Pain Management Ch 12: Max Injections
What are the two most common causes of anesthetic failure associated with maxillary infiltration injections?
The two most common causes of anesthetic failure with infiltrations include deposition of solution too far from the apex of a tooth and inadequate volumes of solution.
What are two maxillary nerve block techniques discussed in this text?
There are three well-recognized techniques for anesthetizing the maxillary nerve. The two discussed in this text include the facial approach and the palatal approach.
What needle is commonly used for PSA nerve blocks?
A 27-gauge short needle is most commonly used, which is consistent with the low rate of positive aspiration.
What needle is commonly used for an MSA nerve block?
A 27-gauge short needle is used most commonly for an MSA nerve block.
Discuss indications and benefits of a maxillary nerve block.
A maxillary nerve block is indicated for hemimaxillary pain management. The benefit of maxillary nerve blocks is that a single injection can replace multiple injections when providing anesthesia for an entire half of the maxilla. Maxillary nerve blocks are also useful when other penetration sites or pathways on the same side of the maxilla are infected and needle penetrations for local anesthesia risk deeper spread of the infections or do not effectively anesthetize the target tissues or both.
Explain the importance of applying 1 to 2 minutes of finger pressure over the deposition site following an IO nerve block?
Applying finger pressure over the deposition site for 1-2 minutes enhances diffusion of the anesthetic solution into the infraorbital canal.
Explain why the PSA nerve block has the second highest risk of hematoma compared to other injections.
Because of the proximity of its deposition site to the pterygoid plexus of veins and associated maxillary arteries, the PSA injection has the highest risk of hematoma formation of intraoral techniques with the exception of the tuberosity approach to the maxillary or second division nerve block.
Discuss common causes of maxillary nerve block failure.
Common causes of anesthetic failure include deposition of solution too far from the maxillary nerve and inadequate volumes of solution. Impassable obstructions and penetration of the nasal cavity or orbit and intravascular deposition are also sources of failure in greater palatine maxillary blocks. Hematoma formation during high tuberosity maxillary blocks and positive aspirations are common sources of failure. Other causes may include inflammation or infection in the area of deposition.
What needle modification may be preferred for a palatal approach maxillary block?
Considering the limited space available in the posterior areas of the oral cavity, some clinicians find it useful to bend needles when performing this technique.
What volume of anesthetic solution is deposited for an infraorbital (IO) nerve block?
Deposit a minimum of 0.9 mL of an appropriately selected local anesthetic drug.
The middle superior alveolar nerve is absent in approximately 28% to 50% of individuals? True or False
False The MSA is PRESENT in 28 to 50%
:What is the distance from the infraorbital ridge to the infraorbital foramen in a typical adult?
In the typical adult, the IO foramen is located approximately 8-10 mm below the IO ridge.
When are infiltration injections indicated?
Infiltration injections are indicated when procedures are confined to one or two teeth or to tissue in a limited area.
What is the indication for a posterior superior alveolar (PSA) nerve block?
Posterior superior alveolar nerve blocks are indicated for pain management of multiple molar teeth in one quadrant.
What structures are affected by infiltration injections?
Structures affected by infiltration injections include the dental plexus of the injected site (the pulps of the teeth and facial areas of the gingiva, periodontal ligament, and alveolus). Additionally, due to the diffusion of the anesthetic solution, some terminal branches of the facial nerve (VII) are affected. All or a portion of the upper lip, cheek, and lower nose are anesthetized with many maxillary injections.
Discuss the possible anatomical variations related to the middle superior alveolar nerve and the significance to the MSA injection.
Studies have reported the absence of an MSA nerve in between 50% and 72% of individuals. In the absence of an MSA nerve, branches of the anterior superior alveolar and/or the posterior superior alveolar nerve innervate the first and second premolars and the mesiobuccal root of the first molar.
Describe the field of anesthesia for an anterior superior alveolar nerve block.
The ASA will anesthetize structures innervated by the anterior segment of the ASA nerve. They include the pulps of the maxillary central incisor through the canine on the injected side and their facial periodontium. Because of diffusion of the anesthetic solution some terminal branches of the facial nerve are affected as well. All or a portion of the upper lip, cheek, and lower nose will be anesthetized.
Describe the field of anesthesia for an infraorbital (IO) nerve block.
The IO nerve block will affect structures innervated by the anterior and middle superior alveolar and IO nerves. Areas anesthetized include the pulps of the maxillary central incisors through the canine, premolars,and their facial periodontium, the lower eyelid, lateral aspect of nose, and upper lip. In some individuals, the mesiobuccal root of the maxillary first molar is also anesthetized.
Describe the angle of the needle insertion for PSA nerve blocks.
The angle of needle insertion for PSA nerve blocks is upward (at a 45-degree angle to the occlusal plane of the maxillary teeth), inward behind the maxillary tuberosity (at a 45-degree angle to the midsagittal plane), and then must be advanced backward behind the posterior aspect of the maxilla. To achieve this, the barrel of the syringe must be angled downward from the occlusal table and outward from the patient's midsagittal plane.
Where is the deposition site for an ASA injection?
The deposition site is above the apical area of the canine at the height of the canine fossa.
What is the depth of penetration to the deposition site for an MSA nerve block?
The depth of penetration to the site of deposition is based on the location of the apex of the tooth and is usually achieved within 5-8 mm.
What anatomical feature of the maxilla allows for a high success rate of anesthesia by infiltration techniques?
The facial bone of the maxilla is relatively thin and permeable. Local anesthetic solutions easily diffuse through maxillary bone.
What vascular structures are located in the infratemporal fossa?
The infratemporal fossa contains the maxillary artery and its branches, and the pterygoid plexus of veins.
17: What is the penetration site for a PSA nerve block?
The penetration site is at the height of the mucobuccal fold, posterior to the zygomatic process of the maxilla and generally superior to the distobuccal root of the maxillary second molar.
What is the optimum depth of insertion for a PSA injection?
The optimum depth of insertion is 16 mm (5 mm from the hub of a 21 mm short needle); however, clinicians should allow for anatomical variances contributing to the depth of insertion which can range from 10-16 mm.
Describe the optimum site of penetration for infiltration injections.
The optimum site of penetration for infiltration injections is at the height of the mucobuccal fold nearest the apex of the tooth to be anesthetized. A bony ridge or eminence can be palpated in the mucosa overlying each facial root of maxillary teeth. This eminence serves as a landmark for visualizing the long axis of the tooth and locating the apex of the tooth for the penetration site.
What is the penetration site and depth of penetration for the palatal approach to the maxillary nerve block?
The penetration site for a greater palatine maxillary nerve block is in the mucosa that lies directly over the greater palatine foramen. The penetration depth is 30 mm.
In a typical adult patient, the Intraorbital forament is approximately 8 to 10 mm below the infraorbital ridge. True or False
True 8 to 10 mm is considered a normal range.
Which one of the following is most likely to increase the risk of hematoma following a PSA nerve block? a. The needle is inserted too deep or too posterior to the deposition siete on the posterior surface of the maxilla. b. The needle is inserted too inferior to the posterior surface of the maxilla. c. The porous bony surface of the maxilla allows the needle to penetrate the maxilla-piercing the blood vessels. d. A long needle is inserted, contacting the bony periosteum on the surface of the maxilla.
a. The needle is inserted too deep or too posterior to the deposition siete on the posterior surface of the maxilla. Over insertion of the needle increases the risk of hematoma formation in PSA blocks. This can occur both by deeper invasion into the pterypalatine fossa or by location too posteriorly initially.
Which one of the following statements best describes the needle pathway for an infiltrative injection technique? a. The needle is parallel to the long axis of the tooth, passing through thin mucosla tissues to superficial fascia containing loose connective tissue, and past small vessels and microvascular, and nerve endings. b. The needle is distal to the long axxess of the tooth, passing through thin mucosal tissue to deep fascia of connective tissues, and past small bessels, alveolar bone, and nerve endings. c. The needle is parallel to the long axis of the tooth, passing through thin mucosal tissues to superficial tissue, and past small vessels, nerves, and bone. d. The needle is perpendicular to the long axis of the tooth, passing through thick mucosal tissue, dense connective tissues, muscle, and vessels, and past microvasculature and nerve endidngs.
a. The needle is parallel to the long axis of the tooth, passing through thin mucosla tissues to superficial fascia containing loose connective tissue, and past small vessels and microvascular, and nerve endings.
When infiltration injections are unsuccessful, it may be helpful to: a. Change the length of the needle and repeat the injection. c. Establish contact with bone before administering one cartridge of anesthetic solution. d. Repeat the same injection and deposit more solution.
b. Visualize, palpate, check radiographs, and reassess the technique.
Which one of the following provides the most accurate description of the field of anesthesia in a PSA injection? a. Pulps of the maxillary premolars and molars, and the facial gingiva, periodontal ligament, and the alveolar bone on the side injected. b. Pulps of the maxillary and mandibular molars on the side injected. c. Pulps of the maxillary teeth to the midline, and their facial gingiva, perio ligament, and alveolar bone on the side injected. d. Pulp of the maxillary molars, except sometims the mesiobuccal root of the first molar, and their facial gingiva, periodontal ligament, and alveolarbone on the side injected.
d. Pulp of the maxillary molars, except sometims the mesiobuccal root of the first molar, and their facial gingiva, periodontal ligament, and alveolarbone on the side injected.