Possibilities of local anesthesia during dental hygiene (2023)

ByDemetra D. Logothetis, RDH, EM emargaret j fehrenbach, RDH, MS

There are always options in providing dental hygiene care, including administering local anesthesia. But experienced dental hygiene professionals look for evidence-based results to deliver successful care to their patients.

Lately, questions have been circulating about some of the options for administering local anesthesia that should be considered in this bright light. This open-ended article strives to shed some light on these concerns by taking a close look at the latest evidence on local anesthesia and its administration.

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I have noticed lately that there is a discussion about using the manufacturers maximum doses with some agents, rather than the traditional lower ones that I tend to use and that are published in most textbooks. How does this affect my dental hygiene practice?

Each medication has a maximum recommended dose (MRD), including local anesthetics and vasoconstrictors, which is determined by the manufacturer based on the results of animal and human studies, with review and approval by the United States Food and Drug Administration (FDA) . The maximum doses determined by the manufacturer have been reviewed by the American Dental Association Council on Dental Therapeutics and the United States Pharmacopeial Convention (USP).

Maximum doses of many local anesthetics have been modified by experts in the field and represent the most conservative of those recommended by the Board, USP, or drug manufacturer. These conservative dosages have been published in most textbooks and traditionally taught in many dental hygiene programs across the country.1,2The MRD for a local anesthetic or vasoconstrictor is defined as the largest amount of an anesthetic that can be safely administered to a patient without complications while maintaining efficacy.

Recently, discussions suggest eliminating the conservative dosing recommended by experts in the field and using only the highest FDA-approved dosing guidelines. This has caused some confusion among dental hygiene educators as well as dental hygiene professionals. Currently, questions are being discussed about why this change is being made and how it affects the practice of dental hygiene.

These dosage levels should be considered by the dental hygienist prior to administering local anesthesia. For the past 30 years, specialists in the field of dentistry have offered lower, more conservative doses that have been used successfully by dentists.1Each practitioner must determine which recommendation to follow: the FDA guidelines or the more conservative guidelines that have traditionally been used.

There is an added benefit to using conservative guidelines as it provides additional patient safety while maintaining patient comfort. Fortunately, maximum doses are unlikely to be achieved for most dental hygiene procedures. If the dental hygiene care plan involves non-surgical periodontal therapy (NSPT) for one quadrant, administration of one or two cartridges is usually sufficient. It is rarely necessary to administer more than four cartridges during any visit involving dental hygiene care.3

Before proceeding with pain management, the dental hygienist must decide which dosage is the appropriate specific level based on the treatment to be administered as well as the patient's state of health. Therefore, MRDs should be adjusted to consider the patient's overall health and any mitigating medical factors that may impair the patient's recovery.1-3These amounts are determined based on the maximum dose for each visit.

The dose calculation is based on the patient's weight and can be calculated in milligrams per pound (mg/lb) or milligrams per kilogram (mg/kg). However, to increase patient safety when administering local anesthetics and vasoconstrictors, the dental hygienist should always administer the lowest clinically effective dose.

Figure 1: Needle insertion during a posterosuperior alveolar block. If the needle is inserted too far, it can penetrate the pterygoid plexus of the veins and the maxillary artery, which can lead to the complication of hematoma. Varying the depth of the needle into the tissue to avoid this complication is an option for the dental hygienist.9

I'm a dental hygienist student. How do all these different local anesthetic dosing guidelines affect my exams?

As a student of dental hygiene, it is important to thoroughly review the candidate guide before taking any written or clinical exams. The Candidate Guide will inform you of the information you will need to successfully pass the exam.

In the past, most board exams have tested students with more traditional and conservative doses. Some board review agencies have recently changed their dosage guidelines to reflect FDA guidelines rather than conservative guidelines, while other agencies have not.

Therefore, students may need to learn both sets of dosing guidelines and use the appropriate guidelines for the exam they will be taking. If you are unsure which standards will be tested on an exam, contact the testing agency for clarification.

Is there any real benefit to using anesthetic tampons in my dental hygiene practice?

Dental hygienists have the unique responsibility and opportunity to alleviate pain. Fear prevents many patients from getting dental care, whether it's fear of dental treatment, local anesthesia, or past dental experiences. Local anesthetics sting and burn when injected, which can negatively affect fearful patients.

Numbing anesthetic is an option to help relieve stinging and burning after the injection. In the past, the benefits of numbing have been well documented in medicine.4-6 Recently, numbing has been provided as an option for use in dentistry through the use of a mixing pen and chair cartridge connectors to provide a way to automated way to adjust the pH of an anesthetic cartridge just prior to injection.

Remember that local anesthetics used in dentistry are weak bases and combine with an acid to form a salt (hydrochloride salt) to make them soluble in water, creating a stable injectable anesthetic solution. The addition of this hydrochloric acid creates undesirable qualities such as stinging and burning after injection, relatively slow onset of action, and unreliable or non-existent anesthesia when injected into infected tissue.2

Buffering of local anesthetics was introduced into dentistry to counteract these undesirable qualities. Anesthetic tamponade provides the practitioner with a way to neutralize the anesthetic immediately prior to injection in vitro (outside the body), rather than the in vivo tamponade process, which relies on the patient's physiology to buffer the anesthetic. The tamponade process uses a sodium bicarbonate solution that is mixed with a local anesthetic cartridge, such as lidocaine with epinephrine. The interaction between sodium bicarbonate (NaHCO3) and hydrochloric acid (HCL) in the local anesthetic creates water (H2O) and carbon dioxide (CO2), bringing the pH of the anesthetic solution closer to physiological.2

Figure 2: Example of a non-surgical periodontal therapy care plan with anesthesia for treating two quadrants in one visit. (From Logothetis. Local anesthesia for the dental hygienist, Elsevier, 2012)

Bringing the anesthetic pH to physiological before injection can improve patient comfort by eliminating stinging, can reduce tissue damage, can reduce anesthetic latency, and can provide more effective anesthesia in the area of ​​infection. Therefore, dental hygienists can increase patient comfort by buffering local anesthetics prior to injection.7,8

How can I be less nervous giving a posterior superior alveolar block to my patients? I don't want to hurt them so I'm using infiltration.

Posterosuperior alveolar block (PSA) is used to achieve pulpal anesthesia in maxillary third, second, and first molars. The target area is the posterosuperior alveolar nerve as it enters the maxilla through the posterosuperior alveolar foramina on the infratemporal surface of the maxilla, which is at the level of the mucobuccal crease at the apex of the maxillary second molar (see Figure 1).9

Obviously, for a patient with a blood clotting disorder, local anesthetic injection techniques that carry a higher risk of positive aspiration, such as PSA blockade, should "be avoided in favor of injections into the periodontal and supraperiosteal ligament, or other techniques that do not pose a threat of excessive bleeding.2But if the patient has no underlying medical risk of bleeding, the clinician has the option of varying the depth of the needle in this area for this block to avoid complications such as a "non-anesthetizing" hematoma in the infratemporal fossa, an extraoral hematoma blue lesion - hemorrhagic swelling reddened with blood in tissue on the affected side of the face in the infratemporal fossa that develops within minutes of injection, progressing with time inferiorly and anteriorly towards the lower anterior region of the cheek.

This complication can occur if the needle is advanced too distally into the tissue during a PSA block, so that the needle enters the pterygoid plexus of the maxillary veins and arteries.9This is a basic risk of local anesthesia; however, care must be taken to avoid this situation.

The current educational method taught in most professional dental programs, and tested by students on exams, is to use a needle penetration depth of 16 mm or less, which is three-quarters the depth of a short 25-gauge needle.1,2In addition, doctors recommend performing "aspiration several times in different planes before administration to reduce the risk of re-aspiration if there is any movement of the needle within the tissue".2

However, a more conservative insertion technique can be considered, which clinicians are using with proven success to reduce the risk of bruising. This means going shallower into the mucobuccal fold by 5-10 mm, which is only a quarter of the depth of the short needle.2Studies are expected to be completed soon to show that this conservative method of administration is successful in placing the agent close to the posterior superior alveolar foramen. Remember, using a block instead of an injection allows for more effective treatment and less discomfort for the patient.

Can I safely numb my entire mouth to completely remove the stone in one visit?

First, it is important to note that gross desquamation where the large supragingival calculus is removed at the initial visit is no longer recommended. Instead, two types of periodontal therapy can be considered for patient care during phase 1 of periodontal therapy (non-surgical phase). Complete oral debridement is a newer procedure in which the calculus is removed in a single visit or, more commonly now, in two visits within a 24-hour period, sometimes with the aggressive use of antimicrobial agents for removal. 🇧🇷10

The most traditional approach is non-surgical periodontal therapy (NSPT). Studies have shown that "modest differences in clinical parameters when comparing healing after one session or multiple sessions were not clinically significant".11Furthermore, microbial parameters were not significantly different after eight months, regardless of treatment.12

Until evidence indicates otherwise, the clinician should determine the sequence and duration of periodontal therapy visits based on the amount of disease present and the patient's systemic health and comfort, not the patient's preference or insurance needs. However, staged therapy allows "the advantage of evaluating and reinforcing oral hygiene care", which is critical to the effectiveness of Phase 1..3

Figure 3: The target area of ​​the anterior mid-upper alveolar block is located at the apices of the upper premolars on the hard palate, midway between the midpalatal raphe and the lingual gingival margin. Possible distribution (purple) is highlighted, but only a variable level of depth and duration that does not meet all of the dental hygienist's needs for periodontal therapy. (From Fehrenbach, Herring. Illustrated Anatomy of the Head and Neck, 4th ed., Saunders, 2012)

Therefore, whether performing FMD or NSPT, the dental hygienist must carefully determine "the degree of periodontal involvement and how much of the treatment can realistically be performed in one visit".2The use of local anesthesia is based on many factors (not listed in importance) such as limited access and pocket topography, tissue tone, root anatomy, bleeding risk, as well as the patient's pain threshold and sensitivity.3Even when ultrasound is used, local anesthesia must be administered prior to use at high power to ensure patient comfort.13

For dental hygienists who are prohibited by state law from administering local anesthesia and who might be tempted to start scraping heavy calculus with fine tips at low power to increase patient comfort, experts have noticed a burning of heavy calculus on smooth veneers , visible only with a toothbrush . endoscope or during open flap surgery, but still able to serve as an "ideal biofilm ground". 14 Therefore, local anesthesia should only be administered in treatment areas that can be completed in one visit. Avoid overestimating the treatment and administering more anesthesia than necessary.2

Most importantly, any successful periodontal debridement performance, whether FMD or NSPT, requires complete removal of any clinically detectable calculus. Calculus removal is critical to the success of periodontal therapy because calculus retains dental biofilm. Furthermore, there will likely never be a simple standard for assessing clinical outcome because the patient's systemic health, immune response, and self-care practices influence healing. Good professional judgment should be exercised "in determining the endpoints of periodontal therapy. Therefore, intentionally leaving detectable calculus constitutes unethical or substandard care."3

However, the dental hygienist should avoid administering local anesthetics to both the right and left mandibular quadrants during the same treatment to prevent the patient's inability to control his jaw; therefore, the use of quadrant or half-assed procedures is generally recommended (see Figure 2). Doctors report that patients have difficulty swallowing and replacing any removable dentures or eating too soon afterward can cause gagging. In addition, when designing the dental hygiene care plan, the dental hygienist should consider the amount of anesthetic needed to complete the procedure so that it always stays within the patient's MRD (see previous question on dosing).15Furthermore, the administration of bilateral inferior alveolar nerve blocks also increases the possibility of the patient self-mutilating their soft tissues.9

There is some discussion about the use of AMSA in patients for periodontal therapy. Should I consider this?

The anterior superior alveolar (AMSA) block can be used for anesthesia of the periodontium and gingival tissue covering a large area that is normally innervated by the anterior superior alveolar (ASA), medial superior alveolar (MSA), greater palatine (GP), and nasopalatine (NP) in the upper arch (see Figure 3). Thus, with a single-site palatal injection, multiple teeth (from the maxillary second premolar to the maxillary central incisor) and the associated periodontium can be anesthetized without causing the usual collateral anesthesia to the soft tissues of the patient's upper lip and face. This is why it is commonly used in performing cosmetic dentistry procedures, because once the procedures are completed, the doctor can immediately and accurately assess the patient's smile line.

It is also important to remember that posterosuperior alveolar block (PSA) must still be administered to allow for pulpal anesthesia in the upper third, second, and first molars.2

The physician will need to use a computer-controlled delivery device with this block for four or more minutes with a short needle to allow a sufficient volume of agent to be delivered to all the necessary branches involved in anesthesia in this tight tissue area. This diffusion will take about the same amount of time. This was the standard method used in the original block research because the device regulates the relationship between pressure and volume of solution delivered, which is not easily achieved with a manual syringe.16,17In fact, most previous studies related to this block have been done with these devices since the block was discovered while the device was being developed.

Therefore, it is not true that only a minimal volume of local anesthetic is needed to provide pulpal anesthesia from the maxillary central incisor to the maxillary second premolar on the injection side, but rather that "a sufficient volume of local anesthetic "must be deposited". which) allows it to diffuse through nutrient channels and porous cortical bone in the palate..."1 Furthermore, any discussion relating to what some have invoked as a "subneural" dental plexus deep to the main nerve branches of the maxilla that supposedly responding to anesthesia is not actually present according to master anatomists.9Rather, the main branches of the maxillary nerve act together as the dental plexus and respond as such to anesthesia in the area.

Experienced clinicians already know how difficult it is to administer even the smallest amounts of agent needed during GP and PN blocks using a manual syringe. Still, some clinicians feel that they can use a hand syringe with AMSA, but that would mean re-injecting the agent multiple times and possibly cause excessive tissue whitening, leading to postoperative tissue ischemia and scaling. A recent study using a manual syringe demonstrates the difficulty of delivering sufficient volume.18 The additional cost of this anesthesia delivery system is a potential disadvantage of the AMSA block.

However, even after a sufficiently large amount of agent is delivered using the computer-controlled delivery device, studies show that, due to the extensive anatomy involved, the blockade can vary in depth and duration of anesthesia, which may compromise its use for non-surgical purposes periodontal therapy. 🇧🇷 NSPT usually requires full depth (quadrant pulp) and long-term anesthesia (greater than 60 minutes) to complete the treatment.18,19

Some previous articles in this block are overly optimistic about delivery time (as low as 2 minutes) and diffusion (as low as 2 minutes) as well as duration (up to 90 minutes), which is not helpful for the practicing physician. Attempts to speed up the AMSA block may increase patient discomfort at the injection site.20

Again, recent studies have shown that "the duration of pulpal anesthesia gradually decreased over the 60 minutes; we cannot confirm the authors' clinical impression that the duration of pulpal anesthesia is 60 minutes".18

It is important to note that the initial study using this injection with the computer-controlled root scaling and planing delivery device was small (20 subjects, split-mouth design) and was based on subjective patient responses regarding the depth of anesthesia using " visual analog". scales and verbal classifications".21One such study using an electric pulp tester showed only "66% anesthetic success on the second premolar, 40% on the first premolar, 0% on the canine, 23.3% on the lateral incisor, and 16.7% on the incisor central". Another similar study of the computer-controlled delivery device reported that successful pulpal anesthesia ranged "from 35% to 58%, and for the hand syringe, the rates were even lower, from 20% to 42%."18,19It's hard to defend the AMSA block with these low numbers.

Figure 5: Horizontal approach at 8 or 9 o'clock, right side by a clinician qualified for incisor locking. (From Fehrenbach and Logothetis. Mandibular Nerve Anesthesia. Logothetis. Local Anesthesia for the Dental Hygienist, Elsevier, 2012)

Other studies observed cases of short-term anesthesia in the maxillary central incisor region.20,22Therefore, the nature of the palate does not always allow for palatal-to-facial penetration to provide pulpal anesthesia, especially for the distal maxillary central incisor. Possibly, additional facial infiltration can be performed to ensure complete quadrant coverage, or even reinjection with another AMSA block when anesthesia is inadequate, but this reduces the positive impact of fewer injections that AMSA promises.

Furthermore, these earlier articles failed to mention the less than stellar hemostatic control of general quadrant gingival tissue, as confirmed by subsequent studies. These studies demonstrated only hemostatic control with palatal tissue, making it an excellent block for graft removal, and with no vasoconstrictors affecting the facial gingiva, excellent blood supply for nutrition is maintained after graft placement. connective tissue graft.18,20

Instead, relying on traditional maxillary arch blocks may allow the dental hygienist to plan treatment instrumentation in quadrants or sextants with more confidence in pain control and hemostasis.2

I heard about a new technique for applying incisor locking to my patients. How it works?

Blocking the incisors anesthetizes the pulp and periodontium of the lower teeth anterior to the mental foramen, generally the lower premolars and anterior teeth, as well as the facial gingiva. One indication for the use of this block is for NSPT in the mandibular anterior sextant.

However, locking the incisors does not provide lingual anesthesia of the soft tissues of the anesthetized teeth; An additional supraperiosteal injection may be indicated for localized lingual soft tissue anesthesia and/or hemostatic control. As bilateral mandibular alveolar (IA) blocks are generally not recommended and AI blocks may even fail, the bilateral use of the lingual supraperiosteal injection of the incisor block is an easy replacement in many situations (see discussion above).2

The target area for the incisor block is anterior to where the mental nerve enters the mental foramen to merge with the incisive nerve to form the inferior alveolar nerve (see Figure 4).9 There are many ways to approach this target area, but one way This is the new way to use a horizontal approach.

The above injection protocol recommends that the clinician sit behind the patient and use a vertical focus with the syringe on the target tissue. Visibility was “poor for the clinician to see the target tissue as well as the large syringe window to verify the negative aspiration. More importantly, the patient was often alarmed to see the syringe with the needle between the eyes.24

With the new recommended horizontal approach, the clinician sits closer to the patient's side, providing better visibility and obstructing the patient's line of sight to the advancing syringe and needle (see Figure 5). In this position, the tip of the needle with its bevel facing the bone can glide smoothly through the periosteum and there is no possibility of injury from scraping the periosteum or perforating the lower lip. The injection is "relatively painless and the landmarks are reliable and consistent."9

Prior to administration, retract the patient's lower lip outward with gauze to tighten the tissue. The injection site itself is anterior to the depression created by the mental foramen in the depth of the mucobuccal crease that was found prior to palpation. Using a short 27 gauge needle, direct the barrel of the syringe from the front of the mouth to the back horizontally while resting on the lower lip.
This will keep the syringe and needle out of the patient's sight. The needle is advanced without making contact with the bony surface of the mandible, with a penetration depth of 5 to 6 mm. The injection is administered slowly after a two-plane negative aspiration.23

Placing the patient in an upright or semi-upright position while the anesthetic agent is massaged has been shown to promote greater diffusion of the solution in the region by gravity.2

Therefore, when considering your next periodontal maintenance case or mandibular anterior sextant patient, or when faced with the failure of the IA lock to fully anesthetize the lower anterior teeth, try using the incisor lock using the horizontal approach.

As we review these questions about options in administering local anesthetics during dental hygiene care and apply evidence-based responses, the background noise around these concerns lessens. Experienced dental hygiene professionals can now see how to achieve successful outcomes for their patients when administering local anesthesia.

Demetra Daskalos Logothetis, RDH, MS, is professor emeritus and program director in the Department of Dental Medicine at the University of New Mexico, and currently visiting professor and director of the graduate program in the university's Division of Dental Hygiene. Demetra has been a professor at the University of New Mexico for 28 years and served as director of the dental hygiene program for 16 years. She has been teaching local anesthesia for 19 years and is the author of "Local Anesthesia for the Dental Hygienist" (Elsevier, 2012), which received an Honorable Mention at the 2013 PROSE Awards. This book deals exclusively with local anesthesia for dental hygiene practice.

margaret j fehrenbach, RDH, MS, is an oral biologist and educational consultant in dental hygiene. Margaret was recently awarded the ADHA AC Phones Award (2013) for her work promoting local anesthesia for dental hygienists, as "Local Anesthesia for the Dental Hygienist" (Elsevier, 2012), as well as the ADHA Award of Excellence (2009) for their contributions to textbooks. She is the lead author of "Illustrated Anatomy of the Head and Neck" (Elsevier, ed. 4, 2012) and "Illustrated Dental Embryology, Histology, and Anatomy" (Elsevier, ed. 4, 2015), as well as a contributor to " Pathology for Dental Hygienists" (Elsevier, ed. 6, 2104) and editor of the "Dental Anatomy Coloring Book" (Elsevier, ed. 2, 2013). Margaret has appeared in the ADEA, ADHA and ADA Annual Sessions, as well as Under One Roof for RDH Magazine. He now participates in webinars and radio broadcasts, as well as on social media. She can be contacted through her website at www.dhed.net.


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12. Rethman J. Is complete mouth disinfection appropriate for your practice? Dimensions of Dental Hygiene. November 2008.
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14. Pattison A. Manage your patients' pain. Dimensions of Dental Hygiene. April 2011.
15. Fehrenbach M. Pain management for dental hygienists: current concepts in local anesthesia are reviewed. HDR, February 2005.
16. Bath-Balogh, Fehrenbach. Illustrated dental embryology, histology and anatomy. 3rd edition, Saunders, 2011.
17. Loomer, Perry. Computer-controlled versus syringing of local anesthetic injections for therapeutic scaling and root planing. Journal of the American Dental Association. 135(3):358-65, 2004.
18. Velasco, Reinaldo. Anterior and middle superior alveolar nerve block for anesthesia of upper teeth with conventional syringe. Journal of Dental Research. 9(5): 535–540, 2012.
19. Lee et al. Anesthetic efficacy of anterior superior-middle alveolar injection (AMSA). Anesthesia progress. 51(3):80-9, 2004.
20. Alam, and others. AMSA (Middle Superior Alveolar Anterior) injection: an advantage for maxillary periodontal surgery. Journal of Clinical and Diagnostic Research. 5:675-678, 2011.
21. Perry, Loomer. Maximizing pain control: AMSA injection can provide anesthesia with fewer injections and less pain. Dimensions of Dental Hygiene. 1:28-33, 2003.
22. Corbett et al. A comparison between anterior median superior alveolar nerve block and infraorbital nerve block for anesthesia of maxillary anterior teeth. Journal of the American Dental Association. 141(12):1442-8, 2010.
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