Local anesthetic agents in dentistry
The most commonly used local anesthetic is lidocaine (also called xylocaine or lignocaine), a modern replacement for procaine (also known as novocaine). Its half-life in the body is about 1.5–2 hours. Other local anesthetic agents in current use include articaine (also called septocaine or ubistesin), marcaine (a long-acting anesthetic), and mepivacaine. A combination of these may be used depending on the situation. Also, most agents come in two forms: with and without epinephrine (adrenaline) or other vasoconstrictor that allow the agent to last longer and also controls bleeding in the tissue during procedures. Usually the case is classified using the ASA Physical Status Classification System before any anesthesia is given.
Types of local anesthesia in dentistry
- Nerve block — a common form of local dental anesthesia; blocks the reception of pain in one region of the mouth at a time.
- Infiltration given inferior to the root the tooth involved in the dental work; used usually for minor procedures such as restorations.
- Palatal block given into the hard palate using pressure anesthesia; useful in anesthetizing the palate side of the maxillary teeth.
- Intraosseous an injection of local anesthetic given directly into the osseous (bone) structure of the tooth for more involved dental procedures such as surgery or endodontic therapy (root canals).
- Intrapulpal an injection of local anesthetic given directly into the pulp of the tooth to completely desensitize the tooth.
- Pressure anesthesia — pressure with a cotton swab in the area to distract the nerve sensation of pain when the needle enters certain areas such as palatal tissue.
- Electrical nerve blocks— a technology that involves using electrical current to block the reception or generation of pain signals; the pain control can be transient.
- Acupuncture or accupressure An alternative to chemical or electrical blocks, but is rarely used.
Most common local anesthetic procedure
The Inferior alveolar nerve anaesthesia or block or IANB (sometimes termed "inferior dental block", or wrongly referred to as the "mandibular block") probably is anesthetized more often than any other nerve in the body. An injection blocks sensation in the inferior alveolar nerve, which runs from the angle of the mandible down the medial aspect of the mandible, innervating the mandibular teeth, lower lip, chin, and parts of the tongue, which is effective for dental work in the mandibular arch. To anesthetize this nerve, the needle is inserted somewhat posterior to the most distal mandibular molar on one side of the mouth. The lingual nerve is also anesthetized through diffusion of the agent to produce a numb tongue as well as anesthetizing the floor of the mouth tissue, including that around the tongue side or lingual of the teeth.
Several nondental nerves are usually anesthetized during an inferior alveolar block. The mental nerve, which supplies cutaneous innervation to the anterior lip and chin, is a distal branch of the inferior alveolar nerve. When the inferior alveolar nerve is blocked, the mental nerve is blocked also, resulting in a numb lip and chin. Nerves lying near the point where the inferior alveolar nerve enters the mandible often are also anesthetized during inferior alveolar anesthesia, such as affecting hearing (auriculotemporal nerve).
The facial nerve lies some distance from the inferior alveolar nerve within the parotid salivary gland, but in rare cases anesthetic can be injected far enough posteriorly to anesthetize that nerve. The result is a transient facial paralysis, with the injected side of the face having temporary loss of the use of the muscles of facial expression that include the inability to close the eyelid and the drooping of the labial commissure on the affected side for a few hours, which disappears when the anesthesia wears off.
In contrast, the superior alveolar nerves are not usually anesthetized directly because they are difficult to approach with a needle. For this reason, the maxillary arch is usually anesthetized locally for dental work by inserting the needle beneath the oral mucosa surrounding the teeth so as to anesthetize the smaller branches.
A dental syringe is a syringe used by licensed dental professionals for the injection of a local anesthetic. It consists of a breech-loading syringe fitted with a sealed cartridge containing anesthetic solution.
Other anesthetics used in dentistry
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- Topical anesthetics benzocaine, eugenol, and forms of xylocaine are used topically to numb various areas before injections or other minor procedures.
- Nitrous oxide (N2O), also known as "laughing gas", easily crosses the alveoli of the lung and is dissolved into the passing blood, where it travels to the brain, leaving a dissociated and euphoric feeling in most cases. Nitrous oxide is used in combination with oxygen. Often (especially with children) a sweet-smelling fruity scent similar to an auto[clarification needed] scent is used with the gas to inspire deep inhalation.
- General anesthesia drugs such as midazolam, ketamine, propofol and fentanyl are used to put a person in a twilight sleep or render them completely unconscious and unaware of pain. Dentists who have completed a training program in anesthesiology may also administer general IV and inhalation anesthetic agents.
- Nebotamine, a drug with similar effects to ketamine, is injected into the anterior lingual glands blocking action potentials from sending signals to the myelinated nerve. The potency of the anesthetic is directly related to its lipid solubility, since 90% of the nerve cell membrane is composed of lipid.
- Midazolam (Versed), a drug that represses memories of the procedure, is usually given two hours prior to the procedure in combination with Tylenol in general anesthesia so the person will go home with no memories of being in surgery.
- Sevoflurane gas in combination with nitrous oxide and oxygen is often used during general anesthesia followed by the use of isoflurane gas to maintain anesthesia during the procedure. In children sweet fruity scents are often used with the gases to inspire deep inhalation. Scents come in cherry, apple, bubblegum, watermelon, etc...
- Propofol, a drug with similar effects to Sodium Pentathol, is often used through intravenous infusion through an IV during general anesthesia after gasses are initiated.
- Morphine is often used to control pain during the dental surgery under general anesthesia. The morphine is usually administered through IV.
- Ketorolac is often administered through IV to suppress both pain and inflammation while under general anesthesia.
Other drugs used in combination with general anesthesia in dentistry
- Decadron a steroid is often administered through IV to suppress inflammation and swelling resulting during the surgery while under general anesthesia.
- Ondansetron brand named Zofran is often administered to prevent nausea during the surgery which may result from the blood draining into the stomach while under general anesthesia, or it is given after the procedure for postoperative nausea which may result from the anesthesia itself which was administered.
- Dental surgery
- American Society of Dentist Anesthesiologists
- American Dental Board of Anesthesiology
- National Dental Board of Anesthesiology
- American Dental Society of Anesthesiology
- Illustrated Anatomy of the Head and Neck, Fehrenbach and Herring, Elsevier, 2012, page 216
- Local Anesthesia for the Dental Hygienist, Logothetis, Elsevier, 2012
- Local Anesthesia for the Dental Hygienist, Logothetis, Elsevier, 2012[page needed]
- Endo T, Gabka J, Taubenheim L (January 2008). "Intraligamentary anesthesia: benefits and limitations". Quintessence International 39 (1): e15–25. PMID 18551207.