Dental Anesthesia Techniques Quiz

Maxillary Anesthesia Techniques

• Techniques for maxillary anesthesia include Anterior Superior Alveolar Nerve Block (ASANB) and Posterior Superior Alveolar Nerve Block (PSANB).
• Dr. Ahmed Mohammed Saaduddin, Assistant Professor of Oral & Maxillofacial Surgery, and Consultant of Oral Surgery at Batterjee Medical College, Jeddah, presented these techniques on August 25, 2024.

Maxillary Nerve Anatomy

• The maxillary nerve has branches within the cranium, including the middle meningeal nerve.
• Other branches are in the pterygopalatine fossa: zygomatic nerve (zygomaticotemporal and zygomaticofacial nerves), pterygopalatine nerves (palatine branches, nasal branches, orbital branches, and pharyngeal branch), and PSA nerve.
• Branches within the infraorbital canal include MSA and ASA nerves.
• Branches on the face include inferior palpebral, external nasal, and superior labial branches.

Posterior Superior Alveolar Nerve Block (PSANB) Technique

• Other names: Zygomatic block, tuberosity block.
• Nerves anesthetized: PSAN.
• Areas anesthetized: Buccal mucoperiosteum over the maxillary molars, buccal and palatal alveolar plates of bone, periodontium of maxillary molars (except MB root of 1st molar), pulps of maxillary molars (except MB root of 1st molar), and adjacent lining of the maxillary sinus.
• Goal: To deposit local anesthetic close to the PSA nerves, located posterosuperior and medial to the maxillary tuberosity.
• Indications: Treatment involving two or more maxillary molars, ineffective supraperiosteal injection (e.g., thick zygomatic buttress), contraindicated supraperiosteal injection (e.g., infection, inflammation).
• Contraindications: Infection at the site of injection, high risk of hemorrhage.
• Positive Aspiration: 3% (high).
• Alternatives: Supraperiosteal infiltrations, maxillary nerve block.
• Armamentarium: Short needle (20 mm length, 25 or 27-gauge), aspirating syringe, local anesthetic cartridge (with or without vasoconstrictor).
• Point of insertion: Height of the mucobuccal fold above the maxillary second molar.
• Target area: PSAN as it enters the posterior surface of the maxilla (posterior, superior, and medial) to the maxillary tuberosity.
• Technique: Open mouth partially, retract cheek with a mirror, pull tissues taut, insert needle into height of mucobuccal fold over second molar. Advance needle slowly in one (not three) movement: upward (45° to occlusal plane), backward (45° to second molar's long axis), and inward (45° toward midline and occlusal plane).
• Depth of needle insertion: For average adults: 3/4 of short needle length (16 mm); for smaller adults and children: 1/2 of short needle length (10 mm).
• Aspiration test: Two perpendicular planes; 0.9ml to 1.8ml of anesthetic solution over 30–60 seconds with aspirations during injection.
• Needle withdrawal: Single hand scoop technique for recapping.
• Post-injection time for treatment: 3 to 5 minutes.

Clinical Findings (PSANB)

• Subjective: Tingling and numbness, difficulty determining extent, only some may report numbness opposite molars.
• Objective: Absence of pain during probing, no response with maximal EPT output, no response with freezing spray, absence of pain during treatment.

Advantages (PSANB)

• High success rate (over 95%).
• Atraumatic, because target area is loose connective tissue and doesn't involve bone.
• Minimizes number of injections.
• Minimizes anesthetic solution volume.

Disadvantages (PSANB)

• Risk of diffuse intraoral hematoma (buccal mandibular region).
• Arbitrary technique because there are no bony landmarks.
• Second injection sometimes required for full anesthesia (in approximately 30%).

Causes of Failures/Complications (PSANB)

• Needle too lateral: redirect medially
• Needle not high enough: redirect superiorly
• Needle too far posterior: withdraw to proper depth

Anterior Superior Alveolar Nerve Block (ASANB) Technique

• Other names: Infraorbital nerve block.
• Nerves anesthetized: Anterior superior alveolar, middle superior alveolar (occasionally), terminal branches of infraorbital nerve (inferior palpebral, lateral nasal, and superior labial branches).
• Areas anesthetized: Pulps of maxillary incisors, canine, premolars and mesiobuccal root of the first molar on the injected side.
• MSA nerve presence: Present in about 30% of population; in majority, anterior superior alveolar nerve carries MSA nerve function.

Clinical Note (ASANB)

• ASA nerve block generally less popular due to lack of experience and fear of injury to the eye.

Indications (ASANB)

• Procedures on two or more maxillary anterior teeth (incisors through premolars) and their buccal tissue.
• Ineffective supraperiosteal injection.
• Inflammation or infection (when supraperiosteal injection contraindicated).

Contraindications (ASANB)

• Areas of inflammation or infection.
• When hemostasis in a localized area is desired.

Advantages (ASANB)

• Minimizes anesthetic solution volume and number of needle punctures.
• Provides a longer anesthetic effect.

Disadvantages (ASANB)

• Doesn't provide hemostasis.

Basic Armamentarium (ASANB)

• The basic armamentarium is a long needle, an aspirating syringe, local anesthetic cartridge with vasoconstrictor.

Auxiliary Armamentarium (ASANB)

• Topical antiseptic, topical anesthetic, hemostat, cotton tweezers.

Patient Position (ASANB)

• Position supine or semisupine with neck extended slightly.
• Dentist stands on the right side (right-handed) facing the patient.

Tissue Preparation (ASANB)

• Dry tissues with sterile gauze.
• Apply topical antiseptic (optional).
• Apply topical anesthetic for 1 minute.

Locate the Infraorbital Foramen (ASANB)

• Feel infraorbital notch and move finger downward, applying gentle pressure.
• Inferior to the notch is the convex bone, representing the infraorbital foramen.
• Feel the concavity below the notch, which is the foramen.

Applied Anatomy (ASANB)

• The infraorbital foramen is funnel-shaped, opening downward and medially.
• Approach the area medially.

Needle Orientation (ASANB)

• Needle parallel to the long axis of ipsilateral first maxillary premolar.

Depth of Needle Insertion (ASANB)

• Average 16 mm (half the length of a typical long needle.)

Safety Measures (ASANB)

• Advance slowly until bone contacted.
• Bone contact at the infraorbital rim.
• Do not palpate the needle; adjust path if it's too superficial.

Aspiration (ASANB)

• Perform twice.
• Rotate the syringe 45 degrees for second aspiration.
• Bevel should not be inside a blood vessel.

Precautions (ASANB)

• Estimate depth before injection.
• Needle tip should contact infraorbital rim of bone.
• Apply finger pressure over the infraorbital foramen.

Amount of Local Anesthetic (ASANB)

• 0.9 ml (1/2 cartridge) to 1.2 ml (2/3 cartridge) over 30–40 seconds using a 25-gauge needle.
• Administrator should feel solution beneath finger on the foramen.

Completion of the Technique (ASANB)

• Withdraw needle slowly from tissues.
• Immediately make the needle safe.
• Apply direct finger pressure over injection site for 1-2 minutes to improve anesthetic solution spread.
• Wait 3–5 minutes before commencing treatment.

Clinical Findings (ASANB)

• Subjective: Tingling, numbness in ipsilateral eyelid, side of nose, upper lip, teeth, and soft tissues along the ASA and MSA nerve pathways.
• Objective: Absence of pain on probing facial mucosa of anterior and premolar teeth, no response to maximal EPT output, no response to freezing spray, absence of pain during treatment.
• Causes for ASANB failure: Needle contacting bone below the infraorbital foramen, (lateral side of nose and upper lip anesthetics may be present). Needle deviating medially and/or laterally in relation to the infraorbital foramen.

Alternative techniques

• Infiltration technique
• Maxillary nerve block
• Periodontal ligament injection.

Complications (ASANB)

• Hematoma (across lower eyelid): prevent with pressure.
• Temporary double vision/horizontal diplopia: due to anesthetic diffusion in the eye socket and extra-orbital muscle anesthesia.