immunocompromised – Infections in Leukaemia patients are very difficult to control and can become fatal
- Dental treatment should be discussed with treating Oncologist or Physician