Posterior Superior Nerve Block Technique

What it numbs:

The posterior superior nerve block (PSA) provides pulpal anesthesia to the three maxillary molars and the supporting buccal soft tissue and bone.  In 28 percent of patient the mesial buccal root of the first molar may not be anesthetized.

The (PSA) Posterior Superior Alveolar never block is a common injection we provide our patients with when performing SRP.

For all maxillary injections, drying the tissue and making it taut helps give you good vision for needle placement and make painless penetration possible. The slower the speed in which you deposit the anesthetic the more comfortable the patient will be.  


A 27-gauge short needle is most commonly used. A 25-gauge short is recommended.  


Patient position is supine or semi supine.  

For the right PSA nerve block and right handed operator, sit at an 8 o’clock position directly facing the patient.  

For the left PSA nerve block and right handed operator, sit at an 10 o’clock position directly facing the patient.  


The landmarks are the mucobuccal fold above the maxillary second premolar, the maxillary tuberosity and the zygomatic process.

Target area:

The target area and injection site is located at the height of the buccal fold above the apex of maxillary second molar.

The bevel of the needle should be toward the bone and inserted upward and inwards at a depth of 16mm. For a small adult or child insert the needle at a depth of 10-14mm.  

Aspirate, if after two negative aspirations slowly inject 1/2 of the cartridge over 30 seconds.  

Observe patient after injection.


Document in patient record, what injection you gave, who gave it, what kind of anesthetic, how much anesthetic, negative aspiration, no complications, ect.  


For more information and references:

Handbook of Local Anesthesia by Stanley F. Malamed  

Good Article with pictures: Pain Control: The Options by Laura J Webb,CDA,RDH,MS, April 2010