1. The Armamentarium
4 PARTS: 1) The Syringe 2) The Needle 3) The Cartridge 4) Preparation

2. The Syringe
Standard of Care  aspirating dental syringes are the standard of care due to their ability to aspirate blood if the tip of the needle is located intravascularly

3. ADA Standards for Injection Syringes
They must be durable and able to withstand repeated
sterilization without damage
2. They should be capable of accepting a wide variety of
cartridges and needles from different manufacturers and
permit repeated use
3. They should be inexpensive, self-contained, lightweight
and simple to use with one hand
4. Provide aspiration so blood can be seen through the glass
cartridge

5. Breech-Loading, Metallic, Cartridge-Type, Aspirating #1 Used Syringe In Dentistry
-breech loading implies that the dental cartridge is loaded from the side
-a needle is attached to the barrel of the syringe at the needle adaptor
-the needle passes into the barrel and pierces the diaphragm of the local anesthetic cartridge

6. Aspirating Syringe
-the needle adaptor is sometimes inadvertently discarded along with the disposable needle -the harpoon is a sharp tip attached to the piston and is responsible for penetrating the thick silicone rubber stopper (bung) at the other end of the cartridge

7. - negative pressure is applied to the thumb ring by the
administrator, if blood enters the glass local anesthetic
cartridge (carpule) then the tip of the needle is
inserted into the lumen of a blood vessel
chrome-plated brass and stainless steel

8. -incidence of positive aspiration is between 10-15% for some injections
-aspiration before injection of local anesthetic is accepted in the practice of dentistry and is overlooked to a great extent
-these syringes use the elasticity of the rubber diaphragm in the anesthetic cartridge to obtain the necessary negative pressure for aspiration

9. -multiple aspirations are possible with very little effort due to a small metal projection that applies pressure to the rubber diaphragm when the thumb ring is depressed  negative pressure  aspiration -this type of aspiration is as reliable as using the harpoon to check for blood aspiration

10. Self-Aspirating Syringes
-Major factor for aspiration is the gauge of the needle being used -Most doctors using the harpoon-type syringe, retract the thumb ring back too far and with excessive force which frequently disengages the harpoon from the silicone rubber stopper of the cartridge

11. -1st generation self-aspirating syringes required a thumb disk
which forced the operator to remove their index and middle
fingers from the thumb ring to the thumb disk to aspirate
-2nd generation self-aspirating syringes have removed this
thumb disk
-Dentists only need to stop applying pressure to the thumb ring for aspiration; aspiration becomes very easy to do

14. Pressure Syringes -PDL (intraligamentary) injections make it
possible to achieve single tooth pulpal
anesthesia in the mandible when, in the past,
complete IANB was necessary

15. -pressure syringes can allow too easy of an administration of
local anesthetic producing pain and post-operative discomfort
-pressure syringes are expensive > $200.00
-can shatter glass cartridge if too much pressure is applied too
quickly

16. 2000 psi Jet Syringes ($1,600)
-needle-less injection -liquids forced through very small openings, called jets, at very high pressure can penetrate skin or intact mucous membrane -Syrijet is the most popular used today -Syrijet holds any 1.8 ml cartridge of local anesthetic

17. -Syrijet is calibrated to deliver. 05 to
-Syrijet is calibrated to deliver .05 to .2 ml of solution at 2000 psi; traditional syringes deliver 600 psi maximum -primary use is to obtain topical anesthesia before using a needle -regional nerve blocks/supraperiosteal injections are still necessary -topical anesthetics provide the same effect at a fraction of the cost -patients complain of soreness where the 2000 psi hit their tissue

18. Safety Syringe
-Aspiration is possible -some brands come with an autoclavable plunger and disposable self-contained injection unit -all dental safety syringes are made to be single use items

19. -more expensive than reusable syringe units
-sliding the index and middle finger forward against the front collar of the guard makes the needle “safe” by sliding a protective plastic sheath over the needle tip that locks into place
-more expensive than reusable syringe units
-large disadvantage arises when it comes to re-injecting; complication ensues due to the needle tips newly acquired safety coping

21. CCLAD (Computer Controlled Local Anesthetic Delivery
-designed to improve ergonomics and precision of injection technique
-foot activated delivery of solution using finger tip precision
-pen-like grasp offers increased tactile sensation

22. The Wand
-flow rates of solution delivery are computer controlled and remain consistent
operator is able to focus attention on the position of the needle tip while the motor of the machine delivers local anesthetic at a preprogrammed rate of flow
50 Dentists were injected with traditional syringes and The Wand; 48 of 50 Dentists preferred to be injected again themselves with The Wand due to a reported threefold decrease in the interpretation of pain

23. -The Wand is less threatening to the patients visually -allows two rates of delivery: 1) Slow: .5 ml/minute 2) Fast: 1.8 ml/minute -releasing the foot rheo-stat will tell the machine to aspirate automatically; the aspiration cycle is approximately 4.5 seconds

24. -less painful PDL, palatal, attached gingiva injections
-extremely high pressure in non-resilient tissues cause (traditional syringe) moderate/severe pain in most patients
The Wand eliminates a lot of this discomfort by maintaining constant pressure delivery of the solution
-less painful PDL, palatal, attached gingiva injections

26. References
Malamed, Stanley: Handbook of Local Anesthesia. 5th Edition. Mosby