Local Anesthetic Delivery Methods: Protocols for Administering Injections to Help Prevent Pain

Tina Clarke, RDH, MEd, FADHA

August 2023 Course - Expires Monday, August 31st, 2026

Inside Dental Hygiene

Abstract

With dental hygienists in most states now permitted to administer local anesthesia, it is advantageous to consider techniques for administering injections in a manner that causes the least amount of pain to the patient. Techniques for delivering medication while reducing discomfort include practical things like effective interpersonal communication with the patient, using a fresh needle, applying pressure, and palpating the injection site. Other elements that can help reduce pain on injection of local anesthesia include application of a topical anesthetic agent on the site of insertion, as well incorporating a buffer into a formulation. The goal is to keep the patient comfortable not only during treatment itself but during the delivery of the anesthesia as well. This article provides an overview of protocols the hygienist can follow to administer injections with less physical irritation.

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Administering local anesthesia can be a tug-of-war on the psyche of a dental hygienist. On the one hand, the hygienist wants to make the patient as comfortable as possible before treatment. The stress of administering an injection and the fear of inflicting even more discomfort from the injection itself can make one wonder if it is all worthwhile. One of the big draws to the profession of dental hygiene is the aspect of providing quality care to patients. Hygienists naturally care about their patients and do not want to cause any additional pain. When hygienists can keep their patients comfortable for both the anesthetic injection and the treatment itself, they are better able to provide the highest quality care during any type of procedure. By employing some simple strategies, hygienists can reduce the pain, stress, and aggravation involved in administering an injection, making the entire experience better for both the patient and the hygienist.

Dental hygienists in most states are permitted to administer local anesthesia at various levels of supervision, but each state has different regulations, which is why it's important to understand state laws.1 Protocols for successful injections include tangible factors, such as the use of a topical anesthetic at the injection site, the type of anesthetic to be used and whether to use a buffering agent, as well as the importance of using a fresh needle. Employing effective technique includes additional factors such as tissue retraction, deposition rate, selecting the correct site for the injection, and the application of pressure. Perhaps most importantly, person-to-person communication with the patient is also key to success.

Communication Strategies

The author recommends talking with the patient about the injection process, taking a moment to listen to and understand any concerns he or she may have, and then addressing any concerns. It might be helpful to remind the patient that it is normal to be fearful of the injection process. The hygienist can assure the patient that getting them numb effectively and keeping them comfortable during treatment is of highest priority.

Other communication strategies include coaching the patient through breathing techniques, using aroma therapy, or incorporating other anxiety reduction methods. Simple acts like these can reinforce the confidence the patient has in the hygienist.

Reassuring words are especially useful when treating pediatric patients, for whom it might be useful to use praise, storytelling, counting, or even singing.2

Using Topical Agents

An obvious and often-used method for reducing discomfort is applying a topical anesthetic before the injection is administered. Topical anesthetics have long been used in dental procedures. While their use is not without risk, they have a record of safety.3 They are prepared in a wide range of formulations and can be delivered as liquids, gels, ointments, and sprays.3

As in the case of local anesthesia, dental hygienists in most states are permitted to administer topical agents, at various levels of supervision, but each state has different regulations pertaining to topical agents, which is why it's important to understand state laws here as well.1

One of the most common uses of a topical anesthetic is placing 20% benzocaine topical for about one minute on the tissue at the insertion site.4 This will numb the first few millimeters of the soft tissue, making the initial pinch of needle insertion more tolerable. Benzocaine is an ester with limited absorption into the circulatory system and low potential for toxicity.3,5,6Benzocaine takes effect within 30 seconds and reaches optimal affect after 2 or 3 minutes, and its duration lasts between 5 and 15 minutes.3

If benzocaine is contraindicated for a patient, if he or she is unable to tolerate esters, has sensitivity, or a medication conflict, other options are available. One of the more popular is 2% to 5% lidocaine gel.3,4,7Lidocaine is an amide with onset at 2 to 10 minutes and duration of about 15 minutes.3

Additional topical agents that are commonly used in dentistry include prilocaine, an amide, and tetracaine, an ester, both used in combination with other agents.3 Dyclonine hydrochloride, a ketone available as a rinse, can be used for patients unable to tolerate either esters or amides.3

An item of note is a little topical goes a long way, especially when used with pediatric patients.2Using too much and having it placed for prolonged periods of time can cause the tissue to slough, creating an ulcer in the area.2

Deposition Rate

Depositing the solution slowly can help alleviate two challenging factors associated with the delivery of local anesthesia. One benefit is that depositing slowly reduces the opportunity for an anesthetic overdose. The second is a slow deposition rate can reduce the burning and stinging sensation often felt by the patient. Due to the solution's acidic pH, the patient may experience a burning sensation. When expressing an anesthetic, especially the first few drops (1/4 cartridge), it is recommended to progress slowly. This allows the anesthetic to diffuse into the submucosal space. When the nerve near the deposition site starts to go numb, the burning sensation goes away. The advised flow rate is about 1 to 2 minutes for the entire cartridge.8

The author recommends that after a negative aspiration, slowly deposit the solution at a rate of about 20 to 25 seconds for the first 1/4 of the cartridge. After a second aspiration, if negative, increase your flow rate back up to 1 minute for the cartridge. Not only will this technique reduce the initial sting, but it is also an ideal way to reduce local anesthetic overdose.9

To help reduce pressure on tissue and to provide a less traumatic injection, slow deposition is especially advisable for pediatric patients, for whom a single penetration-or multiple penetrations-might be advisable.2

Also of note is that because pediatric patients are more likely to bite down on soft tissue after being injected with local anesthesia, consider using a shorter-acting agent for them.2 Advising the patient and his or her parent to delay eating or drinking hot beverages is recommended post procedure, and placing a gauze roll in the mouth may be helpful as well.2

Considering the Anesthetic pH

As mentioned above, the sensation of burning is a common experience for patients. The other factor leading to this sensation is the acidity of the anesthetic solution. In general, anesthetics with vasoconstrictors are about 3-4 on the pH scale while plain anesthetics tend to be about a 6 on the pH scale. Normal, healthy tissue has a pH of about 7. This means that when the anesthetic is delivered into this neutral environment, the patient can feel a burning or stinging sensation.8,10,11 It can be compared to the sensation one might encounter when pouring lemon juice on a cut. Methods of alleviating this sensation include using plain anesthetic solution or using one with buffering agents.

To aid in patient comfort and profound anesthesia, some clinicians use a combination of plain anesthetic followed by an anesthetic with a vasoconstrictor. Since plain anesthetics have a pH closer to the body's natural pH level, it is considered an excellent option for patient pain management.

Another option that is gaining popularity in dentistry is to use a buffering agent with an anesthetic solution.10 The use of sodium bicarbonate in solution with the local anesthetic creates a pH that is closer to the neutral environment of the oral tissues. When a buffering agent is used, it reduces the sting of the solution but also decreases the onset time of the anesthetic solution. A bonus is the clinician does not need to use multiple anesthetic solutions to create a comfortable injection for the patient. There are a few different buffering agents available on the market. It's incredibly important to read and understand the directions for use. Each anesthetic has a different pH which requires a different amount of buffering agent.

Other Factors to Consider

Angulation and Insertion Site

Evaluating the alveolar process and the soft tissue is crucial for administering a comfortable injection. Inserting too close to the bone or over angulation creates the potential to skid across mucoperiosteum. This can cause tremendous pain for the patient.

To avoid this, make sure to insert a few millimeters away from the alveolar process and keep the barrel of the syringe parallel with the angulation of the maxilla or mandible.

Muscle and frenum attachments are another aspect to be aware of. If the needle is inserted into a muscle, not only is it painful for the patient, but trismus is more likely to occur. Similarly, inserting into or immediately next to a frenum can cause minor tissue damage and increase post injection pain for the patient.

To avoid these situations, it is recommended that clinicians review anatomy and palpate the region being anesthetized. Understanding locations of muscles will help clinicians avoid them with the needle. A notable characteristic of frenums is that they are easily moved. When retracting the lip, move it forward or backward and notice the position change of the frenulum.

Using a Fresh Needle

A fresh needle has a beveled angle that allows for penetration without causing tissue trauma.12

When a needle is used several times or has contacted bone, the sharp point becomes dull and even bends. Under magnification the little bent end looks like a small fishhook.13 A used needle makes penetrating the mucosa more challenging, even if the tissue is retracted properly. There is a greater likelihood for the tissue to tear or for there to be a noisy "pop" sound when the needle breaks through the mucosa. If the needle tip has become barbed, it can cause sub-mucosal tissue damage.

The needle can also become dulled or barbed upon recapping. If the clinician has touched the inside of the cap with the needle tip, it is possible that the needle now has a small, barbed end.

To minimize pain on injections resulting from a dull needle, it is recommended to replace a needle if bone has been contacted, if there have been multiple penetrations, or if challenges were encountered when recapping.

Needle gauge

Popular sizes for needles used in dentistry include 25-gauge, 27-gauge, and 30-gauge. The higher the gauge number, the smaller the needle. According to the published literature, it is not possible for a patient to feel the difference in these sizes,2,14-16 and the larger-gauge sizes, 25 or 27, are recommended over the 30 because they are stronger and less likely to break.2,14,15
Further, the larger gauge sizes offer more reliable aspiration of the medication.2,14,15

Tissue Retraction

Proper tissue retraction pulls the mucosa tight, which makes it easier for the needle to penetrate. Often when the mucosa is in a "relaxed" state the needle must push the tissue out of the way to penetrate it. This could cause a micro laceration instead of a smaller puncture point, often resulting in more pain and discomfort for the patient. To avoid this, pull the tissue away from the alveolar process, creating a tight, stretched appearance to the tissue. This also creates greater visibility, making it easier for the hygienist to see the site and penetrate with the needle.

Applying Pressure

Applying pressure pre-injection is a valuable step, especially for palatal injections. Using a cotton swab or the back of a mirror handle to apply pressure to the palatal tissue near the insertion site is effective at reducing the painful poke often felt with these injections. It can be accomplished without the use of additional topical anesthesia, and the patient may only experience a broader sense of pressure.

Conclusion

Performing injections can be a daunting task for the clinician and the patient, but it doesn't have to be so stressful. Implementing a few practical strategies can help the patient stay comfortable during the entire process. Evaluating a patient's anatomy, employing proper retraction, and using properly functioning equipment are among the components of success. Topical agents and the use of buffered compounds can increase patient comfort. Communication is also key. Employing these strategies can make the patient say they want their hygienist to give them all their injections. It's therefore possible to say goodbye once and for all to the tug-of-war over patient comfort.

References

1. American Dental Hygienists' Association. Dental hygiene practice act overview: permitted functions and supervision levels by state. https://www.adha.org/wp-content/uploads/2023/05/ADHA-Practice-Act-Overview-5-2023.pdf. Revised May 2023. Accessed July 21, 2023.

2. Jayaraman J, Schwartz S. Local Anesthesia in Pediatric Dentistry. Dentalcare.com. https://www.dentalcare.com/en-us/professional-education/ce-courses/ce325. Updated Feb. 2, 2022. Accessed July 21, 2023.

3. DiMarco AC, Bassett KB, Radif M. Topical Anesthetic Considerations for Dental Procedures. Inside Dental Hygiene.2022;18(8);16-22.

4. Patel TJ. Update on Dental Topical Anesthetics. Decisions in Dentistry. https://decisionsindentistry.com/article/update-on-dental-topical-anesthetics/. Updated May 9, 2019. Accessed July 21, 2023.

5. Yagiela JA. Safely easing the pain for your patients. Dimensions of Dental Hygiene. 2005;3(5):20,22.

6. Tetzlaff JE. Clinical Pharmacology of Local Anesthetics.1st ed. Butterworth Heinemann; 2000:105.

7. Bassett KB, DiMarco AC, Naughton DK. Local Anesthesia for Dental Professionals. 2nd ed. Upper Saddle River, Florida: Pearson Education Inc; 2015.

8. Malamed S. Handbook of Local Anesthesia. 6th ed. St. Louis, Mo: Elsevier Mosby; 2013.

9. Mahajan A, Derian A. Local Anesthetic Toxicity. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK499964/. Updated October 3, 2022. Accessed July 21, 2023.

10. Falkel M, Malamed SF. Buffering: The Key to More Elective and Comfortable Local Anesthesia. Inside Dentistry CE eBook. . Updated May 2020. Accessed July 21, 2023.

11. Taylor A, McLeod G. Basic pharmacology of local anesthetics. BJA Educ.2020 Feb;20(2):34-41. Doi: 10.1016/j.bjae.2019.10.002. Epub 2019 Dec 4. Erratum in: BJA Educ. 2020 Apr;20(4):140. PMID: 33456928; PMCID: PMC7808030.

12. Mathison M, Pepper T. Local Anesthesia Techniques in Dentistry and Oral Surgery. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: . Updated June 1, 2023. Accessed July 21, 2023.

13. Skapetis T, Doan-Tran PD, Hossain NM. Evaluation of bevelled needle tip deformation with Dental Inferior Alveolar Nerve blocks. Aust Endod J. 2019 Dec;45(3):325-330. Doi: 10.1111/aej.12361. Epub 2019 Jul 3. PMID: 31270893; PMCID: PMC7328719.

14. Flannagan T, Wahl MJ, Schmidt MM, Wahl JA. (2007) Size doesn't matter: needle gauge and injection pain. Gen Dent: 2007 May-Jun; 55(3):216-7.

15. Strassler HE. Size Doesn't Matter: Needle Gauge and Injection Pain. Inside Dentistry. 2007;3(7).

16. McPherson JS, Dixon SA, Townsend R, Vandewalle KS. Effect of needle design on pain from dental local anesthetic injections. Anesth Prog. 2015 Spring;62(1):2-7. doi: 10.2344/0003-3006-62.1.2. PMID: 25849467; PMCID: PMC4389552.

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SOURCE: Inside Dental Hygiene | August 2023
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Learning Objectives:

• Discuss simple techniques that can be employed to reduce patient discomfort during anesthetic injections.
• List topical anesthetics that can be used on the injection site and the advantages and disadvantages of each.
‚Äč• Explain how the use of a buffering agent can reduce the burning sensation that might be felt upon injection of an anesthetic.

Disclosures:

The author received an honorarium from BroadcastMed, LLC for this article but reports no conflicts of interest with any material in the article.

Queries for the author may be directed to justin.romano@broadcastmed.com.