Editing Local anesthetic (section)

== Techniques ==
Local anesthetics can block almost every nerve between the peripheral nerve endings and the central nervous system. The most peripheral technique is topical anesthesia to the skin or other body surface. Small and large peripheral nerves can be anesthetized individually (peripheral nerve block) or in anatomic nerve bundles (plexus anesthesia). Spinal anesthesia and epidural anesthesia merge into the central nervous system.

Injection of LAs is often painful.  A number of methods can be used to decrease this pain, including buffering of the solution with bicarbonate and warming.<ref>{{Cite web|url=https://bestbets.org/bets/bet.php?id=1480|title=BestBets: The Effect of Warming Local anesthetics on Pain of Infiltration|website=bestbets.org}}</ref>

Clinical techniques include:
* Surface anesthesia is the application of an LA spray, solution, or cream to the skin or a mucous membrane; the effect is short lasting and is limited to the area of contact.
* Infiltration anesthesia is [[injection (medicine)#Infiltration|infiltration]] of LA into the tissue to be anesthetized; surface and infiltration anesthesia are collectively topical anesthesia
* Field block is subcutaneous injection of an LA in an area bordering on the field to be anesthetized.
* [[Peripheral nerve block]] is injection of LA in the vicinity of a peripheral nerve to anesthetize that nerve's area of innervation.
* Plexus anesthesia is injection of LA in the vicinity of a [[nerve plexus]], often inside a tissue compartment that limits the diffusion of the drug away from the intended site of action. The anesthetic effect extends to the innervation areas of several or all nerves stemming from the plexus.
* Epidural anesthesia is an LA injected into the [[epidural space]], where it acts primarily on the [[spinal nerve]] roots; depending on the site of injection and the volume injected, the anesthetized area varies from limited areas of the abdomen or chest to large regions of the body.
* Spinal anesthesia is an LA injected into the [[cerebrospinal fluid]], usually at the lumbar spine (in the lower back), where it acts on [[spinal nerve]] roots and part of the [[spinal cord]]; the resulting anesthesia usually extends from the legs to the abdomen or chest.
* [[Intravenous regional anesthesia]] (Bier's block) is when blood circulation of a limb is interrupted using a tourniquet (a device similar to a blood-pressure cuff), then a large volume of LA is injected into a peripheral vein. The drug fills the limb's venous system and diffuses into tissues, where peripheral nerves and nerve endings are anesthetized. The anesthetic effect is limited to the area that is excluded from blood circulation and resolves quickly once circulation is restored.
* Local anesthesia of body cavities includes intrapleural anesthesia and intra-articular anesthesia.
{{anchor|catheter anesthesia}}
* Transincision (or transwound) catheter anesthesia uses a multilumen catheter inserted through an incision or wound and aligned across it on the inside as the incision or wound is closed, providing continuous administration of local anesthetic along the incision or wounds<ref>{{cite journal | vauthors = Kampe S, Warm M, Kasper SM, Diefenbach C | title = Concept for postoperative analgesia after pedicled TRAM flaps: continuous wound instillation with 0.2% ropivacaine via multilumen catheters. A report of two cases | journal = British Journal of Plastic Surgery | volume = 56 | issue = 5 | pages = 478–483 | date = July 2003 | pmid = 12890461 | doi = 10.1016/S0007-1226(03)00180-2 }}</ref>

Dental-specific techniques include:

=== Vazirani–Akinosi technique ===
The Vazirani–Akinosi technique is also known as the closed-mouth mandibular nerve block. It is mostly used in patients who have limited opening of the mandible or in those that have trismus; spasm of the muscles of mastication. The nerves which are anesthetised in this technique are the inferior alveolar, incisive, mental, lingual and mylohyoid nerves.

Dental needles are available in two lengths, short and long. As Vazirani–Akinosi is a local anesthetic technique which requires penetration of a significant thickness of soft tissues, a long needle is used. The needle is inserted into the soft tissue which covers the medial border of the mandibular ramus, in region of the inferior alveolar, lingual and mylohyoid nerves. The positioning of the bevel of the needle is very important as it must be positioned away from the bone of the mandibular ramus and instead towards the midline.<ref name="Malamed_2013">{{cite book|title=Handbook of local anesthesia| vauthors = Malamed SF |date=2013|publisher=Elsevier|isbn=9780323074131|edition=6th|location=St. Louis, Missouri|oclc=769141511|name-list-style=vanc}}</ref>

=== Intraligamentary Infiltration ===
Intraligamentary infiltration, also known as periodontal ligament injection or intraligamentary injection (ILI), is known as "the most universal of the supplemental injections". ILIs are usually administered when inferior alveolar nerve block techniques are inadequate or ineffective.<ref>{{cite journal | vauthors = Meechan JG | title = Intraligamentary anaesthesia | journal = Journal of Dentistry | volume = 20 | issue = 6 | pages = 325–332 | date = December 1992 | pmid = 1452871 | doi = 10.1016/0300-5712(92)90018-8 }}</ref> ILIs are purposed for:

# Single-tooth anesthesia
# Low anesthetic dose
# Contraindication for systemic anesthesia
# Presence of systemic health problems<ref>{{cite journal | vauthors = Blanton PL, Jeske AH | title = The key to profound local anesthesia: neuroanatomy | journal = Journal of the American Dental Association | volume = 134 | issue = 6 | pages = 753–760 | date = June 2003 | pmid = 12839412 | doi = 10.14219/jada.archive.2003.0262 }}</ref>

ILI utilization is expected to increase because dental patients prefer fewer soft tissue anesthesia and dentists aim to reduce administration of traditional inferior alveolar nerve block (INAB) for routine restorative procedures.<ref>{{cite web | vauthors = Boynes SG | title = Intraligamentary Injections in Dentistry | url = https://www.dentalacademyofce.com/courses/3580%2FPDF%2F1807cei_Boynes_web.pdf | publisher = Dental Academy of Continuing Education | date = 1 June 2018}}</ref>

Injection methodology: The periodontal ligament space provides an accessible route to the cancellous alveolar bone, and the anesthetic reaches the pulpal nerve via natural perforation of intraoral bone tissue.<ref>{{cite journal | vauthors = Meechan JG | title = Supplementary routes to local anaesthesia | journal = International Endodontic Journal | volume = 35 | issue = 11 | pages = 885–896 | date = November 2002 | pmid = 12453016 | doi = 10.1046/j.1365-2591.2002.00592.x }}</ref><ref>{{cite journal | vauthors = D'Souza JE, Walton RE, Peterson LC | title = Periodontal ligament injection: an evaluation of the extent of anesthesia and postinjection discomfort | journal = Journal of the American Dental Association | volume = 114 | issue = 3 | pages = 341–344 | date = March 1987 | pmid = 3470356 | doi = 10.14219/jada.archive.1987.0080 }}</ref>

Advantages of ILI over INAB: rapid onset (within 30 seconds), small dosage required (0.2–1.0&nbsp;mL), limited area of numbness,<ref>{{cite journal | vauthors = Shastry SP, Kaul R, Baroudi K, Umar D | title = Hemophilia A: Dental considerations and management | journal = Journal of International Society of Preventive & Community Dentistry | volume = 4 | issue = Suppl 3 | pages = S147–S152 | date = December 2014 | pmid = 25625071 | pmc = 4304051 | doi = 10.4103/2231-0762.149022 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Nazif M | title = Local anesthesia for patients with hemophilia | journal = ASDC Journal of Dentistry for Children | volume = 37 | issue = 1 | pages = 79–84 | date = January 1970 | pmid = 4904493 }}</ref> lower intrinsic risks such as neuropathy, hematoma, trismus/jaw sprain<ref>{{cite journal | vauthors = Moore PA, Haas DA | title = Paresthesias in dentistry | journal = Dental Clinics of North America | volume = 54 | issue = 4 | pages = 715–730 | date = October 2010 | pmid = 20831934 | doi = 10.1016/j.cden.2010.06.016 }}</ref><ref name = shabazfar>{{cite journal | vauthors = Shabazfar N, Daubländer M, Al-Nawas B, Kämmerer PW | title = Periodontal intraligament injection as alternative to inferior alveolar nerve block--meta-analysis of the literature from 1979 to 2012 | journal = Clinical Oral Investigations | volume = 18 | issue = 2 | pages = 351–358 | date = 2014 | pmid = 24077785 | doi = 10.1007/s00784-013-1113-1 | s2cid = 9525498 }}</ref> and self-inflicted periodontal tissue injury,<ref>{{cite journal | vauthors = Nelson PW | title = Injection system | journal = The Journal of the American Dental Association | date = November 1981 | volume = 103 | issue = 5 | pages = 692 | doi = 10.14219/jada.archive.1981.0380 }}</ref><ref name="pmid6439659">{{cite journal | vauthors = Galili D, Kaufman E, Garfunkel AA, Michaeli Y | title = Intraligamentary anesthesia--a histological study | journal = International Journal of Oral Surgery | volume = 13 | issue = 6 | pages = 511–6 | date = December 1984 | pmid = 6439659 | doi = 10.1016/s0300-9785(84)80022-8  }}</ref> as well as decreased cardiovascular disturbances.<ref>{{cite journal | vauthors = Pashley D | title = Systemic effects of intraligamental injections | journal = Journal of Endodontics | volume = 12 | issue = 10 | pages = 501–504 | date = October 1986 | pmid = 3465856 | doi = 10.1016/s0099-2399(86)80206-0 }}</ref> Its usage as a secondary or supplementary anesthesia on the mandible has reported a high success rate of above 90%.<ref>{{cite journal | vauthors = Walton RE, Abbott BJ | title = Periodontal ligament injection: a clinical evaluation | journal = Journal of the American Dental Association | volume = 103 | issue = 4 | pages = 571–575 | date = October 1981 | pmid = 6945341 | doi = 10.14219/jada.archive.1981.0307 }}</ref><ref>{{cite journal | vauthors = Smith GN, Walton RE, Abbott BJ | title = Clinical evaluation of periodontal ligament anesthesia using a pressure syringe | journal = Journal of the American Dental Association | volume = 107 | issue = 6 | pages = 953–956 | date = December 1983 | pmid = 6581222 | doi = 10.14219/jada.archive.1983.0357 }}</ref>

Disadvantages: Risk of temporary periodontal tissue damage, likelihood of bacteriemia and endocarditis for at-risk populations,<ref name=":4">{{cite journal | vauthors = Roberts GJ, Holzel HS, Sury MR, Simmons NA, Gardner P, Longhurst P | title = Dental bacteremia in children | journal = Pediatric Cardiology | volume = 18 | issue = 1 | pages = 24–27 | date = January 1997 | pmid = 8960488 | doi = 10.1007/s002469900103 | s2cid = 7178684 }}</ref> appropriate pressure and correct needle placement are imperative for anesthetic success, short duration of pulpal anesthesia limits the use of ILIs for several restorative procedures that require longer duration,<ref name=":4" /> postoperative discomfort, and injury on unerupted teeth such as enamel hypoplasia and defects.

Technique description:
* All plaque and calculus to be eradicated, optimally before the operative visit to assist gingival tissue healing.
* Before injection, disinfect gingival sulcus with 0.2% chlorhexidine solution.<ref>{{cite journal | vauthors = Kaufman E, Galili D, Garfunkel AA | title = Intraligamentary anesthesia: a clinical study | journal = The Journal of Prosthetic Dentistry | volume = 49 | issue = 3 | pages = 337–339 | date = March 1983 | pmid = 6573480 | doi = 10.1016/0022-3913(83)90273-1 }}</ref>
* Administration of soft tissue anesthesia is recommended prior to ILI administration. This helps to enhance patient comfort.
* Needle gauges of sizes 27-gauge short or 30-gauge ultra-short needle are usually utilized.<ref name = "Malamed_1982">{{cite journal | vauthors = Malamed SF | title = The periodontal ligament (PDL) injection: an alternative to inferior alveolar nerve block | journal = Oral Surgery, Oral Medicine, and Oral Pathology | volume = 53 | issue = 2 | pages = 117–121 | date = February 1982 | pmid = 6949113 | doi = 10.1016/0030-4220(82)90273-0 }}</ref>
* The needle is inserted along the long axis, at a 30 degree angle, of the mesial or distal root for single rooted teeth and on the mesial and distal roots of multi-rooted teeth. Bevel orientation toward the root provides easier advancement of the needle apically.<ref name=":5">{{cite journal | vauthors = Meechan JG | title = How to overcome failed local anaesthesia | journal = British Dental Journal | volume = 186 | issue = 1 | pages = 15–20 | date = January 1999 | pmid = 10028738 | doi = 10.1038/sj.bdj.4800006 | s2cid = 6618968 }}</ref>
* When the needle reaches between the root and crestal bone, significant resistance is experience.
* Anesthetic deposition is recommended at 0.2&nbsp;mL, per root or site, over minimally 20 seconds.
* For its success, the anesthetic must be administered under pressure. It must not leak out of the sulcus into the mouth.
* Withdraw needle for minimally 10–15 seconds to permit complete deposition of solution. This can be slower than other injections as there is pressure build-up from the anesthetic administration.
* Blanching of the tissue is observed and may be more evident when vasoconstrictors are used. It is caused by a temporary obstruction of blood flow to the tissue.<ref name=":5" />

Syringes:
* Standard syringes can be used.
* The intraligamentary syringe offers mechanical advantage by using a trigger-grasp or click apparatus to employ a gear or lever that improves control and results in increased force to push the anesthetic cartridge's rubber stopper forward for medication deposition with greater ease.
* C-CLADs (computer controlled local anesthetic delivery devices) can be used. Its usage of computer microprocessors allows for control of fluid dynamics and anesthetic deposition. This minimizes subjective flow rates and variability in pressure. This thereby results in enhanced hydrodynamic diffusion of solution into bone or the target area of deposition,<ref>{{cite journal | vauthors = Walton RE, Garnick JJ | title = The periodontal ligament injection: histologic effects on the periodontium in monkeys | journal = Journal of Endodontics | volume = 8 | issue = 1 | pages = 22–26 | date = January 1982 | pmid = 6948904 | doi = 10.1016/S0099-2399(82)80312-9 }}</ref><ref>{{cite journal | vauthors = Hochman MN, Friedman MJ, Williams W, Hochman CB | title = Interstitial tissue pressure associated with dental injections: a clinical study | journal = Quintessence International | volume = 37 | issue = 6 | pages = 469–476 | date = June 2006 | pmid = 16752703 }}</ref> thus permitting larger amounts of anesthetic solution to be delivered during ILIs without increased tissue damage.<ref>{{cite journal | vauthors = Aggarwal V, Singla M, Miglani S, Kohli S, Sharma V, Bhasin SS | title = Does the volume of supplemental intraligamentary injections affect the anesthetic success rate after a failed primary inferior alveolar nerve block? A randomized-double blind clinical trial | journal = International Endodontic Journal | volume = 51 | issue = 1 | pages = 5–11 | date = January 2018 | pmid = 28370327 | doi = 10.1111/iej.12773 }}</ref><ref>{{cite journal | vauthors = Berlin J, Nusstein J, Reader A, Beck M, Weaver J | title = Efficacy of articaine and lidocaine in a primary intraligamentary injection administered with a computer-controlled local anesthetic delivery system | journal = Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontics | volume = 99 | issue = 3 | pages = 361–366 | date = March 2005 | pmid = 15716846 | doi = 10.1016/j.tripleo.2004.11.009 }}</ref><ref>{{cite journal | vauthors = Froum SJ, Tarnow D, Caiazzo A, Hochman MN | title = Histologic response to intraligament injections using a computerized local anesthetic delivery system. A pilot study in mini-swine | journal = Journal of Periodontology | volume = 71 | issue = 9 | pages = 1453–1459 | date = September 2000 | pmid = 11022775 | doi = 10.1902/jop.2000.71.9.1453 }}</ref>

Things to note:
* ILIs are not recommended for patients with active periodontal inflammation.
* ILIs should not be administered at tooth sites with 5&nbsp;mm or more of periodontal attachment loss.

=== Gow-Gates Technique ===
Gow-Gates technique is used to provide anesthetics to the mandible of the patient's mouth. With the aid of extra and intraoral landmarks, the needle is injected into the intraoral latero-anterior surface of the condyle, steering clear below the insertion of the lateral pterygoid muscle.<ref name = "Gow-Gates_1998">{{cite journal | vauthors = Gow-Gates GA | title = The Gow-Gates mandibular block: regional anatomy and analgesia | journal = Australian Endodontic Journal | volume = 24 | issue = 1 | pages = 18–19 | date = April 1998 | pmid = 11431805 | doi = 10.1111/j.1747-4477.1998.tb00251.x }}</ref> The extraoral landmarks used for this technique are the lower border of the ear tragus, corners of the mouth and the angulation of the tragus on the side of the face.<ref name = "Gow-Gates_1998" />

Biophysical forces (pulsation of the maxillary artery, muscular function of jaw movement) and gravity will aid with the diffusion of anesthetic to fill the whole pterygomandibular space. All three oral sensory parts of the mandibular branch of the trigeminal nerve and other sensory nerves in the region will come in contact with the anesthetic and this reduces the need to anesthetise supplementary innervation.<ref name = "Gow-Gates_1998" />

In comparison to other regional block methods of anestheising the lower jaw, the Gow-Gates technique has a higher success rate in fully anesthetising the lower jaw. One study found that out of 1,200 patients receiving injections through the Gow-Gates technique, only 2 of them did not obtain complete anesthesia.<ref name = "Gow-Gates_1998" />