Oral and Maxillofacial Regional Anesthesia

Branches of the Mandibular Division

1. Main Trunk
   • Nervous Spinosus
   • Nerve to the Medial Pterygoid

2. Anterior Division
   • Masseteric
   • Deep Temporal
   • Lateral Pterygoid
   • Buccal Nerve

3. Posterior Division
   • Auriculotemporal
   • Lingual
   • Inferior Alveolar
   • Nerve to the Mylohyoid

Three motor and one sensory branch are given off by the anterior division of the mandibular nerve. The masseteric, deep temporal, and lateral pterygoid nerves supply the masseter, temporalis and lateral (external) pterygoid muscles respectively. The sensory division known as the buccal (buccinator or long buccal) nerve, runs forward between the two heads of the lateral pterygoid muscle, along the inferior aspect of the temporalis muscle, to the anterior border of the masseter muscle. Here it passes anterolaterally to enter the buccinator muscle however it does not innervate this muscle. The buccinator muscle is innervated by the buccal branch of the facial nerve. The buccal nerve provides sensory innervation to the skin of the cheek, buccal mucosa and buccal gingiva in the mandibular molar region.

The posterior division of the mandibular branch gives off two sensory branches (the auriculotemporal and lingual nerves) and one branch made up of both sensory and motor fibers (the inferior alveolar nerve).

The auriculotemporal nerve crosses the superior portion of the parotid gland, ascending behind the temporomandibular joint and giving off several sensory branches to the skin of the auricle, external auditory meatus, tympanic membrane, temporal region, temporomandibular joint and parotid gland via postganglionic parasympathetic secretomotor fibers from the otic ganglion.

The lingual nerve travels inferiorly in the pterygomandibular space between the medial aspect of the ramus of the mandible and the lateral aspect of the medial pterygoid muscle. It then travels anteromedially below the inferior border of the superior pharyngeal constrictor muscle deep to the pterygomandibular raphae. The lingual nerve then continues anteriorly in the submandibular region along the hyoglossus muscle, crossing the submandibular duct inferiorly and medially to terminate deep to the sublingual gland. The lingual nerve provides sensory innervation to the anterior two thirds of the tongue, mucosa of the floor of the mouth, and lingual gingiva.

The inferior alveolar branch of the mandibular nerve descends in the region between the lateral aspect of the sphenomandibular ligament and the medial aspect of the ramus of the mandible. It travels along with, but lateral and posterior to, the lingual nerve. While the lingual nerve continues to descend within the pterygomandibular space, the inferior alveolar nerve enters the mandibular canal through the mandibular foramen. Just before entering the mandibular canal the inferior alveolar nerve gives off a motor branch known as the mylohyoid nerve which is discussed below. The nerve travels along with the inferior alveolar artery and vein within the mandibular canal and divides into the mental and incisive nerve branches at the mental foramen. The inferior alveolar nerve provides sensation to the mandibular posterior teeth.

The incisive nerve is a branch of the inferior alveolar nerve which continues within the mandibular canal to provide sensory innervation to the mandibular anterior teeth.

The mental nerve emerges from the mental foramen to provide sensory innervation to the mucosa in the premolar/canine region as well as the skin of the chin and lower lip.

The mylohyoid nerve, as previously stated, branches off the inferior alveolar nerve prior to its entry into the mandibular canal. It travels within the mylohyoid groove and along the medial aspect of the body of the mandible to supply the mylohyoid muscle as well as the anterior belly of the digastric.1,2

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MAXILLARY AND MANDIBULAR REGIONAL ANESTHESIA

Equipment

Administration of regional anesthesia of the maxilla and mandible is achieved via the use of a dental syringe, needle, and anesthetic cartridge. Several types of dental syringes are available for use, however the most common is the breech-loading, metallic, cartridge-type, aspirating syringe. The syringe is comprised of a thumb ring, finger grip, barrel containing the piston with a harpoon, and a needle adaptor (Fig. 3). A needle is attached to the needle adaptor which engages the rubber diaphragm of the dental cartridge (Fig. 4). The anesthetic cartridge is placed into the barrel of the syringe from the side (breech loading). The barrel contains a piston with a harpoon that engages the rubber stopper at the end of the anesthetic cartridge (Fig. 5, A and B). After the needle and cartridge have been attached, a brisk tap is given to the back of the thumb ring to ensure the harpoon has engaged the rubber stopper at the end of the anesthetic cartridge (Fig.6, A, B, and C).

	Figure 3: Breech-loading, metallic, cartridge-type, aspirating syringe
	Figure 4: Needle-syringe assembling: A needle is attached to the needle adaptor.
	Figure 5, A: Needle-syringe assembling : The anesthetic cartridge is placed into the barrel of the syringe from the side (breech loading).
	Figure 5, B: A piston with a harpoon engages the rubber stopper at the end of the anesthetic cartridge while the needle adaptor engages the rubber diaphragm of the dental cartridge
	Figure 6, A and B: Needle-syringe assembling: A brisk tap is given to the back of the thumb ring to ensure the harpoon has engaged the rubber stopper at the end of the anesthetic cartridge.
	Figure 6, C: A fully loaded anesthetic syringe

Dental needles are referred to in terms of their gauge which corresponds to the diameter of the lumen of the needle. Increasing gauge corresponds to smaller lumen diameter. Twenty-five and twenty-seven gauge needles are most commonly used for maxillary and mandibular regional anesthesia and are available in long and short lengths. The length of the needle is measured from the tip of the needle to the hub. The conventional long needle is approximately 40mm in length while the short needle is approximately 25mm in length. Variations in needle length do exist depending upon the manufacturer.

Anesthetic cartridges are prefilled, 1.8cc glass cylinders with a rubber stopper at one end and an aluminum cap with a diaphragm at the other end (Fig. 7, A and B). The contents of an anesthetic cartridge are the local anesthetic, vasoconstrictor (anesthetic without vasoconstrictor is also available), preservative for the vasoconstrictor (sodium bisulfite), sodium chloride, and distilled water. The most common anesthetics used in clinical practice are the amide anesthetics lidocaine and mepivacaine. Other amide anesthetics available for use are prilocaine, articaine, bupivacaine, and etidocaine. Esther anesthetics are not as commonly used however remain available. Procaine, procaine plus propoxycaine, chlorprocaine, and tetracaine are some common esther anesthetics.

Figure 7, A: Dental cartridges. The rubber stopper is on the right end of the cartridge while the aluminum cap with the diaphragm is on the left end of the cartridge. B: Containers of dental anesthetic

Additional armamentarium includes dry gauze, topical antiseptic and anesthetic. The site of injection should be made dry with gauze and a topical antiseptic should be used to clean the area. Topical anesthetic is applied to the area of injection to minimize discomfort during insertion of the needle into the mucous membrane (Fig. 8). Common topical preparations include benzocaine, butacaine sulfate, cocaine hydrochloride, dyclonine hydrochloride, lidocaine, and tetracaine hydrochloride.

Figure 8: Topical anesthesia: Prior to injection, topical anesthetic can be applied on the mucosa in the area of an injection to minimize discomfort to the patient

Universal precautions should always be observed by the clinician which include the use of protective gloves, mask and eye protection. After withdrawing the needle once a block has been completed, the needle should always be carefully recapped to avoid accidental needle stick injury to the operator.1

Retraction of the soft tissue for visualization of the injection site should be performed with the use of a dental mirror or retraction instrument. This is recommended for all maxillary and mandibular regional techniques discussed below. Use of an instrument rather than one’s fingers will help prevent accidental needle stick injury to the operator.

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Techniques of Maxillary Regional Anesthesia

The techniques most commonly employed in maxillary anesthesia include supraperiosteal (local) infiltration, periodontal ligament (intraligamentary) injection, posterior superior alveolar nerve block, middle superior alveolar nerve block, anterior superior alveolar nerve block, greater palatine nerve block, nasopalatine nerve block, local infiltration of the palate, and intrapulpal injection. Of less clinical application are the maxillary nerve block and intraseptal injection.

Clinical pearls Techniques of Anesthesia for Treatment of a Localized Area or One or Two Teeth
TECHNIQUE	AREA ANESTHETIZED
Supraperiosteal Injection Periodontal Ligament Injection Intraseptal Injection Intrapulpal Injection	Individual teeth and buccal soft tissue Individual teeth and buccal soft tissue Localized soft tissue Individual tooth

Supraperiosteal (Local) Infiltration

The supraperiosteal or local infiltration is the one of the simplest and most commonly employed techniques for achieving anesthesia of the maxillary dentition. This technique is indicated when any individual tooth or soft tissue in a localized area is to be treated. Contraindications to this technique are the need to anesthetize multiple teeth adjacent to one another (in which case a nerve block is the preferred technique), acute inflammation and infection in the area to be anesthetized, and less significantly, the density of bone overlying the apices of the teeth. A 25- or 27-gauge short needle is preferred for this technique.

Technique- Identify the tooth to be anesthetized and the height of the mucobuccal fold over the tooth. This will be the injection site. The right handed operator should stand at the nine o’clock to ten o’clock position whereas the left handed operator should stand at the two o’clock to three o’clock position. Retract the lip and orient the syringe with the bevel towards bone. This will prevent discomfort from the needle coming into contact with the bone and will minimize the risk of tearing the periosteum with the needle tip. Insert the needle at the height of the mucobuccal fold above the tooth to a depth of no more than a few millimeters and aspirate (Fig 9, A and B). If aspiration is negative, inject one third to one half (0.6-1.2cc) of a cartridge of anesthetic solution slowly, over the course of thirty seconds. Withdraw the syringe and recap the needle. Successful administration will provide anesthesia to the tooth and associated soft tissue within two to four minutes. If adequate anesthesia has not been achieved repeat the procedure and deposit another one third to one half of the cartridge of anesthetic solution.1

Figure 9, A: Locate the height of the mucobuccal fold over the tooth to be anesthetized. B: Clinical picture depicting a local infiltration of the maxillary left central incisor tooth. Note the penetration of the needle at the height of the mucobuccal fold above the maxillary left central incisor

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Periodontal Ligament (Intraligamentary Injection)

The periodontal ligament or intraligamentary injection is a useful adjunct to the supraperiosteal injection or a nerve block. Often, it is used to supplement these techniques to achieve profound anesthesia of the area to be treated. Indications for the use of this technique are the need to anesthetize an individual tooth or teeth, need for soft tissue anesthesia in the immediate vicinity of a tooth, and partial anesthesia following a field block or nerve block. A 25- or 27-gauge short needle is preferred for this technique.

Technique- Identify the tooth or area of soft tissue to be anesthetized. The sulcus between the gingiva and the tooth is the injection site for the periodontal ligament injection. Position the patient in the supine position. For the right handed operator, retract the lip with a retraction instrument held in the left hand and stand where the tooth and gingiva are clearly visible. The same applies for the left handed operator except that the retraction instrument will be held in the right hand. Hold the syringe parallel to the long axis of the tooth on the mesial or distal aspect. Insert the needle (bevel facing the root), to the depth of the gingival sulcus (Fig. 10). Advance the needle until resistance is met. A small amount of anesthetic (0.2cc) is then administered slowly over the course of twenty to thirty seconds. It is normal to experience resistance to the flow of anesthetic. Successful execution of this technique provides pulpal and soft tissue anesthesia to the individual tooth or teeth to be treated.1

Figure 10: Clinical picture depicting a periodontal ligament injection. Note the position of the needle between the gingival sulcus and tooth with the needle parallel to the long axis of the tooth

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Posterior Superior Alveolar Nerve Block

The posterior superior alveolar (PSA) nerve block, otherwise known as the tuberosity block or the zygomatic block, is used to achieve anesthesia of the maxillary molar teeth up to the 1st molar with the exception of its mesiobuccal root in some cases. One of the potential complications of this technique is the risk of hematoma formation from injection of anesthetic into the pterygoid plexus of veins or accidental puncture of the maxillary artery. Aspiration prior to injection is indicated when the PSA block is given. The indications for this technique are the need to anesthetize multiple molar teeth. Anesthesia can be achieved with fewer needle penetrations providing greater comfort to the patient by preventing the need for multiple injections by the supraperiosteal technique. The PSA can be given to provide anesthesia of the maxillary molars when acute inflammation and infection are present. If inadequate anesthesia is achieved via the supraperiosteal technique, the PSA can be used to achieve more profound anesthesia of a longer duration. The PSA block also provides anesthesia to the premolar region in a certain percentage of cases where the MSA is absent. Contraindications to the procedure are related to the risk of hematoma formation. In individuals with coagulation disorders, care must be taken to avoid injection into the pterygoid plexus or puncture of the maxillary artery. 25- or 27-gauge short needle is preferred for this technique.

Technique- Identify the height of the mucobuccal fold over the 2nd molar. This will be the injection site. The right handed operator should stand at the nine o’clock to ten o’clock position whereas the left handed operator should stand at the two o’clock to three o’clock position. Retract the lip with a retraction instrument. Hold the syringe with the bevel toward the bone. Insert the needle at the height of the mucobuccal fold above the maxillary 2nd molar at a 45 degree angle directed superiorly, medially, and posteriorly (one continuous movement). Advance the needle to a depth of three quarters of its total length (Fig. 11, A and B). No resistance should be felt while advancing the needle through the soft tissue. If bone is contacted, the medial angulation is too great. Slowly retract the needle (without removing it) and bring the syringe barrel toward the occlusal plane. This will allow the needle to be angulated slightly more lateral to the posterior aspect of the maxilla. Advance the needle, aspirate, and inject one cartridge of anesthetic solution slowly over the course of one minute aspirating frequently during the administration. Prior to injecting, one should aspirate in two planes to avoid accidental injection into the pterygoid plexus. After the first aspiration, the needle should be rotated one quarter turn. The operator should then reaspirate. If positive aspiration occurs, slowly retract the needle one to two millimeters and reaspirate in two planes. Successful injection technique will result in anesthesia of the maxillary molars (with the exception of the mesiobuccal root of the first molar in some cases), and associated soft tissue on the buccal aspect.1

Figure 11, A: Location of the PSA nerve. B: Position of the needle during the PSA nerve block. The needle is inserted at the height of the mucobuccal fold above the maxillary 2nd molar at a 45 degree angle aimed superiorly, medially and posteriorly.

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Middle Superior Alveolar Nerve Block

The middle superior alveolar nerve block is useful for procedures where the maxillary premolar teeth or the mesiobuccal root of the 1st molar require anesthesia. Although not always present, it is useful if the posterior or anterior superior alveolar nerve blocks or supraperiosteal infiltration fails to achieve adequate anesthesia. Individuals in whom the MSA nerve is absent, the PSA and ASA nerves provide innervation to the maxillary premolar teeth and the mesiobuccal root of the 1st molar. Contraindications include acute inflammation and infection in the area of injection or a procedure involving one tooth where local infiltration will be sufficient. A 25- or 27-gauge short needle is preferred for this technique.

Technique- Identify the height of the mucobuccal fold above the maxillary 2nd premolar. This will be the injection site. The right handed operator should stand at the nine o’clock to ten o’clock position whereas the left handed operator should stand at the two o’clock to three o’clock position. Retract the lip with a retraction instrument and insert the needle until the tip is above the apex of the 2nd premolar tooth (Fig. 12, A and B). Aspirate and inject two thirds to one cartridge of anesthetic solution slowly over the course of one minute. Successful execution of this technique provides anesthesia to the pulp, surrounding soft tissue and bone of the 1st and 2nd premolar teeth and mesiobuccal root of the 1st molar.1

Figure 12, A: Location of the MSA nerve. B: The needle is inserted at the height of the mucobuccal fold above the maxillary 2nd premolar.

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Anterior Superior Alveolar Nerve Block/Infraorbital Nerve Block

The anterior superior alveolar (ASA) nerve block or infraorbital nerve block is a useful technique for achieving anesthesia of the maxillary central and lateral incisors and canine as well as the surrounding soft tissue on the buccal aspect. In patients that do not have an MSA nerve, the ASA nerve may also innervate the premolar teeth and mesiobuccal root of the 1st molar. Indications for the use of this technique include procedures involving multiple teeth and inadequate anesthesia from the supraperiosteal technique. A 25 gauge long needle is preferred for this technique.

Technique- Place the patient in the supine position. Identify the height of the mucobuccal fold above the maxillary 1st premolar. This will be the injection site. The right handed operator should stand at the ten o’clock position whereas the left handed operator should stand at the two o’clock position. Identify the infraorbital notch on the inferior orbital rim (Fig. 13, A). The infraorbital foramen lies just inferior to the notch usually in line with the second premolar. Slight discomfort is felt by the patient when digital pressure is placed on the foramen. It is helpful but not necessary to mark the position of the infraorbital foramen. Retract the lip with a retraction instrument while noting the location of the foramen. Orient the bevel of the needle toward bone and insert the needle at the height of the mucobuccal fold above the 1st premolar (Fig. 13, B). The syringe should be angled toward the infraorbital foramen and kept parallel with the long axis of the 1st premolar to avoid hitting the maxillary bone prematurely. The needle is advanced into the soft tissue until the bone over the roof of the foramen is contacted. This is approximately half the length of the needle however, this will vary from individual to individual. After aspiration, approximately one half to two thirds (0.9-1.2cc) of the anesthetic cartridge is deposited slowly over the course of one minute. It is recommended that pressure be kept over the site of injection to facilitate the diffusion of anesthetic solution into the foramen. Successful execution of this technique results in aesthesia of the lower eyelid, lateral aspect of the nose, and the upper lip. Pulpal anesthesia of the maxillary central and lateral incisors, canine, buccal soft tissue, and bone is also achieved. In a certain percentage of people, the premolar teeth and the mesiobuccal root of the 1st molar is also anesthetized.1

Figure 13, A: Location of the infraorbital nerve. B: The needle is kept parallel to the long axis of the maxillary 1st premolar and inserted at the height of the mucobuccal fold above the 1st premolar.

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Greater Palatine Nerve Block

The greater palatine nerve block is useful when treatment is necessary on the palatal aspect of the maxillary premolar and molar dentition. This technique targets the area just anterior to the greater palatine canal. The greater palatine nerve exits the canal and travels forward between the bone and soft tissue of the palate. Contraindications to this technique are acute inflammation and infection at the injection site. A 25- or 27-gauge long needle is preferred for this technique.

Technique- The patient should be in the supine position with the chin tilted upward for visibility of the area to be anesthetized. The right handed operator should stand at the eight o’clock position whereas the left handed operator should stand at the four o’clock position. Using a cotton swab, locate the greater palatine foramen by placing it on the palatal tissue approximately one centimeter medial to the junction of the 2nd and 3rd molar (Fig. 14, A and B). While this is the usual position for the foramen, it may be located slightly anterior or posterior to this location. Gently press the swab into the tissue until the depression created by the foramen is felt. Malamed and Trieger found that the foramen is found medial to the anterior half of the 3rd molar approximately 50% of the time, medial to the posterior half of the 2nd molar approximately 39% of the time and medial to the posterior half of the 3rd molar approximately 9% of the time.6 The area approximately one to two millimeters anterior to the foramen is the target injection site. Using the cotton swab, apply pressure to the area of the foramen until the tissue blanches. Aim the syringe perpendicular to the injection site which is one to two millimeters anterior to the foramen. While keeping pressure on the foramen, inject small volumes of anesthetic solution as the needle is advanced through the tissue until bone is contacted. The tissue will blanch in the area surrounding the injection site. Depth of penetration is usually no more than a few millimeters. Once bone is contacted, aspirate and inject approximately one fourth (0.45cc) of anesthetic solution. Resistance to deposition of anesthetic solution is normally felt by the operator. This technique provides anesthesia to the palatal mucosa and hard palate from the 1st premolar anteriorly to the posterior aspect of the hard palate and to the midline medially.1,6

Figure 14, A: Location of the greater palatine nerve. B: Area of insertion for the greater palatine nerve block is one centimeter medial to the junction of the maxillary 2nd and 3rd molars.

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Nasopalatine Nerve Block

The nasopalatine nerve block, otherwise known as the incisive nerve block and sphenopalatine nerve block, anesthetizes the nasopalatine nerves bilaterally. In this technique anesthetic solution is deposited in the area of the incisive foramen. This technique is indicated when treatment requires anesthesia of the lingual aspect of multiple anterior teeth. A 25- or 27-gauge short needle is preferred for this technique.

Technique- The patient should be in the supine position with the chin tilted upward for visibility of the area to be anesthetized. The right handed operator should be at the nine o’clock position whereas the left handed operator should be at the three o’clock position. Identify the incisive papillae. The area directly lateral to the incisive papilla is the injection site. With a cotton swab, hold pressure over the incisive papilla. Insert the needle just lateral to the papilla with the bevel against the tissue (Fig. 15, A and B). Advance the needle slowly toward the incisive foramen while depositing small volumes of anesthetic and maintaining pressure on the papilla. Once bone is contacted, retract the needle approximately one millimeter, aspirate, and inject one fourth (0.45cc) of a cartridge of anesthetic solution over the course of thirty seconds. Blanching of surrounding tissues and resistance to the deposition of anesthetic solution is normal. Anesthesia will be provided to the soft and hard tissue of the lingual aspect of the anterior teeth from the distal of the canine on one side to the distal of the canine on the opposite side.1

Figure 15 A: Location of the nasopalatine nerve. B: Insertion of the needle just lateral to the incisive papilla for the nasopalatine nerve block.

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Local Palatal Infiltration

The administration of local anesthetic for the palatal anesthesia of just one or two teeth is common in clinical practice. When a block is undesirable, local infiltration provides effective palatal anesthesia of the individual teeth to be treated. Contraindications include acute inflammation and infection over the area to be anesthetized. A 25- or 27-gauge short needle is preferred for this technique.

Technique- The patient should be in the supine position with the chin tilted upward for visibility of the area to be anesthetized. Identify the area to be anesthetized. The right handed operator should be at the ten o’clock position whereas the left handed operator should be at the two o’clock position. The area of needle penetration is five to ten millimeters palatal to the center of the crown. Apply pressure directly behind the injection site with a cotton swab. Insert the needle at a forty five degree angle to the injection site with the bevel angled toward the soft tissue (Fig. 16). While maintaining pressure behind the injection site, advance the needle and slowly deposit anesthetic solution as the soft tissue is penetrated. Advance the needle until bone is contacted. Depth of penetration is usually no more than a few millimeters. The tissue is very firmly adherent to the underlying periosteum in this region causing resistance to the deposition of local anesthetic. No more than 0.2 to 0.4cc of anesthetic solution is necessary to provide adequate palatal anesthesia. Blanching of the tissue at the injection site immediately follows deposition of local anesthetic. Successful administration of anesthetic using this technique results in hemostasis and anesthesia of the palatal tissue in the area of injection.1

Figure 16: Local infiltration on the palatal aspect of the maxillary right 1st premolar. The needle is inserted approximately 5 to 10mm palatal to the center of the crown.

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Intrapulpal Injection

Intrapulpal injection involves anesthesia of the nerve within the pulp canal of the individual tooth to be treated. When pain control cannot be achieved by any of the aforementioned methods, the intrapulpal method may be used once the pulp chamber is open. There are no contraindications to the use of this technique as it is at times the only effective method of pain control. A 25- or 27-gauge short needle is preferred for this technique.

Technique- The patient should be in the supine position with the chin tilted upward for visibility of the area to be anesthetized. Identify the tooth to be anesthetized. The right handed operator should be at the ten o’clock position whereas the left handed operator should be at the two o’clock position. Assuming that the pulp chamber has been opened by an experienced dental professional, place the needle into the pulp chamber and deposit one drop of anesthetic. Advance the needle into the pulp canal and deposit another 0.2cc of local anesthetic solution. It may be necessary to bend the needle in order to gain access to the chamber especially with posterior teeth. The patient usually experiences a brief period of significant pain as the solution enters the canal followed by immediate pain relief.1

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Maxillary Nerve Block

Less often used in clinical practice, the maxillary nerve block (second division block) provides anesthesia of a hemimaxilla. This technique is useful for procedures that require anesthesia of multiple teeth and surrounding buccal and palatal soft tissue in one quadrant or when acute inflammation and infection preclude successful administration of anesthesia by the aforementioned methods. There are two techniques one can use to achieve the maxillary nerve block: the high tuberosity approach and the greater palatine canal approach. The high tuberosity approach carries with it the risk of hematoma formation and is therefore contraindicated in patients with coagulation disorders. The maxillary artery is the vessel of primary concern with the high tuberosity approach. Both techniques are contraindicated when acute inflammation and infection is present over the injection site.

High Tuberosity Approach

A 25 gauge long needle is preferred for this technique.
Technique- The patient should be in the supine position with the chin tilted upward for visibility of the area to be anesthetized. Identify the area to be anesthetized. The right handed operator should be at the ten o’clock position whereas the left handed operator should be at the two o’clock position. This technique anesthetizes the maxillary nerve as it travels through the pterygopalatine fossa. Identify the height of the mucobuccal fold just distal to the maxillary 2nd molar. This is the injection site. The needle should enter the tissue at a forty five degree angle aimed posteriorly, superiorly and medially as in the PSA nerve block (See Fig. 11, B). The bevel should be oriented toward the bone. The needle is advanced to a depth of approximately 30mm or a few millimeters shy of the hub. At this depth, the needle lies within the pterygopalatine fossa. The operator should then aspirate, rotate the needle one quarter turn, and aspirate again. After negative aspiration in two planes has been established, slowly inject one cartridge of anesthetic solution over the course of one minute. The needle is then slowly withdrawn and recapped. Successful administration of anesthetic using this technique provides anesthesia to the entire hemimaxilla on the ipsilateral side of the block. This includes pulpal anesthesia to the maxillary teeth, buccal and palatal soft tissue as far medially as the midline, as well as the skin of the upper lip, lateral aspect of the nose and lower eyelid.

Greater Palatine Canal Approach

A 25 gauge long needle is preferred for this technique.
Technique- Place the patient in the supine position. The right handed operator should be at the ten o’clock position whereas the left handed operator should be at the two o’clock position. Identify the greater palatine foramen as described in the technique for the greater palatine nerve block. The tissue directly over the greater palatine foramen is the target for injection. This technique anesthetizes the maxillary nerve as it travels through the pterygopalatine fossa via the greater palatine canal. Apply pressure to the area over the greater palatine foramen with a cotton tipped applicator. Administer a greater palatine nerve block using the aforementioned technique (See Fig. 14, B). Once adequate palatal anesthesia is achieved, gently probe for the greater palatine foramen with the tip of the needle. For this technique, the syringe should be held so that the needle is aimed posteriorly. It may be necessary to change the angulation of the needle in order to locate the foramen. In a case study performed by Malamed and Trieger, the majority of canals were angled 45-50 degrees. Once the foramen has been located, advance the needle to a depth of 30mm. If resistance is met, withdraw the needle a few millimeters and reenter at a different angle. Malamed and Trieger’s study indicates that bony obstructions preventing passage of the needle were found in approximately 5% to 15% of canals. If resistance is met early on and the operator is unable to advance the needle into the canal more than a few millimeters, the procedure should be aborted and the high tuberosity approach should be considered. If no resistance is met and penetration of the canal is successful, aspirate in two planes as described in previous sections and slowly deposit one cartridge of local anesthetic solution. As with the high tuberosity approach, the hemimaxilla on the ipsilateral side as the injection becomes anesthetized with successful execution of this technique.1,6,7

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Intraseptal Injection

The intraseptal technique is a useful adjunct to the aforementioned techniques (supraperiosteal, PSA, MSA, ASA). Although not used as often in clinical practice, the technique is very similar to the PDL injection and offers the added advantage of hemostasis in the area of injection. Terminal nerve endings in the surrounding hard and soft tissue of individual teeth are anesthetized with this technique. Contraindications to the procedure include acute inflammation and infection over the site of injection. A 27 gauge short needle is preferred for this technique.

Technique- Place the patient in the supine position. The target area is the interdental palpillae 2-3mm apical to the apex of the papillary triangle (Fig. 17). The right handed operator should be at the ten o’clock position whereas the left handed operator should be at the two o’clock position. The operator may ask the patient to turn his or her head for optimum visibility. The syringe is held at a 45 degree angle to the long axis of the tooth with the bevel facing the apex of the root. The needle is inserted into the soft tissue and is advanced until bone is contacted. A few drops of anesthetic should be administered at this time. The needle is then advanced into the interdental septum and 0.2cc of anesthetic solution is deposited. Resistance to the flow of anesthetic solution is expected and ischemia of the soft tissue surrounding the injection site will ensue shortly after anesthetic solution is administered.1

Figure 17: Note the position of the needle 3mm apical to the apex of the papillary triangle for the intraseptal technique.

 

Clinical pearls Techniques of Anesthesia for Treatment of a Quadrant or Multiple Teeth
TECHNIQUE	AREA ANESTHETIZED
Maxillary
Posterior Superior Alveolar Nerve Block	Maxillary molars (with exception of mesiobuccal root of maxillary 1st molar in some cases), hard and soft tissue on buccal aspect
Middle Superior Alveolar Nerve Block	Mesiobuccal root of maxillary 1st molar (in some cases), premolars and surrounding hard and soft tissue on buccal aspect
Anterior Superior Alveolar Nerve Block/Infraorbital Nerve Block	Maxillary central and lateral incisors andcanine, surrounding hard and soft tissue on buccal aspect, mesiobuccal root of maxillary 1st molar (in some cases)
Greater Palatine Nerve Block	Palatal mucosa and hard palate from 1st premolar anteriorly to posterior aspect of the hard palate, and to midline medially
Nasopalatine Nerve Block	Hard and soft tissue of lingual aspect of maxillary anterior teeth from distal of canine on one side to distal of canine on the contralateral side
Maxillary Nerve Block	Hemimaxilla on side of injection (teeth, hard and soft, buccal and lingual tissue)
Mandibular
Inferior Alveolar Nerve Block	Mandibular teeth on side of injection, buccal and lingual hard and soft tissue, lower lip
Buccal Nerve Block	Buccal soft tissue of molar region
Gow-Gates Mandibular Nerve Block	Mandibular teeth to midline, hard and soft tissue of buccal and lingual aspect, anterior 2/3 of tongue, FOM, skin over zygoma, posterior aspect of cheek, and temporal region on side of injection
Vazirani-Akinosi Closed Mouth	Mandibular teeth to midline, hard and soft tissue of buccal aspect, anterior 2/3 of tongue, FOM
Mental  Nerve Block	Buccal soft tissue anterior to mental foramen, lower lip, chin
Incisive Nerve Block	Premolars, canine and incisors, lower lip, skin over the chin, buccal soft tissue anterior to the mental foramen

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Techniques of Mandibular Regional Anesthesia

Techniques used in clinical practice for the anesthesia of the hard and soft tissues of the mandible include the supraperiosteal technique, PDL injection, intrapulpal anesthesia, intraseptal injection, inferior alveolar nerve block, long buccal nerve block, Gow-Gates technique, Vazirani-Akinosi closed mouth mandibular block, mental nerve block, and incisive nerve block.

The supraperiosteal, PDL, intrapulpal, and intraseptal techniques are executed in the same manner as described above for maxillary anesthesia. When anesthetizing the mandible the patient should be in the semisupine or reclined position. The right handed operator should stand at the nine o’clock to ten o’clock position whereas the left handed operator should stand at the three o’clock to four o’ clock position.

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Inferior Alveolar Nerve Block

The inferior alveolar nerve block is one of the most commonly employed techniques in mandibular regional anesthesia. It is extremely useful when multiple teeth in one quadrant require treatment. While effective, this technique carries a high failure rate even when strict adherence to protocol is maintained. The target for this technique is the mandibular nerve as it travels on the medial aspect of the ramus, prior to its entry into the mandibular foramen. The lingual, mental, and incisive nerves are also anesthetized. A 25 gauge long needle is preferred for this technique.

Technique- The patient should be in the semisupine position. The right handed operator should be in the eight o’clock position whereas the left handed operator should be in the four o’clock position. With the mouth open maximally, identify the coronoid notch and the pterygomandibular raphae. Three quarters of the anteroposterior distance between these two landmarks, and approximately six to ten millimeters above the occlusal plane is the injection site. Use a retraction instrument to retract the cheek and bring the needle to the injection site from the contralateral premolar region. As the needle passes through the soft tissue, deposit one or two drops of anesthetic solution. Advance the needle until bone is contacted. Once bone is contacted, withdraw the needle one millimeter and redirect the needle posteriorly by bringing the barrel of the syringe towards the occlusal plane (Fig. 18, A and B). Advance the needle to three quarters of its depth, aspirate, and inject three quarters of a cartridge of anesthetic solution slowly over the course of one minute. As the needle is withdrawn, continue to deposit the remaining one quarter of anesthetic solution so as to anesthetize the lingual nerve (Fig. 18, C). Successful execution of this technique results in anesthesia of the mandibular teeth on the ipsilateral side to the midline, associated buccal and lingual soft tissue, lateral aspect of the tongue on the ipsilateral side, and lower lip on the ipsilateral side.1

	Figure 18 A: Location of the inferior alveolar nerve. B: After contacting bone, the needle is redirected posteriorly by bringing the barrel of the syringe towards the occlusal plane. The needle is then advanced to three quarters of its depth.
	Figure 18 C: Location of the lingual nerve which is anesthetized during the administration of an inferior alveolar nerve block.

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Buccal Nerve Block

The buccal nerve block, otherwise known as the long buccal or buccinator block, is a useful adjunct to the inferior alveolar nerve block when manipulation of the buccal soft tissue in the mandibular molar region is indicated. The target for this technique is the buccal nerve as it passes over the anterior aspect of the ramus. Contraindications to the procedure include acute inflammation and infection over the site of injection. A 25 gauge long needle is preferred for this technique.

Technique- The patient should be in the semisupine position. The right handed operator should be in the eight o’clock position whereas the left handed operator should be in the four o’clock position. Identify the most distal molar tooth on the side to be treated. The tissue just distal and buccal to the last molar tooth is the target area for injection (Fig. 19, A and B). Use a retraction instrument to retract the cheek. The bevel of the needle should be toward bone and the syringe should be held parallel to the occlusal plane on the side of the injection. The needle is inserted into the soft tissue and a few drops of anesthetic solution are administered. The needle is advanced approximately one or two millimeters until bone is contacted. Once bone is contacted and aspiration is negative, 0.2cc of local anesthetic solution is deposited. The needle is withdrawn and recapped. Successful execution of this technique results in anesthesia of the buccal soft tissue of the mandibular molar region.1

Figure 19 A: Location of the buccal nerve. B: The tissue just distal and buccal to the last molar tooth is the target area for injection.

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Gow-Gates Technique

The Gow-Gates technique or third division nerve block is useful alternative to the inferior alveolar nerve block and is often used when the latter fails to provide adequate anesthesia. Advantages of this technique versus the inferior alveolar technique are its low failure rate and low incidence of positive aspiration. The Gow-Gates technique anesthetizes the auriculotemporal, inferior alveolar, buccal, mental, incisive, mylohyoid and lingual nerves. Contraindications to this procedure include acute inflammation and infection over the site of injection and trismatic patients. A 25 gauge long needle is preferred for this technique.

Technique- The patient should be in the semisupine position. The right handed operator should be in the eight o’clock position whereas the left handed operator should be in the four o’clock position. The target area for this technique is the neck of the condyle below the area of insertion of the lateral pterygoid muscle. A retraction instrument is used to retract the cheek. The patient is asked to open maximally and the mesiolingual cusp of the maxillary 2nd molar on the side of desired anesthesia is identified. The insertion site of the needle will be just distal to the maxillary 2nd molar at the level of the mesiolingual cusp. Bring the needle to the insertion site in a plane that is parallel to an imaginary line drawn from the intertragic notch to the corner of the mouth on the same side as the injection (Fig. 20, A and B). The orientation of the bevel of the needle is not important in this technique. Advance the needle through soft tissue approximately 25mm until bone is contacted. This is the neck of the condyle. Once bone is contacted, withdraw the needle one millimeter and aspirate. Redirect the needle superiorly and reaspirate. If aspiration in two planes is negative, slowly inject one cartridge of local anesthetic solution over the course of one minute. Successful execution of this technique provides anesthesia to the ipsilateral mandibular teeth up to the midline, and associated buccal and lingual hard and soft tissue. The anterior two thirds of the tongue, floor of the mouth, skin over the zygoma, posterior aspect of the cheek and temporal region on the ipsilateral side of injection are also anesthetized.1,8

Figure 20 A: The patient is asked to open mouth maximally. The mesiolingual cusp of the maxillary 2nd molar is the reference point for the height of the injection. B: The needle is then moved distally and is held parallel to an imaginary line drawn from the intertragic notch to the corner of the mouth.

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Vazirani-Akinosi Closed Mouth Mandibular Block

The Vazirani-Akinosi closed mouth mandibular block is a useful technique for patients with limited opening due trismus or ankylosis of the temporomandibular joint. Limited mandibular opening precludes the administration of the inferior alveolar nerve block or use of the Gow-Gates technique both of which require the patient to be open maximally. Other advantages to this technique are the minimal risk of trauma to the inferior alveolar nerve, artery, vein, and pterygoid muscle, low complication rate and minimal discomfort upon injection. Contraindications to this technique are acute inflammation and infection in the pterygomandibular space, deformity or tumor in the maxillary tuberosity region or an inability to visualize the medial aspect of the ramus. A 25 gauge long needle is preferred for this technique.

Technique- The patient should be in the semisupine position. The right handed operator should be in the eight o’clock position whereas the left handed operator should be in the four o’clock position. The gingival margin above the maxillary 2nd and 3rd molars and the pterygomandibular raphae serve as landmarks for this technique. A retraction instrument is used to stretch the cheek laterally. The patient should occlude gently on the posterior teeth. The needle is held parallel to the occlusal plane at the level of the gingival margin of the maxillary 2nd and 3rd molars. The bevel is directed away from the bone facing the midline. The needle is advanced through the mucous membrane and buccinator muscle to enter the pterygomandibular space. The needle is inserted to approximately one half to three quarters of its length. At this point the needle will be in the midsection of the ptyerygomandibular space. Aspirate and if negative, one cartridge of local anesthetic solution is deposited over the course of one minute. Diffusion and gravitation of the local anesthetic solution will anesthetize the lingual and long buccal nerves in addition to the inferior alveolar nerve. Successful execution of this technique provides anesthesia of the ipsilateral mandibular teeth up to the midline, and associated buccal and lingual hard and soft tissue. The anterior two thirds of the tongue and floor of the mouth are also anesthetized.9,10

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Mental Nerve Block

The mental nerve block is indicated for procedures where manipulation of buccal soft tissue anterior to the mental foramen is necessary. Contraindications to this technique are acute inflammation and infection over the injection site. A 25 or 27 gauge short needle is preferred for this technique.

Technique- The patient should be in the semisupine position. The right handed operator should be in the eight o’clock position whereas the left handed operator should be in the four o’clock position. The target area is the height of the mucobuccal fold over the mental foramen (Fig. 21, A and B). The foramen can be manually palpated by applying gentle finger pressure to the body of the mandible in the area of the premolar apicies. The patient will feel slight discomfort upon palpation of the foramen. Use a retraction instrument to retract the soft tissue. The needle is directed toward the mental foramen with the bevel facing the bone. Penetrate the soft tissue to a depth of five millimeters, aspirate and inject approximately 0.6cc of anesthetic solution. Successful execution of this technique results in anesthesia of the buccal soft tissue anterior to the foramen, lower lip and chin on the side of the injection.1

	Figure 21, A: Location of the mental and incisive nerves.
	Figure 21, B: Block of the mental and incisive nerves: The needle is inserted at the height of the mucobuccal fold over the mental foramen for both the mental nerve block and incisive nerve block.

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Incisive Nerve Block

The incisive nerve block is not as frequently employed in clinical practice however it proves very useful when treatment is limited to mandibular anterior teeth and full quadrant anesthesia is not necessary. The technique is almost identical to the mental nerve block with one additional step. Both the mental and incisive nerves are anesthetized using this technique. Contraindications to this technique are acute inflammation and infection at the site of injection. A 25 or 27 gauge short needle is preferred for this technique.

Technique- The patient should be in the semisupine position. The right handed operator should be in the eight o’clock position whereas the left handed operator should be in the four o’clock position. The target area is the height of the mucobuccal fold over the mental foramen (See Fig. 21, B). Identify the mental foramen as previously described. Give the patient a mental nerve block as described above and apply digital pressure at the site of injection during administration of anesthetic solution. Continue to apply digital pressure at the site of injection two to three minutes after the injection is complete to aid the anesthetic in diffusing into the foramen. Successful implementation of this technique provides anesthesia to the premolars, canine, incisor teeth, lower lip, skin of the chin, and buccal soft tissue anterior to the mental foramen.1
 

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References

1. Malamed, SF Handbook of Local Anesthesia, 4th Edition 1997, Mosby-Year Book Inc.

2. Snell, RS Clinical Anatomy for Medical Students, 5th Edition 1995, Little, Brown and Company Inc.

3. Loestscher CA, and Walton RE Patterns of Innervation of the Maxillary First Molar: A Dissection Study Oral Surgery Oral Medicine Oral Pathology 65: 86-90, 1988

4. McDaniel, WM Variations in Nerve Distributions of the Maxillary Teeth Journal of Dental Research 35: 916-921, 1956

5. Heasman PA, Clinical Anatomy of the Superior Alveolar Nerves British Journal of Oral and Maxillofacial Surgery 22: 439-447, 1884

6. Malamed SF and Trieger N Intraoral Maxillary Nerve Block: an Anatomical and Clinical Study Anesthesia Progress 30: 44-48, 1983

7. Poore, TE and Carney F Maxillary Nerve Block: A Useful Technique Journal of Oral Surgery 31: 749-755, 1973

8. Gow-Gates, GAE Mandibular Conduction Anesthesia: a New Technique Using Extraoral Landmarks Oral Surgery 36: 321-328, 1973

9. Akinosi JO, A New Approach to the Mandibular Nerve Block British Journal of Oral and Maxillofacial Surgery 15: 83-87, 1977

10. Vazirani, SJ, Closed Mouth Mandibular Nerve Block: A New Technique Dental Digest 66: 10-13, 1960

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