the needle.ppt

8/14/2019 The Needle.ppt

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The Needle


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-most needles are stainless steel and disposable

-reusable needles have no place in the practice ofDentistry

-plastic hubs are not pre-threaded; metal hubs arepre-threaded

-a needle whose point is more centered on the longaxis will have less deflection upon entry into softtissues than a beveled needle


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All needles have these components in common:

1) Bevel: point or tip of needle; long, medium andshort

2) Shaft: long portion of the needle(diameter of lumen)

3) Hub: plastic/metal piece that attaches the needleto the syringe

4) Cartridge Penetrating End: perforates thediaphragm of the cartridge


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The Gauge-the diameter of the lumen of the needle; the smaller the

number the greater the diameter of the lumen; 30-gauge

needle has a smaller internal diameter than a 25-gauge

needle; needles in the U.S. are color coded by diameter

30 Gauge (Blue)

27 Gauge (Yellow)25 Gauge (Red)


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-Dentists think that using smaller gauge needles

will result in a less traumatic injection

experience by the patient which is false

-In 1972, Hamburg proved that patients could

not differentiate between 23, 25, 27 and

30-gauge needles


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Larger gauge needles have advantages over

smaller gauge needles:

1) less deflection of the needle tip results in greater

accuracy

2) less chance of needle breakage (separation)

3) easier aspiration of blood through the larger

lumens

4) undetectable pain differences between 25 and

30-gauge needles


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-25 gauge is the needle of choice for injections that

have a high potential for a positive aspiration

(PSA, IANB and Mental Block)

-30-gauge needles are not recommended for any

specific injection


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Rotational Insertion Technique

(minimizes deflection)

Bi-rotational insertion technique

the operator rotates the needle in a back-and-forthrotational movement while advancing the needle

through the tissues; traditional hand-held syringes

cannot be rotated in this manner, however, TheWand can be rotated in this fashion results in lessdeflection, less force is needed for needle

penetration


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Length-there are three lengths to dental needles: long, short

and ultrashort

-average length of short needles: 20 mm (hub to tip)

-average length of long needles: 32 mm (hub to tip)

-needles should not be inserted to the hub unlessabsolutely necessary for the success of the

injection


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-hub is the most common area for breakage becausethis area has the highest level of stress

-when a needle is separated the elastic properties of

the tissues permit a rebound effect that completelycovers the needle (buries it)

-25 gauge long needle is the only needle any Dentistneeds to perform any dental injections per Malamed

(25 or 27-gauge short possible too)


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Problems-Stainless steel needles dull after 3-4 penetrations into

soft tissue causing more pain/post-operativediscomfort; change your needle

-If needles are to be penetrated into soft tissue morethan 5 mm then the needle should not be bent;

bending needles weaken them

-No attempt should be made to change the direction of aneedle when it is embedded into tissue; you should

remove the needle and reinsert it completely

-Of 60 needles that separated and lead to litigation,59 of them were 30-gauge short needles

(probably inserted too far and above rules broken)


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Problems-Pain on withdrawal of needle could be due to fishhook

barbs due to errors in manufacturing or too hard contact

against bone

-Needle should be recapped immediately after it is withdrawn

from a patients mouth; avoids unintentional sticks

-Never put an uncapped needle on the tray for yourself or

someone else to inadvertently be stuck; always recap the

needle after you have given any injection


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ReferencesMalamed, Stanley. Handbook of Local Anesthesia. 5thEdition. Mosby.

2004

the needle.ppt

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