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Armamentarium of local anesthesia

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Lubna Elsayed

on 27 September 2017

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Transcript of Armamentarium of local anesthesia

Armamentarium of Local Anesthesia
& Introduction to techniques


Additional armamentarium

The syringe
It is the vehicle whereby the contents of the anesthetic cartridge are delivered through the needle to the patient.

American Dental Association criteria for acceptance of local anesthetic syringes
They must be durable and able to withstand repeated sterilization without damage.
They should be accepting a wide variety of cartridges and needles of different manufacture, and should permit repeated use.
They should be inexpensive, lightweight, and simple to use with one hand.
They should provide for effective aspiration and be constructed so that blood may be easily observed in the cartridge.

Syringe types:
Nondisposable syringes:
Breech-loading, metallic, cartridge-type, aspirating
Breech-loading, plastic, cartridge-type, aspirating
Pressure syringe for periodontal ligament injection
Jet injector (“needleless” syringe)

Disposable syringes

Safety syringes
Computer-controlled local anesthetic delivery systems

Breech-Loading, Metallic, Cartridge-Type, Aspirating
Most commonly used in dentistry
The term breech-loading implies that the cartridge is inserted into the syringe from the side.
Constructed of chrome-plated brass & stainless steel.

Breech-Loading, Metallic, Cartridge-Type, Aspirating
Weight (heavier than plastic syringe)
Syringe may be too big for small operators

Breech-Loading, Plastic, Cartridge-Type, Aspirating
A plastic, reusable, dental aspirating syringe is available that is both autoclavable and chemically sterilizable.

Breech-Loading, Plastic, Cartridge-Type, Aspirating
Plastic eliminates metallic, clinical look
Light weight provides better “feel” during injection
Cartridge is visible
Aspiration with one hand
Rust resistant
Lower cost

Size (may be too big for small operators)
Possibility of infection with improper care
Deterioration of plastic with repeated autoclaving

Pressure Syringes
Pressure syringes offer advantages over the conventional syringe when used for PDL injections because their trigger delivers a measured dose of local anesthetic and enables a relatively physically weak administrator to overcome the significant tissue resistance encountered when the technique is administered properly.

Pressure Syringes
Measured dose
Overcomes tissue resistance
Cartridges protected
Easy to inject too rapidly (‹20 sec/0.2 ml dose)
Threatening (original devices)

Jet Injector
Introduced by Figge & Scherer in 1947.
Based on the principle that liquids forced through very small openings, called jets, at very high pressure can penetrate intact skin or mucous membrane.

The Syrijet holds any 1.8ml dental cartridge .
It is calibrated to deliver 0.05 to 0.2 ml of solution at 2000 psi.(pounds per square inch)

The primary purpose of the jet injector is to obtain topical anesthesia before insertion of a needle.
It may be used to obtain mucosal anesthesia of the palate.
Jet Injector
Does not require use of needle
Delivers very small volumes of local anesthetic
Used as replacement of topical anesthetics

Inadequate for pulpal anesthesia or for regional block
Some patients are disturbed by the “jolt” of the injection

Disposable Syringes
Disposable Syringes
Contain a Luer-Lok screw-on needle attachment but no aspirating tip.
Care must be taken to avoid contaminating the vial.

Disposable Syringes
Disposable, single use
Sterile until opened

Does not accept prefilled dental cartridges
Aspiration requires two hands

Safety Syringes
Non - Disposable Syringes
Disposable Syringes
Disposable, single use
Sterile until opened

Does not accept prefilled dental cartridges
Aspiration requires two hands

Safety Syringes
Safety Syringes
Disposable, single use
Sterile until opened
Lightweight (better tactile sensation)

Cost: more expensive than reusable syringe
May feel awkward to a first-time user

Computer – controlled local anesthetic delivery systems
In 1997 the first computer-controlled local anesthetic delivery (C-CLAD) system was introduced into dentistry.
It was designed to improve on the ergonomics and precision of the dental syringe.
Available flow rates of local anesthetic delivery are computer controlled and thus remain consistent from one injection to the next.
The operator is able to focus attention on needle insertion and positioning, allowing the motor in the device to administer the drug at a preprogrammed rate of flow.
Computer – controlled local anesthetic delivery systems
The Wand/CompuDent system
Precise control of flow rate & pressure produces a more comfortable injection even in tissues with low elasticity (eg. Palate, attached gingiva, PL)
Automatic aspiration
Rotational insertion technique minimizes needle deflection

Requires additional armamentarium

Leakage during injection
An off-center perforation during syringe reloading produces an ovoid puncture of the diaphragm that allows leakage of LA solution.

Broken Cartridge
A badly worn syringe may damage the cartridge, leading to breakage.
This can also result from a bent harpoon.
A needle that is bent at its proximal end may not perforate the diaphragm on the cartridge.

Bent Harpoon
A bent harpoon produces an off-center puncture of rubber plunger, causing the plunger to rotate as it moves down the glass cartridge. This occasionally results in cartridge breakage.

Surface Deposites
An accumulation of debris, saliva & disinfectant solution interferes with syringe function.
Deposits which resemble rust may be removed with a thorough scrubbing.

The Needle
The Needle
Most needles used in dentistry are stainless steel and disposable.
All needles have the following components in common: the bevel, the shaft, the hub, and the cartridge-penetrating end.
When needles are selected for use in various injection techniques, two factors that must be considered are

Gauge refers to the diameter of the lumen of the needle: the smaller the number, the greater the diameter of the lumen.
A 30-gauge needle has a smaller internal diameter than a 25-gauge needle.
In the United States, needles are color-coded by gauge.
25-gauge, red;
27-gauge, yellow;
30-gauge, blue.

Advantages of Larger-Gauge Needles Over Smaller-Gauge Needles

1. Less deflection, as needle advances through tissues
2. Greater accuracy of injection
3. Less chance of needle breakage
4. Easier aspiration
5. No perceptual difference in patient comfort
Short : 20mm
Long : 32mm
Ultrashort : available with 30G needles
Weakest portion of needle is at hub.

Care And Handling of Needles
1. Needles must never be used on more than one patient.
2. Should be changed after several (three or four) tissue penetrations in the same patient.
3. Should be covered with a protective sheath when not being used.
4. Attention should always be paid to the position of the uncovered needle tip
5. Needles must be properly disposed after use

Problem with needles
Pain on insertion : Dull needle. Should be changed after 3-4 penetrations of mucosa.
Breakage : Direction of needle should not be changed when it is embedded in tissue.
Pain on withdrawal : will develop when the needle tip forcefully contacts a hard surface, such as bone. A needle should never be forced against resistance.
Injury to patient/administrator

The Cartridge
is a glass cylinder containing the local anesthetic drug.
As prepared today, the dental cartridge contains approximately
1.8 mL
of local anesthetic solution.

The dental cartridge is, by common usage, referred to by dental professionals as a “carpule”.

The Cartridge
The Cartridge
The prefilled 1.8-mL dental cartridge consists of four parts:
1. Cylindrical glass tube
2. Stopper (plunger, bung)
3. Aluminum cap
4 Diaphragm (semi-permeable membrane)

Care and Handling
Local anesthetic cartridges should be stored in their original container, preferably at room temperature (e.g., 21° C to 22° C), and in a dark place.
Cartridges should not be permitted to soak in alcohol or other sterilizing solutions because the semipermeable diaphragm allows diffusion of these solutions into the dental cartridge, thereby contaminating it.

The Cartridge
Contents of the anesthetic cartridge:
Local anesthetic drug
: It interrupts the propagated nerve impulse, preventing it from reaching the brain.
The drug contained within the cartridge is listed by its percent concentration. The number of milligrams of the local anesthetic drug can be calculated by multiplying the percent concentration (e.g., 2% = 20 mg/mL) by the volume1.8 = Thus a 1.8-mL cartridge of a 2% solution contains 36 mg
A vasopressor drug
: is included in most anesthetic cartridges to enhance safety and the duration and depth of action of the local anesthetic
The Cartridge
:most often sodium (meta)bisulfite. Sodium bisulfite prevents oxidation of the vasopressor by oxygen, which can be trapped in the cartridge during manufacture or can diffuse through the semipermeable diaphragm after filling.
Sodium chloride
:is added to the cartridge to make the solution isotonic with the tissues of the body.
Distilled water
:is used as a diluent to provide the volume of solution in the cartridge.
?? Allergic reaction, cartridge is single use.

Bubble in the cartridge
A small bubble of ~ 1-2mm in diameter is found in the dental cartridge.
It is composed of nitrogen gas, which was bubbled into LA solution during its manufacture to prevent oxygen from being trapped & destroying the vasopressor.
A larger bubble, which may be present with a plunger that is extruded beyond the rim, is the result of freezing of LA solution
Such cartridges should not be used because sterility of the solution cannot be assured.

Extruded Stopper
The stopper can become extruded when a cartridge is frozen & the liquid inside expands.
An extruded stopper with no bubble is indicative of prolonged storage in a chemical disinfecting solution.

Burning on injection
Normal response to pH of drug
Overheated cartridge
The addition of vasopressor & antioxidant lowers the pH to 3.3-4. A further decrease in pH results when sodium bisulfite is oxidised to sodium bisulfate.
A more intense burning
on injection is usually the result of diffusion of disinfecting solution into the dental cartridge and its subsequent injection into the oral mucous membranes.

Corroded cap
The Al can be corroded if immersed in disinfecting solutions that contain quaternary ammonium salts.
Al-sealed cartridges should be disinfected in either 91% isopropyl alcohol or 70% ethyl alcohol.
Corrosion may be easily distinguished from rust, which appears as a red deposit.

Leakage during injection
occurs if the cartridge and the needle are prepared improperly and the needle puncture of the diaphragm is ovoid and eccentric.

Broken cartridge
The most common cause of cartridge breakage is the use of a cartridge that has been cracked or chipped during shipping.
Excessive force to engage harpoon in the stopper
Attempting to use a cartridge with an extruded plunger
Syringes with bent harpoons.
Two areas that must be examined carefully are the thin neck of the cartridge where it joins the cap and the glass surrounding the plunger

1. Dental cartridges must never be used on more than one patient.
2. Cartridges should be stored at room temperature.
3. It is not necessary to warm cartridges before use.
4. Cartridges should not be used beyond their expiration date.
5. Cartridges should be checked carefully for cracks, chips, and the integrity of the stopper and cap before use
Problems with the cartridge
1. Bubble in the cartridge
2. Extruded stopper
3. Burning on injection
4. Corroded cap
5. Leakage during injection
6. Broken cartridge

Topical antiseptic
Topical anesthetic
Applicator sticks
Cotton gauze

Topical Antiseptic
Available agents include Betadine (povidone-iodine) and thimerosal.
Allergy to iodine-containing compounds is common, ask the patient or test before use

If a topical antiseptic is not available, a sterile gauze wipe should be used to prepare the tissues adequately before injection.

Topical Anesthetic
For effectiveness, it is recommended that a minimal quantity of topical anesthetic be applied to the end of the applicator stick and placed directly at the site of penetration for approximately 1 minute.
Most contain the ester anesthetic

Of the amides, only
possesses topical anesthetic activity in clinically acceptable concentrations.
Topical forms of lidocaine are available as ointments, gels, pastes, and sprays.

Additional Armamentarium
Cotton applicator
Cotton gauze
1) Wiping the area of injection before needle penetration
2) Drying the mucous membrane to aid in soft tissue retraction for increased visibility.

Thank You !
Minimizes the risk of accidental needle-stick injury occurring with a contaminated needle.
These syringes possess a sheath that “locks” over the needle when it is removed from the patient’s tissues, preventing accidental needle stick.

Visible cartridge
Aspiration with one hand
Rust resistant
Long lasting with proper maintenance

Types of Local Anesthesia injection
Surface or topical
Local Infiltration
Field block
Nerve block

Local Infiltration
Small terminal nerve endings in the area of dental treatment are flooded with L.A. solution

Solution is injected beneath the mucous membrane, or along the periosteum, or beneath the skin

Field Block
L.A. solution is deposited at or above the apex of the tooth to be treated, near the larger terminal nerve branches.

The anesthetized area is circumscribed, preventing the passage of impulses from the tooth to the CNS.
Common usage identifies them as infiltration or supraperiosteal.

“Infiltration Anesthesia”

The maxilla has thin labial/buccal cortical plate

Shows areas of porosity, the compact bone presents numerous foramina which aid in absorption of local anesthetic solution


The bone is generally dense, has thicker cortical plates than maxilla, particularly in posterior region ”in the region of external oblique ridge”

Only the anterior part of mandible presents sufficient porosity, which is favorable for infiltration techniques

Nerve Block
L.A. solution is deposited near to main nerve trunk, at a distance from the site of operative intervention

Infiltration Anesthesia
Easy and simple
High success rate
Good control of bleeding

Multiple penetrations when larger field is to be anesthetized
Contraindication: Inflammation, Infection
Difference between Field & Nerve Block
Field block is more circumscribed, involving tissues in and around one or more teeth.
The nerve block involves a larger area, such as seen following Inferior Alveolar nerve block.

Nerve Block
Avoids multiple penetration of the needle
Avoids deposition of large volume of LA agent

Larger area than required is anesthetized
Additional local infiltration is required if hemostasis is required at the site of surgery

Selection of anesthesia technique
Local Infiltration
: small, isolated areas

Field block
: two or three teeth

Pain control in quadrant dentistry
: regional block

Use sterile sharp needle
Check the temperature of the local anesthetic solution
Check the flow of local anesthetic solution
Operator position
Position the patient
Dry the tissue.
Apply topical antiseptic.
Apply topical anesthetic.
Communicate with the patient.

Make the tissue taut.
Keep the syringe out of the patients line of sight.
Orientation of the bevel.
Insert the needle into the mucosa.

Watch and communicate with the patient.
Inject several drops of solution
Slowly advance the needle to the target site.
Slowly deposit the solution
(slow : 1ml/1min., realistic : 1.8ml/1min.)
Communicate with the patient.
Slowly withdraw the syringe.
Observe the patient after injection.
Record the injection on the patient’s chart
(eg. R-IANB, 25-long, 2% lido + 1:1,00,000 epi, 36mg; tolerated procedure well)

Surface or Topical Anesthesia
Prior to infiltration or bock
Prior to incision and drainage
prior to suture removal
Spray ( 10% or 15% lignocaine ) or ethyl chloride (produces anesthesia by refrigeration)
Ointment (5% of lignocaine) prior to scaling of inflamed gingiva
Emulsion (2% lignocaine)
Example: incision or interdental papilla for root planning
Types of Infiltration Anesthesia
Submucosal or subcutaneous anesthesia
Paraperiosteal or supraperiosteal anesthesia
Subperiosteal anesthesia
Palatal infiltration

Submucosal Injection:
The L.A solution is deposited in the immediate submucosal tissue layers.

Procedure: The needle is inserted beneath the mucosal layers
Excessive amount injected superficially may lead to sloughing of the tissues
Supraperiosteal or Paraperiosteal
Commonly called "local infiltration", used for obtaining anesthesia in the region of all maxillary teeth and mandibular anterior teeth because of thin cortical plates.

Technique: the needle is inserted through mucosa, solution is deposited close the periosteum or along periosteum (as close to the bone as possible)
Subperiosteal Injection
The L.A solution is injected beneath the periosteum, it confines the solution below periosteum.

Technique: recommended gauge of needle is 25, needle is inserted midway between gingival margin and the apex of the tooth.
Needle is placed at angle of 90 degree to the alveolar plate first then 45 degree, bevel facing bone, then advanced towards apex of the root
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