The nasopalatine nerve innervates the palatal tissues of the six anterior teeth. If the needle is inserted into the nasopalatine foramen, it is possible to completely anesthetize the six anterior teeth. However, this technique is painful and not used routinely. The indications for a nasopalatine injection is when palatal soft tissue anesthesia is necessary for restorative therapy on more than two teeth (subgingival placement of matrix bands) and for periodontal and surgical procedures involving the hard palate. Local infiltration is indicated for treatment of one or two teeth. It is contraindicated when there is infection or inflammation in the area of the injection site.
There are two techniques; single penetration and multiple penetration. The single penetration consists of a single penetration of the mucosa directly into the incisive foramen relying on pressure anesthesia and slow deposition of anesthetic solution for pain management. Some clinicians feel this technique is still traumatic, especially for the pediatric patient and suggest a multiple penetration technique to minimize pain. The suggested technique is after buccal anesthesia is achieved with local infiltration, anesthetic solution is injected into the interdental papilla penetrating from the labial and diffusing solution palatally. The palatal tissue is sufficiently anesthetized to proceed with an atraumatic nasopalatine block.
Technique (single penetration):
- A 25 or 27 gauge short or ultra-short needle may be used.
- The area of insertion is the palatal mucosa just lateral to the incisive papilla (located in the midline behind the central incisors).
- The path of insertion is approaching the incisive papilla at a 45 degree angle with the orientation of the bevel toward the palatal tissue.
- Clean and dry the tissue with sterile gauze.
- Apply topical anesthetic lateral to the incisive papilla for two minutes.
- After two minutes move the cotton applicator directly onto the incisive papilla. Apply sufficient pressure so there is blanching.
- Place the bevel of the needle against the blanched soft tissue at the injection site.
- Apply enough pressure to slightly bow the needle. Deposit a small amount of anesthetic.
- Straighten the needle and penetrate the tissue with the needle.
- Continue to apply pressure with the cotton applicator while injecting.
- Slowly advance the needle toward the incisive foramen while injecting until bone is contacted (about 5mm).
- Withdraw the needle 1mm and aspirate.
- If negative, slowly deposit no more than a ¼ cartridge of anesthetic.
- The needle is withdrawn and recapped.
- Wait 2-3 minutes before commencing with treatment.
Technique (multiple penetration)
- A 25 or 27 gauge short or ultra-short needle is recommended.
- There are 3 points of insertion:
- The labial frenum between the maxillary central incisors.
- The interdental papilla between the maxillary central incisors.
- The palatal soft tissue lateral to the incisive papilla.
- First injection: If labial anesthesia has not been achieved with labial local infiltration of the area, the following injection is performed. If the area is anesthetized, proceed to the second injection.
- The path of insertion is into the labial frenum with the orientation of the bevel of the needle toward the bone.
- Clean and dry area with sterile gauze.
- Apply topical anesthetic for 1 minute.
- Retract the upper lip to improve visibility.
- Insert the needle into the frenum and deposit 0.3ml anesthetic solution over 15 seconds. The tissue may balloon. Anesthesia of the tissue should develop immediately.
- Withdraw the needle.
- Second injection:
- Hold the needle at right angles to the papilla. The orientation of the bevel is not relevant.
- Retract the lip to improve visibility.
- Insert the needle into the papilla just above the crest of bone.
- Direct it toward the incisive papilla on the palatal side of the interdental papilla while slowly injecting anesthetic solution. Do not penetrate through the palatal tissue.
- When blanching is noted in the incisive papilla, aspirate.
- If negative administer 0.3ml of anesthetic solution over 15 seconds.
- Withdraw the syringe.
- Third injection:
- Proceed as above for the single penetration injection; however, application of topical anesthetic and pressure anesthesia is unnecessary.
Palatal anesthesia in the area of the canine may be inadequate due to overlapping fibers from the greater palatine nerve. To correct this, it may be necessary to supplement the anesthesia with local infiltration.