Local Anesthesia is a very integral part of almost every Dental Treatment performed which is used in making treatment procedures painless for the patient. Having good understanding of the composition of Local Anesthetic agent is important for treatment planning and to avoid any complications of LA such as allergies, etc. Local Anesthesia is used in a wide range of treatments ranging from a Simple Extraction to Wisdom Tooth removal, Rootcanal treatment, Flap surgery, Implant placement or some simple procedures like tooth cutting in a vital tooth and some cervical abrasion cases as well. So it is important to know everything about the Local Anesthetic agent which is being administered as it contains substances which some patients might be allergic to.
How to perform Skin test for Local Anesthesia Allergy
Some of components of the agent are known to be allergic to certain types of patients and it is also important to keep in mind that any patients with any heart disease should not be administered the Vasoconstrictor like adrenaline or Epinephrine. Some patients are known to be allergic to the preservative in the LA Agent and it is important to give a test dose before giving the Nerve block to check for any allergic reactions – Complications of Local Anesthesia.
Composition of Local Anesthetic agent
1) Local anaesthetic agent : Lignocaine HCL – 2% (20 mg/ml)
2) Vasoconstrictor : Adrenaline – 1:80,000 (0.012 mg) or Epinephrine
3) Reducing Agent: Sodium Metabisulphite – 0.5 mg
4) Preservative: Methylparaben – 0.1% (1mg)
5) Isotonic Solution: Sodium Chloride – 6 mg
6) Fungicide: Thymol
7) Vehicle: Ringer’s Solution
8) Diluting Agent: Distilled water
9) To adjust pH: Sodium Hydroxide
10) Nitrogen Bubble: 1-2mm in diameter and is present to prevent Oxygen from being trapped in the cartridge and potentially destroying the Vasopressor or vasoconstrictor.
Actions of each component of Local Anesthetic agent:
Vasoconstrictor function: Decrease blood flow to the site of injection, absorption of local anesthetic into the cardiovascular system is solved, decrease the risk of local toxicity, higher volume of local anesthetic agent remain in and around the nerve for longer period, thereby increasing the duration of action, vasoconstrictor decreases bleeding at the site of their administration.
Preservative : Stability of modern local anesthetic solution is maintained by adding caprylhydro-cuprienotoxin which includes xylotox and methyl paraben.
Reducing agent : These act as preservatives for vasoconstrictor agents. Vasoconstrictors are unstable in solution and may oxidize, especially on a prolonged exposure to sunlight. Sodium metabisulphite which competes for the available oxygen is added in the concentration between 0.05% and 0.1%
Vehicle : All the above solutions and local anesthetic agent are dissolved in a modified ringer solution. This isotonic vehicle minimizes discomfort during injection.
Function of Nitrogen bubble in LA cartridge
Why is Nitrogen Bubble present in the cartridge: 1-2mm in diameter and is present to prevent Oxygen from being trapped in the cartridge and potentially destroying the Vasopressor or vasoconstrictor, so this is the function of Nitrogen Bubble in the LA cartridge.
We see many patients who ask “what do dentists use to numb teeth or mouth” before performing a procedure and the answer is dental anesthetics which help in making dental procedures painless be it related to the tooth or the gums and other soft tissue in the mouth or oral cavity. Having proper knowledge about the Allergic Reactions to LA and also we should have good knowledge about the amount of LA to be given to avoid Local Anesthesia Toxicity due excess LA administration.
I could not find anywhere about the air bubble in the LA cartridge, thanx for sharing it with us
thanks for the post it helpd me alot
sensitivity to methylparaben is quiete common…so what do we do in that case..??? What is the substitute..??
methylparaben causes allergy…….what is the substitute for it??
why is injecting an air bubble along with la dangerous?or what are the effects of it?
You must have read about Air Embolism, so if you inject Air bubbles into the blood stream by mistake it may lead to air embolism.
Hence Air bubbles along with LA injection are dangerous
what is the alternative of methyl paraben used dese days?
the substitute for methyl paraben is cupryl hydrocuprinotoxin
Nyc post
Good post…Have so many things to learn..
Is sodium benzoate used as preservative in local aneasthesia
den wt is d bacteriostatic component in LA
Methylparaben is the preservative as well as the bacteriostatic component in LA .
What is isotonic solution mean for expunged with detail .
Why it’s not written percentage of other rest of composition .
What is the role of HCl in lignocaine?
I like the way uve presented the topics… Simplified n a quick review..
Really helpful
Thank you very much, I look forward to such comments to keep myself going.
How can I subscribe to ur write ups
Cupryl hydrocuprinotoxin
Nyc post… Thanks for dis.
How can i subscribe to ur writes….
Can’t find any link here.
In that case we can use LA without methylparaben…its commercial name is Loxicard..
What’s the metal part were the needle goes, what it’s called and what is made of
Hello Varun,
A small amount of nitrogen or air in the local anesthetic vile is too small to cause an air embolism. I am a dentist and dental anesthesiologist. On occasion a small air bubble goes through the IV line. It diffuses into the blood stream very quickly and is of no consequence to the patient. Although large amounts of air can cause a problem of course. small bubbles in the cartridges or IV lines are no issue.
thanks for sharing knowledge
thanks Dr. varun you doing much in other to help the dental student that they used to conduct a research.
Dr I need I your contact pls
You can mail me at juniordentist@gmail.com
Reference please?
Nice article.Found it very much useful.Thanks a lot.
Why only 2%HCL is used why not 1or 3 ..?
Hi doctor, I am a psychiatric patient using Clonazepam 0.5 mg a day and also used Esitalopram 5mg but now I cant take Esitalopram as I it give me side effect on heart. Now I cant able to take Pain killer it gives me several side effect on heart, chest burning and breathing problem. I am a weak person, age 37 now. I have 3 decay teeth badly pain but I cant take any pain killer. The teeth are bad condition. Once I took a Knock-2 tablet it give me several side effect on heart and chest. Now I want to extract my bad teeth but Our Dentist cant take any risk so he did not extracted my teeth. What should I do now. What is right for me. Most teeth are going hole in it and black. Please give me any suggestion.. does Dental anesthesia give me harm like a pain killer and what should I do after extracted if it is givining pain.. please help..
in case of heart pt or hypertensive pt ,can we use adrenaline in case of root canal treatment
Before working on a patient, always perform patch test
Yes, it is a must in patients who have never undergone any surgical procedure in life Dental or Medical. We can never know who is allergic to what and getting a patch test done is the best way to avoid any complications during or after the procedure. A simple procedure cna turn complicated in case of any Allergy which could have been avoided with a simple patch test.
Nice post it’s really helpfull for Dental or Anesthesia student ….
My professor told to flush the catridge with plain adrenaline and then take loxicard in case of allergy , what is the reason of doing that?
And what is the substitute of thymol in LA it being a fungicide
Fungicide is been used rit …? How does fungus even grow ??
It is used to prevent any growth o fungus while the Anesthetic solution is stored. It is to protect the LA agent from fungal infection.
Sir can you please tell me the contraindications of adrenaline when used with lignocaine
Like We know that it should not be used in thyroid and cardiac patients and diabetics too but I want to know the exact reason for that?
It is because of the Effect which Adrenanline causes on the Body – It causes the Blood Vessels to contract and aids in redirecting the blood towards major organs and muscle groups which can lead to unwanted stress on the Heart. It triggers the Fight or Flight response of the body which increases the Blood Pressure as well. This can be a problem in patients suffering the Heart ailments.