Local Anesthesia in Dental Hygiene Practice

An Introduction

Christine N. Nathe, RDH, MS

Learning Objectives

1. Describe the history of pain control in health care and specifically to the practice of dental hygiene.

2. Describe how anesthesia is practiced by dental hygienists.

3. List state requirements for local anesthesia provided by dental hygienists.

4. Discuss patients’ perception of anesthesia and pain control.

5. Describe the human needs paradigm as it relates to pain control.

See comment in PubMed Commons below www.ncbi.nlm.nih.gov/pubmed/21396265#comments

Introduction

Pain is an unpleasant sensory and emotional experience and can be thought of as one of the oldest of all dental problems. In fact, the control of pain during routine dental procedures is an important part of dental care delivery. Pain relievers are routinely referred to as analgesics. Specifically, the use of topical and local anesthetics provided by the dental hygienist is necessary for many dental hygiene appointments. Local anesthesia creates a numbing feeling that eliminates the feeling of sensation in a specific area without loss of consciousness. Although pain is seemingly associated with dental care, dental providers have the ability to control and alleviate pain during and after procedures. This chapter details the history of pain control and anesthetics in general, introduces the concept of anesthesia in dental hygiene practice, and discusses pain control in practice.

History of Pain Control

Pain control is the mechanism that alleviates pain. Although some methods of pain control have probably always existed, historical evidence suggests that modern anesthetics can be traced to medieval times.¹ Early methods of pain reduction included religious techniques of scaring off demons and praying for the touch of God to stop the suffering.² Early on, plants and herbs, including roots, berries, and seeds, became the prominent method for treating pain.² Interestingly, many drugs are still derived from plant-based substances.

The use of narcotics to reduce pain was a universally accepted practice and involved the use of cannabis, opium, and alcohol³ (Box 1-1). However, the drugs used were not completely effective at altering pain, caused side effects, and were addictive. Opium was most useful for pain control. In fact, opium proved even more effective when converted into a more potent form, morphine, and injected into the bloodstream.⁴

Interestingly, chemists also prepared acetylated salicylic acid, a plant compound used in headache powder, which often left the patient with severe gastric distress. A new compound containing salicylic acid introduced as aspirin in 1899, was highly effective as an analgesic and antipyretic, and proved to be remarkably safe and well tolerated by patients.² However, for severe pain, more pain reducers and controllers were still in need.

The chemical that finally proved to be an effective surgical anesthetic was ether.³ Several individuals were involved in the development of the concept of gas inhalation for anesthesia. In 1842, it was reported that William Clarke administered ether, via a towel, to a woman as one of her teeth was extracted by a dentist.⁴ Horace Wells, a dentist, first tried nitrous oxide for dental pain control after attending several “laughing gas” parties. He practiced on himself by using nitrous oxide, which he considered safer than ether, and had a fellow dentist extract his tooth. He felt nothing during the extraction and discovered nitrous oxide to be an effective anesthetic. Halothane, a safe and stable chemical for inhalation anesthesia, was introduced in 1956. Short-acting anesthetics have also been introduced and are generally administered intravenously.⁵

During the 1800s, in both Europe and the United States, there was an extended debate over the ethics of operating on an unconscious patient and whether or not the relief from pain might actually retard the health process. Furthermore, some found religious offense in the new practice. Evidently, some physicians felt that it violated God’s law, whom they believed inflicted pain to strengthen faith.² Physicians used a calculus (measurement benchmark) to determine which patients were of the correct sensibility (exhibiting overall health) and who needed to benefit from the use of anesthesia.^2,6,7

During World War II, Dr. Henry Beecher observed that seriously wounded soldiers reported much lower levels of pain than his civilian patients. Based on his inference that clinical pain was a compound of the physical sensation and a cognitive and emotional reaction component he challenged laboratory studies in healthy volunteers and argued that pain could only be legitimately studied in a clinical situation. These observations formed the basis for real clinical research trials on pain control.^2,8-11 Eventually, in 1956, the gate control theory was published. The classic articles proposed a spinal cord mechanism that related the transmission of pain sensations between the peripheral nervous system and the brain.¹²

History of Local Anesthetics

The first local anesthetic, cocaine, was isolated from coca leaves by Albert Niemann and Francesco Di Stefano in Germany in the 1860s.¹³ Cocaine was first used as a local anesthetic in 1884 by Karl Koller, who demonstrated the use during painless ophthalmological surgery.^14,15 Although effective as an anesthetic, it was addictive, and many of those pioneer researchers who first studied cocaine’s effects on themselves became addicted.³

In 1905, the ester procaine (Novocaine) was created in Germany and, when mixed with a proportion of epinephrine, was found to be effective and safe¹ (Box 1-2). Procaine took a long time to produce the desired anesthetic result, wore off quickly, and was not as potent as cocaine. Additionally, many patients were allergic to procaine because procaine is an ester that has a high potential for allergic reactions.

In the 1940s, a new group of local anesthetic compounds, the amides, were introduced. The initial amide local anesthetic, lidocaine, was synthesized by the Swedish chemist Nils Lofgren in 1943. Lidocaine revolutionized pain control in dentistry worldwide, because it was both more potent and less allergenic than procaine. In the succeeding years, other amide local anesthetics (prilocaine in 1959, bupivacaine and mepivacaine in 1957) were introduced. These new amide local anesthetics provided the dental practitioner with an array of local anesthetics for pulpal anesthesia that could last from 20 minutes (mepivacaine plain) to 3 hours (bupivacaine with epinephrine). In 1969, Rusching and colleagues prepared a new drug, carticaine, which differed from the previous amide local anesthetics. Renamed articaine in 1984, the drug was derived from thiophene and thus contained a thiophene ring in its molecule instead of the usual benzene ring. Articaine became available in 2000 for marketing in the United States in a 4% 1:100,000 epinephrine formulation. Today, lidocaine remains the most popular anesthetic used in dentistry in the United States; however, articaine is increasing in its popularity and is a close second to lidocaine. Many patients do not understand the distinction among the agents and still ask for Novocaine, which is no longer available in dentistry.

BOX 1-1 Drugs Used in the Past to Reduce Pain

BOX 1-2 History of Local Anesthetics

Articaine: 1969; available in United States in 2000

Anesthesia in Dental Hygiene Practice

Dental hygienists often treat patients with painful gingival and/or periodontal infections, which is why it is paramount for dental hygienists to be able to reduce and control pain while treating patients. Local anesthetics work by blocking the travel of the pain signal to the brain.¹⁶ In addition to pain control, local anesthetics can provide vasoconstriction if vasoconstricting drugs such as epinephrine or levonordefrin is added to the anesthetic. During the course of treatment, patients may have gingival inflammation and bleeding. Hemostasis is achieved via the vasoconstrictor in the anesthetic. By controlling the bleeding, proper visualization of the tissues and the working end of the instrument can be achieved.¹⁷

Many dental practices will hire a dental hygienist with certification in local anesthesia to provide local anesthesia for all dental and dental hygiene patients in the practice. Just as a nurse anesthetist or anesthesiologist focuses his or her nursing or medical specialization in the provision of anesthetics, many dental hygienists exclusively provide local anesthesia without providing any traditional dental hygiene services.

The delivery of local anesthetic and nitrous oxide has been added to the scope of dental hygiene practice over the past 40 years (Table 1-1 and Figure 1-1). Washington State added the provision of local anesthesia to state law in 1971, followed by New Mexico in 1972, and Missouri in 1973. Currently, 44 states allow dental hygienists to deliver local anesthetics. New York and South Carolina are states where dental hygienists may provide local infiltration but not block anesthesia.¹⁸

TABLE 1-1

Local Anesthesia Administration by Dental Hygienists State Chart

State & Year Implement	Supervision Required	Block and/or Infiltration	Education Required	Exam Required	Implement Language in Statute or Rules	Legal Requirements for Local Anesthesia Courses?
AK 1981	General	Both	Specific	Yes—WREB	Statute	16 didactic 6 clinical 8 lab
AZ 1976	General	Both	Accredited	Yes—WREB	Statute	36 hours, 9 types of injections
AR 1995	Direct	Both	Approved and accredited	No	Statute	16 didactic 12 clinical
CA 1976	Direct	Both	Course taken as part of a dental hygiene program or course approved by the Dental Hygiene Committee of California	No	Rules	16 didactic 3 clinical 8 types of injections listed
CO 1977	General	Both	Accredited	No	Statute	12 didactic 12 clinical
CT 2005	Direct	Both	Accredited	No	Statute	20 didactic 8 clinical
DC 2004	Direct	Both	Board approved	No	Rules	20 didactic 12 clinical
FL 2012	Direct	Both	Accredited or board approved course	No	Statute	30 didactic 30 clinical
HI 1987	Direct	Both	Accredited	Yes—Exam given by course	Statute	39 didactic and clinical 50 injections
ID 1975	General	Both	Accredited	Yes—Board approved	Statute	No
IA 1998	Direct	Both	Accredited	No	Rules	Must be conducted by an accredited RDH or DDS school
IL 2000	Direct	Both	Accredited	No	Statute	24 didactic 8 clinical
IN 2010	Direct	Both	Accredited	Yes—CDCA local anesthesia exam or equivalent state or regional exam	Rules	15 didactic 14 clinical Permit required
KS 1993	Direct	Both	Accredited and board approved	No	Statute	12 hours total
KY 2002	Direct	Both	Accredited and board approved	Yes—Written exam given by course	Statute	32 hours didactic 12 hours clinical
LA 1998	Direct	Both	Accredited	Yes—Board approved	Rules	72 total hours; minimum of 20 injections
MA 2004	Direct	Both	Accredited	Yes—CDCA written exam by CDCA	Statute	35 total hours; no less than 12 hours clinical
MD 2009	Direct	Both	Accredited/board approved	Yes—CDCA	Rules	20 didactic 8 clinical
ME 1997	Direct	Both	Accredited	Yes—CDCA administered	Rules	40 hours total; minimum of 50 injections
MN 1995	General	Both	Accredited	No	Rules	No
MO 1973	Direct	Both	Accredited/board approved	No	Rules	No
MI 2002	Direct	Both	Accredited	Yes—State or regional board-administered written exam (CDCA)	Statute	15 didactic 14 clinical
MT 1985	Direct	Both		Yes—WREB	Statute	No
Table Continued

State & Year Implement	Supervision Required	Block and/or Infiltration	Education Required	Exam Required	Implement Language in Statute or Rules	Legal Requirements for Local Anesthesia Courses?
ND 2003	Direct	Both	Accredited	No	Rules	Course must include clinical and didactic components, but there are no specific hourly requirements.
NE 1995	Direct	Both	Approved	No	Statute	12 didactic 10 types of injections listed 12 clinical
NH 2002	Direct	Both	Accredited	Yes—CDCA local anesthesia exam	Statute	20 didactic 12 clinical
NJ 2008	Direct	Both	Accredited/board approved	Yes—CDCA local anesthesia	Rules	20 didactic 12 clinical Including a minimum of 20 hours monitored administration of local anesthesia
NM 1972	Direct/general	Both	Accredited and approved	Yes—WREB	Statute	24 didactic 10 clinical
NV 1982	Direct/general	Both	Accredited and approved	No	Rules	No
NY 2001	Direct	Infiltration	Accredited	No	Statute	30 didactic 15 clinical and lab
OH 2006	Direct	Both	Accredited	Yes—Written regional or state exam	Statute	15 didactic 14 clinical
OK 1980	Direct	Both	Approved	No—Exam given by course	Rules	20½ hours
OR 1975	Direct/general	Both	Accredited or approved	No	Rules	No
PA 2009	Direct	Both	Accredited/approved	No	Rules	30 hours didactic and clinical Permit, must renew
RI 2005	Direct	Both	Accredited	Yes—WREB	Statute	20 didactic 12 clinical
SC 1995	Direct	Infiltration	Approved	Yes—Board	Statute	No
SD 1992	Direct	Both	Accredited/approved	No	Statute	No
TN 2004	Direct	Both	Accredited/approved	No	Rules	24 didactic 8 clinical
UT 1983	Direct	Both	Accredited	Yes—WREB	Statute	No
VA 2006	Direct	Both (only on patients older than age 18)	Accredited	Yes—Accredited program Board of another jurisdiction accepted	Statute	36 didactic-clinical
VT 1993	Direct	Both	Accredited	Yes—Board administered	Statute	24 hours total
WA 1971	Direct	Both	Approved	Yes—WREB	Statute	10 listed injections
WI 1998	Direct	Both	Accredited	No	Statute	10 didactic 11 clinical
WV 2003	Direct	Both	Board approved	CDCA local anesthesia exam or equivalent state or regional exam	Statute	12 didactic 15 clinical
WY 1991	Direct	Both	Approved	Yes	Rules	No

From www.adha.org/resources-docs/7514_Local_Anesthesia_Requirements_by_State.pdf

TABLE 1-2

Synopsis of Local Anesthesia Administration Safety and Efficacy Studies With Dental Hygienists

Category	Subject	Findings
Anderson Safety	Aspiration safety protocol	86% of responding hygienists reported the use of consistent aspiration before injection; 7% reported the use of aspiration most of the time, and 3% reported infrequently aspirating before injection
Anderson Safety	Complication rates	87.8% of dental hygienists signified no complications when administering local anesthesia injections
Anderson Efficacy	Self-reporting of success	76% of surveyed dental hygienists reported successful anesthetization 90%–100% of the time, and 16% reported success 75%–89% of the time
Cross-Poline et al Efficacy	Employer/dentist observer ratings	Dentists (n = 57) identified a benefit to both their practices and their patients as a result of the administration of local anesthesia by their dental hygiene employees; the mean percentage of agreement with this statement was reported at 80.4%
DeAngelis and Goral Efficacy	Employer/dentist observer ratings	92% of dentist employers were satisfied with their dental hygienists’ ability in administering local anesthesia injections
Lobene Safety	Complication rates	Out of 19,849 anesthetizations by dental hygienists, only three cases of temporary paresthesia were identified
Lobene Efficacy	Success rates	Out of 19,849 injections performed by dental hygienists, a success rate of 96.7% with supraperiosteals and an 85.7% success rate with nerve block techniques were found with dental hygienists
Rich and Smorang Safety/efficacy	Continued delegation of anesthesia administration to hygienists	100% of periodontists and 86% of general dentists delegated the administration of local anesthesia to dental hygienists based on this survey of California dental hygiene graduates
Scofield et al Safety	Disciplinary reports	No formal complaints associated with local anesthesia administration against dental hygienists were known to state dental boards or American Dental Hygienists’ Association constituent presidents based on surveys reported in 1990 and again in 2005
Sisty-LePeau et al Efficacy	Adequacy of anesthesia with dental hygiene students	Through evaluations completed by restorative dentistry and periodontics faculty, it was determined that out of 3926 injections administered by dental hygiene students, adequate anesthesia was achieved 95% of the time

From Boynes SG, Zovko J, Peskin RM: Local anesthesia administration by dental hygienists. Dent Clin North Am 54(4):769-778, 2010.

Proficiency is determined by coursework during the dental hygiene program or completion of appropriate training in an accredited continuing education setting. States vary in the amount of coursework, required minimal education, and necessity of examination before certification. Additionally, some states govern anesthetic practices by statutes, some by rules.¹⁷

Thirty-three states permit the administration of nitrous oxide by dental hygienists. The first state to enact this increase in the scope of practice for dental hygienists was Washington in 1971.¹⁹ Some states may allow dental hygienists to monitor nitrous oxide, but not actually administer the drug. This simply means that the dental hygienist may not turn on the nitrous oxide but may change settings during the dental hygiene appointment as needed. More states are permitting this pain control modality for dental hygienists, which increases the need for educational preparation of the dental hygienist in nitrous oxide fundamentals.

A recent study of dental hygienists mirrored past results, which revealed that the majority of dental hygienists reported a perceived need and use for pain control in practice.²⁰ Moreover, a review study confirmed patient and dentist satisfaction with dental hygienists providing local anesthesia. This review also reported on safety issues²¹ (Table 1-2). These research studies suggest acceptance and advancement in the practice of dental hygiene pain control modalities.

Patient Perception of Local Anesthesia

Patients often present to the dental office with pain. By definition, pain is the sensation of discomfort and can range from mild to severe. It is well recognized that patients react differently to painful stimuli, and the same patient may react differently to painful stimuli depending on a variety of environmental, social, emotional, or physical factors. The term pain threshold is often used when discussing pain. Pain threshold pertains to the point at which a sensation starts to be painful and discomfort results. This threshold varies among individuals and may be altered by some drugs such as local anesthesia. Pain perception is a neurologic experience of pain. Pain is perceived when painful stimuli are received and transmitted to the brain; pain perception differs little among individuals. Pain reaction is the personal interpretation and response to the pain message and is highly variable among individuals.²² Pain reaction threshold is the moment when pain crosses the threshold of tolerance and at which point a reaction may occur. It may be influenced by the patient’s emotional state, fatigue, age, culture, and fear and apprehension^22,23 (Table 1-3).

The fear of pain is not only associated with dental problems, but also with the administration of local anesthesia.²³ Many patients fear the dental provider because they are apprehensive about a “dental shot.” Dental hygienists must be cognizant of the common fear associated with local anesthesia and communicate sincerely and empathetically to patients about the provision of pain control.

TABLE 1-3

Influences of Pain Reaction Threshold

Influence	Clinical Relevance
Emotional state	Personal pain interpretation may vary within an individual based upon their emotional state at the time of dental treatment. Patients who are in a difficult emotional condition generally have a lower pain reaction threshold.
Fatigue and stress	Personal pain interpretation may vary within an individual based upon their level of fatigue and stress. Patients who are overly tired or stressed at the time of their appointment will generally have a lower pain reaction threshold.
Age	Older patients generally have higher pain reaction thresholds compared with younger patients, as they have accepted pain as part of life.
Cultural characteristics	Individuals from different cultures will react to pain differently as influenced by what is considered an appropriate reaction to convey within their culture.
Fear and apprehension	The more fear and apprehension the patient has regarding their dental appointment, the lower the pain reaction threshold. These are patients who frequently miss dental appointments.

From Human needs paradigm in relation to dental hygiene. From Darby ML, Walsh MM. Dental hygiene theory and practice, ed 4, St Louis, 2014, Saunders.

A tool used to help a person rate the intensity of certain sensations and feelings such as pain is the Visual Analog Scale (VAS). A VAS is a measurement instrument that attempts to measure pain believed to range across a continuum of values that cannot easily be directly measured. For example, the amount of pain that a patient feels ranges across a continuum from none to an extreme amount of pain. Operationally, a VAS is usually a horizontal line, 100 mm in length, anchored by word descriptors at each end as illustrated in Figure 1-2. The patient marks on the line the point that they feel represents their perception of their current state. The VAS score is determined by measuring in millimeters from the left hand end of the line to the point that the patient marks. Pain scales are subjective but nonetheless useful for clinicians. The VAS scale will be used in Chapters 12 and 13 to describe the average level of pain associated with maxillary and mandibular injections.

BOX 1-3 Eight Human Needs Related to Dental Hygiene Care

Protection from health risks

Freedom from fear and stress

Freedom from pain

Wholesome facial image

Skin and mucous membrane integrity of the head and neck

Biologically sound and functional dentition

Conceptualization and problem solving

Responsibility for oral health

From Darby ML, Walsh, MM: Dental hygiene theory and practice, ed 4, St Louis, 2014, Saunders.

Human-Needs Paradigm

Dental hygiene care promotes health and prevents oral disease over the human life span through the provision of educational, preventive, and therapeutic services.²⁴ The human-needs paradigm helps dental hygienists understand the relationship between human-need fulfillment and human behavior. A human-need is a tension within a person. This tension expresses itself in some goal-directed behavior that continues until the goal is reached.²⁵ The human-needs theory explains that need fulfillment dominates human activity and that behavior is organized in relation to unsatisfied needs (Figure 1-3). Dental pain can be an unsatisfied need, because pain can be such an overwhelming force. Treating the cause of and alleviating dental pain using local anesthesia can be a welcome asset for the dental hygienist.

Interestingly, Darby discusses eight human-needs related to dental hygiene that have many implications for pain control in dental hygiene²⁵ (Box 1-3). The human-needs theory emphasizes the use of a patient-centered approach and relates to pain control and prevention, which may include the provision of dental anesthesia.

Most of these needs relate directly to the need and use of local anesthesia for dental patients. Specifically, two of these needs relate to the provision of stress reduction principles and the use of local anesthesia. Freedom from fear and stress is the need to feel safe and to be free from emotional discomfort in the oral health care environment and to receive appreciation, attention, and respect from others. Freedom from pain is the need to be exempt from physical discomfort in the head and neck area. Once again, the use of local anesthesia by the dental hygienist can help attain these human needs.

Management of Fearful Patients

Fear prevents many patients from obtaining dental care, whether it is fear of dental treatment, local anesthesia, or past experiences. Studies have revealed that from 50% to 85% of patients who report dental anxiety had the onset of fear during their childhood or adolescence and the remainder became fearful of dental care during adulthood.²⁶ Patients who are anxious may have had unpleasant experiences in the past or may have a learned fear of dental care. Interestingly, the majority of studies confirmed a relationship between parental and child dental fear.²⁷ It is important to discuss this anxiousness with patients so that the dental hygienist can respond effectively to help alleviate fear.

Many patients do present to the dental provider when they are anxious and nervous. Although significant fear may be termed dental phobia, many patients are anxious about dental treatment, and all dental hygienists can expect to treat many anxious patients.²⁵ A patient with dental phobia may not be a regular (recall) dental patient, based on the extreme fearfulness toward dental care in general.

The effects of fear on the body can physiologically evoke the stress response. Stress is a physical and emotional response to a particular situation. The response to stress is often termed fight or flight and occurs automatically (see Chapter 4). Studies suggest that patients who are fearful of dental treatment may have elevated blood pressure, heart rate, and salivary cortisol levels immediately before dental checkups and treatment, although not all studies confirm this.^25,28 Dental hygienists must be cognizant of the important role patient fear plays in the provision of dental care.

Stress Reduction Principles

Prevention is the best method to manage an anxious patient. Basically, the dental hygienist should look for symptoms of stress immediately, so that stress reduction principles are enacted before stress levels elevate. Box 1-4 lists signs of moderate anxiety, including patients’ discussion with the receptionists or other patients in the waiting room about their fear, cold or sweaty palms, or unnaturally stiff posture. An astute practitioner looks for signs of anxiousness.

During the health and dental history review dental hygienists should determine whether or not the patient is anxious. Some patients will express their apprehension and stress immediately, directly to the provider, whereas other patients may need questioning or persistent listening by the provider to find out about anxiousness. Ensuring a complete health history review at each appointment is important to recognize stressors and health conditions that may complicate procedures. Even a patient who is feeling fatigued or “under the weather” may be more anxious and stressed during dental appointments. Obtaining the patient’s vital signs is also important to understand a patient’s total health history.

BOX 1-4 Clinical Signs of Moderate Anxiety

Reception Area

Questions receptionist regarding injections or use of sedation

Nervous conversations with others in reception area

History of emergency dental care only

History of canceled appointments for nonemergency treatment

Cold, sweaty palms

Dental Chair

Unnaturally stiff posture

Nervous play with tissue

White-knuckle syndrome

Perspiration on forehead and hands