The posterior superior alveolar (PSA) nerve block is a widely used technique for anesthetizing the maxillary molars, though it may not sufficiently anesthetize the mesio buccal root of the maxillary first molar in up to 28% of patients. Key considerations include the risk of hematoma and the depth of needle penetration, with an average recommended depth of 16mm using a short needle. Indications for the PSA block include treatment of multiple maxillary molars and instances where supraperiosteal injection is contraindicated.

1. Posterior superiorPosterior superior
alveolar (PSA)alveolar (PSA)
nerve blocknerve block
Chirag M A
3rd
year BDS

2. Posterior superior alveolarPosterior superior alveolar
(PSA) nerve block(PSA) nerve block
•The posterior superior alveolar nerve block is a most
commonly used nerve block, although it is a highly successful
technique (>95%)
•The PSA nerve block is effective for the maxillary 3rd
, 2nd
and
1st
molar except the mesio buccal root of maxillary 1st
molar
(doesn’t anesthetize in 28%of patients), which is supplied by
middle superior alveolar nerve.
•Therefore the second injection, usually supraperiosteal, is
indicated after PSA nerve block when effective Anesthesia of
1st
molar is not developed.

3. • The risk of a potential complication must be consideredThe risk of a potential complication must be considered
whenever the PSA block is used .whenever the PSA block is used .
• Insertion of the needle too far distally may lead to aInsertion of the needle too far distally may lead to a
temporarily unesthetic hematoma.temporarily unesthetic hematoma.
• When the PSA is to be administered, one must alwaysWhen the PSA is to be administered, one must always
consider the patients skull size in determining the depthconsider the patients skull size in determining the depth
of soft tissue penetration.of soft tissue penetration.
• In order to decrease the risk of hematoma formation afterIn order to decrease the risk of hematoma formation after
PSA nerve block,PSA nerve block, SHORT DENTAL NEEDLESSHORT DENTAL NEEDLES havehave
been recommended.been recommended.
• The average depth of soft tissue penetration is 16mm, theThe average depth of soft tissue penetration is 16mm, the
short needle (=20mm) can be successfully and safely used.short needle (=20mm) can be successfully and safely used.

4. Other common names:Other common names:
Tuberosity block and Zygomatic blockTuberosity block and Zygomatic block
Nerves anesthetized:
Posterior superior alveolar nerves and its branches
Area anesthetized:
1) Pulps of maxillary 3rd, 2nd and 1st molars (entire tooth
= 72%; mesio buccal root of maxillary 1st molar not
anesthetized = 28%)
2) Buccal periodontium and bone overlying these teeth

5. Contraindications:
1. When the risk of hemorrhage is too great (as with a
hemophiliac), in which case a supraperiosteal injection or
PDL injection is recommended
Indications:
1.When treatment involving two or more maxillary1.When treatment involving two or more maxillary
molarsmolars
2.When supraperiosteal injection is contraindicated like2.When supraperiosteal injection is contraindicated like
infections and acute inflammationsinfections and acute inflammations
3.When supraperiosteal injection has proved ineffective3.When supraperiosteal injection has proved ineffective

6. Advantages:
1. Atraumatic
2. High success rate (>95%)
3. Minimum number of injections, 1 injection compared
with 3 infiltrations
4. Minimizes the total volume of local anesthetic solution
administered
Disadvantages:
1. Risk of hematoma
2. Technique somewhat arbitrary
3. Second injection necessary for treatment of the mesio
buccal root of maxillary 1st
molar in 28% of patients

7. Posterior superior alveolar nervePosterior superior alveolar nerve

8. Area of anesthetizationArea of anesthetization

10. PSA nerve (arbitrary view)

11. PSA nerve blockPSA nerve block
TechniquesTechniques

12. TechniqueTechnique  PSA Nerve BlockPSA Nerve Block
1) 25 gauge1) 25 gauge shortshort needle is recommendedneedle is recommended
2) Insert needle at the height of the2) Insert needle at the height of the mucobuccal foldmucobuccal fold above theabove the
maxillarymaxillary 22ndnd
molarmolar
3) Target area is the PSA nerve which is3) Target area is the PSA nerve which is posteriorposterior,, superiorsuperior andand
medialmedial to the posterior border of the maxillato the posterior border of the maxilla
4) Landmarks: mucobuccal fold, maxillary tuberosity and4) Landmarks: mucobuccal fold, maxillary tuberosity and
zygomatic process of maxillazygomatic process of maxilla
5) Have patient open their mouth5) Have patient open their mouth half wayhalf way which makes morewhich makes more
roomroom
6)6) RetractRetract the patient’s cheek with mirrorthe patient’s cheek with mirror
7) Pull the tissues at the injection site7) Pull the tissues at the injection site tauttaut

13. 8) Orient bevel8) Orient bevel towardtoward bonebone
9) Insert needle at height of mucobuccal fold over the9) Insert needle at height of mucobuccal fold over the 22ndnd
maxillary molarmaxillary molar
10) Advance needle10) Advance needle upwardupward,, inwardinward andand backwardbackward directiondirection
11) Odd feeling of having no resistance whatsoever11) Odd feeling of having no resistance whatsoever
12) Penetrating to an average depth of12) Penetrating to an average depth of 1616 mm is adequate andmm is adequate and
10-1410-14mm adequate for smaller skulled patientsmm adequate for smaller skulled patients
13)13) Aspirate in two planes by rotating bevel one quarter turnAspirate in two planes by rotating bevel one quarter turn
14) Deposit 0.9-1.8ml of anesthetic solution14) Deposit 0.9-1.8ml of anesthetic solution
15)15) WaitWait 33 toto 55 minutes to start treatmentminutes to start treatment
Note:Note: Goal is to deposit LA close to PSA nerve. Advance the needle inGoal is to deposit LA close to PSA nerve. Advance the needle in
one movement, not three separate movements; usually atraumatic toone movement, not three separate movements; usually atraumatic to
most patients. For left PSA nerve block, administrator should be at 10’omost patients. For left PSA nerve block, administrator should be at 10’o
clock position and for right PSA nerve block administrator should be atclock position and for right PSA nerve block administrator should be at
8’o clock position8’o clock position

14. Signs and symptoms:
1. Absence of pain during treatment
2. Use of electrical pulp testing with no response from tooth
with maximal EPT output
Safety features:
1. Slow injection
2. No anatomic safety features to prevent over insertion of
the needle; therefore careful observation is necessary
Precautions: The depth of needle penetration should be
correct: over insertion, increases the risk of hematoma and
too shallow might still provide adequate Anesthesia

15. Failure of Anesthesia:
1. Needle too lateral. To correct: redirect the tip medially
2. Needle not high enough. To correct: redirect the needle tip
superiorly
3. Needle too far posterior. To correct: withdraw the needle to
the proper depth
Complications:
1. Hematoma: commonly produced by inserting the needle too
far posteriorly into pterygoid plexus of veins.
2. Mandibular anesthesia: The mandibular division of the 5th
cranial nerve is located lateral to the PSA nerve. Deposition
of LA lateral to the desired location may produce varying
degrees of mandibular anesthesia.

16. Thank youThank you