The document discusses the components of the local anesthetic armamentarium including syringes, needles, and cartridges. It describes different types of syringes such as non-disposable, disposable, safety, and computer-controlled syringes. It also discusses needles in terms of bevel, gauge, and length. For cartridges it describes the components, color coding, and composition of the local anesthetic solution. It provides recommendations for proper care and handling of the components to avoid problems such as leakage, breakage, deposits and corrosion.

1. LA - ARMAMENTARIUM

2. LA ARMAMENTARIUM

3. THE SYRINGE
It is the vehicle whereby the contents of the anesthetic cartridge are
delivered through the needle to the patient.

4. ADA criteria for acceptance of
syringe
• They must be durable & able to withstand repeated sterilization
without damage.
• They should be capable of accepting a wide variety of cartridges &
needles of different manufacture, & permit repeated use.
• They should be inexpensive, self-contained, lightweight, & simple to
use with one hand.
• They should provide for effective aspiration & be constructed so that
blood may be easily observed in the cartridge.

5. Non-disposable
syringes
Disposable syringes
Safety syringes
Computer-controlled
local anesthetic
delivery systems
Syringe types

6. NONDISPOSABLE
SYRINGES

7. Nondisposable syringes
• Breech-loading, metallic, cartridge-type, aspirating
• Breech-loading, plastic, cartridge-type, aspirating
• Breech-loading, metallic, cartridge-type, self-aspirating
• Pressure syringe for periodontal ligament injection
• Jet injector (“needleless” syringe)

8. Breech-loading, metallic,
cartridge-type syringe

9. Breech-loading, metallic,
cartridge-type syringe

10. Breech-loading, metallic,
aspirating syringe
Advantages
• Visible cartridge
• Aspiration with one hand
• Autoclavable
• Rust resistant
• Long lasting with proper
maintenance
Disadvantages
• Weight (heavier than plastic
syringe)
• Syringe may be too big for small
operators
• Possibility of infection with
improper care

11. Breech-loading, metallic, harpoon-type aspirating syringes with small
and large thumb rings

12. To increase the ease of aspiration, self-aspirating syringes
have been developed.These syringes use the elasticity of
the rubber diaphragm in the anesthetic cartridge to obtain
the necessary negative pressure for aspiration.

13. Plastic, Reusable, Aspirating
Syringe
Advantages
• Plastic eliminates metallic, clinical
look
• Lightweight: provides better
“feel” during injection
• Cartridge is visible
• Aspiration with one hand
• Rust resistant
• Long lasting with proper
maintenance
• Lower cost
Disadvantages
• Size (may be too big for small
operators)
• Possibility of infection with
improper care
• Deterioration of plastic with
repeated autoclaving

14. Pressure syringe
• (Re)introduced in the late 1970s
• Periodontal ligament injection/PDL
(also known as the intraligamentary
injection), although usable for any
tooth, makes it possible to achieve more
reliable pulpal anesthesia of one
isolated mandibular tooth without the
attendant prolonged soft tissue of nerve
block anesthesia

15. Pressure syringe
Original design 2nd generation design

16. Pressure syringe
Advantages
• Measured dose
• Overcomes tissue resistance
• Nonthreatening (new devices)
• Cartridges protected
Disadvantages
• Easy to inject too rapidly (0.2 ml
in ‹20 sec)
• Threatening (original devices)

17. Jet injector
• It is 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 primary purpose of the jet injector is to obtain topical
anesthesia before insertion of a needle.
• It may even be used to obtain mucosal anesthesia of palate.
• The most used jet injectors in dentistry is the MadaJet.

18. Jet injector
Advantages
• Does not require use of needle
(recommended for persons with
needle phobia)
• Delivers very small volumes of
local anesthetic (0.01–0.2 mL)
• Used in place of topical
anesthetics
Disadvantages
• Inadequate for pulpal anesthesia
or for regional block
• Some patients are disturbed by
the “jolt” of the injection
• Cost
• May damage periodontal tissues

19. DISPOSABLE
SYRINGES

20. Disposable syringe
• These syringes contain a Luer-Lok screw-on needle attachment but no
aspirating tip.
• Care must be taken to avoid contaminating the multiuse vial.
• 2-mL and 3-mL syringes with 25- or 27-gauge needles are
recommended when the system is used for intraoral LA administration.
• This system is also practical when diphenhydramine hydrochloride is
used as a local anesthetic in cases of alleged LA allergy.

21. Disposable syringe
Advantages
• Disposable, single use
• Sterile until opened
• Lightweight
Disadvantages
• Does not accept prefilled dental
cartridges
• Aspiration requires two hands

22. SAFETY SYRINGES
Dental safety syringes are designed as single-use items,
although they permit reinjection.

23. Safety syringe
(A) Ultra Safety Plus XL aspirating syringe, ready for injection.
(B) Ultra Safety Plus XL aspirating syringe with the needle sheathed to
prevent needlestick injury. (Courtesy of Septodont, Inc, Lancaster, PA)

24. COMPUTER –
CONTROLLED LOCAL
ANESTHETIC DELIVERY
SYSTEMS

25. C-CLAD device, Dentapen

26. C-CLAD device, Anaject

27. C-CLADs
• In 1997 the first computer-
controlled local anesthetic
delivery (C-CLAD) system was
introduced into dentistry.
• The Wand (Milestone Scientific
Inc., Livingston, New Jersey,
United States) was designed to
improve on the ergonomics and
precision of the dental syringe,
with a controlled flow rate.
• Reduced overall pain perception

28. TheWand STA system
• Introduced in 2007, the Wand STA
system is a 3rd generation C-CLAD
instrument with dynamic
pressure-sensing technology
(DPS technology).
• DPS technology enables the
precise monitoring and control of
fluid pressure at the needle tip
when an injection is performed.
• Fluid exit pressure at the needle
tip is used to identify a given
anatomic location and/or a
specific tissue type on the basis
of this repeatable finding.

29. TheWand STA system
• Dynamic pressure sensing on the STA
SingleTooth Anesthesia system
provides both visual and audible
feedback regarding placement of the
needle tip during the periodontal
ligament (PDL) injection.
• Horizontal color bars (arrow) indicate
pressure at the tip of the needle. Red
means pressure is too low. Orange and
dark yellow mean increasing pressure
but not yet adequate. Light yellow
means correct pressure for PDL
injection.
• At this point the STA unit will also
provide an audible clue “PDL, PDL,
PDL” that the needle tip is properly
situated.

30. TheWand STA system
• TheWand STA system provides a safe
and effective alternative to the
mandibular block anesthesia in
children that minimizes the risk of self-
inflicted soft tissue injury (e.g., lip
biting).
• TheWand STA system has two basic
components: hand piece and drive
unit.
• TheWand STA hand piece is a single-
use (per patient visit) lightweight hand
piece (weighing less than 10 g);
available with many standard dental
needle sizes: 30-gauge 0.5-inch, 27-
gauge 0.5-inch, 30-gauge 1-inch, and
27-gauge 1.25-inch needle lengths.

31. TheWand STA system -
Advantages
• DPS technology provides continuous real-time feedback when an
injection is performed, resulting in a more predictable injection site
location
• Allows the periodontal ligament injection to be used as a
predictable primary injection
• Can be used for all traditional injection techniques
• Recommended device for newer injection techniques such as
anterior middle superior alveolar nerve block, palatal anterior
superior alveolar nerve block, and STA periodontal ligament
injection
• Reduces pain-disruptive behavior in children and adults
• Reduces stress for patient
• Reduces stress for operator

32. Care & handling of syringes
• After each use, the syringe should be thoroughly washed and rinsed so as
to be free of any LA solution, saliva, or other foreign matter. Should be
autoclaved in the same manner as other surgical instruments.
• After every 5 autoclavings, the syringe should be dismantled and all
threaded joints and the area where the piston contacts the thumb ring
and guide bearing should be slightly lubricated.
• The harpoon should be cleaned with brush after each use.
• Prolonged use of harpoon will result in decreased sharpness.
Replacement pistons and harpoons are readily available at low cost.

33. PROBLEMS

34. Leakage during injection
• When a syringe is reloaded with a 2nd LA cartridge and a needle is
already in place, care must be taken to ensure that the needle
penetrates the center of the rubber diaphragm.
• An off-center perforation during syringe reloading produces an
ovoid puncture of the diaphragm that allows leakage of LA
solution.

35. 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. Positive pressure on the thumb ring
increases pressure within the cartridge, which may cause the
cartridge to break.

36. 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 may result in cartridge breakage.

37. Disengagement of harpoon
• Disengagement occurs if the harpoon is dull or too much pressure
is applied during aspiration.
• If this occurs the harpoon should be cleaned & sharpened or
replaced.

38. Surface deposits
• An accumulation of debris, saliva & disinfectant solution interferes
with syringe function.
• Deposits which resemble rust may be removed with a thorough
scrubbing.
• Ultrasonic cleaning will not harm syringes.

39. THE NEEDLE
The needle is the vehicle that permits LA solution
to travel from the dental cartridge into the tissues
surrounding the needle tip.

40. The Needle
• LA needles are made of stainless
steel; are presterilized and
disposable.
• Needles represent the most fear-
inducing component of the LA
armamentarium for the patient. Fear
of needles is termed trypanophobia.
• The needle is composed of a single
piece of tubular metal around which
is placed a plastic or metal syringe
adaptor and the needle hub.

41. Needle bevel
• The bevel which is the tip of the
needle, provides a cutting surface
allowing the needle to penetrate
mucosa with as little resistance as
possible.
• The scalpel bevel needle is
recommended for infiltration and
periodontal ligament (PDL) injections.
It is not recommended for nerve
blocks where the nerve may be
directly contacted (e.g., inferior
alveolar nerve block).
• Greater the angle of the bevel with
the long axis of the needle, the
greater will be the deflection.

43. Needle gauge
Gauge refers to the diameter of the lumen of the needle: the smaller the
number, the greater the diameter of the lumen.

44. Advantages of Larger-Gauge Needles
Over Smaller-Gauge Needles
1. Less deflection as the 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

45. Needle gauge
• The 25-gauge (long or short) needle remains the preferred needle
for all injections presenting a high risk of positive aspiration.
• The 27-gauge needle can be used for all other injection techniques,
provided the aspiration percentage is low and tissue penetration
depth is not great (increased deflection with this thinner needle).
• The 30-gauge needle is not specifically recommended for any
injection, although it may be used in instances of localized
infiltration, as when hemostasis is attained during periodontal
therapy.

46. Minimizing Needle Deflection:
Birotational InsertionTechnique

47. Needle length (in mm)
The length—measured from hub to tip—of a short needle is between 20 and 25
mm, with a standard of about 20 mm, whereas the dental long needle measures
between 30 and 35 mm, with a standard of about 32 mm.

48. • A very important rule concerning needle penetration is that
“needles should not be inserted into tissues all the way to their
hubs”.
• The weakest portion of the needle is at the hub, which is where
needle breakage happens.
• When a needle that is inserted into the soft tissues to its hub
breaks, the elastic properties of the tissues permit them to rebound
and cover (bury) the needle remnant entirely. Retrieval is usually
difficult.

49. Recommendations
• Needles must never be used on more than one patient.
• Attention should always be paid to the position of the uncovered
needle tip, whether inside or outside the patient’s mouth.
• Needles should be changed after three or four tissue penetrations
in the same patient.
• Needles should not be bent if they are to be inserted into soft
tissue to a depth greater than 5 mm.
• No attempt should be made to change the direction of a needle
while it is embedded in tissue. If the direction of a needle must be
changed, the needle should first be withdrawn almost completely
from the tissue and then its direction altered.

50. Recommendations
• No attempts should be made to force a needle against resistance
(needles are not designed to penetrate bone).This may result in
“fishhook” barbs causing pain on needle withdrawal.
• Needles should be covered with a protective sheath when not
being used to prevent accidental needle stick with a contaminated
needle.
• Contaminated needles should be disposed of in special “sharps”
containers.

51. THE CARTRIDGE
Referred to as “carpule” by dental professionals.
In US, the dental cartridge contains 1.8ml of LA solution whereas in
UK & Australia, it contains 2.2ml of LA solution.

52. Components

53. Color coding of cartridges (ADA)

54. Components
• The plunger occupies a little less
than 0.2 mL of the volume of the
entire cartridge.
• In an intact dental cartridge, the
stopper is slightly indented from the
lip of the glass cylinder.
• The diaphragm is a semipermeable
membrane that allows any solution
in which the dental cartridge is
immersed to diffuse into the
cartridge, thereby contaminating the
local anesthetic solution.

55. Cartridge (Mylar plastic) label

56. Composition of LA solution

57. Question of the week
Why does a patient experience increased burning
(discomfort) on injection of an “older” LA cartridge with
vasoconstrictor, when compared to a “fresher” cartridge?
• Cartridges containing a vasoconstrictor also contain an antioxidant,
most often sodium (meta)bisulfite. Sodium bisulfite reacts with
oxygen faster than the oxygen is able to destroy the
vasoconstrictor.When oxidized, sodium bisulfite becomes sodium
bisulfate, having an even lower pH.

58. Care & handling
• Should be stored in their original container at room temp. & in a
dark place.
• No need to “prepare” a cartridge before use.

59. PROBLEMS

60. Bubble in the cartridge
• A small bubble of ~ 1-2mm in diameter (“BB”-sized) 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.

61. 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.
• LA solutions containing alcohol produce burning on injection.
Alcohol in sufficiently high concentrations is a neurolytic agent &
can produce long-term paresthesia.
• Anti rust tablets should not be used in disinfectant solutions.The
sodium nitrate that they contain is capable of releasing metal
ions, which have been related to an increased incidence of edema
after LA administration.

62. Burning on
injection
• Normal response to pH of
drug
• Cartridge containing
sterilizing solution
• Overheated cartridge
• Cartridge containing
vasospressor
Sticky stopper
• The “sticky stopper” has become
rare today, with the inclusion of
silicone as a lubricant & the
removal of paraffin as a sealant in
the cartridge.

63. Corroded cap
• The aluminium cap can be corroded if immersed in disinfecting
solutions that contain quaternary ammonium salts such as
benzalkonium chloride.
• Aluminium-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.
Rust on the cap
• Indicates that atleast 1 cartridge in the tin container has broken or
leaked.
• With the introduction of non-metal packaging, rust is rarely seen.

64. Leakage during injection
• Ovoid and eccentric perforation of diaphragm
Broken cartridge
• 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.

65. ADDITIONAL
ARMAMENTARIUM
Topical antiseptic
Topical anesthetic
Applicator sticks
Cotton gauge
Hemostat
Needle-recapping device

66. Topical antiseptic
• Application of a topical antiseptic is considered an optional step in
tissue preparation before intraoral injection.
• The topical antiseptic, on an applicator stick, may be placed at the
site of injection for 15 to 30 seconds.
• Available agents include povidone-iodine (Betadine) and
thimerosal (Merthiolate).
• Topical antiseptics containing alcohol (eg.Tincture of iodine or
tincture of merthiolate) should not be used because it produces
irrittation.

67. Topical anesthetic
• Minimize sensation of needle penetrating the soft tissue.
• A minimal quantity of topical anesthetic is applied to the end of the
applicator stick and placed directly at the site of needle penetration for at
least 1 minute, preferably 2 minutes.
• Used in greater concentration than injectable LA in order to penetrate the
mucous membrane.

68. Topical anesthetic agents
Lidocaine
• 5% ointment, gel, liquid
• 10% metered spray
• Onset 3-5 minutes
Benzocaine
• 14-20% liquid, gel
• Onset 30 seconds
• Longer duration than the others
• Lower toxicity potential than the
others
• EMLA (eutectic mixture of local anesthetics) is a combination
of lidocaine and prilocaine in a topical cream formulation designed
to provide surface anesthesia of intact skin.

69. Applicator sticks & hemostat

70. Needle-recapping device

71. PREPARATION OF
ARMAMENTARIUM

72. Loading of LA syringe

74. Recapping the needle

75. Unloading the LA syringe

76. Placing an additional cartridge
• Recap the needle using the scoop technique.
• Remove the needle from the syringe.
• Retract the piston (disengaging the harpoon from the rubber
stopper).
• Remove the used cartridge.
• Insert the new cartridge.
• Embed the harpoon.
• Reattach the needle.

77. Reference
• Malamed SF. Handbook of Local Anesthesia. 7th ed. St.
Louis:Mosby (Elsevier) Publishing; 2019.

78. THANKYOU