Posterior Posterior superior superior alveolar alveolar

(PSA) nerve (PSA) nerve blockblock

Chirag M A3rd year BDS

Posterior superior Posterior superior alveolar (PSA) nerve alveolar (PSA) nerve

blockblock•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.

• The risk of a potential complication must be The risk of a potential complication must be considered whenever the PSA block is used .considered whenever the PSA block is used .

• Insertion of the needle too far distally may Insertion of the needle too far distally may lead to a temporarily unesthetic hematoma.lead to a temporarily unesthetic hematoma.

• When the PSA is to be administered, one When the PSA is to be administered, one must always consider the patients skull size must always consider the patients skull size in determining the depth of soft tissue in determining the depth of soft tissue penetration.penetration.

• In order to decrease the risk of hematoma In order to decrease the risk of hematoma formation after PSA nerve block, formation after PSA nerve block, SHORT SHORT DENTAL NEEDLESDENTAL NEEDLES have been recommended. have been recommended.

• The average depth of soft tissue penetration The average depth of soft tissue penetration is 16mm, the short needle (=20mm) can be is 16mm, the short needle (=20mm) can be successfully and safely used.successfully and safely used.

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

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 1.When treatment involving two or

more maxillary molarsmore maxillary molars2.When supraperiosteal injection is 2.When supraperiosteal injection is

contraindicated like infections and contraindicated like infections and acute inflammationsacute inflammations

3.When supraperiosteal injection has 3.When supraperiosteal injection has proved ineffectiveproved ineffective

Advantages:1.Atraumatic2.High success rate (>95%)3.Minimum number of injections, 1

injection compared with 3 infiltrations4.Minimizes the total volume of local

anesthetic solution administered

Disadvantages:1.Risk of hematoma2.Technique somewhat arbitrary3.Second injection necessary for

treatment of the mesio buccal root of maxillary 1st molar in 28% of patients

Posterior superior alveolar Posterior superior alveolar nervenerve

Area of anesthetization Area of anesthetization

PSA nerve (arbitrary view)

PSA nerve PSA nerve block block

TechniquesTechniques

TechniqueTechnique PSA Nerve PSA Nerve BlockBlock

1) 25 gauge 1) 25 gauge shortshort needle is recommended needle is recommended2) Insert needle at the height of the 2) Insert needle at the height of the mucobuccal mucobuccal

foldfold above the maxillary above the maxillary 22ndnd molar molar3) Target area is the PSA nerve which is 3) Target area is the PSA nerve which is posteriorposterior, ,

superiorsuperior and and medial medial to the posterior border of to the posterior border of the maxillathe maxilla

4) Landmarks: mucobuccal fold, maxillary 4) Landmarks: mucobuccal fold, maxillary tuberosity and zygomatic process of maxillatuberosity and zygomatic process of maxilla

5) Have patient open their mouth 5) Have patient open their mouth half wayhalf way which which makes more roommakes more room

6) 6) RetractRetract the patient’s cheek with mirror the patient’s cheek with mirror

7) Pull the tissues at the injection site 7) Pull the tissues at the injection site tauttaut

8) Orient bevel 8) Orient bevel towardtoward bone bone9) Insert needle at height of mucobuccal 9) Insert needle at height of mucobuccal

fold over the fold over the 22ndnd maxillary molar maxillary molar10) Advance needle 10) Advance needle upwardupward, , inwardinward and and

backward backward directiondirection11) Odd feeling of having no resistance 11) Odd feeling of having no resistance

whatsoever whatsoever 12) Penetrating to an average depth of 12) Penetrating to an average depth of 1616

mm is adequate and mm is adequate and 10-1410-14mm adequate mm adequate for smaller skulled patientsfor smaller skulled patients

13)13) Aspirate in two planes by rotating bevel Aspirate in two planes by rotating bevel one quarter turnone quarter turn

14) Deposit 0.9-1.8ml of anesthetic solution14) Deposit 0.9-1.8ml of anesthetic solution15)15) Wait Wait 33 to to 55 minutes to start treatment minutes to start treatmentNote: Note: Goal is to deposit LA close to PSA nerve. Goal is to deposit LA close to PSA nerve.

Advance the needle in one movement, not three Advance the needle in one movement, not three separate movements; usually atraumatic to most separate movements; usually atraumatic to most patients. For left PSA nerve block, administrator patients. For left PSA nerve block, administrator should be at 10’o clock position and for right PSA should be at 10’o clock position and for right PSA nerve block administrator should be at 8’o clock nerve block administrator should be at 8’o clock positionposition

Signs and symptoms:1.Absence of pain during treatment2.Use of electrical pulp testing with no

response from tooth with maximal EPT output

Safety features:1.Slow injection2.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

Failure of Anesthesia:1.Needle too lateral. To correct: redirect

the tip medially2.Needle not high enough. To correct:

redirect the needle tip superiorly3.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.

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