local anesthesia techniques

Local Anesthesia in Dentistry

Dr. Iyad Abou Rabii

Reminder

The trigeminal nerve is the largest of the cranial nerves. It has both motor and sensory components

Figure of trigeminal nerve

Reminder

The ophthalmic nerve carries sensory information from the scalp and forehead, the upper eyelid, the conjunctiva and cornea of the eye, the nose (including the tip of the nose), the nasal mucosa, the frontal sinuses,

Reminder : The maxillary nerve

The maxillary nerve carries sensory information from the lower eyelid and cheek, the nares and upper lip, the upper teeth and gums, the nasal mucosa, the palate and roof of the pharynx, the maxillary, ethmoid and sphenoid sinuses, and parts of the meninges.

Reminder; The maxillary nerve

The maxillary nerve continues into the infraorbital canal as the infraorbital nerve.

The zygomatic nerve emerges and branches into its two major terminal branches, the zygomaticofacial and zygomaticotemporal nerves, which innervate the lateral cheek and side of the forehead, respectively.

As it projects anteriorly, the infraorbital nerve gives off the anterior and middle superior alveolar nerves, innervating the upper teeth. It then exits the canal through the infraorbital foramen to innervate the upper lip, cheek and side of the nose.

Reminder : Mandibular nerve

The mandibular nerve carries sensory information from the lower lip, the lower teeth and gums, the chin and jaw (except the angle of the jaw, which is supplied by C2-C3), parts of the external ear, and parts of the meninges.

Reminder : Mandibular nerve

The buccal nerve innervates the mucosa of the mouth and gums.

The auriculotemporal nerve innervates the external auditory meatus and portions of the external surface of the tympanic membrane.

The lingual nerve provides general sensation to the anterior 2/3 of the tongue.

The inferior alveolar nerve enters the mandibular canal through the mandibular foramen to innervate the lower teeth and gums. Its terminal branch exits the mental foramen as the mental nerve, innervating the chin and lower lip.

Other several branchial motor nerves

Tools

Dental Syringe

Dental Needles

Tools

Local anesthetics cartridges

Local anesthetic cartridge color codes

Indications

Parenteral local anesthetics are used for infiltration and nerve block anesthesia.

Because of variation in systemic absorption and toxicity, the ideal choice of local anesthetic and concentration depends on the intended procedure. – Infiltration anesthesia is often used for minor surgical and dental procedures.

– Nerve block anesthesia is used for surgical, dental, and diagnostic procedures and for pain management

nerve block anesthesia

Mandible

IDB (inferior alveolar block)

Technique of choice for mandibular molars; also effective for premolars, canines, and incisors

Aim is to deposit solution around the inferior alveolar nerve as it enters the mandibular foramen

IDB (inferior alveolar block)Technique

The patient's mouth must be widely open.

Palpate the landmarks of external and internal oblique ridges and note the line of the ptyerygomandibular raphe.

With the palpating thumb lying in the retromolar fossa, the needle should be inserted at the midpoint of the tip of the thumb slightly above the occlusal plane lateral to the ptyerygomandibular raphe.

The needle is inserted ~0.5 cm and if a lingual nerve block is required 0.5 ml of LA is injected at this point.

IDB (inferior alveolar block)Technique

The syringe is then moved horizontally across the dorsum of the tongue and advanced to make contact with the lingula.

Once bony contact is made the needle is withdrawn slightly and the remainder of the LA injected.

It should never be necessary to insert the needle up to the hub.

Note that the mandibular foramen varies in position with age. In the edentulous, the foramen, and hence the point of needle insertion, is relatively higher than in the dentate.

Nerve to mylohyoid

Additional Block (higher injection) Why : the standard block often fails to anesthetize branches of cranial

nerve V3 that originate proximal to the injection site and provide accessory innervation to the mandibular teeth. The relatively distal location of the injection also leads to lack of anesthesia of soft tissues posterior to the mental foramen. That why a higher injection site technique are proposed

Gaw-Gates Technique

Akinosi Technique

Gow-Gates Technique

Blocks sensation by depositing LA at head of condyle

Landmarks:– Corner of the mouth (contralateral side)

– Tragus of the ear

– Disto palatal cusp of the maxillary second molar

– AIMING FOR THE NECK OF THE CONDYLE

Efficacy of the Gow-Gates Technique

Author Year GG (%) IANB (%)

Watson and Gow-Gates

1976 98.4 85.4

Gow-Gates and Watson

1977 96.2 85.5

Levy 1981 96 65

Malamed 1981 97.5

Montagnese et al. 1984 35 38

Akinosi Technique

LA deposited above lingua

Closed-mouth technique

Does not rely on a hard-tissue landmark

Parallel to occlusal plane, height of the mucogingival junction

Advanced until hub is level with distal surface of maxillary second molar

Delayed onset of anaesthesia

• Pain to puncture more than Akinosi

• More Effective

• Onset is more rapid

• Less effective• More accepted

by patients.

SCENE

5Gow Gates or Akinosi

Mental nerve block

Mental nerve block The mental nerve emerges from the mental foramen lying apical to and between the first and second mandibular premolars.

LA injected in this region will diffuse in through the mental foramen and provide limited analgesia of premolars and canine, and to a lesser degree incisors on that side. It will provide effective soft-tissue analgesia.

Mental nerve block

Place the lip on tension and insert the needle parallel to the long axis of the premolars angling towards bone, and deposit the LA.

Do not attempt to inject into the mental foramen as this may traumatize the nerve.

LA can be encouraged in by massage.

Buccal Nerve Block

The buccal nerve is not anesthetized by an inferior alveolar nerve block.

This nerve innervates the tissues and periosteum buccal to the molars, so if these soft tissues are involved in treatment, the buccal nerve should be injected as well.

The additional injection is unnecessary when treating only the teeth.

A 25 gauge long needle is recommended

Buccal Nerve Block(Continue)

The needle is inserted in the mucous membrane distal buccal to the last molar

Insert the needle to 2 to 4 mm to gently contact bone, and aspirate. If negative, slowly deposit about 1/8 of the solution in the cartridge.

Sublingual nerve block

Sublingual nerve block An anterior extension of the lingual nerve can be blocked by placing the needle just submucosally lingual to the premolars, use 0.5 ml of LA.

nerve block anesthesia

Maxilla

Nasopalatine block anaesthesia

Nasopalatine block Profound anaesthesia can be achieved by passing the needle through the incisive papilla and injecting a small amount of solution.

This is extremely painful

Infra-orbital block

Infra-orbital block Rarely indicated.

A 25 gauge long needle is recommended and inserted with the bevel toward the bone in the muco-buccal fold over the first premolar.

Palpate the inferior margin of the orbit as the infra-orbital foramen lies ~1 cm below the deepest point of the orbital margin. Hold the index finger at this point while the upper lip is lifted with the thumb.

Inject in the depth of the buccal sulcus towards your finger, avoid your finger, and deposit LA around the infra-orbital nerve.

Anterior Middle Superior Alveolar Block

If the infraorbital nerve block does not provide adequate anesthesia to the teeth distal of the canine or if the PSA injection does not provide anesthesia for the mesiobuccal root of the first molar, an MSA block injection should be administered.

A 25 gauge short needle is recommended with insertion in the mucobuccal fold by the maxillary second premolar.

About 1/2 to 2/3 of a cartridge of anesthetic is slowly deposited at the height of the apex of the second premolar after negative aspiration

Anterior Middle Superior Alveolar Block (continue)

One injection site - Central to second premolar, palatal and buccal soft tissue

Is used to anesthetize pulp tissue and facial periodontium of the maxillary premolars and the mesiobuccal root of the first molar in some cases.

Posterior superior alveolar block

The posterior superior alveolar (PSA) nerve block is a commonly used technique for achieving anesthesia for the maxillary molars

Posterior superior alveolar block A rarely indicated technique.

The short 25 or 27 gauge needle is recommended to decrease the risk of a hematoma

Needle is inserted distal to the upper second molar and advanced inwards, backwards, and upwards close to bone for ~2 cm.

LA is deposited high above the tuberosity after aspirating to avoid the ptyerygoid plexus

Greater Palatine Nerve Block

The greater palatine nerve innervates the palatal tissues and bone distal of the canine on the side anesthetized.

Use a 27 gauge short needle with the bevel toward the palate.

Palpate the palate until the depression of the foramen is felt (usually somewhere medial to the second molar).

Dry the tissue, and apply antiseptic and topical anesthetic for 2 minutes. Apply pressure with the swab for 30 seconds.

Continue pressure with the swab until the injection is completed.

Greater Palatine Nerve Block(Continue)

Place the bevel against the tissue and apply pressure enough to slightly bow the needle.

Inject a few drops of anesthetic.

Release the pressure of the needle and advance the tip of the needle into the tissue slightly.

Continue with this procedure of applying pressure to the bevel and depositing a few drops of anesthetic, then advancing, until the needle is in contact with the palatal bone.

Deposit less than a fourth to a third of a cartridge of anesthetic after negative aspiration is proven

Maxillary Nerve Block

The maxillary (V2) nerve innervates half of the maxilla, including the buccal and palatal aspects.

This injection technique is used especially in quadrant surgery or when extensive treatment is indicated for a single appointment.

It is also used when another site of injection has failed or if there is an infection in the area

his technique is used more with adult patients. It is not for the inexperienced.

Maxillary Nerve Block(continue)

Administration through the buccal aspect involves the possibility for hematoma.

The long 25 gauge needle is recommended with the bevel of the needle facing the bone.

The needle is inserted at the mucobuccal fold near the distal of the second molar after the usual protocol of tissue preparation.

The path of the needle is similar to that of the PSA nerve block, but is inserted approximately 30 mm to the pterygopalatine fossa.

Aspirate, then rotate the needle bevel 1/4 turn, reaspirate. If both aspirations are negative, slowly deposit one cartridge of anesthetic (deposit 1/4 then aspirate, then deposit 1/4 until the entire cartridge has been administered).

local infiltrations

Infiltrations

The aim is to deposit LA supraperiosteally in as close proximity as possible to the apex of the tooth to be anaesthetized.

The LA will diffuse through periosteum and bone to bathe the nerves entering the apex.

Lower concentrations of local anesthetics are typically used for infiltration anesthesia.

Variation in local anesthetic dose depends on the procedure, the degree of anesthesia required, and the ndividual patient's circumstances.

Reduced dosage is indicated in patients who are desbilitated or acutely ill, very young or very old, and in patients with liver disease, arteriosclerosis, or arterial disease.

Infiltrations Administrative techniques

The aim is to deposit LA supraperiosteally in as close proximity as possible to the apex of the tooth to be anaesthetized.

Patient comfort is essential during administration of local anesthetic agents.

Warming the local anesthetic solution prior to administration to 25-40o C has been recommended.

Reflect the lip or cheek to place mucosa on tension and insert the needle along the long axis of the tooth aiming towards bone.

Infiltrations Administrative techniques (Continue)

At approximate apex of tooth, withdraw slightly to avoid sub- periosteal injection, LA is slowly deposited. .

For palatal infiltrations, achieve topical analgesia first and infiltrate interdental papillae; then penetrate palatal mucosa and deposit small amount of LA under force.

Infiltration in Mandible

Buccal infiltration anaesthesia in the mandible can be effective in some areas.

Indeed in children this may the preferred technique when treating the deciduous dentition.

In adult patients buccal infiltrations may be effective in the mandibular incisor region.

Adjunctive Strategies for Infiltration

Adjunctive Strategies

PDL Injection

Sub-periosteal injection

Intraosseous Injection

Intrapulpal Injection

Intraseptal Injection

Different anaesthetic

PDL Injection

Technique:– needle inserted into the gingival sulcus at a 30 degree angle towards the tooth

– bevel placed towards bone

– advanced until resistance felt

– anaesthetic injected with continuous force for about 15 seconds.

– approx. 0.2 mL of solution

– 25 vs. 30 gauge needle

PDL Injection

Conventional vs. specific PDL syringes: – Malamed (1982):

• similar rates of success

– D’Souza et al (1987):

• no sig. difference in anaesthesia achieved.

• using the pressure syringe resulted in more spread of anaesthetic to adjacent teeth

PDL Injection: Primary Technique

Melamed 1982: 86% overall Faulkner 1983: 81% overall White 1988: variable, short duration esp. md. molars Walton 1990: “In reviewing the clinical and experimental literature…the

periodontal ligament injection does not meet all of the necessary requirements for a primary technique.”

PDL Injection: Supplemental Technique

Walton and Abbott 1981:– Inadequate pulpal anaesthesia following IAB– 92% overall – included situations where multiple PDL injections required– most critical factor was to inject under strong resistance

Smith, Walton, Abbott 1983: – 83% overall with high pressure syringe

PDL Injection: Anaesthetic Distribution

Garfunkel et al 1983, Smith and Walton 1983, Tagger et al 1994, Tagger et al 1994*– spread along path of least resistance

– influenced by anatomical structures and fascial planes

– through marrow spaces

– avoided PDL route

– appears to be a form of intraosseous injection

PDL Injection: Effects on the Periodontium

Animal histological studies

Most studies: no long term evidence of tissue disruption or inflammation

Roahen and Marshall 1990: evidence of localized external resorption


PDL Injection







Local anesthesia onset is more rapid than normal infiltration

Anesthesia Duration is less

Other possible negative effects include ischemia and necrosis of the periosteum tissue.

Rarely used

An advanced sub-periosteal dental anesthetic method involvs apparatus for motorized injection of anesthetic liquids


PDL Injection







Technique for mandibular infiltration

Perforate the cortical plate to introduce LA in medullary bone

Bathes the periradicular region in LA

2 commercial systems available:– Stabident (Patterson)

– X-Tip (Tulsa Dentsply)

Stabident


PDL Injection






Intrapulpal Anaesthesia

When a small access cavity is available into the pulp

a needle which fits snugly into the pulp should be chosen.

A small amount (about 0.1 ml) of solution is injected under pressure.

There will be an initial feeling of discomfort during this injection,

however this is transient and anesthetic onset is rapid.

Intrapulpal Anaesthesia

When the exposure is too large to allow a snug needle fit

the exposed pulp should be bathed in a little local anaesthetic for about a minute

before introducing the needle as far apically as possible into the pulp chamber and injecting under pressure.


PDL Injection







The intraseptal injection is used for hemostasis, soft tissue anesthesia, and osseous anesthesia.

Prepare the tissues of the site with antiseptic and topical.

Use a 27 gauge short needle and insert it into the papilla of the area to be anesthetized at an angle of 90° to the tissue.

Slowly deposit 0.2 ml of solution.


PDL Injection






Articaine

What about a mandibular infiltration?

Recommended by Steve Buchanan

Kanaa et al. 2006– Cross-over design comparing articaine and lidocaine for mandibular infiltration

for first molars

– Anaesthesia measured

– Lidocaine 38% effective

– Articaine 65% effective

Topical Anaesthetic

Benzocaine or Lidocaine Effectiveness?

– Gill and Orr 1979: 15 second application no more effective than placebo

– Stern and Giddon 1975: 2-3 minutes=profound soft tissue anaesthesia

Topical Anaesthetic

Recommendations:– Dry mucous membranes first

– 2-3 minutes, but concern with tissue sloughing

– Tip of the tongue

Topical Anaesthetic

Benzocaine Spray

RCDSO Dispatch 21, 1, Feb/Mar 2007 pp.28-29– Advice to Dentists

– Benzocaine Sprays and Methemoglobinemia (MHb)

• Health Canada—9 suspected cases, none fatal

Topical Anaesthetic

Benzocaine spray/Methemoglobinemia

Recommendations:– Avoid in patients with a history of MHb

– Consider lidocaine as an alternative

– Broken/inflamed tissue may promote uptake

– Use only amount deemed necessary

– If suspicious, send patient to hospital for methylene blue tx

– O2 won’t help, but give it anyways

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local anesthesia techniques

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