Surface Anesthesia

Surface anesthesia is used when topical anesthetics are applied to the surface by gels, creams, or sprays to block the free nerve endings supplying the mucosal surfaces. The effect is short lasting and limited to the direct area of contact. Topical anesthetics are used as a preinjection technique to obtund the pain associated with needle insertion.¹

Local Infiltration

Local infiltration techniques are used when soft tissue anesthesia is needed in a limited area. The anesthesia is deposited close to the smaller terminal nerve endings providing pain relief only in the area of anesthetic diffusion. Dental hygienists can use this technique during nonsurgical periodontal therapy when anesthesia is needed only in the immediate area of injection, and for bleeding control provided by the vasoconstrictor.1,2

Field Block

Field block is a form of regional anesthesia deposited near large terminal nerve branches. It is also referred to as supraperiosteal injections. Anesthesia usually involves pulpal and soft tissue anesthesia of a single tooth in the maxilla (by depositing the solution above the apex of the tooth to be anesthetized) except in the area of the anterior superior alveolar block (ASA) and middle superior alveolar block (MSA) where anesthesia is achieved on more than one tooth using this technique (see Chapter 12). Field block injections are most effective in the maxillary arch due to the porous nature of the bone allowing the anesthetic to easily diffuse through the bone to the nerve. However, this technique can be used on the mandibular laterals and incisors, and is an excellent injection technique when crossover anesthesia is needed (see Chapters 12 and 13). In dentistry, field block injections are often referred to incorrectly as infiltration injections.

Nerve Block

Nerve block anesthesia refers to the injection of local anesthetic in the vicinity of a major nerve trunk to anesthetize the nerve’s area of innervations, usually at a greater distance from the area of treatment. This technique offers an advantage over the other techniques by providing profound pulpal and soft tissue anesthesia over a larger area. The disadvantage is that arteries and veins accompany major nerve trunks, and the potential for piercing the artery or vein with this technique is greatly enhanced.¹ Examples of nerve blocks are the inferior alveolar, posterior superior alveolar, mental/incisive, and infraorbital blocks.

Step 1: Preanesthetic Patient Assessment And Consultation

The patient assessment should be conducted as described in Chapter 7, and vital signs should be obtained and recorded. Appropriate medical and dental consultations should be completed before administration of local anesthetics.

Step 2: Confirm Care Plan

The care plan should be developed by the dental hygienist in collaboration with the patient, and confirmed before treatment. If the dental hygiene care plan involves nonsurgical periodontal therapy with anesthesia, the dental hygienist should carefully determine the extent of periodontal involvement, and how much of the treatment can be realistically accomplished in one visit. Local anesthesia should only be administered in the areas of treatment that can be completed in one visit. Overestimating the treatment and administering more anesthesia than necessary should be avoided.

Depending on the time available for treatment and the extent of periodontal involvement, the dental hygienist should design a care plan by dividing the mouth into quadrants or sextants for treatment. Figure 11-2 illustrates examples of nonsurgical periodontal therapy with anesthesia care plan designs. With advanced periodontal disease and heavy deposits the dental hygienist may only realistically be able to complete a few teeth in a single visit. The dental hygienist should then divide the mouth into sextants rather than quadrants for treatment. (see Figures 11-2A,B) If either sextant or quadrant dental hygiene treatment is planned on the maxillary arch, the posterior superior alveolar (PSA) block is given before any of the other maxillary facial injections as well as any maxillary palatal injections to allow the necessary time for the larger molars to become completely anesthetized, with instrumenting proceeding in the same manner. After the PSA block, the middle superior alvolar (MSA) and then the anterior superior alveolar (ASA) block (or infraorbital [IO] block instead) is then given (in that order). For patients with initial to moderate periodontal disease, the dental hygienist may complete one to two quadrants during a single visit. When two quadrants are treated in a single visit, it is recommended to treat upper and lower quadrants on either the right or left side of the patient’s face. (Figure 11-2C) The dental hygienist should avoid administering local anesthetics to both the mandibular right and left quadrants during a single treatment to prevent the inability of the patient to control his or her mandible. Administering bilateral inferior alveolar nerve blocks also increases the possibility of the patient causing self-mutilation of their soft tissues (see Chapter 14). If half-mouth treatment is planned, the inferior alveolar and buccal blocks are given first, then the maxillary facial, and then palatal injections follow in order as described earlier, with instrumenting proceeding first on the maxillary arch. This allows time for the entire mandibular arch to become completely anesthetized. When designing the dental hygiene care plan, the dental hygienist must consider the amount of anesthetic needed to complete the procedure (always staying within the patient’s MRD).

Step 3: Informed Consent

The benefits and risks associated with all treatment including the administration of local anesthetics should be discussed, as should the risks involved in not receiving treatment. The dental hygienist should discuss with the patient the type of anesthetic that will be used, and the injection procedure. The patient should be advised of the temporary numbing feeling associated with the administration of the drug, and the anticipated duration of anesthesia. Following the care plan discussion, informed consent to treatment should be received by the patient. In the case of a minor, the informed consent must be given by the parent or guardian. Figure 11-3 is a sample informed consent form that includes the consent to the administration of anesthetics. The written agreement of the care plan becomes a legal contract between the patient and the dental hygienist.²

Step 4: Selection Of Injection

After the care plan has been determined, the dental hygienist should determine the appropriate injections for complete pulpal and/or soft tissue anesthesia. There are many factors to take into consideration for injection selection:

Step 5: Preparation Of Equipment

The preparation of equipment should be completed as described in Chapter 9. The appropriate selection of a syringe is important, taking into consideration the hand size of the dental hygienist and the hygienist’s ability to properly conduct the aspiration test (Figure 11-4). The bulkiness of the anesthetic syringe and the length of dental anesthetic needles can be frightening to the patient; therefore, they should be covered or placed out of the patient’s sight (Figure 11-5). The equipment may be set up before the patient’s arrival if the care plan and selection of appropriate anesthetic has already been determined at a previous appointment. However, any recent changes in the patient’s medical history may require a modification in anesthetic selection.

Step 6: Check The Anesthetic Equipment

Before administration of the local anesthetic, the dental hygienist should check the needle bevel orientation for planned injections in close proximity to the periosteum. The bevel should be oriented toward the bone. For these injections, the bevel indicator (Figure 9-21) should be turned opposite the large window. This will ensure that when the dental hygienist is holding the syringe palm up with the large window facing him or her, the bevel will be toward the bone when the injection is commenced. Although the bevel of the needle does not affect success rates of the injection, it will provide added comfort to the patient and less trauma to the periosteum if the bone is contacted.

It is recommended to expel a few drops of anesthetic to ensure free flow of the solution. The dental hygienist should confirm that the harpoon is fully secured into the rubber stopper by gently pulling back on the thumb ring. The syringe is then ready for use. The dental hygienist should confirm that all protective equipment is in place, including re-capping devices, and personal protective equipment for the clinician and patient.

Step 7: Patient Position

Supine positioning (head and heart parallel to the floor) (Figure 11-6) with the patient’s feet slightly elevated is the most effective position to administer anesthesia. Because supine positioning is the recommended position to treat vasodepressor syncope, this adds the benefit of decreasing the risk of a patient fainting before, during, or after the administration of the anesthetic.^3,4 The dental hygienist should ask the patient to turn his or her head appropriately for the greatest visibilty of the penetration site.