1. The Cartridge or Carpule
1.1. glass cylinder containing L.A drug among other ingredients
1.2. Volume of the Cartridge is 1.8 ml
1.3. Components
1.3.1. Cylindrical glass tube
1.3.2. Stopper ( Plunger, Bung )
1.3.3. Aluminium cap
1.3.4. Diaphragm
1.4. Contents
1.4.1. L.A drugs
1.4.1.1. Lignocaine
1.4.1.2. Mepivacaine
1.4.2. Vaso-constrictor
1.4.2.1. Adrenaline
1.4.2.2. Levonordefrine
1.4.3. Anti-Oxidant
1.4.3.1. Sodium Metabisulfite
1.4.4. Sodium Chloride
1.4.4.1. Isotonic maker
1.4.5. Distilled water
1.4.6. Bacteriostatic agent – ( may or may not be present)
1.4.6.1. Methyl paraben
1.5. Care & Handling
1.5.1. comes in Vacuum sealed pouches or containers
1.5.2. They come pre-sterilized
1.5.3. L.A should be stored in the original boxes at room temperature
1.5.4. There is no need to prepare a cartridge
1.5.5. should not be immersed in any fluids
1.5.6. should not be warmed
1.5.7. should not be exposed to direct sunlight
1.5.8. Read the Information leaflet inside the box of cartridges
1.6. Problems With Cartridges
1.6.1. Bubble in the cartridge
1.6.1.1. bubble of 1-2 mm diameter is in the cartridge usually & this is (nitrogen)
1.6.1.1.1. placed to prevent Oxygen from getting into it
1.6.1.1.2. Oxygen can destroy the Adrenaline in the solution by Oxidation
1.6.2. Extruded Stopper
1.6.2.1. due to freezing of the liquid and expansion
1.6.2.2. cartridge with extruded stopper should not be used
1.6.3. Burning on Injection can be due to :
1.6.3.1. Normal response to the PH of the drug
1.6.3.2. Cartridge containing sterilizing liquid
1.6.3.3. Overheated cartridge
1.6.3.4. Cartridge containing vasoconstrictor
1.6.4. Sticky Stopper
1.6.4.1. rare now-a-days due to the use of Silicone
1.6.4.2. more common in Plastic cartridges
1.6.4.3. Using cartridges at room temperatures seems to eliminate this problem
1.6.5. Corroded cap
1.6.5.1. cartridge is immersed in disinfecting solutions this is a possibility
1.6.5.2. Cartridges with corroded caps should not be used
1.6.6. Rust on the Caps
1.6.6.1. indicates that atleast one of the cartridges in the box is broken or leaked
1.6.6.2. Cartridges containing rust should not be used
1.6.6.3. With the current use of Non metal packing – rust is not usually seen
1.6.7. Leakage during Injection
1.6.7.1. due to an improperly prepared cartridge
1.6.7.2. needle or the syringe is not loaded properly
1.6.8. Broken cartridge
1.6.8.1. can happen during shipping
1.6.8.2. broken cartridge is found in a container all the rest of them has to be discarded
1.6.8.3. Do not subject a cartridge to excessive pressure
1.6.8.3.1. it can explode
1.6.8.4. Syringes with bent Harpoon’s can also cause breakage of the cartridges
2. The needle
2.1. Most needles used in Dentistry are Stainless steel
2.2. Reusable needles should not be used
2.3. most likely to cause injury to the patient & also the Doctor
2.4. Parts of needle
2.4.1. Bevel
2.4.1.1. is the tip which penetrates the tissue
2.4.1.2. Deflection Possibility
2.4.1.2.1. Greater is the angle of the Bevel greater is the deflection
2.4.1.2.2. best to have a rotational injection method & grasp like below
2.4.2. Shaft
2.4.2.1. Long tubular metal which can bend, so careful
2.4.3. Hub
2.4.3.1. The joint to the plastic end
2.4.3.1.1. Needles usually break at this point
2.4.4. Syringe adaptor
2.4.4.1. can help the needle screw on to the syringe
2.4.5. Cartridge penetration end
2.4.5.1. dwells in the cartridge & perforates the Diaphragm
2.5. Gauge
2.5.1. Diameter of the lumen of the needle
2.5.2. Smaller the number – Greater is the Diameter
2.5.3. Greater the number – Smaller is the Diameter
2.5.4. Larger gauge ( 25 ) of the needle is better than smaller because of ;
2.5.4.1. Less deflection
2.5.4.2. Grater accuracy in needle insertion
2.5.4.3. Needle breakage is lesser
2.5.4.4. Aspiration result is more reliable
2.5.5. Most Commonly used Needles in dentistry
2.5.5.1. 27 gauge long
2.5.5.2. 30 gauge short
2.5.5.3. 25 gauge is most preferred for IANB
2.6. Length
2.6.1. Long
2.6.1.1. 32 mm ( Used in Inferior Alveolar Nerve Block )
2.6.2. Short
2.6.2.1. 20 mm
2.6.3. Ultrashort
2.6.4. Needles should never be injected all the way till the HUB of the needle
2.6.4.1. This can lead to needle breakage, as it is the HUB which is the weakest point
2.7. Care & Handling of Needles
2.7.1. Needles should never be used on more than one patient
2.7.2. Needle should be changed after 3 or 4 penetrations
2.7.3. Needles should be covered with the protective sheath
2.7.4. Attention to be given to the uncovered needle tip
2.7.5. Needles should be disposed of after use into the sharps bin
2.8. Problems Due to Needles
2.8.1. Pain on Insertion
2.8.1.1. due to the use of a needle that is NOT sharp
2.8.1.2. prevented by using
2.8.1.2.1. New needle
2.8.1.2.2. Sharp needle
2.8.1.2.3. Topical Anaesthesia
2.8.1.2.4. Change needles after 3 or 4 needle insertions
2.8.2. Breakage
2.8.2.1. due to Bending which weakens the needle
2.8.2.1.1. Never bent needles if you have to insert into soft tissue
2.8.2.2. Do Not change the direction of the needle in the soft tissue
2.8.2.3. Do not force the needle into tissues
2.8.2.4. 30 gauge Short or Ultra Short is the most common needle that is Broken
2.8.3. Pain on withdrawal
2.8.3.1. due to the “Fish Hook Barb” like effect of needle.
2.8.3.2. manufacturing defect
2.8.3.3. also happen due to pressure & change in the Shape of the tip of needle
2.8.4. Injury to the patient or administrator
2.8.4.1. Needles have to be Capped until it is used
2.8.4.1.1. immediately after use “Made Safe” to prevent needle stick Injury
2.8.4.2. Prevention of needle stick Injury is very important to prevent Transmission of
2.8.4.2.1. HEP B
2.8.4.2.2. HEP C
2.8.4.2.3. HIV
2.8.4.3. Use an Anti-stick device
2.8.4.3.1. Use Scoop technique
3. The syringe
3.1. An instrument that will deliver the contents of the anaesthetic cartridge to the patient by the needle
3.2. Type of Syringes
3.2.1. Non disposable syringes
3.2.1.1. Breech loading, metallic, cartridge type, aspirating
3.2.1.1.1. most commonly used one in dentistry
3.2.1.1.2. Aspirating syringe has a Harpoon
3.2.1.1.3. ADV
3.2.1.1.4. DisADV
3.2.1.2. Breech loading, Plastic, cartridge type, aspirating
3.2.1.2.1. these ones are Autoclavable & Sterilisable If handled properly
3.2.1.2.2. ADV
3.2.1.2.3. DisADV
3.2.1.3. Breech loading, metallic, cartridge type, self aspirating
3.2.1.3.1. Potential Hazard of Intra-vascular
3.2.1.3.2. allow multiple aspirations before depositing the entire solution
3.2.1.3.3. NOT RELIABLE
3.2.1.3.4. ADV
3.2.1.3.5. DisADV
3.2.1.4. Pressure syringe for periodontal ligament injection
3.2.1.4.1. TOO GOOD, as large amount of solution is injected very quickly
3.2.1.4.2. rapid injection can cause Pain & discomfort
3.2.1.4.3. preferred injection syringe & technique in Hemophilia patients
3.2.1.4.4. if used slowly, it is a very good
3.2.1.4.5. ADV
3.2.1.4.6. DisADV
3.2.1.5. Jet injector ( needle-less syringe )
3.2.1.5.1. based on the principle of Liquids forced through very small openings, called jets at very high pressure
3.2.1.5.2. can deliver 0.05 to 0.2 ml of solution at 2000 psi
3.2.1.5.3. Primary use
3.2.1.5.4. Regional blocks are still necessary & it is NOT a substitute for regular injection
3.2.1.5.5. Limited use
3.2.1.5.6. ADV
3.2.1.5.7. DisADV
3.2.2. Disposable syringes
3.2.2.1. contain a Luer-Lok screw on needle attachment
3.2.2.2. No aspirating tip
3.2.2.2.1. Aspiration has to be done by pulling the plunger back using both hands
3.2.2.3. They do not accept dental cartridges
3.2.2.4. NOT recommended for routine dental use
3.2.2.4.1. should be used in only situations where the patient is Allergic to Latex
3.2.2.4.2. where(Diphenhydramine) is used as an anaesthetic alternative
3.2.2.5. ADV
3.2.2.5.1. Disposable, Single use
3.2.2.5.2. Sterile until opened
3.2.2.5.3. Light weight
3.2.2.6. DisADV
3.2.2.6.1. Does not accept prefilled cartridges
3.2.2.6.2. Aspiration is difficult
3.2.3. Safety syringes
3.2.3.1. minimize the risk of Needle Stick Injury
3.2.3.2. needle have a sheath that locks over the needle after injection
3.2.3.3. cartridge is visible & so can see the solution while aspirating
3.2.3.4. ADV
3.2.3.4.1. Disposable, Single use
3.2.3.4.2. Sterile until opened
3.2.3.4.3. Light weight
3.2.3.5. DisADV
3.2.3.5.1. Cost
3.2.3.5.2. Awkward for the first time user
3.2.4. Computer controlled local anaesthetic delivery system
3.2.4.1. Systems
3.2.4.1.1. The Wand / CompuDent system
3.2.4.1.2. Comfort control syringe
3.2.4.2. ADV
3.2.4.2.1. Precise control of flow rate & pressure produces more comfortable injection
3.2.4.2.2. Increased Tactile feel & ergonomics
3.2.4.2.3. Non Threatening appearance
3.2.4.2.4. Automatic Aspiration
3.2.4.2.5. Rotational insertion technique minimizes needle deflection
3.2.5. Problems with Conventional Syringes
3.2.5.1. Leakage during injection
3.2.5.2. Broken cartridge
3.2.5.3. Bent harpoon
3.2.5.4. Disengagement of the harpoon
3.2.5.4.1. from the plunger during aspiration
3.2.5.5. Surface deposits
3.2.6. Care & Handling of the Syringes
3.2.6.1. syringes have to washed & rinsed and Autoclaved
3.2.6.2. After every 5 autoclaves, the parts have to be Lubricated
3.2.6.3. Harpoon should be cleaned with a brush
3.2.6.4. Harpoon can become less sharp so then it has to be replaced