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A R M A M E N T A R I U M 

Objectives:

  • Select correct dental anesthesia armamentarium necessary for corresponding injections.

  • Display the proper technique of recapping the needle.

  • Properly dispose of anesthetic cartridges and needles.

SYRINGE

The syringe is one of the three essential components of the local anesthetic armamentarium (others include the needle and cartridge).  It is the vehicle in which the contents of the anesthetic cartridge are delivered though the needle to the patient.

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Eight types of syringes for local anesthetic administration are available for use in dentistry today.  Two of the eight types are used in the UHMDH clinic.  These two syringes are non-disposable, breech-loading (cartridge is inserted or loaded), metallic, and cartridge types.

  1. Aspirating

    • Most common​

    • Harpoon attached to the piston (penetrates rubber stopper at the end of the local anesthetic cartridge)

    • Allows for aspiration testing

  2. Self-Aspirating 

    • Uses the elasticity of the rubber diaphragm in the anesthetic cartridge to obtain the required negative pressure for aspiration testing​

    • Permits for multiple aspirations easily 

NEEDLE

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The needle is the vehicle that allows local anesthetic solution to travel from the dental cartridge into the tissues surrounding the needle tip.   Most needles used in dentistry are stainless steel and disposable.  Needles manufactured for dental intraoral injections are stainless steel, pre-sterilized, and disposable.  

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Factors to consider when selecting needles:

  1. Gauge: diameter of the lumen of the needle

    • Refers ​to size

    • 25, 27, and 30 gauge most commonly used

    • Smaller the number, greater the diameter

    • Larger gauge (smaller number) more advantages

      • Less deflection​

      • Less traumatic

      • Greater accuracy

      • Less chance of needle breakage

      • Aspiration of blood easier and more reliable

  2. Length: most commonly available in two lengths

    1. Long: about 1-5/8 inches (32mm)​

    2. Short: about 1 inch (20mm)

Aspirating Syringe 

Self-Aspirating Syringe

The needle represents the most dangerous component of the armamentarium, the one most likely to produce injury to a patient or clinician.  Needles should not be inserted into tissues all the way to their hub unless this is necessary for the success of the injection.  One reason for this precaution is needle breakage, which rarely occurs.  The weakest portion of the needle is in fact at the hub, as it receives the greatest stress during needle advancement through tissues.  

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Care and Handling of Needles

  • Never use on more than one patient

  • Should be changed after several (three or four) tissue penetrations in the same patient

    • needles become dull, while tissue penetration becomes increasingly traumatic with each insertion​

  • Should be capped when not in use to prevent accidental needle-stick with contaminated needle

  • Be aware of position of uncapped needle intra and extraorally to minimize the risk of potential injury to patient/clinician

  • Properly dispose of after use to prevent possible injury or reuse by unauthorized individuals 

    • Use needle cappers or the "scoop" technique to recap needles

    • NEVER discard needles into open trash containers

    • Dispose in "contaminated" sharps container 

CARTRIDGE

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Glass cylinder cartridges usually contain 1.7mL of solution.  It should never be sterilized as it will render the effectiveness of the contents.  Cartridges should never be soaked in alcohol (or other sterilizing solutions) and needs to be stored in the original container in a dark or cool area.

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Components of a cartridge:

  • Rubber stopper (plunger)

    • End of cartridge that receives the harpoon​

  • Aluminum cap

    • Located at the opposite end of the rubber stopper, holding the diaphragm​

  • Diaphragm

    • Semipermeable membrane where needle penetrates​

  • Cylindrical glass tube

    • Holds the local anesthetic contents​

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