Dental anesthesia. Types. Action principles

Dental anesthesia. Description. Explanation.

Anesthesia removes any pain or embarrassment, the patient can cooperate with the doctor during the dental procedure, and there is no discomfort after treatment.

Absolutely sterile conditions, professionalism, competence and thoroughness! These conditions are met and the success of the medical procedure is guaranteed!

By dental anesthesia we mean the introduction of substances into the body to temporarily suppress painful sensitivity.

Anesthesia is the way in which the dentist removes, suppresses, interrupts the nervous sensitivity in a certain predetermined region, in order to be able to operate without the patient experiencing pain or discomfort during the operation.

During anesthesia, the patient does not lose consciousness, he is awake and perceives what is happening to him. Anesthesia by injecting chemicals is the most common method of reducing the sensitivity of a region.

Anesthetics are synthetic substances that block the transmission of impulses along nerve branches. Each cranial nerve is responsible for providing sensation in a specific region.

By injecting the anesthetic substance into the region where the nerve distributes, pain is eradicated for 30 minutes or even 2-3 hours, depending on the substance used and the technique the doctor applies.

An anesthetic is a substance that temporarily blocks the transmission of nerve impulses.

Examples of anesthetic substances include:

  • Xylocaine (lidocaine)
  • Prilocaine
  • Mepivacaine
  • Articaine
  • Bupivacaine
  • Procaine
  • Cocaine
  • Tetracaine

Dental anesthesia is indicated when the dentist performs therapeutic procedures that can be painful. The purpose of dental anesthesia is to make the treatment session as comfortable as possible and to reduce or eliminate the patient’s anxiety and pain. Not all dental procedures require dental anesthesia, but the most common ones include tooth extractions, dental implants, nerve extraction, and treatment of microbial tissue conditions.

Principle of action of dental anesthesia

Anesthetics act locally by stopping nerve conductivity by decreasing the flow of sodium ions into the cytoplasm of neurons.

As sodium does not enter the neuron, the potassium ion is no longer able to leave, so depolarization of the nerve is inhibited and dental anesthesia is induced.

The effect and duration of anesthesia depends on several factors:

  • weight
  • the amount of fat in the body
  • the concentration of the anesthetic
  • the gap between the pH of the anesthetic and the anesthetized area
  • the presence of other substances in the body (various medicines, alcohol, caffeine, etc.)

Toxicity of anesthetics

The maximum dose of anesthetic that can be administered is between 70 mg – 500 mg, taking into account the patient’s age, state of health, type of anesthetic and the presence or absence of vasoconstrictor (adrenaline).

This maximum dose is not the lethal dose, but it has toxic effects on the body resulting in headache, hypotension, tremor, convulsions, slurred speech.

Types of dental anesthesia

  1. Local dental anesthesia is done with substances that temporarily eliminate pain and act only in a specific area of the oral cavity.

This is the type of dental anesthesia most commonly used in dental offices in cases such as: filling deep carious lesions, grinding teeth for veneer crowns, nerve removal or other surgical procedures.

Dental anesthesia is of 2 types:

  • Topical – anesthetics in the form of sprays, pastes, gels, powders, liquids, ointments, are applied directly to the mucosa in order to prepare the tissue for an injectable dental anesthesia or for the extraction of temporary teeth in children.
  • By injection – the anesthetic solution is locally introduced into the tissues that will be surgically intervened upon or around them, or the anesthetic injection is performed at a distance from the site of intervention.

This can be done through various techniques:

  • Intramucosal
  • Intragingival
  • Intraplexal (anesthetizes a tooth)
  • Infiltration
  • Truncular
  • Intraligamentary
  • Intrapapillary
  • Intraseptal
  • Intraosseous
  • Intrapulpary
  1. Regional anesthesia is performed by numbing a region of the body while the patient is conscious.
  2. Sedation can be oral, with gas, or intravenous. Sedation is most often used in conjunction with local anesthesia for a soothing procedure.
  • Gas sedation, called inhalation sedation, uses inhalation gas similar to general anesthesia, but in lower doses, so that after removal of the gas mask, the patient recovers in a few minutes without pain if local anesthetic has also been administered.
  • In the dental surgery, inhalation is used mainly to treat children to reduce their anxiety and make it easier for them to work.
  • Regional anesthesia is performed by numbing a region of the body while the patient is conscious.
  • Sedation can be oral, with gas, or intravenous. Sedation is most often used in conjunction with local anesthesia for a soothing procedure.
  • Gas sedation, called inhalation sedation, uses inhalation gas similar to general anesthesia, but in lower doses, so that after removal of the gas mask, the patient recovers in a few minutes without pain if local anesthetic has also been administered.
  • In the dental surgery, inhalation is used mainly to treat children to reduce their anxiety and make it easier for them to work.
  • Liquid and oral sedatives or suppositories can be given to children to relax them during dental procedures.
  • Deep sedation and general anesthesia are used for complex procedures when patients cannot control their reactions. He will be in a depressed state of consciousness, in which he may feel pain, so a local dental anesthetic is necessary.
  • General anesthesia causes loss of sensation and absence of consciousness. It is rarely used in dentistry and is indicated in situations where local anesthesia is ineffective or cannot be achieved. Anesthetic is introduced intravenously or by inhalation of anesthetic gas, but endotracheal intubation is also required, monitoring the patient’s vital functions at all times.

The anesthetic technique varies according to the doctor’s preference but also according to the regions to be desensitized.

If dental procedures are minor, routine procedures, a short-acting anesthesia is chosen.

If, on the other hand, the therapeutic procedures are more extensive, more invasive, we prefer an anesthesia technique that abolishes sensitivity over a large area but also covers the dental structures more deeply.

The potency of anesthetics depends on the following factors:

  • Type of anesthetic used – these differ depending on the base substance. In principle, anesthetics used in dentistry can be of the ester or amide type.
  • Concentration of anesthetics – the maximum concentration allowed depends on the type of anesthetic, the age and weight of the patient.
  • Presence or absence of vasoconstrictor – adrenaline is the most commonly used vasoconstrictor in the composition of anesthetics. Its role is to prolong the time of action of the anesthetic, reduce the severity of side effects, reduce bleeding at the puncture site and slow its absorption into the bloodstream.

Patients with cardiac pathologies should report this type of condition to their dentist in order to choose an anesthetic that does not contain adrenaline, so as not to provoke a hypertensive crisis.

Before the anesthesia is performed, the dentist will interview the patient during the history to discover data that may influence the anesthesia process. Among these, caution is recommended in patients with hepatic impairment, given the metabolism of anesthetics at this level, but also cardiac pathologies, which require the choice of a non-vasoconstrictor anesthetic.

The puncture site should be dry and clean and to limit the discomfort caused by the needle penetrating the tissues, sprays or gels may be used to produce a surface anesthesia.

During anesthesia, the doctor may perform a single puncture or multiple punctures and, once the puncture is in place, the patient will feel tingling accompanied by a decrease in perception. During dental operations, the doctor may complete the anesthesia.

Complications of dental anesthesia

The administration of anesthetic is a routine procedure for all dental practitioners, as it is a real weapon against pain and also combats the patient’s anxiety, as dental treatment can be carried out without discomfort. Anesthetic has been around for over 175 years and is used for various surgical procedures in all fields. However, although quite rare, some patients may experience complications.

Anesthetic toxicity (overdose)

Although rare in adults, young children are more likely to experience toxic reactions because of their smaller weight.

Most adverse reactions to anesthetic occur within 5-10 minutes of injection. Local anesthetic overdose is caused by high levels of anesthetic in the blood as a result of accidental intravascular injection or repeated injections.

Local anesthetic overdose results in excitation, followed by depression of the central nervous system and to a lesser extent the cardiovascular system.

Early subjective symptoms include dizziness, anxiety and confusion and may be followed by diplopia, tinnitus, drowsiness and tingling. Objective signs include muscle twitching, tremors, slowed speech and chills, followed by obvious seizure activity.

Unconsciousness and respiratory arrest may occur.

Local anesthetic toxicity can be prevented by following injection protocols, i.e. performing aspiration and injecting the anesthetic slowly.

Doctors also need to know the maximum doses according to weight. After anesthesia, the patient should be observed for any possible toxic response, as early recognition and intervention are the keys to a successful outcome.

Allergic reactions

Although allergic reactions to injectable amide local anesthetics are rare, patients may experience a reaction to the bisulphite preservative added to adrenaline-containing anesthetics. Patients may also experience allergic reactions to topical anesthetics containing benzocaine.

Allergies can manifest in a variety of ways, including urticaria, dermatitis, angioedema, fever, photosensitivity and anaphylaxis. To avoid this, the dentist will usually perform a subcutaneous test on the forearm to observe the body’s reaction to the injected anesthetic. You can ask your doctor to perform this test yourself.


Paresthesia is the persistence of anesthetic symptoms beyond the expected duration. It can be caused by trauma to the nerve by the needle during injection. It can also be caused by bleeding around the nerve. The tongue and lips are the most common areas affected. Most cases resolve within 8 weeks without treatment.

In addition to these intraoperative complications, there are also some that can occur post-anesthesia, such as:

The appearance of a hematoma

A hematoma is caused by penetration of the vessel with a needle or an intravascular injection, which causes trauma to the affected blood vessel.

Trauma causes bleeding into the tissue and the formation of a hematoma. Many intraoral areas are highly vascular and the target nerves are accompanied by large vessels.

Hematomas can be large, can occur rapidly and can have a dramatic appearance, especially in the infraorbital space.

It is important for the doctor to inform the patient, to explain without alarming the patient and to reassess the possibilities of further treatment.

Onset of trismus

This represents the impossibility of maximum intermaxillary opening. Trismus is usually caused by intramuscular injection of anesthetics into the pterygomandibular space. It may occur as early as 2 to 5 days after anesthesia. It usually disappears within a few days with mechanotherapy, warm compresses and, if necessary, myorelaxants.

After the end of the therapeutic procedure, it is recommended to avoid eating as biting of soft parts may occur.

Also avoid drinking extreme temperatures, very cold or very hot liquids, as the patient does not perceive these variations to their full capacity and ulcers or accidents may occur.

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