Needle
• Permits the LA solution to travel from the
dental cartridge into the tissues surrounding
the needle tip
• Most needles used in dentistry – stainless
steel & disposable
• Other needles-platinum or iridium-platinum
or ruthenium-platinum alloy
Parts
• Bevel-Point or tip of the needle
• Shaft-Long piece of tubular metal running from
tip of the needle through hub & continuing to the
piece that penetrates cartridge
• Hub-Plastic or metal piece through which needle
attaches to syringe
• Cartridge penetrating end-Perforates the
diaphragm of the LA cartridge
Gauge
• The diameter of the lumen of the needle
• Smaller the number ,greater the diameter of
the lumen
• 25 gauge needle is the preferred needle for
all injections
Advantages of larger-gauge
needles over small gauge needles
• Less deflection occurs as needle passes
through the tissues
• Aspiration of blood is easier
• Greater accuracy of injection
• Less chance of needle breakage
Length
• 2 types – short & long
• Average length of short needle is 20mm & long
needle is 32mm
• Long needle is preferred for all injections where
the penetration of significant thickness of soft
tissue is needed ( eg : inferior alveolar nerve
block,Vasirani Akinosi,Gow-Gates
mandibular,infra orbital & maxillary nerve blocks)
• Needle should not be inserted into the
tissues to their hubs unless it is absolutely
neccesary for the success of injection
• If a needle inserted till the hub breaks,the
elastic properties of the tissues permit them
to rebound and cover(bury)the needle
entirely
Care & handling
• Needles must never be used
more than one patient
• Should be changed after 3 or
4 injections in same patient
• Should be covered with a
protective sheath when not
being used
• Must be properly disposed
off after use
• ‘’Scoop’’ technique for recapping the LA
needle must be used
Problems
•
•
•
•
Pain on insertion
Breakage
Pain on withdrawal
Injury to the patient or administrator