Chapter 12: local anaesthetics in dentistry classification, materials Flashcards
What is regional anaesthetics?
The area anaesthetised belongs to the main nerve or an important branch
When we anaesthetise we must take into account the nerves that innervate the _____ _____ around the tooth and not just the nerve innervating the tooth itself
Soft tissues
LA: drug action is on _____ (around) level
Periferic
Advantages of LA
- Gold standard when tooth insensitivity is needed
- Conscious patient
- Exceptional mortality
- It does not need special training for practitioners
- Easy technique
- Low failure rate
Disadvantages of LA
- Allergies to any local anaesthetics component
- In patients with cerebral palsy, there is no collaboration
- Insufficient in more complex or aggressive techniques
- Not indicated in an acute infectious process.
LA techniques
- Topical
- Local infiltration
- Field block
- Nerve block
- Intravascular
What does topic LA act on?
Sensory nerve endings
What does local infiltration act on?
Small terminal nerve endings in the area of dental treatment (they get flooded with LA solution)
How does the field block work?
LA solution is deposited near the larger terminal nerve branches so the
the anaesthetised area will be circumscribed
How does the nerve block work?
LA is deposited close to the main nerve trunk, usually at a distance from the site of
operative intervention
Risks of intravascular technique
- Cardiac risk
- Large ischemia
What do we use when we want to restore 2-3 teeth?
Field block
What do we use when we want to control pain in a quadrant?
Regional block
What do we do if there is a 3rd molar extraction and a cut that exposes the pulp?
We use intrapulpal anaesthesia
Is intrapulpal harmful?
Yes it is, but it is also very useful
Is intraosseous anaesthesia harmful? If yes why?
Intraosseous is harmful because the LA is injected into a small space that cannot be stretched and the pressure will be great
What is the least painful technique?
Infiltration
Injection of LA in the mucosa:
- Low toxicity
- Low concentration
- Better ointment than spray
- Bests results in dry mucosa
- Unpleasant taste
Injection of LA in the submucosa:
- Superficial submucosa: in superficial lesions, forms papule
- Supraperiosteal: infiltration, goes through periosteum, external cortical
a. = Local infiltration, paraperiosteal injection.
b. Nerves anaesthetised: large terminal branches of the dental plexus
Injection of LA in subperiosteal:
- Between cortical and periosteum
- Very painful
Injection of LA intraligamentary:
- PDL
- Recommended as an adjunct to other techniques or for limited treatment
protocols - Maintain the needle’s 45-degree orientation
- Insert the needle into the sulcus, inside the attachment
Injection of LA intraosseus:
- LA is deposited in the medular (medular cavity)
- Recommended for single teeth when other techniques have failed
- Intraseptal
- Hard because our needles are thin and our bones are hard, might need thicker needles
- Used as a last resort
Injection of LA intrapulpal:
- LA is specifically deposited in the pulp
- Tooth must be anaesthetised before
- Complementary technique
LA armentarium:
- Syringe
- Needles
- Cartridges
ADA criteria for LA syringes:
- They must be durable
- Capable of accepting a wide variety of cartridges and needles
- Inexpensive, self-contained, easy to use with 1 hand
- Provide effective aspiration, and blood may be easily observed in the cartridge
Types of syringes
- Non-disposable syringes
- Disposable syringes
- Safety syringes
- Computer-controlled LA delivery systems
Not all syringes are necessary aspirating. True or False
False, all of them are aspirating syringes, because they represent the standard of care
Who created the first dental syringe? And when?
Charles Pravaz patented the 1st dental syringe in 1853
Safety syringes benefits
- Minimise the risk of incidental needle-stick injury
- Sheath that locks over the needle when it is removed from the patient’s area after LA is administered
Non-disposable syringes characteristics
- Breech-loading
- Metallic or Plastic
- Cartridge-type
- Aspirating/Self-aspirating
What happens when negative pressure is exerted on the thumb ring?
Blood enters in the cartridge
Aspirating is done with the sharp tip. True or False
True
What does positive pressure do when it is exerted?
It forced the LA into the patient’s tissues
Are disposable syringes available in a variety of sizes?
Yes they are, with an assortment of needles gauges as well
What syringe is most often used for intramuscular or intravenous drug administration?
The disposable syringe
When was the first computer-controlled LA delivery systems created?
In 1997, the first CCLAD was introduced into dentistry
What is the purpose of computer-controlled LA delivery systems?
CCLAD was designed to improve on precision and ergonomics of the dental syringe
Parts of the syringe
- Thumb ring
- Finger grip
- Barrel
- Harpoon/Piston (there are different types of harpoons)
- Tip / Needle adaptor
What is the needle of a syringe?
A single piece of tubular metal around which is placed a plastic or metal syringe adaptor and the needle hub
Components of a needle
- Bevel
- Shaft
- Hub
- Syringe adaptor
- Cartridge penetration end
What does the gauge refer to?
It refers to the diameter of the lumen of the needle
Needle sizes (long and short)
Long: 31-40 mm
Short: 16-30 mm
What size of long needle do we use in dentistry?
35 mm
What size of short needle do we use in dentistry?
23-25 cm
What are cartridges known as?
Carpule
How much LA solution do cartridges contain?
1.8 mL
When were cartridges introduced into dentistry? And by who?
Cook-Waite in 1920
Components of cartridges
- Cylindrical glass tube
- Stopper (plunger, bung)
- Aluminium cap
- Diaphragm
Function of LA drug
Blockade of nerve conduction
Function of sodium chloride
- Isotonicity of the solution
- Antioxidant
Function of sterile water
Volume
Function of vaspressor
Higher depth and duration of anaesthesia
Function of methylparaben
Bacteriostatic agent
What LA can be topical?
- Lidocaine: liquid and ointment
a. Xylonor solution 5%
b. Xylonor spray 15%
c. Xylonor gel 20% - Tetracaine: peryl spray 3.5%
- Benzocaine: hurricane gel 20%
