Sura H. khraisat diagnosis –sheet no.12

Today we are going to talk about local anesthesia.

First, what we mean by local anesthesia?

Local anesthesia is loss of sensation in a circumscribe area of the body cause by a depression in nerve endings excitation or inhibition of conduction process in peripheral areas.

There are some related medical expressions we have to be familiar with like:

- anesthesia : total loss of sensation which mean all types of sensation like touch ,pressure , heat and pain.

-analgesia : loss of pain sensation only…so when we said that we gave the patient local anesthesia that is not exact mean but if we want to be more precise we said local analgesia, because we don’t gain total loss of all sensation for example sense of pressure it will be felt .

The prefix “ana” = mean NO or LOSS like anemia which mean loss of blood cells and so on.

-paresthesia : is a sensation of tingling, tickling, prickling, pricking, or burning of a person's skin with no apparent long-term physical effect. The manifestation of a paresthesia may be transient or chronic.

-Dysesthesia (dysaesthesia) comes from the Greek word "dys", meaning "not-normal" and "aesthesis", which means "sensation" (abnormal sensation). It is defined as an unpleasant, abnormal sense of touch. It often presents as pain but may also present as an inappropriate, but not discomforting, sensation. It is caused by lesions of the nervous system, peripheral or central, and it involves sensations, whether spontaneous or evoked, such as burning, wetness, itching, electric shock, and pins and needles.

-Hypoesthesia (or hypesthesia) refers to a reduced sense of touch or sensation, or a partial loss of sensitivity to sensory stimuli. In everyday speech this is sometimes referred to as "numbness".

Historically, there were various methods to induce local anesthesia like:

-mechanical trauma

-freezing or low temperature

-anoxia

-chemical irritation

-using of nueroleptic agents: alcohol and phenol for example.

So local anesthesia was introduced more than one hundred years ago which is simple and predictable method of preventing pain during procedures.

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Sura H. khraisat diagnosis –sheet no.12Local anesthesia made a big step in dentistry .because almost all patients decided according to the

pain that had been felt if the dentist were good or not.

Ideal local anesthetic agent should be:

- Enough potency reability which mean something that you can depend on “always working”

-reversibility which mean that the local anesthesia is functioning during the procedure only we don’t want it to be permanent

-safety

-lake of irritation and rabidity of onset which mean that it is working directly

-duration of effect enough to complete the procedure without pain

- Sterile and has adequate shelf life

Local anesthetic cartridge components:

-local anesthetic agent “active component”

-vasoconstrictor

-reducing agent if there was a vasoconstrictor in the cartridge

-preservative

-fungicide

-carrier solution

Types of local anesthesia:

According to cross linking chains.1- Ester type 2- Amide type

Ester local anesthesia:Rarely used, because they make allergic rxn that why the amide type are more common.For example for ester type: cocaine and procaine.And for amide type: lidocaine

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Sura H. khraisat diagnosis –sheet no.12Duration of anesthesia:The effective duration of local anesthesia depend on 1- the diffusion away from that area2- number of blood vessel that supply the area for example in inflammation state where the blood vessels were dilated so in that situation the local anesthesia will be absorbed quickly that’s why the effect of local anesthesia in inflammation state were limited. 3- It also depend on the concentration of the local anesthetic agent, more concentration >>long duration 4-types of local anesthesia some types are long active like: provocaine 8-10 hrs Unlike the lidocaine which commonly used in dentistry 2-3 hrs.

Vasoconstrictor:Mainly adrenaline or felypressin.They add these agents for increasing the duration and potency for the local anesthesia, decreasing the systemic toxicity and decreasing bleeding

Reducing agent:Sodium metabisulfate t prevents the oxidation of the vasoconstrictor.So the plain local anesthesia “anesthesia without vasoconstrictor” does not contain a reducing agent.

Preservative:To increase the shelf life. And mainly is the causing of allergy that is happened to the patient.

Fungicide:Is occasionally used as antiseptic agent.

Carrier:Solution that all these components will dissolve in. Which is modified ringer’s lactate solution

All these constituents are sterile.

____________________________________________________________________________instuments:

1-caridage 2-needle3-syringe

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Sura H. khraisat diagnosis –sheet no.12Cartridge: A glass containor, 1.8-2.2 ml There is a rubber diaphragm on one side.And all the components will be written at the cartridge plus the shelf life.

Needles:Mainly tow types: short and long - Long needle for nerve block …length 35 mm- Short needle for infiltration …length 20 mm

There is something called gauge “G” which we concern about when we choose the needle which is related to the diameter of the needle …. Bigger no. >> Smaller diameter So 30 mm smaller than 27 mm in diameter, the importance of that related to how painful the needle is >>smaller diameter >> less painful.Needles are made from stainless steel and used only once.

Syringe: The metal part which we carry the cartridge and needle by.Syringes are two types:Aspirated syringe >> that allow us to suck back to insure that we are not giving the anesthesia at the blood vesselsNon-aspirated syringe >> which that what we saw in the lab.

Techniques of local anesthesia:-infiltration: it is just injections around the area that we must work in.

- nerve block : which mean we give the anesthesia at the entrance of the nerve like inferior dental nerve block, mental nerve block ,nasopalatine block,infraorbital nerve block.

To give local anesthesia we have to:- prepare the instrument.- prepare the patient physically and mentally.And we wait a while to let the anesthesia to start working (seconds to few minutes); finally and before starting the procedure we have to ensure that the anesthesia is working.

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Sura H. khraisat diagnosis –sheet no.12

Mandibular injection:

Anatomy of mandibular nerve:

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Sura H. khraisat diagnosis –sheet no.12

We checked the anesthesia by asking the patient if he feels numbness at lower lip.

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Sura H. khraisat diagnosis –sheet no.12We almost do the same with lingual and long buccal infiltration.

Nerve block technique mainly for inferior alveolar and lingual nerve:

Steps:

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Sura H. khraisat diagnosis –sheet no.12

Then administer the anesthetic agent slowly.

And about maxilla we usually do an infiltration around the procedure area.

I tried my best to include all the details that had been showed in the video at the lecture.

Good luck.

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